ORGANOTIN(IV) COMPLEXES WITH OXYGEN DONOR LIGANDS: …prr.hec.gov.pk/jspui/bitstream/123456789/1753/1/1335S.pdf · 2018-07-23 · The bioassay results of the synthesized complexes

ORGANOTIN(IV) COMPLEXES WITH OXYGEN DONOR LIGANDS: SYNTHESIS,

CHARACTERIZATION AND BIOLOGICAL ACTIVITY

ISLAMABAD

A Thesis Submitted to the Department of Chemistry, Quaid-i-Azam University, Islamabad, in partial fulfillment of the

requirement for the degree of

Doctor of Philosophy

in

Inorganic/Analytical Chemistry

by

Farooq Ali Shah

Department of Chemistry Quaid-i-Azam University

Islamabad, Pakistan (2011)

DECLARATION This is to certify that this dissertation entitled “Organotin(IV) Complexes with

Oxygen Donor Ligands: Synthesis, Characterization and Biological Activity”

submitted by Mr. Farooq Ali Shah is accepted in its present form by the Department of

Chemistry, Quaid-i-Azam University, Islamabad, Pakistan, as satisfying the partial

requirement for the degree of Doctor of Philosophy in Inorganic/Analytical Chemistry.

External Examiner(1): ___________________________________

External Examiner(2): ___________________________________

Head of Section: ___________________________________Prof. Dr. Amin Badshah Department of Chemistry Quaid-i-Azam University

Islamabad

Supervisor and Chairman: ___________________________________Prof. Dr. Saqib Ali

Department of Chemistry Quaid-i-Azam University

Islamabad

IN THE NAME OF ALLAH THE COMPASSIONATE

THE MERCIFUL

Dedicated

to

All those who helped me when I was unable to survive

CONTENTS Acknowledgements i

Abstract iii

List of Tables v

List of Figures ix

Chapter -1 Introduction 1

1.1 Organotin(IV) compounds 1

1.2 Historic view of organotin(IV) compounds 1

1.3 Synthetic methods for organotin(IV) carboxylates 2

1.4 Properties of organotin(IV) compounds 4

1.5 Structural aspects of organotin(IV) carboxylates 5

1.6 Positive impact of organotin(IV) carboxylates on daily life 12

1.6.1 Biological applications 12

1.6.1.1 Pharmaceuticals 12

1.6.1.2 Antifouling agents: 13

1.6.1.3 Wood protection 13

1.6.1.4 Agrochemicals 13

1.6.1.5 Antiviral agents 13

1.6.1.6 Anthelmintics 14

1.6.2 Non-biological applications 14

1.6.2.1 As a PVC stabilizer 14

1.6.2.2 Catalytic activity 14

1.6.2.3 Glass coating 15

1.6.2.4 Water repellent agents 15

1.7 Some factors contributing to structure-activity relationships 15

1.7.1 Role of organic groups 16

1.7.2 Role of anionic ligands and geometry around tin 17

1.8 Organotin(IV) carboxylates delivery system 18

1.8.1 Surfactants 18

(i) Anionic surfactant 18

(ii) Cationic surfactant 18

(iii) Nonionic surfactant 18

1.8.1.1 Role of surfactant in drug delivery 19

1.8.1.2 Cell membrane structure 20

References 23

Chapter-2 Experimental 30

2.1 Materials 30

2.2 Instrumentation 30

2.3 General procedure for synthesis of carboxylic acids 31

2.3.1 General procedure for synthesis of schiff base 32

2.4 Synthesis of organotin(IV) complexes 36

2.4.1 From organotin(IV) chloride 36

2.4.2 From organotin(IV) oxide 36

2.5 Antifungal activity 53

2.6 Antibacterial activity 53

2.7 Antiviral study 54

2.8 Drug delivery system 54

References 56

Chapter-3 Results and Discussion 57

3.1 Synthesis of organotin(IV) complexes 57

3.2 FT-IR spectroscopy 57

3.3 NMR spectroscopy 65

3.3.1 1H NMR spectroscopy 65

3.3.2 13C NMR spectroscopy 76

3.3.3 119Sn NMR spectroscopy 77

3.4 Mass spectrometry 90

3.5 Biological activity 103

3.5.1 Antibacterial activity 103

3.5.2 Antifungal activity 108

3.6 Antiviral studies 113

3.7 Surfactant-organotin(IV) carboxylate interaction study 117

3.7.1 Conductometry 117

3.7.2 Electronic absorption spectra of the complexes 121

3.7.3 Fluorescence spectroscopy 139

3.8 Thermal studies 150

References 159

Chapter-4 Crystallographic Analysis 161

4.1 Crystal structures of free ligands (HL1, HL3, HL4, HL5, and

HL6)

161

4.2. X-ray crystal structure of triorganotin(IV) carboxylates 166

4.3 X-ray crystal structure of diorganotin(IV) dicarboxylates 176

References 182

Conclusions 183

Publications list 185

ACKNOWLEDGEMENTS

All praise of Almighty Allah, the most gracious, the most benevolent and kind, Who

blessed me with potential, determination and capability to complete my Ph. D work.

I wish to express fervent and vehement sense of thankfulness to my affectionate

supervisor, Prof. Dr. Saqib Ali, Department of Chemistry, Quaid-i-Azam University,

Islamabad, for his wholehearted, enthusiastic interest and dedicated supervision. His

inspiring guidance, invigorating encouragement, generous help, good manners and

friendly discussion, valuable suggestions, energizing encouragement enable me to

complete my Ph.D work.

I am highly indebted to pay my cordial gratitude to Dr. Sajjad Ahmad for his kind

guidance, mammoth help, and cooperation as a co-supervisor and acknowledge his

valuable discussions.

Many thanks to crystallographer, Prof. C. Rizzoli Department of Inorganic Chemistry,

University of Degli Studi di Parma, Italy, and Prof. Dr. Nawaz Tahir, Sargodha

University, Pakistan, for crystal analysis and fruitful collaboration.

I am grateful to Prof. Dr. B. Wrackmeyer and Dr. Ezzat Khan, University of

Bayreuth, Germany, for providing facilities to collect multinuclear NMR data, Prof. Dr.

S. Sakhawat Shah, Ex-chairman Department of Chemistry, Quaid-i-Azam University,

Islamabad for providing the facilities to conduct surfactant-organotin(IV) carboxylates

interaction studies, Dr. Kaneez Fatima, Faculty of NCVI, National University of

Science and Technology for antiviral studies, Dr. Safia Ahmad, Faculty of Biological

Sciences, Quaid-i-Azam University, Islamabad, and Dr. Sadia Andaleeb, Faculty of

NCVI, National University of Science and Technology, for arranging biological

screening of my compounds.

I am also grateful to Dr. Khalid M. Khan, HEJ, Research Institute of Chemistry,

Karachi, Pakistan, for mass spectrometric studies of the synthesized complexes.

A special word of thanks is due to Dr. Sadaf Ramzan and Mrs. Ramsha Raza,

NESCOM for non forgetful favors during analysis.

It is also my pleasure to thank Prof. Dr. Amin Badshah, Head, Inorganic/ Analytical

Chemistry section, Department of Chemistry, Quaid-i-Azam University, Islamabad, for

his enormous help and cooperation throughout my research work.

i

I would like to express my deepest appreciation to all lab. fellows whom in one way or

the other assisted me, mentioning them individually by name is rather impossible.

I am greatly honored to mention the nice cooperation of all employees of the

Department, especially Mr. Sharif Chohan, Mr. Shamas Pervaiz, Mr. Ali Zaman

and Muhammad Ilyas.

Last but not least, no words to express my heartfelt gratitude and admiration about my

family members, Their prayers enabled me to achieve this goal.

(Farooq Ali Shah)

ii

ABSTRACT Eleven series of tri- and diorganotin(IV) carboxylates were synthesized by using

stoichiometric amounts of various carboxylic acids with R2SnCl2, R2SnO, R3SnCl and

R3SnOH in dry toluene. The carboxylic acids having different functional groups were

used in order to study their effect on the biological assay and their role for the delivery of

these compounds.

Elemental analysis, FT-IR, multinuclear (1H, 13C and 119Sn) NMR, mass spectrometry

and X-ray single crystal analysis were used for the structural assignment of the

synthesized complexes, and for the determination the coordination mode of the ligands.

Based on results, the ligands appear to coordinate to the Sn atom through the COO

moiety. The results obtained from different analytical techniques ascertain the tetrahedral

environment around the tin atom in solution while penta coordination is found in the

solid state for triorganotin(IV) carboxylates. In diorganotin(IV) dicarboxylates, a skew

trapezoidal geometry was observed both in solid and solution form.

Single crystal analysis shows that bulky phenyl groups present in the complexes hinder

the carbonyl oxygen of the neighboring ligand from interacting with the Sn atom for

further coordination. The ORTEP diagrams for compounds 18, 26 and 33 show that the

triphenyltin(IV) species coordinate to only one ligand and exist in monomeric form.

Small sized groups do not show any hindrance to the carbonyl oxygen of the neighboring

ligands. Therefore, in complexes 19, 28, 31, 46, 56 and 67 a polymeric behavior is

observed. Diorganotin(IV) carboxylates mostly show a distorted octahedral geometry,

with four strong and two weaker bonds in the solid state which is also called as skew

trapezoidal geometry.

The interaction of four But3SnL compounds (where L= 3-[(2′-

flurophenylamido)]propanoic acid, 3-[(3′,5′-dimethylphenylamido)]propenoic acid, 3-

[(3′,4′-dichlorophenylamido)]propanoic acid, 3-[(3′,5′-dimethylphenylamido)]propanoic

acid) with cetyl N,N,N-trimethyl ammonium bromide (CTAB), a cationic surfactant, was

studied as a model of organotin(IV) carboxylate-cell membrane interaction using

conductometry, UV-Vis and steady state fluorescence spectroscopy.

All the four complexes and CTAB showed interaction in the pre and post micellar region

of CTAB. The higher partition constant value between the bulk water and the micelles

of CTAB, Kx and the negative values of the standard free energy change of partition ΔG

iii

designate the spontaneity of the complex - CTAB binding. The partition constant and the

free energy change of the partition values obtained from all three techniques showed the

following increasing order of binding strength: 21> 17> 32> 9. The complex containing

more electronegative atoms showed higher interaction which decreases the permeability.

Selected complexes were tested for their antiviral studies. Compounds 1, 5 and 18

showed high potential against HCV and reduced the viral load up to 80%, at low

concentrations. The tributyl compounds with more electronegative atoms showed lower

HCV potential.

All the synthesized complexes were screened for antibacterial and antifungal activities,

against various medically important bacteria and fungi. In general, the triorganotin(IV)

derivatives showed higher potential against bacteria and fungi than the diorganotin(IV)

derivatives.

The bioassay results of the synthesized complexes suggest that these compounds may be

used for chemotherapy in the treatment for HCV, bacterial infection and fungal action in

future.

Selected organotin(IV) complexes were subjected to thermal decomposition by means of

thermogravimetry analysis (TGA). Decomposition kinetics like order of reaction,

activation energy, enthalpy and entropy were calculated for each step of decomposition.

iv

List of table

Table Title Page 2.1: Physical data of synthesized carboxylic acids 33

2.2: Physical data of carboxylic acids 35

2.3: Physical data of synthesized organotin(IV) complexes 37

3.1: Assignments of characteristic FT-IR vibrations of 3-[(2′-flurophenyl amido)]propenoic acid and its organotin(IV) complexes

59

3.2: Assignments of characteristic FT-IR vibrations of 3-[(3′,5′-dimethylphenylamido)]propenoic acid and its organotin(IV) complexes

60

3.3: Assignments of characteristic FT-IR vibrations of 3-[(2′-flurophenyl amido)]propanoic acid and its organotin(IV) complexes

60

3.4: Assignments of characteristic FT-IR vibrations of 3-[(3′,4′-dichlorophenylamido)]propanoic acid and its organotin(IV) complexes

61

3.5: Assignments of characteristic FT-IR vibrations of 3-[(3′,5′-dichlorophenylamido)]propanoic acid and its organotin(IV) complexes

61

3.6: Assignments of characteristic FT-IR vibrations of 3-[(3′,5′-dimethyl phenylamido)]propanoic acid and its organotin(IV) complexes

62

3.7: Assignments of characteristic FT-IR vibrations of [(E)-4-((2-hydroxy benzylideneamino)methyl)cyclohexane and its organotin(IV) complexes

62

3.8: Assignments of characteristic FT-IR vibrations of 4,5-dimethoxy- 2-nitrobenzoic acid and its organotin(IV) complexes

63

3.9: Assignments of characteristic FT-IR vibrations of 2,4,6-trichlorobenzoic acid and its organotin(IV) complexes

63

3.10: Assignments of characteristic FT-IR vibrations of 3,4-dimethoxybenzoic acid and its organotin(IV) complexes

64

3.11: Assignments of characteristic FT-IR vibrations of 3,5-dimethylbenzoic acid and its organotin(IV) complexes

64

3.12: 1H NMR data of 3-[(2′-flurophenylamido)]propenoic acid and its organotin(IV) complexes

67

3.13: 1H NMR data of 3-[(3′, 5′-dimethylphenylamido)]propenoic acid and its organotin(IV) complexes

68

3.14: 1H NMR data of 3-[(2′-flurophenylamido)]propanoic acid and its organotin(IV) complexes

69

3.15: 1H NMR data of 3-[(3′,4′-dichlorophenylamido)]propanoic acid and 70

v

its organotin(IV) complexes

3.16: 1H NMR data of 3-[(3′,5′-dichlorophenylamido)]propanoic acid and its organotin(IV) complexes

71

3.17: 1H NMR data of 3-[(3′,5′-dimethylphenylamido)]propanoic acid and its organotin(IV) complexes

72

3.18: 1H NMR data of [(E)-4-((2-hydroxybenzylideneamino)methyl) cyclohexane and its organotin(IV) complexes

73

3.19: 1H NMR data of 4,5-dimethoxy-2-nitrobenzoic acid and its organotin(IV) complexes

74

3.20: 1H NMR data of 2,4,6-trichlorobenzoic acid and its organotin(IV) complexes

75

3.21: 1H NMR data of 3,4-dimethoxybenzoic acid and its organotin(IV) complexes

75

3.22: 1H NMR data of 3,5-dimethylbenzoic acid and its organotin(IV) complexes

76

3.23: 13C and 119Sn NMR data of 3-[(2′-flurophenylamido)]propenoic acid and its organotin(IV) complexes

79

3.24: 13C and 119Sn NMR data of 3-[(3′,5′-dimethylphenylamido)]propenoic acid and its organotin(IV) complexes

80

3.25: 13C and 119Sn NMR data of 3-[(2′-flurophenylamido)]propanoic acid and its organotin(IV) complexes

81

3.26: 13C and 119Sn NMR data of 3-[(3′,4′-dichlorophenylamido)]propanoic acid and its organotin(IV) complexes

82

3.27: 13C and 119Sn NMR data of 3-[(3′,5′-dichlorophenylamido)]propanoic acid and its organotin(IV) complexes

83

3.28: 13C and 119Sn NMR data of 3-[(3′,5′-dimethylphenylamido)]propanoic acid and its organotin(IV) complexes

84

3.29: 13C NMR data of [(E)-4-((2-hydroxybenzylideneamino) methyl)cyclohexane and its organotin(IV) complexes

85

3.30: 13C NMR data of 4,5-dimethoxy-2-nitrobenzoic acid and its organotin(IV) complexes

86

3.31: 13C NMR data of 2,4,6-trichlorobenzoic acid and its organotin(IV) complexes

87

3.32: 13C NMR data of 3,4-dimethoxybenzoic acid and its organotin(IV) complexes

88

3.33: 13C NMR data of 3, 5-dimethylbenzoic acid and its organotin(IV) complexes

89

vi

3.34: Mass spectral data of organotin(IV) complexes of 3-[(2′-flurophenylamido)]propenoic acid

92

3.35: Mass spectral data of organotin(IV) complexes of 3-[(3′,5′-dimethylphenylamido)]propenoic acid

93

3.36: Mass spectral data of organotin(IV) complexes of 3-[(2′-flurophenylamido)]propanoic acid

94

3.37: Mass spectral data of organotin(IV) complexes of 3-[(3′,4′-dichlorophenylamido)]propanoic acid

95

3.38: Mass spectral data of organotin(IV) complexes of 3-[(3′,5′-dichlorophenyl amido)]propanoic acid

96

3.39: Mass spectral data of organotin(IV) complexes of 3-[(3′,5′-dimethylphenyl amido)]propanoic acid

97

3.40: Mass spectral data of organotin(IV) complexes of [(E)-4-((2-hydroxybenzyl ideneamino)methyl)cyclohexane

98

3.41: Mass spectral data of organotin(IV) complexes of 4,5-dimethoxy-2-nitrobenzoic acid

99

3.42: Mass spectral data of organotin(IV) complexes of 2,4,6-trichlorobenzoic acid

100

3.43: Mass spectral data of organotin(IV) complexes of 3,4-dimethoxybenzoic acid

101

3.44: Mass spectral data of organotin(IV) complexes of 3,5-dimethylbenzoic acid

102

3.45 Antibacterial activity data of ligands and their organotin(IV) derivatives

104

3.46 Antifungal activity data of free ligands and their organotin(IV) derivatives

109

3.47 Organotin(IV)carboxylate and CTAB interaction parameters determined by conductometry.

120

3.48 The binding constants and Gibbs free energies of organotin(IV) carboxylates calculated by using Uv-visible Spectroscopy

139

3.49 The binding constants, binding sites and Gibbs free energies of organotin(IV) carboxylates calculated by using Fluorescence Spectroscopy.

150

3.50 Thermal decomposition pattern of selected organotin(IV) carboxylates

151

3.51 Kinetics parameters obtained from TGA of selected organotin(IV) carboxylates

153

4.1: Crystal data and structure refinement parameters for HL1, HL3, HL4, HL5 and HL6

163

4.2: Selected bond lengths (Å) and bond angles (˚) of HL1, HL3, HL4, HL5 and HL6

165

vii

4.3: Crystal data and structure refinement parameters for 18, 22, 28, 31, 33, 46 and 67.

172

4.4: Selected bond lengths (Å) and bond angles of 18, 26, 28, 31, 33, 46 and 67.

174

4.5: Crystal data and structure refinement parameters for compounds 49, 69 and 70.

179

4.6: Selected bond lengths (Å) and bond angles for compounds 49, 69 and 70.

180

viii

Figures List

Figure Title Page 1.1: Four structure classes for compounds of the type R3SnOCOR′ 6

1.2: ORTEP diagram of (2-PyCH2SC6H4CO2) SnPh3 7

1.3: ORTEP diagram of 2-Hydroxybenzoate triphenyltin(IV) 7

1.4: ORTEP diagram of [(Ph3Sn)2][(C6H10) (COO)2 7

1.5: ORTEP diagram of {[(Ph3Sn)2][(C6H10)(COO)2]}n 8

1.6: ORTEP diagram of [4-OCH3C6H4CH2CO2]SnBut3 8

1.7: ORTEP diagram of Me3SnOCOCH2(4-NO2C6H5) 8

1.8: ORTEP diagram of But3SnOCOCH2(4-NO2C6H5) 9

1.9: ORTEP diagram of [4-OCH3C6H4CH2CO2]SnMe3 9

1.10: ORTEP diagram of [Me3SnOCO(C14H9)] 9

1.11: ORTEP diagram of (CH3)3SnOCO(C14H9) 10

1.12: Diorganotin(IV) dicarboxylates in the solid state. 10

1.13: ORTEP diagram of Et2Sn[OCOCH2(4-MeOC6H5)] 2 11

1.14: ORTEP diagram of Et2Sn [OCOCH2(4-NO2C6H5)]2 11

1.15: ORTEP diagram of [Sn4O2(C7H2ClN2O6)4(C4H9)8] 11

1.16: ORTEP diagram of {[(CH2O2C6H2(o-NO2)COO)SnBu2]2O}2 12

1.17: Surfactant molecule and surfactant micelle 19

1.18: Role of surfactant in drug delivery 20

1.19: Cell membrane structure and composition 21

1.20: Structure of phosphatidylserine 21

3.1: Antibacterial activity of organotin(IV) derivatives against E. coli. 106

3.2: Antibacterial activity of organotin(IV) derivatives against B. subtilis. 106

3.3: Antibacterial activity of organotin(IV) derivatives against S. lexenari. 107

3.4: Antibacterial activity of organotin(IV) derivatives against P. aeroginosa.

107

3.5: Antifungal activity of organotin(IV) derivatives against T. longifuses. 111

3.6: Antifungal activity of organotin(IV) derivatives against A. flavus 111

3.7: Antifungal activity of organotin(IV) derivatives against C. glabrata. 112

3.8: Antifungal activity of organotin(IV) derivatives against C. albicans 112

3.9: Dose-response curve of organotin(IV) carboxylates in the range of 5-10nM

114


114

ix


116

3.12: Dose-response curve of But3SnL 116

3.13: Specific conductivity curves of CTAB in the presence of 21 in water 118

3.14: Specific conductivity curves of CTAB in the presence of 17 in water. 119

3.15: Specific conductivity curves of CTAB in the presence of 32 in water. 119

3.16: Specific conductivity curves of CTAB in the presence of 9 in water 120

3.17: Delocalization of electrons in organotin(IV) carboxylate molecule 122

3.18: Interaction of organotin(IV) carboxylate with CTAB 122

3.19: Adsorption of organotin(IV) carboxylate at the surface of CTAB micelle

123

3.20: Interaction of CTAB with complex 9 124

3.21: Diagram showing the resonance of pi electrons in complex 124

3.22: Adsorption in the palisade layer of CTAB micelle (up to 2-3 carbon) 125

3.23: Absorption of 21 in pre and postmicellar concentration of CTAB (Ca = 7.5 х 10-6mM)

127

3.24: Effect of the CTAB concentration on the absorbance of 21 127

2.25: Differential absorption spectra of 21 in the postmicellar concentrations of CTAB (Ca = 7.5х10-6mM)

128

3.26: Effect of the CTAB concentration on the differential absorbance of 21 128

3.27: Relationship between 1/ΔA and 1/(Ca+Csmo) for 21 129

3.28: Effect of the CTAB concentration on the relative solubility of 21 129


130



131





133



134



x



136


3.43: Differential absorption spectra of 9 in the postmicellar concentrations of CTAB (Ca = 7.0 х 10-6mM)

137



3.46: Effect of CTAB concentration on relative solubility of 9 138

3.47: Interaction of organotin(IV) carboxylates with micelles 141

3.48: Plot of I versus wave length for postmicellar concentrations of CTAB for 21 (Ca= 1.0х10-9)

142

3.49: Plot of [I-Io)I] versus (Cs) for 21 143

3.50: Plot of log [I-Io)I] versus log (Cs) for 21 143

3.51: Plot of I versus wave length for postmicellar concentrations of CTAB for 17 (Ca = 1.0 х 10-9)

144



3.54: Plot of I versus wave length for postmicellar concentrations of CTAB for 32 (Ca = 1.0х10-9)

146



3.57: Plot of I versus wave length for postmicellar concentrations of CTAB for 9 (Ca = 1.0х10-9)

148



3.60: Thermal decomposition pattern of organotin(IV) complexes of HL7 156

3.61: Thermal decomposition pattern of organotin(IV) complexes of HL8 157

3.62 Numbering scheme of organic moiety attached to Sn atom. 157

3.63 Numbering scheme of free ligands 158

4.1: ORTEP drawing of 3-[(2′-florophenylamido)]propenoic acid (HL1) 161

4.2: ORTEP drawing of 3-[(2′-florophenylamido)]propanoic acid (HL3) 162

4.3: ORTEP drawing of 3-[(3′,4′-dichlorophenylamido)]propanoic acid (HL4)

162

4.4: ORTEP drawing of 3-[(3′,5′-dichlorophenylamido)]propanoic acid (HL5)

162

4.5: ORTEP drawing of 3-[(3′,5′-dimethylphenylamido)]propanoic acid 162

xi

xii

(HL6)

4.6: ORTEP drawing of complex 18 with atomic numbering scheme. 168










Chapter−1

INTRODUCTION

1.1 Organotin(IV) compounds Organotin(IV) compounds have a wide range of industrial applications and a remarkable

impact on the agricultural field as well. The number of C-Sn bonds categorize

organotin(IV) compounds as mono-, di-, tri- or tetraorganotin(IV) compounds, and they

have a profound effect on their properties [1,2]. Number and nature of R groups decide

its use. The toxicity of alkyl containing organotin(IV) compounds is higher than those of

aryl containing organotin(IV) compounds [3,4]. Almost all organotin compounds are of

the SnIV type. In tetravalent organotin(IV) compounds the C-Sn bonds are covalent and

stable. In organotin(IV) compounds, the C-Sn bond energy is low which make it fragile

and sensitive to high temperature.

1.2 Historic view of organotin(IV) compounds The chemistry of organotin(IV) compounds started with the synthesis of diethyl tin

diiodide, by Frankland in 1849 [5].

2EtI+Sn ⎯⎯→ Et2SnI2 (i)

The development of Grignard reagents in 1900 was the turning point in the history of

organometallic chemistry, but before that there were 37 research papers in the field of

organotin(IV) chemistry. In 1903, Pope and Peachey used Grignard reagents as

precursors for the preparation of new organotin(IV) complexes [6]. The application of

organotin(IV) derivatives in 1940’s as PVC stabilizers opened a new chapter in

organotin(IV) chemistry [7]. In late 1950s, the biocidal applications of organotin(IV)

compounds were discovered by van der Kerk at the TNO Institute, Utrech [8].

A quantum jump was observed in the chemistry of organotin(IV) compounds during the

last 30 years owing to their broad spectrum applications in daily life [9-11]. Smith [12]

reported crystals structures of a series of organotin(IV) compounds, while Tiekink [13]

reviewed the structural chemistry of organotin(IV) carboxylates in solid states. In 2002

Pellerito and Nagy [14] surveyed organotin(IV) complex studies by means of different

equiliberia and structural techniques. Martin et al., [15] reviewed tin NMR as a tool for

studies of organotin(IV) complexes in solution. Recently, Holloway and Melink [16]

reviewed and explained the structural aspects of organotin(IV) compounds with the help

1

of more than 400 references. Yamamoto, edited proceeding of synopsia comprising 27

papers on organotin(IV) compounds in organic synthesis [17]. Zuckerman summarized

the research work reported before 1978 [18]. In 1989 Saxena and Huber [19] published

the biological aspect of organotin(IV) carboxylates in independent reports. Tsangaris

and Williams [20] reported their pharmaceutical applications and Crowe [21,22] their

agriculturally importance. In 1985, use of organotin(IV) in various syntheses has been

reviewed [23,24] and Grindley described its role in carbohydrate chemistry [25]. Burger

and Nagy [26], Gyurcsik and Nagy [27] elaborate Grindley’s studies with sugar

examples. Specified compounds from a 1975-1993 survey are presented in a set of 20

volumes of Gmelin [28-33]. A dictionary of organometallic compounds, comprises of

1000 organotin(IV) compounds, is a major source of references for organotin(IV)

chemistry [34].

1.3 Synthetic methods for organotin(IV) carboxylates Esterification of diorganotin(IV) oxide or triorganotin(IV) hydroxide is one of the most

commonly used methods for the preparation of organotin(IV) carboxylates [35]. The

reaction of carboxylic acid with organotin(IV) oxide or hydroxide is carried out in

benzene or toluene [36]. In diorganotin(IV) oxide, the nature of the R group and the ratio

of reactants decide the geometry around the central tin atom and the nature of the product

[37,38].

R3SnOH + R'CO2H R3SnO2CR'

(R3Sn)2O + 2R'CO2H 2R3SnO2CR'

R2SnO + 2R'CO2H R2Sn(O2CR')2

RSn(O)(OH) + 3R'CO2H RSn(O2CR')3

+ H2O

+ H2O

+ H2O

+ 2H2O

(ii)

(iii)

(iv)

(v)

R and R′ play an important role in the nature of the product of the reaction, which is

described below;

R2SnO + R'CO2H

R2Sn(OH)O2CR'

R2Sn(O2CR')2

(R'CO2)R2SnOSnR2(O2CR') (vi)

(viii)

(vii)

2

Another method which is adopted for the synthesis of organotin(IV) carboxylates is the

replacement of alkyl groups, in alkyl tin bonds, with a carboxylic group by the cleavage

of an alkyl tin bond. This method is more successful in case of R= vinyl or aryl than

alkyl.

R4Sn + R'CO2H

R3SnO2CR' + RMR4Sn + R'CO2M

R3SnO2CR' + RH

(ix)

(x)

One alternative synthetic rout is the addition of an aliquot of organotin(IV) chloride to

the aliquot of sodium salt of carboxylic acids [39].

LNa + Ph3SnCl + Ph3SnLNaCl

2LNa + Ph2SnCl2 + Ph2SnL22NaCl

(xi)

(xii)

Organotin(IV) carboxylates can also be synthesised by the reaction of organotin(IV)

iodide and silver acetate [40].

RnSnI4-n + 4-n R'CO2Ag RnSn(O2CR')4-n + 4-nAgI (xiii)

Organotin(IV) carboxylates can be synthesized by the addition of an organotin(IV)

chloride to a ligand solution in the presence of triethylamine [41].

R3SnCl + R′CO2H + Et3N ⎯→ R3SnOCOR′ + Et3NHCl (xiv)

R2SnCl2 + 2R′CO2H + 2Et3N ⎯→ R2Sn(OCOR′)2 + 2Et3NHCl (xv)

Organotin(IV) carboxylates can be synthesized by mixing solution of sodium methoxide

with solution of free ligand in benzene and it is then refluxed for half an hour. At this

stage, a benzene solution of Ph2SnCl2 or Ph3SnCl is added dropwise to the above

solution and the resultant solution is stirred under reflux for about 6 hours. Upon cooling,

the NaCl precipitates [42].

CH3ONa + LH CH3OH + LNa

2LNa + Ph2SnCl2

LNa

L2SnPh2 + 2NaCl

+ Ph3SnCl NaCl + Ph3SnL

(xvi)

(xvii)

(xviii)

3

In addition to these procedures, organotin(IV) carboxylates can also be synthesized by

exchange reactions as given below [43].

R2SnCl2 + R2Sn(OCOR′)2 ⎯→ 2R2Sn(OCOR′)Cl (xix)

1.4 Properties of organotin(IV) compounds

The structure of organotin(IV) compounds and the geometry around the tin atom

determines the physical and chemical properties of organotin(IV) carboxylates.

Compared to di-, triorganotin carboxylates are more toxic in nature. The biological

activities i.e. antibacterial, anti-fungal, anti-viral, phytotoxicity and wood preservation of

triorganotin(IV) carboxylates, are higher than those of the diorganotin(IV) carboxylates.

The triorganotin(IV) carboxylates are more lipophilic and have vacant coordination sites

for interactions with the biological system. Organotin carboxylates are not soluble in

water, whereas, soluble in organic solvents like toluene, acetone, chloroform and

dimethyl sulfoxide etc. In basic media, the organotin(IV) carboxylates hydrolyse to form

the appropriate organotin(IV) oxide, hydroxide and bishydroxide. Organotin(IV)

carboxylates with less number of alkyl groups are more soluble than those with higher

number of alkyl groups. Triorganotin(IV) carboxylates are less soluble than

diorganotin(IV) carboxylates because the former ones form polymeric associated

structures. The water soluble organotin(IV) includes distannoxane and organotin(IV)

tricarboxylates e.g. (RCO2)R2SnOSnR2(O2CR) and (R2CO)R2SnOSnR2(OH). Due to

their solubility and stability in water, they are used for the treatment of cancer cells as

they are discharged through the urinary tract from the body. Organotin(IV) compounds

show Lewis acidity due to lone pair of electrons. The strength can be measured by an

extent of interaction with triethylphosphinoxide using the 31P NMR shift. Thus, the

stability of organotin(IV) carboxylates increases as the strength of anion increases, i.e.,

organotin(IV) chloride is a stronger Lewis acid than organotin(IV) carboxylates [44].

Triorganotin(IV) carboxylates are more stable in air containing moisture but are sensitive

to higher temperature. At higher temperatures, organotin(IV) carboxylates decompose,

undergo decarboxylation and form different types of organic derivatives.

4

1.5 Structural aspects of organotin(IV) carboxylates Organotin(IV) complexes are of considerable importance due to their versatile bonding

modes and the considerable diversity in their structure. The nature and number of R

groups around the tin atom, stiric interaction, and the nature of carboxylic groups decide

the stereochemistry of the complex and the geometry around the central tin atom. The

number of R groups, the geometry around the central tin atom and the structure of the

complex play an important role in the bioassay of the complex. Complexes with

electronegative atoms such as O, N or S show inter/ intra molecular interactions and this

increases the coordination number. These inter/ intra molecular interactions in

organotin(IV) carboxylates results in fascinating structures features, such as hexametric

cyclic diorganotin(IV) carboxylate [45,46]. Organotin(IV) halides are the best source to

study the reactivity of organotin(IV) species [47]. Therefore, organotin(IV)

carboxylates of wide structural diversity are known. They have a variety of geometries

like polymers, tetramers, monomers, oligomers, and dimers etc [48-52]. Triorganotin(IV)

carboxylates are found in different types of structure in the crystalline form i.e. a, b, c

and d as shown in Figure 1.1. In structure class a compounds, tin is tetracoordinated to

form distorted tetrahedral geometry around the central tin atom. Typical examples of

class a are (2-pyCH2SC6H4CO2)SnPh3 [53] and 2-hydroxybenzoato triphenyltin(IV) [54]

shown in Figure 1.2 and 1.3, respectively. In (2-pyCH2SC6H4CO2)SnPh3, there is only

one SnO bond as the other SnO bond distance (3.040 Å) is greater than the normal SnO

distances (2.737 Å). In structural class b compounds, central tin atom is penta

coordinated i.e coordinated with 3 alkyl groups and two oxygen of bidentate carboxylate

group. A typical example of class b is [(Ph3Sn)2][(C6H10)(COO)2] [55] shown in Figure

1.4. In this example, the tin is five coordinated i.e. with three phenyl groups and two

oxygen atoms of the same carboxylate group. {[(Ph3Sn)2][(C6H10)(COO)2]}n, is the good

example for both a and b shown in Figure 1.5. The SnO bond lengths [Sn(1)-O(1) =

2.056Å] for [(Ph3Sn)2][(C6H10)(COO)2] and Sn(1)-O(2)#1= 2.185Å, Sn(2)-O(3) =

2.057Å for {[(Ph3Sn)2][(C6H10)(COO)2]}n] agree with a SnO covalent bond length

reported in the literature, which proves that the tin oxygen coordination is a strong

chemical bond. Other Sn-O bond lengths do not agree with the literature. The Sn-O bond

length values Sn(1)-O(1) = 2.310Å and Sn(2)-O(4) =2.675Å for

[(Ph3Sn)2][(C6H10)(COO)2]n are comparable to covalent bond lengths but shorter than

literature reported values for van der Waals radii (3.68Å).

5

In structural class c compounds exist in polymeric form, in which the penta coordinating

tin atoms are bridge by bidentate carboxylate ligand to form the polymeric chain. Typical

examples are [4-OCH3C6H4CH2CO2]SnBut3, [OCOCH2(4-NO2C6H5)]SnMe3,

[OCOCH2(4-NO2C6H5)]SnBu3 [56] and [4-OCH3C6H4CH2CO2]SnMe3 [58] shown in

Figures 1.6-1.9. In these complexes, the tin centers show a trans trigonal–bipyramidal

coordination center with oxygen at an axial position. The central tin atom is

asymmetrically attached to two oxygen atoms as axial tin–oxygen bonds are different in

length. The O−Sn−O angles for [OCOCH2(4-NO2C6H5)]SnMe3 and [OCOCH2(4-

NO2C6H5)]SnBu3 are 170˚ and 177˚, respectively, which is less than 180˚. Alkyl groups

in these structures occupy equatorial positions as the C-Sn-C angles are in the range of

115.95-125.68o and 117.37-121.86o for the compounds trimethyltin(IV) 4-

nitrophenylethanoate and tributyltin(IV) 4-nitrophenylethanoate.

Sn

R

R

RO R

O

Sn

R

R

R O

O

R

(a) (b)

O O Sn

R

R

R R

O O Sn

R

R

R R

O

n

O Sn

R

O O

SnR

O

OSn

R

OO

O

Sn R

R

R

R

R

R R

R

R

R R R

R

(c) (d)

Figure 1.1: Four structure classes for compounds of the type R3SnOCOR′

6

Figure 1.2: ORTEP diagram of (2-pyCH2SC6H4CO2)SnPh3

Figure 1.3: ORTEP diagram of 2-hydroxybenzoate triphenyltin(IV)

Figure 1.4: ORTEP diagram of [(Ph3Sn)2][(C6H10) (COO)2

7

Figure 1.5: ORTEP diagram of {[(Ph3Sn)2][(C6H10)(COO)2]}n

Figure 1.6: ORTEP diagram of [4-OCH3C6H4CH2CO2]SnBut3

Figure 1.7: ORTEP diagram of Me3SnOCOCH2(4-NO2C6H5)

8

Figure 1.8: ORTEP diagram of But3SnOCOCH2(4-NO2C6H5)

Figure 1.9: ORTEP diagram of [4-OCH3C6H4CH2CO2]SnMe3

Figure 1.10: ORTEP diagram of [Me3SnOCO(C14H9)]

9

Figure 1.11: ORTEP diagram of (CH3)3SnOCO(C14H9)

Structure class d compounds are in a macrocyclic tetrameric form, in which bidentate

carboxylic ligand bridge four unit of penta coordinated tin atoms. An example of class d

is Me3SnOCO(C14H9) [57] shown in Figures 1.10 as a monomer and in Figure 1.11 as a

tetramer. The carboxylate groups bridge two neighboring tin atoms such as the Sn−O

bonds formed by the bridging ligands. They are asymmetric and are comparable with the

linear polymers of class c.

The diorganotin(IV) dicarboxylates have monomeric structures in the solid state as

illustrated in Figure 1.12 as a bicapped tetrahedron.

OSn

O

O O

R

R

R

R

Figure 1.12: Diorganotin(IV) dicarboxylates in the solid state.

The tetrahedron is comprises of two Sn-C bonds and two short Sn-O bonds. Examples

are diethyltin(IV) bis(4-methoxyphenylethanoate) [58], diethyltin bis(IV) 4-

nitrophenylethanoate [56], [Sn4O2(C7H2ClN2O6)4(C4H9)8] [59] and {[(CH2O2C6H2(o-

NO2)COO)SnBu2]2O}2 [60] shown in Figure 1.13-1.16.

10

Figure 1.13: ORTEP diagram of Et2Sn [OCOCH2(4-MeOC6H5)]2

Figure 1.14: ORTEP diagram of Et2Sn [OCOCH2(4-NO2C6H5)]2

Figure 1.15: ORTEP diagram of [Sn4O2 (C7H2ClN2O6)4(C4H9)8]

11

Figure 1.16: ORTEP diagram of {[(CH2O2C6H2(o-NO2)COO)SnBu2]2O}2

1.6 Positive impact of organotin(IV) carboxylates on daily life

Organotin(IV) compounds have variety of applications in our daily life and are

widespread in different areas for 60 years. Over the last several decades, they have been

successfully used for different applications. The synthesis of new organotin(IV)

carboxylates with different structures has novel and valuable biological and non-

biological applications.

1.6.1 Biological applications The use of organotin(IV) carboxylates for any specific biological activity is bound to the

nature and number of organic groups R directly attached to the tin atom and carboxylate

groups attached to the tin atom through Sn-O bonds. These factors decide the

effectiveness of organotin(IV) compounds for required purposes. The nature of the R

group decides its site of attack for organotin(IV), binding to the different locations in the

body, e.g. carbohydrates, nucleic acid derivatives, amino acids [61-64] and to proteins

[65,66]. The presence of hetero atoms such as N, O or S in the ligand play a key role in

the geometry and thus effect the biological activity of these complexes [67,68]. Higher

biological activity of organotin(IV) compounds encourage their applications in

pharmaceutical. Some of the biological applications are discussed below.

1.6.1.1 Pharmaceuticals Metal ions have a significant role in various physicochemical processes that take place in

the living body and they are known for their metallopharmaceutical applications.

Organotin(IV) compounds are used as potential biologically agent against various

diseases [69,70]. Study of organotin(IV) activity and their mode of effect by interaction

12

with different parts like ATPase and hemoglobin’s are a model for studying interactions

of drugs with the human body [71,72]. The synthesis of organotin(IV) complexes with

new ligands and different coordination geometries are attempts to develop new drugs for

different purposes. Potential biological activities of organotin(IV) compounds

encouraged their applications in the fields of muoluscicides, veterinary science,

antibacterial, antifungal, antitumour, schizonticidal, antimalarial [73] and amoebicidal

[74] agents.

1.6.1.2 Antifouling agents Organotin(IV) compounds particularly tributyltin (TBT) are used as a part of paint to

protect the underwater surface of ships against the attack of microorganism. The ship

without this paint causes higher fuel consumption, premature dry docking, and raise the

cost of cleaning due to increase weight and roughness of the hull.

1.6.1.3 Wood protection Insects, fungi and bacteria decompose the cellulose of wood. Tributyltin(IV) complexes

show potential biological activities against microorganism (fungi and bacteria) and are

used for treatment and preservations of wood [75]. The wood is treated with

organotin(IV) compounds in a vacuum [76]. Releasing the vacuum results in a flow of

organotin(IV) into the wood and the organotin(IV) compound is attached with terminal

OH groups of cellulose preventing the damage of wood by microorganisms [77,78].

1.6.1.4 Agrochemicals Triorganotin(IV) compounds are worldwide used in agriculture due to their usefulness

in treating pest diseases in crops [79,80]. They are frequently used against fungi, mites

and ticks. Triorganotin(IV) compounds are used to prevents plant pathogenicity and

spoilage of natural and synthetic materials [81,82]. Organotin(IV) compounds have good

adhesion to the leaf surface, and rain resistant properties. Triorganotin(IV) compounds

attack the plasma membrane and induce the extensive release of K+ by increasing the

permeability of plasma membrane. They also disturb the function of mitochondria by

distorting its structure. Triphenyltin hydroxide (TPTH), tricyclohexyltin hydroxide

(TCTH), tricyclohexyltin triazole (TCTT), trineophenyltin oxide (TNTO), and

triphenyltin acetate (TPTA) are successfully used in the field of agriculture.

1.6.1.5 Antiviral agents

Organotin(IV) compounds can be applied as metal-based drugs used for the treatment of

tumor and some show a higher potential than cis-platin [83,84]. This encourages

13

scientists to make attempts for designing tin based drugs having good activity and low

toxicity for cancer chemotherapy due to their apoptotic inducing character [85-88],

which is linked to the inhibition of mitochondrial oxidative phosphorylation. There are a

number of reviews available dealing with anti-tumor potential of organotin(IV)

compounds [89-91]. The diorganotin(IV) complexes potential against tumor is geometry

based as their coordination to target site depends upon their geometry [92]. The

anticancer potential of drugs can be evaluated by their ability of hydrolysis in a suitable

medium. Drug molecules produce cis-configuration with at least two water molecules

and have both hydrophobic and hydrophilic groups. Both the anticancer complex and its

active intermediate species should be polar. The metal should be capable of bonding with

DNA. Organotin(IV) compounds fulfilled all the above cited rules and show activity by

changing the gene sequence in the DNA.

1.6.1.6 Anthelmintics Organotin(IV) compounds are successfully used for the prevention of protozoal

infections in poultry. Organotin(IV) compounds are used for prevention and curing of

coccidiosis in the small intestines of fowl. Dibutyltin(IV) dilaurate and dibutyltin(IV)

maleate are the main components of most of veterinary formulations. Other types of

organotin(IV) compounds also may have anthelmintic properties [93,94].

1.6.2 Non-biological applications Organotin(IV) compounds have wide ranging industrial and synthetic applications which

catch the interest of scientists and demands an increase in production.

1.6.2.1 As a PVC stabilizer

The main use of organotin(IV) compounds is to stabilize PVC at high temperatures

[95,96]. During its processing at higher temperatures, HCl is eliminated which catalyses

further elimination and generated conjugated polyene as an end product. This also causes

of change of color and the physical state of the resin. The extensive use of organotin(IV)

compounds in bottles for carrying and packing foods is due to its stability. Organotin(IV)

stabilizers are good oxidation catalysts and they fulfill all the requirements necessary for

an ideal stabilizer.

1.6.2.2 Catalytic activity Mono and diorganotin(IV) compounds possess outstanding catalytic activities because

of the bonding capability of lone pair electrons on tin [97,98]. They are utilizing in the

14

field of chemical synthesis. In chemical synthesis, the organotin(IV) compounds are used

as catalysts for the esterification and transesterification. The tin-based catalysts donot

decompose at high temperatures. Organotin(IV) based catalysts are used for the

formation of various types of polymers which are used for coating purposes.

1.6.2.3 Glass coating Organotin(IV) halides are used to form electrically conductive thin films on the surface

of glass [99] by using Atmospheric Pressure Chemical Vapor Deposition (AP-CVD)

techniques [100-102] due to its economical reason and wide range commercial

applications. Tin chloride is used as a precursor for the formation of transparent

conductive oxide (TCO) films.

SnCl4 + 2H2O →SnO2 + 4HCl

The coatings of 10 nm thickness provide strength, thermal stability and resistance to

oxidation. Coated glass is used in deicing wind shield screens, security glass, or display

systems [103] owing to their low electrical resistance and high resistance to chemicals

[104]. TCO film also control the loss of heat through glass which is due to the metal

oxide film deposition on glass surface. Coating also acts as a p-type or n-type

semiconductor or conductor.

1.6.2.4 Water repellent agents Due to good water repellent properties of organotin(IV) compounds, particularly mono-

n-butyl- and mono-n-octyltin(IV) compounds are used in cotton textiles, paper and wood

to impart the water repellent character [105]. Sodium n-butanestannoate, n-

butylchlorotin(IV) dihydroxide, n-octylchlorotin(IV) dihydroxide and n-

butyltris(triphenyl-silanoxy)tin(IV) compounds are some of the examples used as water

repellent in fabric industries [106]. Similarly, n-octyltin(IV) trilaurate has replaced

silicone treatment technology, which were used on building materials, bricks, concrete

[107] and on cellulose substrates [108].

1.7 Some factors contributing to structure-activity relationships

The main factors that play a key role in structure-activity relationships for organotin(IV)

derivatives are the number and the nature of organic groups R, the nature of halides or

donor ligands and the geometry of the complex.

15

1.7.1 Role of organic groups The alkyl group (R) in organotin(IV) complexes and the partition coefficients greatly

affect the toxicities and biological activities of the complexes [109]. The activity of an

organotin(IV) compound depends upon the number and the chemical nature of organic

groups bound to tin. Organotin(IV) compounds with a greater number of “R” groups are

known to be the more toxic. This toxicity decreases when the bulky group is attached to

tin metal. In General, trisubstituted complexes of tin R3SnX show maximum

toxicological effects. The order of toxicity is R3Sn(IV) > R2Sn(IV) > RSn(IV) > Sn(IV).

The application of organotin(IV) in particular field is decided by the length of the

organic radical. Among the trialkyl substituted organotin(IV) complexes, trimethyltin

species are more toxic against microorganisms. Triethyltin complexes are known for

their activity against mammals while tripropyl and tributyltin species show activities

against fish and molluscs. Butyl substituted organotin(IV) derivatives are hydrophobic

agents and are used as water repellent agent on building materials and cellulosic matter

[110]. The toxicity of tributyltin(IV) chloride (10–100 times more active than

dibutyltin(IV) dichloride) is related to the number of butyl groups [111,112]. This

phenomenon is best observed in tetraorganotin(IV) complexes, which are not toxic but

have delayed toxic effects due to their degradation to triorganotin(IV) in the first step.

This degradation is confirmed in liver [113]. Tin metal itself is non-toxic. The impact of

the length of the alkyl group on toxicity cannot be negated. The toxicity decreases as the

length of the alkyl chain attached with tin metal increases. This lower toxicity is the main

reason for the extensive use of organotin(IV) having higher alkyl chains in industries

[114]. Triorganotin(IV) compounds disturb the mitochondrial function in three ways:

Triorganotin(IV) compounds change the movement of Cl-/OH- across cell membranes

which damage the structure of mitochondria [115-118]. It also inhibits oxidative

phosphorylation or hydrolysis of ATP [119]. Organotin(IV) complexes with smaller R

groups in (R2SnX2) compounds distorb Krebs cycle [120]. R2Sn+2 compounds are active

antitumor agents and their activity exceeds the activity of corresponding mono-, tri- and

tetra organotin(IV) compounds. Et2Sn+2 and Ph2Sn+2 complexes show higher activities

against tumor among the diorganotin(IV) class. The (C2H5)2SnCl2 (phen) modes of

interactions with DNA are intercalative and electrostatic binding to phosphate groups of

DNA in tumor cells and damaging them. Thus, the anti-tumor activity mode of the

16

compound is retarding the replication and synthesis of new DNA with the same defect

[121].

1.7.2 The role of anionic ligands and geometry around tin The activity is also found to be dependent on ligands as well [122]. The organic anionic

ligand is responsible for the transportation of the organotin(IV) moiety to the target area,

where the organotin(IV) species performs its biocidal activity [123-126]. Although the

toxic action of organotin(IV) compounds is independent of X group, yet it is controlled

by the anionic ligand through its role in the delivery of the active R2Sn(IV) +2 species to

the target area [127]. Anionic ligands are displaced at receptor site in biological system

by a suitable donor atom. However, some results show that the anionic X group does

play a role in the toxicity of organotin(IV) compounds [128,129]. Dimethyltin(IV)

dichloride and dimethyltin(IV) diisooctyl thioglycolate [(CH3)2Sn (SCH2CO2-i-Oct)2]

studies results are good evidences. The former is moderately toxic, while the later one is

relatively non-toxic due to different ligands attached to the organotin(IV) species [130].

In triorganotin(IV) compounds, tin is capable of increasing its coordination number to

more than four by the interaction with the donor sites N, S or O present in the ligand

[131]. Compounds in which tin atom is tetra coordinated in solution undergo such

interactions but in species in which tin is penta coordinated are considered to be

coordinatively saturated and will not experience such interactions. It shows that the

nature of the ligand define the activity to some extent and the structural feature of the

organotin(IV) molecule distinguishes active organotin(IV) compounds from inactive

ones [132]. It shows that the action of organotin(IV) compound is dependent on the

coordination capability of tin to the site of action. The presence of donor atoms on the

ligand results in an intramolecular interaction which directly affects the biological

activity of the complex [133,134]. The chirality of the ligand also affects the activity of

organotin(IV) derivatives [135]. Triorganotin(IV) carboxylates with trans geometry

around tin metal shows higher activity than with monomeric cis conformation as tin

metal has more space for interaction. These studies support that bioactivity of complex

depends on availability of coordination position at Sn, stability of ligand-Sn bonds, and

rate of hydrolytic decomposition of these bonds. It may be concluded with certain

reservations that the number and nature of alkyl groups are the major factors that decide

the choice of organotin(IV) complex for some specific purpose.

17

1.8 Organotin(IV) carboxylates delivery systems A thorough study of organotin(IV) interactions with cell membranes is essential for a

better understanding of the well established broad spectrum biological activity that is

related to organotin(IV) compound. Organotin(IV) compounds are membrane active with

well established biological activities. The n-Bu3Sn(IV)X derivatives exert their effect

due to n Bu group lipophilicity that results in the lation of n-Bu3Sn(IV)X into the lipid

bilayer of cell membranes [136,137]. n-Bu3Sn(IV) has an affinity for band 3 proteins of

human erythrocyte membrane [138,139], cell membranes and cellular proteins of murine

erythroleukemic cells [140].

1.8.1 Surfactants The interaction of organotin(IV) carboxylates with biological cell membrane can be

studied by using a surfactant. Surfactants are composed of a hydrophilic head group

which contains heteroatoms such as O, S, P, or N, incorporated in a functional groups

such as alcohol, thiol, ether, ester, acid, sulfate, sulfonate, phosphate, amine, amide etc.

and a hydrophobic tail which is in general an hydrocarbon chain of the alkyl or

alkylbenzene type composed of 8 to 18 carbon hydrocarbon.

On the basis of a hydrophilic head group and the solubility, the surfactants are classified

into following groups:

(i) Anionic surfactants

These surfactants dissolve in water to give an amphiphilic anion and a cation (Na+, K+ or

a quaternary ammonium). This type of surfactant is commonly used in our daily life.

Some examples are soaps, foaming agents, detergents, wetting agents, dispersants etc

(ii) Cationic surfactants

This type of surfactant dissociates in water into an amphiphilic cation and an anion. Most

of the cationic surfactants are nitrogen coordinating compounds like fatty amine salts and

quaternary ammoniums, having long alkyl chain or natural fatty acids. These surfactants

are also used as bactericides and for the creation of an antistatic effect.

(iii) Nonionic surfactants

These surfactants do not ionize in water because their hydrophilic group does not

dissociate in water, such as alcohol, phenol, ether, ester, or amide. A large proportion of

18

these nonionic surfactants are made hydrophilic by the presence of a polyethylene glycol

chain.

Hydrophilic headHydrophobic tail

Surfactant molecule

micelle

micelle

Figure 1.17: Surfactant molecule and surfactant micelle

When the concentration of a surfactant increases in solution, the surfactant molecules

organize themselves to form micelles, at a specific surfactant concentration. The physical

behavior of surfactant micelles are like the model membrane and are used as an

alternative for the study of cell membrane interaction with the organic substances

[141,142].

This property of micelle formation is of prime importance as it dissolves the sparingly

soluble organotin(IV) complexes in aqueous media. Monomers of surfactants rearrange

to form the micelle, in such a way that the polar head group of the monomers oriented

outward and the hydrocarbon chains directing inward. This arrangement results in the

micro heterogeneity i.e. high polar surface of the micelle to the non-polar hydrocarbon

core of micelle, which is best environment for solubilization. Micelles are important

pharmaceuticals as well because they increase the bioavailability of drugs and decrease

the side effects of drugs.

1.8.1.1 The role of surfactant in drug delivery Figure 1.17 shows the behavior of surfactants and drug transportation phenomenon

across the cell membrane to the target site facilitated by surfactants. The surfactant

monomers rearrange to form the micelles after the critical micelle concentration.

19

Miscells capture the hydrophobic drugs and carry them to cell membranes. Miscells

having drug molecules ruptures and release the drug molecules into the cell membrane.

The drug molecules pass through the membrane into cell. This illustration demonstrates

role of surfactant in the transportation of a drug and its delivery to target site in

biological system.

Hydrophobic drug

Miscelles Drug loaded inside the miscelles

Miscelles carry the drug to the target

Drug is unloaded in to bilayer memberane

Drug crosses the bilayers to reached the target

Monomers

Figure 1.18: Role of Surfactant in drug delivery

1.8.1.2 Cell membrane structures The body is divided by cell membranes into aqueous filled compartments. These cell

membranes are mainly comprises of phospholipid bilayers which surround cells. The

internal organelles of cell are also surrounded by this phospholipids bilayer.

Phospholipid bilayers are the main barrier for the movement of materials across the cell

membrane. These phospholipid bilayers are formed with polar ionized head groups

oriented outside towards aqueous media and inward oriented lipid chains creating a

hydrophobic inner core. Due to the polarity of the head group and the charge on the head

20

group of phospholipid monolayers, the overall surface of the cell membrane presents a

net charge to the incoming interacting molecule. This character is highly close to the

cetyl N,N,N-trimethyl ammonium bromide (CTAB) micelle because the surface of

CTAB micelles is also positively charged. For the movement across the cell membrane, a

molecule should have hydrophobic character to facilitate its movement. Lipophilicity is a

pre-requisite for drugs to cross the cell membrane barrier and to perform its function.

Figure 1.19: Cell membrane structure and composition

Figure 1.20: structure of phosphatidylserine

21

Proteins have hydrophobic binding sites which interact with the hydrophobic part of the

molecule and facilitate the transportation of materials due to lipophilicity [143]. The

CXC motif (Cys-32 and Cys-34 correspond to Cys-4 and Cys-6) of protein is located at

the end of the trans membrane helix at the lipid/solvent interface providing a site for the

binding to the interacting molecules.

The interaction of organotin(IV) carboxylate molecules with the cell membrane is a

complex phenomenon. The organotin(IV) carboxylate molecules remain embedded into

the hydrophobic core of the phosphobilipid membrane and alter the cell kinetics by

changing the transportation across the cell membrane by the interaction with a

lipid/water interface [144] or affecting the intracellular function by dissolution through

the cell membrane. The lipophilicity role is important and effects the organotin(IV)

carboxylate activity. The hydrophilic and hydrophobic character of organotin(IV)

compounds decide the extent of interactions with biological systems through weak

Coulomb interactions, causing denaturation [145]. Organotin(IV) compounds with

differing polarity and hydrophobic moieties produce different effects because of the

different location of organotin(IV) complexes in the phospholipid bilayers.

Organotin(IV) compounds exert specific toxic effects by breaking hydrogen-bondings in

the interfacial regions of membranes and then with the lipidic (hydrophobic region)

component, followed by a change in the function of cell membranes.

22

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Chapter−2

EXPERIMENTAL

2.1 Materials Organotin(IV) compounds are sensitive to air and moisture, so all glassware of a reaction

assembly was dried before use. All reactions were performed under an argon atmosphere

in anhydrous toluene. 2-Fluroaniline, 3,5-dichloroaniline, 3,4-dichloroaniline, maleic

anhydride, succinic anhydride, 2-hydroxybenzaldehyde, 3,5-dimethylbanzoic acid, 2-

nitro-3,4-dimethoxybenzoic acid, cetyl N,N,N-trimethyl ammonium bromide (CTAB),

3,4-dimethoxybenzoic acid, 2,4,6-trichlorobenzoic acid, organotin(IV) chlorides and

dioctyltin(IV) oxide were procured from Aldrich Chemical Company (USA). Glacial

acetic acid, acetone, toluene, dichloromethane, methanol, diethyl ether, and chloroform

were obtained from Merck Chemicals (Germany). All solvents were purified before use,

according to the literature [1,2].

2.2 Instrumentation Melting points of the synthesized compounds were recorded by MP-D Mitamura Riken

Kogyo (Japan), an electrothermal melting point apparatus in which samples are mounted

by using capillary tubes and are uncorrected. The quantitative determination of C, H, and

N was carried out using an LECO CHNS-932 analyzer. The IR spectra of the synthesized

complexes were obtained using KBr pellets on a Bio-Rad Excaliber FT-IR

spectrophotometer in range of 4000-200 cm−1.

Mass spectral data was collected on a Finnigan MAT-311A spectrometer (Germany).

The stimulated isotopic distribution was computed with a CHEMTOOL software

package [3].

The 1H, 13C and 119Sn NMR data were recorded on a Bruker ARX 300 MHz-X

spectrometer at room temperature operating at 300, 75.3, and 111.9 MHz, respectively.

The chemical shifts were given in ppm using CDCl3 as an internal reference.

X-ray crystallography was performed with a Nonius Kappa CCD detector as a Smart

apex Diffractometer (Bruker, Switzerland) using graphite monochromated Mo−Kα

radiation. Crystal data was collected by mounting a crystal on a fiber glass. The collected

data was processed by a direct [4] and subsequent difference Fourier map [5] to solve the

30

structure which was finally refined on an F2 using a full-matrix least-squares method

through anisotropic displacement parameters technique [6]. The structure of the expected

compound was plotted with the help of ORTEPII [7]. Hydrogen bondings and their

effects on the structure was also included in the crystal data.

A PerkinElmer TGA-7 Thermal Analyzer was used for thermal degradation studies and

kinetic parameters. The instrument was calibrated using the Curie point of Ni as

reference. Accurately weighed (20-30 mg) samples of complex were taken in to platinum

pans and the degradation studies were carried out in the temperature range of 50-1000 °C

with heating rates of 20 °C min-1.

Steady state florescence spectrophotometery was performed using a Perkin Elmer

Luminescence Spectrometer, Model LS 55. A clear cell having 10 mm path length was

used for these measurements at a constant temperature.

UV-visible spectrophotometeric measurements were performed with Perkin Elmer

spectrometer Lambda 20 double beam spectrophotometer, with the help of an UV Win

lab software. Simple and difference UV-visible spectroscopy was performed at 25 °C.

For difference UV-visible spectroscopy, organotin(IV) compounds of fixed

concentrations were used as a reference and samples were prepared by the addition of

different amounts of surfactants. The visible absorption spectra of additive solutions

containing surfactants in the concentration range, from pre-micellar concentration to

post-micellar concentration, were recorded using the spectrophotometer.

Electrical conductivities of CTAB and the synthesized organotin(IV) carboxylate

solutions were measured at 25 ⁰C using an Inolab 720 Precision Conductivity Meter with

a cell constant value of 0.475 cm-1.

2.3 General procedure for synthesis of carboxylic acids Solutions of maleic/succinic anhydride (0.1mmol) in acetic acid (100mL) were mixed

with a solution of the substituted aniline (0.1mmol) in acetic acid (80mL) in a 250mL

round bottom flask. The reaction mixture was magnetically stirred at room temperature

for 24 hours. The product thus obtained was precipitated due to its low solubility in

acetic acid, which was subsequently filtered and washed with cold distilled water

(400mL) in order to remove impurities and byproducts (Scheme 2.1). The physical data

for ligands are given in Table 2.1.

31

O

O

O

+R-NH2

glacial CH3COOH

24 h OH

O O

R N

H

O

O

O

+R-NH2glacial CH3COOH

24 h

R =

OH

O O

R N

H

F CH3H3C Cl

Cl

Cl

Cl

, , ,

Scheme 2.1

2.3.1 General procedure for the synthesis of Schiff Bases Solutions containing 0.1mmol of 2-hydroxbenzaldehyde in 50mL of ethanol were added

dropwise to a 50mL aqueous solution of 0.1mmol of 4-(amino methyl)cyclohexane

carboxylic acid at 25 ⁰C. The resulting solution was then refluxed for 4 hours and stirring

was continued for 24 hours at room temperature. Yellow crystals were obtained upon

cooling the flask contents (Scheme 2.2). The physical data for Schiff bases is reported in

Table 2.1.

CH2

COOHOH

CHO

NH2

+CH2

COOH

OH

CN

(i) Etoh+H2O(ii) 4 hrs reflux

(iii) 24 hrs

H

Scheme 2.2

32

Table 2.1: Physical data of synthesized carboxylic acids

Lig. No.

Reactants M.P. (oC)

Yield (%)

Recrystallization Structural formula with IUPAC name

Concentrations

Calculated (Found)

1 2 C(%) H(%) N(%)

HL1 2-Fluoroaniline

20 g (0.179 mmol)

Maleic anhydride 17.6 g (0.179 mmol)

170-171 90 Acetone

F OHN

OH

O

3-[(2′-fluorophenylamido)]propenoic acid

57.42 (57.39)

3.83 (3.79)

6.69 (6.61)

HL2

3,5-Dimethyl aniline 20.0 g

(0.165 mmol)

Maleic anhydride 16.20 g

(0.165 mmol) 208-209 95 Acetone

OHN

OHH3C

O

CH3 3-[(3′,5′-dimethylphenylamido)]propenoic acid

65.75 (65.71)

5.94 (5.92)

6.39 (6.34)

HL3

2-Fluoroaniline 20 g

(0.179 mmol)

Succinic anhydride

17.9 g (0.179 mmol)

162-163 85 Acetone

F OHN

OH

O

3-[(2′-fluorophenylamido)]propanoic acid

56.87 (56.82)

4.74 (4.71)

6.64 (6.60)

33

34

HL4

3,4-Dichloro aniline 20.0 g

(0.123 mmol)

Succinic anhydride

12.3 g (0.123 mmol)

220-221 90 Acetone

HN

OH

O

O

Cl

Cl

3-[(3′,4′-dichlorophenylamido)]propanoic acid

45.80 (45.78)

3.44 (3.40)

5.34 (5.29)

HL5

3,5-Dichloro aniline 20.0 g

(0.123 mmol)

Succinic anhydride

12.3 g (0.123 mmol) 164-165 80 Acetone

HN

OH

O

O

Cl

Cl

3-[(3′,5′-dichlorophenylamido)]propanoic acid

45.80 (45.75)

3.44 (3.41)

5.34 (5.31)

HL6

3,5-Dimethyl aniline 20.0 g

(0.165 mmol)

Succinic anhydride

16 g (0.165 mmol) 195-196 92 Acetone

HN

OH

O

O

CH3

H3C

3-[(3′,5′-dimethylphenylamido)]propanoic acid

65.16 (65.10)

6.78 (6.74)

6.33 (6.29)

HL7

4-(aminomethyl) cyclohexane

carboxylic acid 1.0g

(0.6mmol)

2-Hydroxy benzaldehyde

0.89g (0.6mmol) 160-162 70 Ethanol

COOH

CH2

N

OH

C

H

[(E)-4-((2-hydroxy benzylidene amino)methyl] cyclohexane carboxylic acid

68.96 (68.90)

7.28 (7.25)

5.36 (5.33)

The following carboxylic acids were purchased and used as ligands for complexation without further purification.

Table 2.2: Physical data of carboxylic acids

Ligand No. Mol. Wt. M.P. (oC) Structural Formula with IUPAC

Name

HL8 227.18 200-201

COOH

NO2

H3CO

OCH3 3,4-Dimethoxy- 2-nitrobenzoic acid

HL9 225.46 160-162

COOH

Cl Cl

Cl 2,4,6-Trichlorobenzoic acid

HL10 182.17 180-181

COOH

OCH3

OCH3 3,4-Dimethoxybenzoic acid

HL11 150.18 172-173

COOH

CH3H3C 3,5-Dimethylbenzoic acid

35

2.4 Synthesis of organotin(IV) complexes 2.4.1 From organotin(IV) chloride The ligand (1mmol) was dissolved in dry toluene (50mL) in a two neck round bottom

flask fitted with a condenser (for reflux purpose). A stoichiometeric amount of

triethylamine was added, followed by an appropriate amount of diorganotin(IV)

dichloride (0.5mmol) or triorganotin(IV) chloride (1mmol) solution in anhydrous

toluene (50mL) dropwise with constant stirring. The reaction mixture was refluxed for 8-

10 hours. The so obtained byproduct crystals of Et3NHCl were removed by filtration of

the reaction mixture. The synthesized organotin(IV) derivatives were isolated by

removing the solvent with the help of a rotary evaporator. A purified product was

obtained by crystallization from a chloroform: pet. Ether mixture (1:1).

R2SnCl2 + 2Et3NHL R2SnL2 + 2Et3NHCl

R3SnCl + Et3NHL R3SnL + Et3NHCl

Toluene

Reflux for 8-10 hours


Toluene

WhereR = Me/ Bu/ Ph

Scheme 2.3

2.4.2 From organotin(IV) oxide Dialkyltin(IV) derivatives of carboxylic acids were synthesized by mixing carboxylic

acid (1.0mmol) and dialkyltin(IV) oxide (0.5mmol) in anhydrous toluene (150mL) with

constant stirring under inert atmosphere of dry nitrogen using a Dean and Stark

apparatus. The mixture obtained was refluxed for 8-10 hrs. The equilibrium of the

reaction was shifted to the product by removing the water from toluene. The resultant

solution was then processed to obtained organotin(IV) derivatives in a solid state.

Recrystallization was carried out in a chloroform: pet. Ether mixture (1:1).

R2SnO + 2HL R2SnL2 + H2OToluene


WhereR = Oct/ Bu

Scheme 2.4

36

Table 2.3: Physical data of synthesized organotin(IV) complexes

Comp. No.

Quantity Used M.P (oC)/ color

Structural formula with IUPAC name

Concentrations Calculated (Found)

1st Reactant

2nd Reactant

3rd Reactant C(%) H(%) N(%)

(1) HL1 1 g

(4.78mmol)

But3SnCl 1.55 g

(4.78mmol)

Et3N 0.67 mL

(4.78mmol)

156-158/ Yellow

F OSn(C4H9)3

HN

O

O

Tributylstannicbis[3-(2-fluorophenylamido)propionate]

52.91 (52.88)

6.81 (6.79)

2.80 (2.76)

(2) HL1 1 g

(4.78mmol)

But2SnCl2 0.726 g

(2.39mmol)

Et3N 1.34 mL

(4.78mmol)

135-138/ Yellow

HN Sn(C4H9)2

2

O

O

OF

Dibutylstannicbis[3-(2-fluorophenylamido)propionate]

51.69 (51.65)

4.92 (4.89)

4.31 (4.28)

(3) HL1

1 g (4.78mmol)

Oct2SnO 0.86 g

(2.39mmol) - 85-87/

Yellow

F OSn(C8H17)2

2

HN

O

O

Dioctylstannicbis[3-(2-fluorophenylamido)propionate]

56.69 (56.65)

6.29 (6.26)

3.67 (3.63)

(4) HL1

1 g (4.78mmol)

Me2SnCl2 0.53 g

(2.39mmol)

Et3N 1.34 mL

(4.78mmol)

98-100/ Yellow

HN Sn(CH3)2

2

O

O

OF

Dimethylstannicbis[3-(2-fluorophenylamido) propionate]

48.26 (48.23)

3.65 (3.62)

5.12 (5.10)

37

F O

(5) HL1 1 g

(4.78mmol)

Ph3SnCl 1.84 g

(4.78mmol)

Et3N 0.67 mL

(4.78mmol)

105-107/ Yellow

Sn(C6H5)3HN

O

OTriphenylstannic[3-(2-fluorophenylamido)propionate]

60.11 (6.06)

3.94 (3.90)

2.50 (2.47)

(6) HL1 1 g

(4.78mmol)

Me3SnCl 0.95 g

(4.78mmol)

Et3N 0.67 mL

(4.78mmol)

140-141/ Yellow

HN Sn(CH3)3

O

O

OF

Trimethylstannic[3-(2-fluorophenylamido)propionate]

41.82 (41.77)

4.29 (4.26)

3.75 (3.72)

(7) HL1 1 g

(4.78mmol)

Ph2SnCl2 0.82 g

(2.39mmol)

Et3N 1.34 mL

(4.78mmol)

76-78/ Yellow

HN Sn(C6H5)2

2

O

O

OF

Diphenylstannicbis[3-(2-fluorophenylamido)

propionate]

55.65 (55.61)

3.48 (3.45)

4.06 (4.01)

(8) HL2 1 g

(4.6 mmol)

Ph3SnCl 1.76 g

(4.6 mmol)

Et3N 0.64mL

( 4.6mmol)

114-115/ Yellow

OSn(C6H5)3

HN

OH3C

O

CH3 Triphenylstannic [3-(3′,5′-dimethylphenylamido)

propionate]

63.27 (63.22)

4.75 (4.72)

2.46 (2.43)

38

O

(9) HL2 1 g

(4.6 mmol)

Bu3SnCl 1.48 g

(4.6 mmol)

Et3N 0.64mL

( 4.6mmol)

152-155/ Yellow

Sn(C4H9)3HN

OH3C

O

CH3 Tributylstannic [3-(3′,5′-dimethylphenylamido)

propionate]

56.58 (56.52)

7.66 (7.62)

2.75 (2.73)

(10) HL2 1 g

(4.6 mmol)

Me3SnCl 0.92 g

(4.6 mmol)

Et3N 0.64mL

( 4.6mmol)

141-143/ Yellow

OSn(CH3)3

HN

OH3C

O

CH3 Trimethylstannic[3-(3′,5′-dimethylphenylamido)

propionate]

46.99 (46.94)

5.48 (5.45)

3.66 (3.62)

(11) HL2 1 g

(4.6 mmol)

Bu2SnCl2 0.69 g

(2.3 mmol)

Et3N 1.3mL

( 4.6mmol)

107-108/ Yellow

OSn(C4H9)2

2

HN

OH3C

O

CH3

Dibutylstannicbis[3-(3′,5′-dimethylphenylamido) propionate]

58.54 (58.50)

6.40 (6.35)

2.13 (2.10)

(12) HL2 1 g

(4.6 mmol)

Me2SnCl2 0.5 g

(2.3 mmol)

Et3N 1.3mL

( 4.6mmol)

208-210/ Yellow

OSn(CH3)2

2

HN

OH3C

O

CH3

Dimethylstannicbis[3-(3′,5′-dimethylphenylamido) propionate]

53.24 (53.20)

5.12 (5.09)

4.78 (4.76)

39

O

(13) HL2 1 g

(4.6 mmol)

Ph2SnCl2 0.78 g

(2.3 mmol)

Et3N 1.3mL

( 4.6mmol)

228-230/ Yellow

Sn(C6H5)2

2

HN

OH3C

O

CH3

Diphenylstannicbis[3-(3′,5′-dimethylphenylamido) propionate]

60.84 (60.80)

4.79 (4.73)

3.94 (3.90)

(14) HL3 1 g

(4.74mmol)

Oct2SnO 0.86 g

(2.37mmol) - 88-90/

White

F OSn(C8H17)2

2

HN

O

O

Dioctylstannicbis[3-(2-fluorophenylamido)propanoate]

61.38 (61.32)

7.42 (7.38)

3.58 (3.54)

(15) HL3 1 g

(4.74mmol)

Ph2SnCl2 0.81 g

(2.37mmol)

Et3N 1.3mL

(4.74mmol)

41-43/ White

F OSn(C6H5)2

2

HN

O

O

Diphenylstannicbis[3-(2-fluorophenylamido) propanoate]

55.33 (55.28)

4.03 (3.98)

4.03 (4.00)

(16) HL3 1 g

(4.74mmol)

Bu2SnCl2 0.72 g

(2.37mmol)

Et3N 1.3mL

(4.74mmol)

114-116/ White

F OSn(C4H9)2

2

HN

O

O

Dibutylstannicbis[3-(2-fluorophenylamido)propanoate]

51.38 (51.32)

5.50 (5.45)

4.28 (4.22)

(17) HL3 1 g

(4.74mmol)

Bu3SnCl 1.54 g

(4.74mmol)

Et3N 0.65mL

(4.74mmol)

38-40/ White

HN Sn(C4H9)3

O

O

OF

Tributylstannic[3-(2-fluorophenylamido)propanoate]

52.69 (52.64)

7.19 (7.16)

2.79 (2.77)

40

F O

(18) HL3 1 g

(4.74mmol)

Ph3SnCl 1.82 g

(4.74mmol)

Et3N 0.65mL

(4.74mmol)

133-135/ White

Sn(C6H5)3HN

O

O

Triphenylstannic[3-(2-fluorophenylamido)propanoate]

55.89 (55.85)

4.28 (4.25)

2.49 (2.45)

(19) HL3 1 g

(4.74mmol)

Me3SnCl 0.94 g

(4.74mmol)

Et3N 0.65mL

(4.74mmol)

158-161/ White

HN Sn(CH3)3

O

O

OF

Trimethylstannic[3-(2-fluorophenylamido)propanoate]

41.60 (41.53)

4.80 (4.75)

3.73 (3.70)

(20) HL4 1 g

(3.80mmol)

Oct2SnO 0.69 g

(1.9 mmol) - 128-131/

White

OSn(C8H17)2

2

HN

OCl

OClDioctylstannicbis[3-(3′,4′-dichlorophenylamido)

propanoate]

49.77 (49.72)

5.76 (5.72)

3.22 (3.20)

(21) HL4 1 g

(3.80mmol)

Bu3SnCl 1.25 g

(3.80mmol)

Et3N 0.53mL

(3.80mmol)

66-68/ White

OSn(C4H9)3

HN

OCl

OCl

Tributylstannic[3-(3′,4′-dichlorophenylamido) propanoate]

47.83 (47.80)

6.34 (6.30)

2.54 (2.52)

(22) HL4 1 g

(3.80mmol)

Bu2SnCl2 0.58 g

(1.9 mmol)

Et3N 1.0mL

(3.80mmol)

189-190/ White

OSn(C4H9)2

2

HN

OCl

OCl Dibutylstannicbis[3-(3′,4′-dichlorophenylamido)

propanoate]

44.44 (44.40)

4.49 (4.43)

3.17 (3.13)

41

O

(23) HL4 1 g

(3.80mmol)

Ph3SnCl 1.47 g

(3.80mmol)

Et3N 0.53mL

(3.80mmol)

161-162/ White

Sn(C6H5)3HN

OCl

OCl

Triphenylstannic[3-(3′,4′-dichlorophenylamido) propanoate]

52.46 (52.41)

3.55 (3.52)

3.83 (3.81)

(24) HL4 1 g

(3.80mmol)

Me3SnCl 0.75 g

(3.80mmol)

Et3N 0.53mL

(3.80mmol)

159-160/ White

OSn(CH3)3

HN

OCl

OCl

Trimethylstannic[3-(3′,4′-dichlorophenylamido) propanoate]

36.62 (36.58)

3.99 (3.96)

3.29 (3.25)

(25) HL5 1 g

(3.80mmol)

Oct2SnO 0.69 g

(1.9mmol) - 145-146/

White

OSn(C8H17)2

2

HN

OCl

O

Cl Dioctylstannicbis[3-(3′,5′-dichlorophenylamido)

propanoate]

49.77 (49.74)

5.76 (5.72)

3.22 (3.18)

(26) HL5 1 g

(3.80mmol)

Ph3SnCl 1.47 g

(3.80mmol)

Et3N 0.53mL

(3.80mmol)

189-190/ White

OSn(C6H5)3

HN

OCl

O

Cl Triphenylstannic[3-(3′,5′-dichlorophenylamido)

propanoate]

52.46 (52.42)

3.55 (3.52)

3.83 (3.80)

42

O

(27) HL5 1 g

(3.80mmol)

Bu2SnCl2 0.58 g

(1.9 mmol)

Et3N 1.0mL

(3.80mmol)

128-130/ White

Sn(C4H9)2

2

HN

OCl

O

ClDibutylstannicbis[3-(3′,5′-dichlorophenylamido)

propanoate]

44.44 (44.41)

4.49 (4.47)

3.17 (3.15)

(28) HL5 1 g

(3.80mmol)

Bu3SnCl 1.25 g

(3.80mmol)

Et3N 0.53mL

(3.80mmol)

69-70/ White

OSn(C4H9)3

HN

OCl

O

ClTributylstannic[3-(3′,5′-dichlorophenylamido)

propanoate]

47.83 (47.79)

6.34 (6.30)

2.54 (2.51)

(29)

HL5 1 g

(3.80 mmol)

Me2SnCl2 0.42 g

(1.9 mmol)

Et3N 1.0mL

(3.80mmol)

semisolid/ White

OSn(CH3)2

2

HN

OCl

O

ClDimethylstannicbis[3-(3′,5′-dichlorophenylamido)

propanoate]

39.23 (39.20)

3.27 (3.25)

4.16 (4.14)

(30)

HL5 1 g

(3.80 mmol)

Me3SnCl 0.75 g

(3.80mmol)

Et3N 0.53mL

(3.80mmol)

190-192/ White

OSn(CH3)3

HN

OCl

O

Cl Trimethylstannic[3-(3′,5′-dichlorophenylamido)

propanoate]

36.62 (36.58)

3.99 (3.94)

3.29 (3.26)

43

O

(31) HL6 1 g

(4.6 mmol)

Me3SnCl 0.89 g

(4.6 mmol)

Et3N 0.63mL

( 4.6mmol)

98-100/ White

Sn(CH3)3HN

OH3C

O

CH3 Trimethylstannic[3-(3′,5′-dimethylphenylamido)

propanoate]

30.77 (30.74)

3.95 (3.93)

2.39 (2.37)

(32) HL6 1 g

(4.6 mmol)

Bu3SnCl 1.46 g

(4.6 mmol)

Et3N 0.63mL

( 4.6mmol)

Liquid state/ White

OSn(C4H9)3

HN

OH3C

O

CH3 Tributylstannic[3-(3′,5′-dimethylphenylamido)

propanoate]

56.36 (56.31)

8.02 (8.01)

2.74 (2.69)

(33) HL6 1 g

(4.6 mmol)

Ph3SnCl 1.73 g

(4.6 mmol)

Et3N 0.63mL

( 4.6mmol)

128-129/ White

OSn(C6H5)3

HN

OH3C

O

CH3Triphenylstannic[3-(3′,5′-dimethylphenylamido)

propanoate]

63.05 (63.01)

5.08 (5.01)

2.45 (2.41)

(34) HL6 1 g

(4.6 mmol)

Me2SnCl2 0.489 g

(2.3 mmol)

Et3N 1.26mL

( 4.6mmol)

163-165/ White

OSn(CH3)2

2

HN

OH3C

O

CH3

Dimethylstannicbis[3-(3′,5′-dimethylphenylamido) propanoate]

52.88 (52.85)

5.76 (5.74)

4.75 (4.73)

44

O

(35) HL6 1 g

(4.6 mmol)

Bu2SnCl2 0.68 g

(2.3 mmol)

Et3N 1.26mL

( 4.6mmol)

140-142/ White

Sn(C4H9)2

2

HN

OH3C

O

CH3

Dibutylstannicbis[3-(3′,5′-dimethylphenylamido) propanoate]

58.18 (58.15)

4.85 (4.81)

4.24 (4.20)

(36) HL6 1 g

(4.6 mmol)

Ph2SnCl2 0.77 g

(2.3 mmol)

Et3N 1.26mL

( 4.6mmol)

210-211/ White

OSn(C6H5)2

2

HN

OH3C

O

CH3 Diphenylstannicbis[3-(3′,5′-dimethylphenylamido)

propanoate]

60.50 (60.44)

5.32 (5.29)

3.92 (3.87)

(37) HL6 1 g

(4.6 mmol)

Oct2SnO 0.80g

(2.3 mmol)

Et3N 1.26mL

( 4.6mmol)

218-221/ White

OSn(C8H17)2

2

HN

OH3C

O

CH3 Dioctylstannicbis[3-(3′,5′-dimethylphenylamido)

propanoate]

53.50 (53.43)

7.64 (7.61)

4.46 (4.43)

(38) HL7 1 g

(3.83mmol)

Me2SnCl2 0.42 g

(1.92mmol)

Et3N 1.07 mL

(3.83mmol)

166-168/ Yellow

COO Sn(CH3)2OH

CH

CH2

2

N

Dimethylstannicbis[(E)-4-((2-hydroxy benzylidene amino)methyl) cyclohexanecarboxylate]

57.31 (57.29)

6.27 (6.25)

4.18 (4.15)

45

COO Sn(C4H9)2OH

(39) HL7 1 g

(3.83mmol)

Bu2SnCl2 0.58 g

(1.92mmol)

Et3N 1.07 mL

(3.83mmol)

153-154/ Yellow

CH

CH2

2

N Dibutylstannicbis[(E)-4-((2-hydroxybenzylidene

amino)methyl)cyclohexanecarboxylate]

61.97 (61.92)

4.89 (4.87)

3.80 (3.77)

(40) HL7 1 g

(3.83mmol)

Ph2SnCl2 0.66 g

(1.92mmol)

Et3N 1.07 mL

(3.83mmol)

143-145/ Yellow

COO Sn(C6H5)2OH

CH

CH2

2

N Diphenylstannicbis[(E)-4-((2-hydroxybenzylidene


63.32 (63.27)

6.03 (6.01)

3.52 (3.48)

(41) HL7 1 g

(3.83mmol)

Oct2SnO 0.69 g

(1.92mmol) - semisolid/

Yellow

COO Sn(C8H17)2OH

CH

CH2

2

N Dioctylstannicbis[(E)-4-((2-hydroxybenzylideneamino)

methyl) cyclohexanecarboxylate]

65.09 (65.03)

6.13 (6.09)

3.30 (3.28)

(42) HL7 1 g

(3.83mmol)

Me3SnCl 0.76 g

(3.83mmol)

Et3N 0.535 mL

(3.83mmol)

166-167/ Yellow

COO Sn(OH

CH

CH2N

CH3)3

Trimethylstannic[(E)-4-((2-hydroxybenzylidene

amino)methyl) cyclohexanecarboxylate]

50.82 (50.77)

6.35 (6.31)

3.29 (3.27)

(43) HL7 1 g

(3.83mmol)

Bu3SnCl 1.25 g

(3.83mmol)

Et3N 0.535 mL

(3.83mmol)

67-68/ Yellow

COO Sn(C HOH

CH

CH2N

4 9)3

Tributylstannic[(E)-4-((2-hydroxybenzylidene


58.80 (58.76)

8.17 (8.14)

2.54 (2.50)

46

COO Sn(C6H5)3OH

(44) HL7 1 g

(3.83mmol)

Ph3SnCl 1.48 g

(3.83mmol)

Et3N 0.535 mL

(3.83mmol)

143-144/ Yellow

CH

CH2N Triphenylstannic[(E)-4-((2-hydroxybenzylideneamino)

methyl) cyclohexanecarboxylate]

80.65 (80.61)

6.72 (6.70)

2.85 (2.82)

(45) HL8 1 g

(4.4 mmol)

Me3SnCl 0.88g

(4.4 mmol)

Et3N 0.62 mL

(4.4 mmol)

58-59/ Yellow

H CO3

H3CO COO Sn(CH3)3

NO2 Trimethylstannic(4′,5′-dimethoxy -2′-nitrobenzoate)

36.83 (36.80)

4.35 (4.32)

3.58 (3.56)

(46) HL8 1 g

(4.4 mmol)

Bu3SnCl 1.43 g

(4.4 mmol)

Et3N 0.62 mL

(4.4 mmol)

185-187/ Yellow

H CO3

H3CO COO Sn(C4H9)3

NO2 Tributylstannic(4′,5′-dimethoxy -2′-nitrobenzoate)

48.74 (48.70)

6.77 (6.75)

2.71 (2.70)

(47) HL8 1 g

(4.4 mmol)

Ph3SnCl 1.69 g

(4.4 mmol)

Et3N 0.62 mL

(4.4 mmol)

168-169/ Yellow

H CO3

H3CO COO Sn(C6H5)3

NO2 Triphenylstannic(4′,5′-dimethoxy -2′-nitrobenzoate)

56.15 (56.12)

3.99 (3.98)

2.43 (2.40)

(48) HL8

1 g (4.4 mmol)

Me2SnCl2 0.48 g

(2.2 mmol)

Et3N 1.2 mL

(4.4 mmol)

112-113/ Yellow

H3CO

H3CO COO Sn(CH3)2

2NO2

Dimethylstannicbis(4′,5′-dimethoxy -2′-nitrobenzoate)

39.87 (39.84)

3.65 (3.64)

4.65 (4.63)

47

H3CO

(49) HL8 1 g

(4.4 mmol)

Bu2SnCl2 0.67g

(2.2 mmol)

Et3N 1.2 mL

(4.4 mmol)

130-131/ Yellow

H3CO COO Sn(C4H9)2

2NO2

Dibutylstannicbis(4′,5′-dimethoxy -2′-nitrobenzoate)

45.58 (45.55)

4.08 (4.04)

4.96 (4.92)

(50) HL8 1 g

(4.4 mmol)

Ph2SnCl2 0.76 g

(2.2 mmol)

Et3N 1.2 mL

(4.4 mmol)

170-171/ Yellow

H CO3

H3CO COO Sn(C6H5)2

2NO2

Diphenylstannicbis(4′,5′-dimethoxy -2′-nitrobenzoate)

53.1 (53.06)

3.8 (3.77)

4.1 (4.07)

(51) HL8 1 g

(4.4 mmol)

Oct2SnO 0.79 g

(2.2 mmol) - 68-70/

Yellow

H CO3

H3CO COO Sn(C8H17)2

2NO2

Dioctylstannicbis(4′,5′-dimethoxy -2′-nitrobenzoate)

51.13 (51.10)

6.26 (6.24)

3.54 (3.63)

(52) HL9 1 g

(4.4 mmol)

Ph3SnCl 1.7 g

(4.4 mmol)

Et3N 0.62mL

(4.4 mmol)

147-148/ White

Cl COO Sn(C6H5)3

Cl

Cl

Triphenylstannic(2′,4′,6′-trichlorobenzoate)

52.13 (52.10)

2.95 (2.90) -

(53) HL9 1 g

(4.4 mmol)

Ph2SnCl2 0.76 g

(2.2 mmol)

Et3N 1.2mL

(4.4 mmol)

278-280/ White

Sn(C6H5)2

2

Cl COO

Cl

Cl

Diphenylstannicbis(2′,4′,6′-trichlorobenzoate)

43.19 (43.16)

1.94 (1.92) -

48

Cl

(54) HL9 1 g

(4.4 mmol)

Oct2SnO 0.8 g

(2.2 mmol) - 117-118/

White Sn(C8H17)2

2

Cl COO

Cl Dioctylstannicbis(2′,4′,6′-trichlorobenzoate)

45.28 (45.24)

4.78 (4.75) -

(55) HL9 1 g

(4.4 mmol)

Bu2SnCl2 0.67g

(2.2 mmol) - 224-225/

White Sn(C4H9)2

2

Cl COO

Cl

Cl

Dibutylstannicbis(2′,4′,6′-trichlorobenzoate)

38.65 (38.60)

3.22 (3.20) -

(56) HL9 1 g

(4.4 mmol)

Bu3SnCl 1.3g

(4.4 mmol)

Et3N 0.62mL

(4.4 mmol)

79-80/ White

Cl COO Sn(C4H9)3

Cl

Cl

Tributylstannic(2′,4′,6′-trichlorobenzoate)

44.23 (44.16)

5.63 (5.59) -

(57) HL9 1 g

(4.4 mmol)

Me3SnCl 0.88 g

(4.4 mmol)

Et3N 0.62mL

(4.4 mmol)

159-160/ White

Cl COO Sn(CH3)3

Cl

Cl

Trimethylstannic(2′,4′,6′-trichlorobenzoate)

30.81 (30.79)

2.82 (2.82) -

(58) HL10 1 g

(5.5 mmol)

Ph3SnCl 2.11 g

(5.5 mmol)

Et3N 0.77mL

(5.5 mmol)

269-270/ White

H CO3

COOH3CO Sn(C6H5)3

Triphenylstannic(3′,4′-dimethoxybenzoate)

60.90 (60.86)

4.51 (4.48) -

49

H3CO

(59) HL10 1 g

(5.5 mmol)

Bu2SnCl2 0.83 g

(2.75mmol)

Et3N 1.4mL

(5.5 mmol)

133-134/ White

Sn(C4H9)2

2

H3CO COO

Dibutylstannicbis(3′,4′-dimethoxybenzoate)

53.29 (53.25)

5.92 (5.89) -

(60) HL10 1 g

(5.5 mmol)

Bu3SnCl 1.78 g

(5.5 mmol)

Et3N 0.77mL

(5.5 mmol)

89-90/ White

H CO3

COOH3CO Sn(C4H9)3

Tributylstannic(3′,4′-dimethoxybenzoate)

53.39 (53.35)

7.63 (7.60) -

(61) HL10 1 g

(5.5 mmol)

Me3SnCl 1.09 g

(5.5 mmol)

Et3N 0.77mL

(5.5 mmol)

141-142/ White

H CO3

COOH3CO Sn(CH3)3

Trimethylstannic(3′,4′-dimethoxybenzoate)

41.62 (41.59)

5.20 (5.18) -

(62) HL10 1 g

(5.5 mmol)

Me2SnCl2 0.60 g

(2.75mmol)

Et3N 1.4mL

(5.5 mmol)

78-80/ White

H3CO

Sn(CH3)2

2

H3CO COO

Dimethylstannicbis(3′,4′-dimethoxybenzoate)

47.06 (47.01)

4.71 (4.68) -

(63) HL10 1 g

(5.5 mmol)

Ph2SnCl2 0.94 g

(2.75mmol)

Et3N 1.4mL

(5.5 mmol)

117-119/ White

H3CO

Sn(C6H5)2

2

H3CO COO

Diphenylstannicbis(3′,4′-dimethoxybenzoate)

52.94 (52.91)

4.12 (4.10) -

50

H3CO

(64) HL10 1 g

(5.5 mmol)

Oct2SnO 1.0 g

(2.75mmol) -

Jelly like/

White Sn(C8H17)2

2

H3CO COO

Dioctylstannicbis(3′,4′-dimethoxybenzoate)

57.63 (57.60)

7.35 (7.33) -

(65) HL11 1 g

(6.7 mmol)

Ph3SnCl 2.57 g

(6.7 mmol)

Et3N 0.93mL

(6.7 mmol)

254-255/ White

H C3

COO Sn(C6H5)3

H3C Triphenylstannic(3′,5′-dimethylbenzoate)

64.80 (64.73)

4.80 (4.77) -

(66) HL11 1 g

(6.7 mmol)

Oct2SnO 1.2 g

(3.35mmol) - 145-146/

White Sn(C8H17)2

2

H C

COO

H3C

3

Dioctylstannicbis(3′,5′-dimethylbenzoate)

63.35 (63.32)

8.07 (8.01) -

(67) HL11 1 g

(6.7 mmol)

Me3SnCl 1.33 g

(6.7 mmol)

Et3N 0.93mL

(6.7 mmol)

114-115/ White

H C3

COO Sn(CH3)3

H3C Trimethylstannic(3′,5′-dimethylbenzoate)

45.85 (45.80)

5.73 (5.70) -

51

52

(68) HL11 1 g

(6.7 mmol)

Bu3SnCl 2.2 g

(6.7 mmol)

Et3N 0.93mL

(6.7 mmol)

121-123/ White

COO

H3C

H3C

Sn(C4H9)3

Tributylstannic(3′,5′-dimethylbenzoate)

57.27 (57.21)

8.18 (8.15) -

(69) HL11 1 g

(6.7 mmol)

Me2SnCl2 0.73 g

(3.35mmol)

Et3N 1.8mL

(6.7 mmol)

183-184/ White

Sn(CH3)2

2

COO

H3C

H C3

Dimethylstannicbis(3′,5′-dimethylbenzoate)

58.97 (58.93)

3.69 (3.67) -

(70) HL11 1 g

(6.7 mmol)

Bu2SnCl2 1.01 g

(3.35mmol)

Et3N 1.8mL

(6.7 mmol)

131-132/ White

Sn(C4H9)2

2

COO

H3C

H C3

Dibutylstannicbis(3′,5′-dimethylbenzoate)

58.65 (58.62)

6.77 (6.73) -

2.5 Antifungal activity The synthesized complexes were tested for their biocidal activity against various

pathogens; trichphyton longifuses, aspergillus flavus, candida glabrata and candida

albicans. Solutions of organotin(IV) complexes of 200μg/mL in sterile DMSO were

added to a medium containing potato, agar, dextrose, and distilled water. The inhibition

effect of organotin(IV) complexes on the growth of fungi was taken after 96 hours and is

reported as the activity of these complexes [8]. The diameter of the fungal colony was

taken as a linear growth of the fungus. Controls were also run and 03 replicates were

used in each case. The percent growth inhibition in all the replicates was recorded and

calculated by the following equation:

Percentage inhibition = (C-T) × 100/C

where C is the linear growth of the fungus in the control plate and T is the linear growth

of the fungus in the test plate.

2.6 Antibacterial activity Synthesized organotin(IV) complexes were subjected to screening tests for their

antibacterial activity, against different bacterial strains including bacillus subtilis,

eschericha coli, shigella flexenari and pseudomonas aeruginosa, using the agar well

diffusion method [9]. A broth culture medium was prepared by the combination of 3g of

beef cream, 10g of albumin and 5g of sodium chloride in 1000mL distilled water at 37

⁰C. In the first step, 5mm of the broth culture medium in Petri-dishes was allowed to

solidify and then 0.2mL of the broth culture medium containing approximately 1х106

colony forming unit (CFU)/mL of Colon was poured on the surface followed by making

three holes of 3mm diameter carefully. These were completely filled with the test

solutions of 1mg/mL strength in DMSO. Negative and positive controls were also run by

making holes containing DMSO (negative control) and the reference antibacterial drug

(positive control). The bacterium was incubated for 24 hours at 37 ⁰C and then the

diameter of the inhibiting area around each hole was measured and that was reported as

the biocidal activity of organotin(IV) complexes [10]. The average of three diameters

was calculated for each sample, using streptomycin as a reference drug.

53

2.7 Antiviral study To test the antiviral activities of these compounds, the Gaussia luciferase Assay system

were used. In this assay Jc1FLAG2(p7-nsGluc2A) [11], was used to infect the Huh 7.5

cells. It is a monocistronic reporter virus encoding the full-length infectious Jc1 genome

with a secreted Gaussia luciferase reporter. The assay of luciferase activity in infected

cell supernatants was used to monitor viral replication.

Huh7.5 cells were maintained in Dulbecco’s modified Eagle’s medium (DMEM;

Invitrogen) supplemented with 4,500mg/L glucose, 2mM L-glutamine, 10% heat-

inactivated fetal calf serum (FCS), nonessential amino acids, 20mM HEPES, 100U/mL

penicillin, and 100µg/mL streptomycin, and incubated at 37 °C, 5% CO2, and 100%

relative humidity. Test compounds were diluted in dimethylsulfoxide (DMSO) to give a

final concentration in the assay of 1mg/mL. The cells were infected (with or without

inhibitors), with Jc1FLAG2 (p7-nsGluc2A) with MOI-0.1 (1E4 TCID50/well) in the

presence of selected inhibitors tested in this study. The concentration of each inhibitor

used was 1nM to 1000nM. Assays were performed in triplicate. All cells were

maintained at 37 °C in a humidified environment containing 5% CO2 in a cell culture

incubator. Huh-7.5 cells were incubated at 37 °C for 3 days. To measure the luciferase

activity the EnduRen substrate (Promega) was used. The culture medium was removed

on the third day and cells were washed with 1xPBS after 48 hours. A maximum activity

(100% of control) and the background were derived from control wells containing

DMSO alone or from uninfected wells. 100µL of Lysis Buffer were added per well

(Renilla Luciferase Assay Lysis Buffer 5x-needs to be diluted to 1x in water). Then

incubate for 5 min at room temperature and mixing occurred before transferring it to a

96-Well plate. Whirle parafilm around the plate, label and store at -80 °C until it get

ready to read on luminometer.

2.8 Drug delivery system A drug delivery study for selected compounds was carried out using a UV-visible

spectrophotometer, a steady state florescence spectrophotometer and a conductivity

meter.

A stock solution of organotin(IV) carboxylates, 5×10-3 molar, was prepared in methanol.

The stock solution was diluted with distilled water (≤ 1μScm-1) in the range of 10-6 molar

for UV-visible spectrometric studies. For steady state spectroscopy dilutions were made

54

in the range of 10-9 molar. These solutions were further used for the surfactant-organotin

interaction studies by preparing a series of samples, each containing the fixed

concentration of the corresponding organotin(IV) carboxylate. Successive additions of

2mL surfactant solution to the above mentioned solution was made for the spectroscopic

and conductivity measurements. Resultant solutions were incubated overnight at 37 °C.

Critical micelle concentrations (cmc) of the surfactant used in the study were confirmed

by conductivity measurements. The specific conductance of the surfactant solution with

and without organotin(IV) carboxylates was measured at 37 ⁰C.

55

56

REFERENCES

[1] W. L. F. Armarego and D. D. Perin, in “Purification of laboratory chemicals”, 4th Edn, Pergamon, Oxford, (1997).

[2] W. L. F. Armaergo and C. L. L. Chai, in “Purification of Laboratory Chemical”, 5th Edn, Butterworth-Heinemann, New York, (2003).

[3] S. Frank, Chem. Tool Prog., (1990).

[4] A. Altmore, M. Cascarano, C. Giacovazzo and A. Guagliardi, SIR92, J. App. Cryst., 26 (1993) 343.

[5] P. T. Beurskens, G. Admiraal, G. Beurskens, W. P. Bosman, R. De Gelder, R. Israel and J. M. M. Smiths, “The DIRDIF-94 Program System”, Technical Report of the Crystallography Laboratory, University of Nijmwegen, The Netherlands, (1994).

[6] G. M. Sheldrick, SHELX97. Program for Crystal Structure Solution and Renement, University of Gottingen, Germany, (1997).

[7] C. K. Johnson, ORTEPII, Report ORNL-5138, Oak Ridge National Laboratory, Tennessee, USA, (1976).

[8] F. Junich, U. Yasuhiko, I. Kouzou, Method of Pesticide Experiment Fungicide, Agricultural Press of China, Beijing, (1991).

[9] A. Rahman, M. I. Choudhary and W. J. Thomsen, in ‘Bioassay Techniques for Drug Development’, Harward Academic Press, Amsterdam, (2001) pp.14-20.

[10] Z. L. You, H. L. Z. Zhu, Anorg. Allg. Chem., 630 (2004) 2754.

[11] D. M. Tscherne, M. J. Evans, T. von Hahn, C. T. Jones, Z. Stamataki, J. A.

McKeating, B. D. Lindenbach, C. M. Rice. J. Virol., 81 (2007) 3693.

Chapter−3

RESULTS AND DISCUSSIONS

3.1 Synthesis of organotin(IV) complexes The carboxylic acids used for complexation were synthesized by methods described in

the experimental section. Triorganotin(IV) carboxylates and diorganotin(IV)

dicarboxylates were synthesized by refluxing a solution of carboxylic acid with

triorganotin(IV) chloride (1:1 molar ratio) or diorganotin(IV) dichloride (2:1molar ratio),

using dry toluene as a media of reaction in the presence of triethylamine. Dioctyltin(IV)

dicarboxylates were synthesized by the reaction of the carboxylic acid with a

dioctyltin(IV) oxide in a 2:1molar ratio in toluene. The water formed was removed from

the reaction mixture by azeotropic distillation in dry toluene using a Dean and Stark

apparatus. The complexes obtained by these methods were solid and are stable to light

and dry air. Their yield was good. Various analytical techniques like FT-IR, NMR, mass

spectrometry and X-ray single crystal analysis have been used for the characterizations

of these complexes. The various kinetic parameters were studies from their

thermogravimetric analysis. The biological activity of the synthesized complexes was

also studied. The drug delivery system of the selected synthesized complexes was

studied by different techniques like UV-visible, steady state florescence and

conductometry.

3.2 FT-IR spectroscopy The ligand coordinated to the tin(IV) atom of the organotin(IV) moiety through the

oxygen forms the organotin(IV) complex. The complex formation and the coordination

sites of the ligand considering a stable complex formation is confirmed by comparing the

selected vibrational bands of the ligands and their organotin(IV) complexes using FT-IR

spectroscopy. The bands of our interest are νOH, νNH, νC=C, νC=N and νCO of the ligands,

νSn-C, νCH of the alkyl or aryl of the organotin(IV) moiety and νSn–O of the complex.

When comparing the FT-IR spectra of the free ligand (HL) and their complexes, it is

found that the characteristic νOH band of the carboxylic acid is not present in the spectra

of the synthesized complexes. This is an indication that the hydrogen attached to oxygen

of the carboxylic group is replaced by the organotin(IV) species and also provides the

preliminary information about complex formation through Sn-O bond. The characteristic

57

stretching frequencies of complexes are νSn–C, νSn–O and νSn–O–Sn. The new absorption

bands in the spectra of the complexes, which characterize the complex formation are the

Sn–O stretching vibrations at 486-412 cm-1 while a band for Sn–C appears in the range of

501-586 cm-1. These bands confirm the formation of organotin(IV) carboxylates [1-4].

The C=O band of the peptide group appears in the range of 1680-1748 cm-1 in the free

ligands 1-6 and are observed in the range of 1690-1746 cm-1 in the complexes which

confirms that the C=O groups of the peptide linkage did not coordinate to organotin(IV)

moieties.

Moreover, the strong band in the range from 3308-3388 cm-1 is characteristic for an NH

group and it is present in the spectra of the free ligands HL1-HL6. The presence of νNH

absorptions in the complexes shows that the NH group did not participate via intra/

intermolecular modes of interactions.

The band for C=N appeared in the region of 1650-1665 cm-1 for a Schiff base and its

complexes, shows that the C=N group is not involved in the complexation with

organotin(IV) moieties.

FT-IR spectroscopy is not only used for the determination of complex formation but also

reflects the mode of co-ordination in di- and tri-substituted organotin(IV) carboxylates.

The value of Δν i.e. the difference of asymmetric νasym(COO) and symmetric νsym(COO)

absorption frequencies suggests the mode of coordination of the ligand. A value smaller

than 200 cm-1 indicates that the carboxylate moiety is bidentate and is coordinated

through both oxygen atoms, while the value greater than 200 cm-1 indicates that the

carboxylate moiety coordinates in a monodentate manner. For the symmetric bidentate

coordination Δν is considerably smaller compared to that of the ionic carboxylate

compounds [5-7]. In case of a bidentate coordination mode, the carboxylate group in the

organotin(IV) carboxylates exists in a bridged structure in the solid state, when

substituted R groups at tin atom are small in size. These values are also used for the

geometry predictions as well.

The carboxylate group in diorganotin(IV) carboxylates containing Δν value < 200 cm-1

shows bidentate nature which is considered to occur in five and six coordination metal

centers named as skew- trapezoidal bipyramidal geometry. The co-ordination geometry

of tin, in triorganotin(IV) carboxylates, is known to adopt a variety of motifs because it

depends upon the nature of the R group attached to the metal center. Triorganotin(IV)

58

carboxylates having Δν values < 200 cm-1 indicate a trigonal bipyramidal geometry and

the carboxylate group is coordinating to two different tin atoms. In some phenyl

substituted organotin(IV) moieties the both oxygen atoms are coordinating to the same

tin atom as the bulky phenyl groups in these cases do not allow the other organotin(IV)

moiety to approach the oxygen of the same carboxylic group. The case of compounds

having Δν > 200 cm-1 reflects a monodentate nature with a tetrahedral geometry.

Important IR bands from the FT-IR spectra of the free ligands and their synthesized

complexes are reported in the Table 3.1-3.11.

Table 3.1: Assignments of characteristic FT-IR vibrations of 3-[(2′-fluorophenylamido)]propenoic acid and its organotin(IV) complexes.

Compound

IR Band (cm-1)

νOH νNH νC=O νCOO

Δν νSn-C νSn-O νCOOasymm νCOOsymm

HL1 3410 3375 1726 1531 1310 221 - -

1 - 3381 1712 1591 1474 117 519 423

2 - 3359 1721 1547 1408 139 558 439

3 - 3365 1719 1551 1410 141 560 472

4 - 3364 1720 1556 1421 135 533 467

5 - 3384 1700 1586 1470 116 258 467

6 - 3368 1699 1586 1465 121 546 415

7 - 3392 1713 1543 1428 115 259 444

59

Table 3.2: Assignments of characteristic FT-IR vibrations of 3-[(3′, 5′-dimethylphenylamido)]propenoic acid and its organotin(IV) complexes.

Compound

IR Band (cm-1)



HL2 3435 3308 1730 1580 1350 230 - -

8 - 3320 1726 1550 1411 139 240 428

9 - 3300 1713 1556 1412 144 535 431

10 - 3301 1709 1540 1429 111 547 425

11 - 3309 1724 1560 1420 140 580 439

12 - 3315 1708 1562 1417 145 515 447

13 - 3327 1712 1535 1415 120 248 449

Table 3.3: Assignments of characteristic FT-IR vibrations of 3-[(2′-fluorophenylamido)]propanoic acid and its organotin(IV) complexes.

Compound

IR Band (cm-1)



HL3 3415 3373 1714 1533 1320 213 - -

14 - 3380 1697 1585 1430 155 522 462

15 - 3378 1703 1598 1465 133 250 466

16 - 3386 1703 1575 1445 130 519 462

17 - 3374 1713 1565 1412 153 513 454

18 - 3383 1709 1556 1422 134 245 466

19 - 3385 1699 1578 1419 156 530 462

60

Table 3.4: Assignments of characteristic FT-IR vibrations of 3-[(3′,4′-dichlorophenylamido)]propanoic acid and its organotin(IV) complexes.

Compound

IR Band (cm-1)



HL4 3460 3324 1718 1531 1319 212 - -

20 - 3330 1700 1552 1403 149 516 432

21 - 3327 1705 1548 1406 142 520 416

22 - 3328 1697 1541 1410 131 509 419

23 - 3335 1702 1546 1424 122 244 453

24 - 3321 1705 1544 1416 128 519 454

Table 3.5: Assignments of characteristic FT-IR vibrations of 3-[(3′, 5′-dichlorophenylamido)]propanoic acid and its organotin(IV) complexes.

Compound

IR Band (cm-1)



HL5 3435 3388 1709 1565 1335 230 - -

25 - 3387 1695 1544 1407 137 540 471

26 - 3375 1686 1583 1463 120 241 438

27 - 3379 1703 1565 1435 130 564 422

28 - 3383 1694 1548 1442 106 586 454

29 - 3385 1707 1556 1439 117 518 426

30 - 3382 1699 1560 1426 134 549 412

61

Table 3.6: Assignments of characteristic FT-IR vibrations of 3-[(3′, 5′-dimethylphenylamido)]propanoic acid and its organotin(IV) complexes.

Compound

IR Band (cm-1)



HL6 3415 3326 1748 1532 1310 222 - -

31 - 3302 1736 1570 1433 164 512 465

32 - 3337 1745 1565 1450 115 534 423

33 - 3320 1735 1554 1416 138 244 452

34 - 3317 1746 1550 1432 118 526 486

35 - 3334 1740 1560 1444 116 540 460

36 - 3340 1736 1575 1456 119 253 474

37 - 3300 1754 1568 1429 139 513 445

Table 3.7: Assignments of characteristic FT-IR vibrations of [(E)-4-((2-hydroxybenzylideneamino)methyl)cyclohexane Carboxylic acid and its

organotin(IV) complexes.

Compound

IR Band (cm-1)

νOH νCOO


HL7 3240 1635 1372 263 - -

38 - 1641 1447 194 516 403

39 - 1634 1450 184 525 459

40 - 1645 1452 193 248 456

41 - 1633 1449 184 526 452

42 - 1635 1495 140 510 449

43 - 1637 1488 149 520 457

44 - 1645 1480 165 242 453

62

Table 3.8: Assignments of characteristic FT-IR vibrations of 4, 5-dimethoxy- 2-nitrobenzoic acid and its organotin(IV) complexes.

Compound

IR Band (cm-1)

νOH νCOO


HL8 3435 1500 1389 211 - -

45 - 1526 1379 147 563 440

46 - 1518 1360 158 547 446

47 - 1518 1375 143 259 448

48 - 1528 1355 173 565 435

49 - 1528 1376 152 566 448

50 - 1508 1363 145 235 445

51 - 1522 1373 149 554 448

Table 3.9: Assignments of characteristic FT-IR vibrations of 2,4,6-trichlorobenzoic acid and its organotin(IV) complexes.

Compound

IR Band (cm-1)

νOH νCOO


HL9 3435 1536 1325 211 - -

52 - 1556 1390 166 253 453

53 - 1545 1390 150 245 443

54 - 1555 1400 155 565 435

55 - 1566 1436 130 564 452

56 - 1562 1438 124 548 482

57 - 1569 1394 175 541 465

63

Table 3.10: Assignments of characteristic FT-IR vibrations of 3, 4-dimethoxybenzoic acid and its organotin(IV) complexes.

Compound

IR Band (cm-1)

νOH νCOO


HL10 3347 1605 1342 263 - -

58 - 1603 1409 194 249 443

59 - 1598 1412 186 526 441

60 - 1602 1438 164 517 431

61 - 1603 1419 184 528 438

62 - 1605 1465 140 510 449

63 - 1601 1442 159 250 447

64 - 1592 1351 165 525 453

Table 3.11: Assignments of characteristic FT-IR vibrations of 3, 5-dimethylbenzoic acid and its organotin(IV) complexes.

Compound

IR Band (cm-1)

νOH νCOO


HL11 3441 1560 1351 209 - -

65 - 1547 1354 193 240 419

66 - 1556 1359 197 509 427

67 - 1566 1424 142 506 448

68 - 1555 1397 158 505 459

69 - 1567 1425 142 515 462

70 - 1555 1387 168 521 459

64

3.3 NMR Spectroscopy Nuclear magnetic resonance (NMR) spectroscopy is one of the main techniques used for

the characterization of organotin(IV) complexes. It is also helpful to predict the geometry

of the complexes. The parameters nJ(119Sn,1H), nJ(119Sn,13C) and δ(119Sn) are determined

by this technique and provide the information about the geometry of the organotin(IV)

complexes.

3.3.1 1H NMR spectroscopy 1H NMR spectral data of the free ligands and their complexes were recorded in CDCl3

and DMSO-d6. The data are reported in Tables 3.12-3.22. The assignments of the signals

in the 1H NMR spectra were based on the intensity pattern, multiplicity and satellites.

Protons of the organotin(IV) carboxylates were identified by integration of these signals

in the 1H NMR spectra.

The 1H NMR spectra of the complexes showed that the signal for proton attached to the

oxygen atom of the carboxylic group of the ligand was absent. Moreover, the appearance

of the proton signal of the organic group attached to the tin atom supported the idea of

complex formation.

Signals for hydrogen atoms attached to nitrogen i.e. –NH were present in the spectra of

all complexes of HL1- HL6, which indicated that the ligands were coordinated only

through oxygen atoms of the carboxylic group. Similarly, the signals for –N=CH- in the

spectra of HL7 and its complexes appeared in the same range, which indicated that this

group is not involved in a bonding with the tin atom. These observations were supporting

the evidence that these ligands coordinate to the tin atom through the oxygen atoms of

the carboxylic group.

The data given in Tables 3.12-3.22 showed that the value for the coupling constants 3J(1H, 1H) were less than10. This revealed that the hydrogen atoms of the CH=CH unit

were cis to each other.

In case of the dimethyl and trimethyl organotin(IV) derivatives, the CH3 groups gave a

sharp singlet in the range of δ = 0.06-0.95 and δ = -0.05-0.97ppm with well defined

satellites. The 2J(119Sn-1H) for the trimethyltin(IV) complexes are found in the range of

52.2-60Hz, which corresponds to tetrahedral geometry. Then2J(119Sn-1H) calculated for

dimethyltin (IV) compounds are 62-81Hz, which confirms that tin has coordination

65

number greater than four and most probably between five and six which is named as

skew trapezoidal geometry.

Unlike dimethyl and trimethyl substituted organotin(IV) derivatives, a complex pattern

was observed in the spectra of phenyltin(IV), and n-butyltin(IV) derivatives due to

phenyl and n-butyl moieties. The 2J(119Sn-1H) for these complexes could not be

calculated owing to their complex pattern. Therefore, no clue for the geometry was

found. In case of di and tri-n-butyl substituted organotin(IV) moieties, there was a

characteristic signal in the form of a clear triplet representing a terminal methyl group for

butyl in the range of 0.73-1.0ppm while the n-octyltin(IV) moiety showed a different

behavior as its terminal methyl group signal was broad and multiplet.

66

Table 3.12: 1H NMR data of 3-[(2′-fluorophenylamido)]propenoic acid and its organotin(IV) complexes

F

Comp.

δ (-CH=CH-) [1J(H, H) in Hz] δ(-NH) δ(R)

[1J(Sn, H) in Hz] δ(-COOH)

HL1 7.19-7.29(m) 7.78-7.82d(8.1) 7.95-7.99d(8.1)

8.0s - 10.38

1 7.28-7.30(m) 7.81-7.84d(8.3) 7.98-8.02d(8.3)

8.4s 0.88t(7.2)

1.28-1.4(m) -

2 7.45-7.51(m) 6.45-6.42d(8.0) 7.37-7.34d(8.0)

7.5s 0.83t(7.3)

1.20-1.45(m) -

3 7.23-7.39(m) 6.34-6.31d(7.9) 7.26-7.23d(7.9)

8.1s 0.85-1.74(m) -

4 7.21-7.31(m) 6.43-6.49d(8.2) 7.21-7.27d(8.2)

8.3s 0.91(s)

[62] -

5 7.41-7.51(m) 6.40-6.43d(8.1) 7.49-7.51d(8.1)

8.2s

7.49-7.53(m) -

6 7.28-7.35(m) 6.50-6.53d(8.1) 7.44-7.41d(8.1)

8.2s 0.64(s)

[60,57.3] -

7 7.23-7.30(m) 6.56-6.53d(8.1) 7.29-7.26d(8.1)

8.4s 7.65-7.32(m) -

Chemical shifts (δ) are given in ppm. 2J[117/119Sn,1H] and J(1H,1H) values are reported in Hz are shown in square brackets and parenthesis, respectively. s(singlet), d(doublet),

t(triplet), m(multiplet) stands for multiplicity

67

Table 3.13: 1H NMR data of 3-[(3′, 5′-dimethylphenylamido)]propenoic acid and its organotin(IV) complexes.

Comp. Me Me

c

ba

δ(-CH=CH-) [1J(H, H) in Hz]

δ(-NH) δ(R)

[1J(Sn, H) in Hz] δ(-OOH)

HL2

a=2.24s

b=6.73s

c=7.25s

6.3-6.33d(8.0)

6.44-6.47d(8.0) 10.30s - 12.0

8

a=2.24s

b=6.90s

c=7.31s

6.30-6.33d(8.0)

7.23-7.26d(8.0) 10.40s 7.35-7.74(m) -

9

a=2.30s

b=6.76s

c=7.31s

6.64-6.67d(8.0)

7.14-7.10d(8.0) 11.09s

0.85t(7.5)

1.22-1.34(m) -

10

a=2.27s

b=6.84s

c=7.56s

6.86-6.81d(8.1)

7.06-7.01d(8.1) 10.66s

0.43(s)

[57.6,59.9] -

11

a=2.29s

b=6.88s

c=7.28s

6.75-6.71d(8.0)

7.06-7.03d(8.0) 10.81s

0.96t(7.2)

1.264-1.66(m) -

12

a=2.29s

b=6.88s

c=7.31s

6.99-6.93d(8.3)

7.06-7.00d(8.3) 10.71s

0.69(s)

[66] -

13

a=2.24s

b=6.88s

c=7.31s

6.67-6.64d(8.0)

7.17-7.14d(8.0) 10.35s 7.12-7.31(m) -



68

Table 3.14: 1H NMR data of 3-[(2′-fluorophenylamido)]propanoic acid and its

organotin(IV) complexes.

F

Comp.

δ(-CH2-CH2-) [1J(H, H) in Hz]

δ(-NH) δ(R)


HL3 7.19-7.09(m) 2.79-2.76d,d(9.0)

2.83-2.80d,d(9.0) 9.06s - 11.5

14 7.20-7.10(m) 2.48-2.5d,d(6.0)

2.65-2.63d,d(6.0) 9.74s 0.83-1.44(m) -

15 7.28-7.12(m) 2.36-2.34d,d(6.0)

2.67-2.65d,d(6.0) 9.7s 7.33-7.99(m) -

16 7.21-7.10(m) 2.63-2.61d,d(6)

2.74-2.72d,d(6) 9.74s

0.79t(6.9)

1.35-1.41(m) -

17 7.19-7.10(m) 2.39-2.37d,d(6.0)

2.56-2.54d,d(6.0) 9.60s

0.84t(7.1)

1.0-1.59(m) -

18 7.20-7.09(m) 2.42-2.40d(6.0)

2.53-2.51d(6.0) 9.66s 7.30-8.0(m) -

19 7.20-7.10(m) 2.68-2.65d,d(9.0)

2.75-2.72d,d(9.0) 9.48s

0.08(s)

[56.1,58.8] -

Chemical shifts (δ) are given in ppm. 2J[117/119Sn,1H] and J(1H,1H) values are reported in Hz are shown in square brackets and parenthesis, respectively. s(singlet), d,d(doublet of

doublet), t(triplet), m(multiplet) stands for multiplicity

69

Table 3.15: 1H NMR data of 3-[(3′,4′-dichlorophenylamido)]propanoic acid and its organotin(IV) complexes.

Comp. a

c

Cl

b

Cl


δ(-NH) δ(R)


HL4

a=7.50s

b=7.43d(2.5)

c=7.47d(7.7)

2.56-2.58d,d(6.0)

2.67-2.69d,d(6.0) 8.00s - 10.67

20

a=7.58s

b=7.45d(2.6)

c=7.49d(7.6)

2.61-2.63d,d(6.0)

2.93-3.95d,d(6.0) 8.2s 0.86-1.39(m) -

21

a=7.70s

b=7.53d(2.8)

c=7.69d(7.6)

2.57-2.59d,d(6.0)

2.69-2.71d,d(6.0) 8.5s

0.89t(7.2)

1.23-1.37 -

22

a=7.68s

b=7.48d(2.4)

c=7.68d(7.7)

2.56-2.58d,d(7.0)

2.73-2.75d,d(7.0) 8.4s

0.85t(7.5)

1.20-1.36 -

23

a=7.72s

b=7.53d(2.5)

c=7.71d(7.7)

2.58-2.60d,d(6.0)

2.77-2.79d,d(6.0) 8.3s 7.25-7.43(m) -

24

a=7.70s

b=7.55d(2.7)

c=7.57d(7.6)

2.60-2.62d,d(6.0)

2.71-2.73d,d(6.0) 8.1s

0.08(s)

[56.3,58.2] -


d,d(doublet of doublet), t(triplet), m(multiplet) stands for multiplicity

70

Table 3.16: 1H NMR data of 3-[(3′, 5′-dichlorophenylamido)]propanoic acid and its organotin(IV) complexes.

Comp.

Clb

b

Cl

a


δ(-NH) δ(R)


HL5 a=7.68s

b=7.10s

2.04-2.07d,d(9.0)

2.15-2.12d,d(9.0) 9.5s - 11.1

25 a=7.48s

b=7.2s

2.63-2.60d,d(9.0)

2.79-2.76d,d(9.0) 9.7s 0.84-1.6(m) -

26 a=7.41s

b=7.27s

2.45-2.42d,d(9.0)

2.54-2.51d,d(9.0) 10.4s 7.28-7.7(m) -

27 a=7.39s

b=7.23s

2.43-2.40d,d(9.0)

2.55-2.51d,d(9.0) 9.5s

0.79t(7.2)

1.3-1.59(m) -

28 a=7.43s

b=7.28s

2.59-2.56d,d(9.0)

2.78-2.75d,d(9.0) 9.6s

0.88t(7.2)

1.22-1.65(m) -

29 a=7.43s

b=7.20s

2.63-2.60d,d(9.0)

2.76-2.79d,d(9.0) 9.9s

0.28(s)

[80.0] -

30 a=7.48s

b=7.28s

2.63-2.60d,d(9.0)

2.77-2.74d,d(9.0) 9.8s

0.51(s)

[56.7,59.9] -



71

Table 3.17: 1H NMR data of 3-[(3′, 5′-dimethylphenylamido)]propanoic acid and its organotin(IV) complexes.

Comp. Me Mea

c

b

c

a


δ(-NH)δ(R)


HL6

a=2.22s

b=6.65s

c=7.23s

2.52-2.54d,d(6.0)

2.53-2.55d,d(6.0)9.8s - 10.4

31

a=2.21s

b=6.64s

c=7.2s

2.45-2.43d,d(6.0)

2.52-2.50d,d(6.0)9.7s

0.38(s)

[57.5,59.6] -

32

a=2.20s

b=6.63s

c=7.21s

2.46-2.49d,d(6.0)

2.51-2.49d,d(6.0)9.6s

0.85t(7.2)

1.29-1.50(m) -

33

a=2.25s

b=6.68s

c=7.25s

2.43-2.45d,d(6.0)

2.5-2.52d,d(6.0) 9.7s 7.40-7.92(m) -

34

a=2.21s

b=6.65s

c=7.20s

2.2-2.23d,d(6.0)

2.50-2.53d,d(6.0)9.7s

0.95(s)

[66] -

35

a=2.20s

b=6.65s

c=7.22s

2.20-2.23d,d(6.0)

2.50-2.53d,d(6.0)9.7s

0.821t(7.6)

1.30-1.39(m) -

36

a=2.22s

b=6.66s

c=7.210s

2.48-2.5d,d(6.0)

2.51-2.53d,d(6.0)9.8s 6.84-7.08(m) -

37

a=2.21s

b=6.65s

c=7.21s

2.20-2.22d,d(6.0)

2.50-2.48d,d(6.0)9.7s 0.82-1.18(m) -



72

Table 3.18: 1H NMR data of [(E)-4-((2-hydroxybenzylideneamino) methyl)cyclohexane Carboxylic acid and its organotin(IV) complexes.

Comp.

δ(−CH2−)

δ(CH=N) δ(-OH) δ(COOH) δ (R)

HL7 1.20-1.80(m) 1.57s

6.93d(8.1)6.94t(8.3)6.95t(8.3)6.93d(8.2)

5.20s 5.1s 11.4s -

38 1.22-1.83(m) 1.58s

6.92d(8.1)6.91t(8.3)6.92t(8.1)6.94d(8.1)

5.2s 5.3s - 0.27(s) [81]

39 1.21-1.82(m) 1.57s

6.91d(8.1)6.92t(8.3)6.93t(8.1)6.93d(8.1)

5.20s 5.2s 0.87t(7.5)

1.30-1.41(m)

40 1.23-1.81(m) 1.58s

6.92d(8.1)6.94t(8.3)6.95t(8.1)6.94d(8.1)

5.20s 5.1s - 7.26-7.30(m)

41 1.21-1.82(m) 1.59s

6.90d(8.1)6.91t(8.3)6.91t(8.1)6.92d(8.1)

5.20s 5.2s - 0.91-1.82(m)

42 1.20-1.81(m) 1.57s

6.94d(8.1)6.93t(8.3)6.94t(8.1)6.94d(8.1)

5.20s 5.2s - -0.05(s) [57]

43 1.21-1.83(m) 1.58s

6.93d(8.1)6.92t(8.3)6.93t(8.1)6.93d(8.1)

5.20s 5.2s - 0.95t (7.8)

1.31-1.42(m)

44 1.22-1.84(m) 1.58s

6.91d(8.1)6.93t(8.3)6.91t(8.1)6.94d(8.1)

5.20s 5.1s - 7.28-7.39(m)



73

Table 3.19: 1H NMR data of 4, 5-dimethoxy-2-nitrobenzoic acid and its organotin(IV) complexes.

Comp. δ(H3) δ(H6) δ(H7) δ(H8) δ(R) δ(COOH)

HL8 7.553 6.96 7.56 3.79 - 9.5

45 7.38 7.28 3.99 3.97 0.97(s)

[58] -

46 7.42 7.28 3.17 3.14

1.41-1.35(m)

1.25-1.30(m)

0.78t(7.0)

-

47 7.99 7.98 3.00 2.98

7.70(m)

7.45(m)

7.75(m)

-

48 8.72 7.46 3.19 3.16 0.06(s)

[77] -

49 7.28 7.23 3.13 3.10

2.20-1.98(m)

1.75-1.80(m)

1.00t(7.0)

-

50 7.41 7.28 3.95 3.88

7.39(m)

7.30(m)

7.45(m)

-

51 7.41 7.27 3.98 3.96 0.86-1.95(m) -

Chemical shifts (δ) are given in ppm. 2J[117/119Sn,1H] and J(1H,1H) values are reported in Hz are shown in square brackets and parenthesis, respectively. s(singlet), t(triplet),

m(multiplet) stands for multiplicity

74

Table 3.20: 1H NMR data of 2, 4, 6-trichlorobenzoic acid and its organotin(IV) complexes.

Comp. δ(COOH) δ(H3/H5) δ(R)

HL9 11.0 7.75 -

52 - 7.78 7.1-7.8(m)

53 - 7.80 7.15-7.42(m)

54 - 7.76 0.80-1.40(m)

55 - 7.78 0.73t(6.8) 1.31-1.45(m)

56 - 7.79 0.81t(6.9) 1.0-1.51(m)

57 - 7.77 0.079(s) [55.0, 56.2]



Table 3.21: 1H NMR data of 3, 4-dimethoxybenzoic acid and its organotin(IV) complexes.

Comp. δ(H2) δ(H5) δ(H6) δ(H7/H8) δ(R)

HL10 7.55 6.96 7.56 3.79 -

58 7.57 7.02 7.57 3.79 7.05-7.42(m)

59 7.57 7.02 7.60 3.81 0.77t(7.2) 0.72-1.50(m)

60 7.58 6.99 7.60 3.79 0.77t(7.1) 0.76-1.60

61 7.57 7.02 7.60 3.81 0.112(s) [56.2,59.1]

62 7.57 7.01 7.60 3.81 0.71(s) [65.2]

63 7.57 7.02 7.59 3.82 7.02-7.44(m)

64 7.56 7.02 7.59 3.82 0.74-1.47(m)



75

Table 3.22: 1H NMR data of 3, 5-dimethylbenzoic acid and its organotin(IV) complexes.

Comp. δ(H2/H6) δ(H4) δ(H7/H8) δ(R)

HL11 7.56 7.18 2.29 -

65 7.82 7.79 2.50 7.41-7.43(m)

66 7.56 7.21 2.50 0.78-1.49(m)

67 7.70 7.25 2.37 0.105(s) [52.8,58.2]

68 7.71 7.28 2.37 0.95t(7.2) 1.28-1.45(m)

69 7.58 7.21 2.50 0.83(s) [65.6]

70 7.82 7.24 2.44 0.92t(7.2) 1.38-1.85(m)



3.3.2 13C NMR spectroscopy The 13C NMR data of the free ligands and their synthesized complexes (di- and

triorganotin(IV) complexes) are reported in Tables 3.23-3.33. The values were assigned

to each carbon atom of the ligands and their complexes on the basis of incremental

methods and by comparison with literature values.

The obtained data from the 13C NMR spectra of the free ligands and their complexes

were in agreement with the 1H NMR and FT-IR data for the formation of the complexes.

The values assigned to resonance signals provided the expected results. A small shift of

the signals for the carboxylate carbon atoms to lower fields in the complexes was

observed, which showed the participation of the carboxylic group in coordination to

tin(IV).

On comparing the spectra of the complexes with the spectra of the ligands, downfield or

high field shift of signals for other carbon atoms in the complexes was observed.

76

However, the signals for -CH=N-, -CH=CH-, -CH3O, and -CH3 groups appeared in their

specific regions.

In 3-[(2′-fluorophenylamido)]propenoic acid, 3-[(2′-fluorophenylamido)]propanoic acid

and their complexes, the assignments of signals was difficult due to the fluorine

substituent. The substituted fluorine atom coupling with carbon atoms caused splitting of

signal as doublet. The signal for C2 appeared as a doublet due to a strong 1J[13C, 19F]

coupling in the range of 151.25-156.10ppm with a coupling constant of 1J[13C, 19F] =

243.8Hz and 243Hz for 3-[(2′-fluorophenylamido)]propenoic acid complexes and 3-[(2′-

fluorophenylamido)]propanoic acid complexes. Similarly, the signals for C3 and C4 also

appeared as doublets due to the presence of fluorine in the environment. The coupling

values 2J[13C, 19F] and 3J[13C, 19F] were calculated for 3-[(2′-

florophenylamido)]propenoic acid complexes as 18.8Hz and 15Hz while the coupling

constant 2J[13C, 9F] and 3J[13C, 19F] for 3-[(2′-fluorophenylamido)]propanoic acid

complexes were 18.8Hz and 11.3Hz respectively.

The additional signals in the 13C NMR spectra of the complexes for R = Me, But, Oct

and Ph carbon atoms attached to tin also supported the formation of organotin(IV)

complexes.

The coupling constants nJ[119Sn, C] were helpful for the determination of the structure

and geometry of the organotin(IV) carboxylates. The magnitude of 1J[119Sn, 13C]

coupling values for trimethyl and tributyl derivatives of organotin(IV) compounds are in

the range of 332-396Hz, while triphenyltin(IV) complexes exhibit coupling values in the

range of 635-664Hz, suggest monomeric tetrahedral geometry around the tin atom in

solution for these complexes. In the case of the diorganotin(IV) carboxylates the

coupling constant values range between 555-664Hz, this demonstrates, the fluxional

behavior of the carboxylate oxygen atoms caused uncertainity. The coordination number

of the tin atom was reduced from six to five in solution state and this change in the

coordination number resulted in a change of geometry of the diorganotin(IV) complexes

from octahedral to skew trapezoidal.

3.3.3 119Sn NMR spectroscopy In all synthesized complexes of organotin(IV) carboxylates, only one sharp singlet was

observed in the 119Sn NMR spectra which showed that only one specie was present in

solution. The tin chemical shift δ (119Sn) values indicated the coordination number of tin

77

and thus provided the information about the geometry of organotin(IV) complexes. The δ

(119Sn) values were found to depend on the nature of the group attached to Sn. In case of

electron donating group the tin atom was shielded and the δ (119Sn) value shifted to

higher field. The nature of the ligands in organotin(IV) complexes also affected the

values of δ (119Sn). The electronegativity of the coordinating group of the ligand played a

key role in the δ (119Sn) value. A higher electronegativity of the coordinated atom shifted

the δ (119Sn) value to lower fields.

78

Table 3.23: 13C and 119Sn NMR data of 3-[(2′-fluorophenylamido)]propenoic acid and its organotin(IV) complexes.

Carbon atom

Chemical shifts (ppm) of compounds 1-7

HL1 1 2 3 4 5 6 7

C1 124.6 124.5 124.6 124.6 124.5 124.5 124.7 124.6

C2 155.8 152.5

(243.8)

154.7 151.5

(243.8)

155.2 151.9

(243.8)

156.1 152.8

(243.8)

155.9 152.6

(243.8)

156 152.7

(243.8)

154.8 151.6

(243.8)

155.7 152.4

(243.8)

C3 116.2 115.9 (18.8)

117.0 116.7 (18.8)

116.6 116.4 (18.8)

116.6 116.3 (18.8)

116.3 116.1 (18.8)

116.8 116.6 (18.8)

116.7 115.4 (18.8)

116.7 116.4 (18.8)

C4 124.9 124.7 (15)

124.9 124.7 (15)

124.9 124.7 (15)

124.9 124.7 (15)

124.9 124.7 (15)

125 124.8 (15)

124.8 124.6 (15)

124.8 124.6 (15)

C5 131.6 131.9 131.6 131.8 131.8 131.9 132 131.7

C6 131.6 131.9 131.7 132.1 131.9 131.8 131.8 131.9

C7 163.8 164.1 164.4 164.3 163.8 163.9 163.9 167.8

C8 126.3 126.7 127.9 127.6 126.4 126.4 126.4 127.1

C9 126.1 126.6 127.5 127.8 127.1 126.2 126.3 126.1

C10 167.7 170.9 169.6 186.7 196.2 169.3 170.7 169.6

R

α - 29.3 1J[350,334] 29.4 31 29.8 138.1

1J[639,661] -1.8 1J

[396,378] 128.7

β - 28.3 2J[20.3] 27.5 31.9 - 137.3 - 127.8

γ - 26.5 3J[66] 26.3 31.8 - 134.6 - 126.1

δ - 14.8 14.2 29.7 - 130.6 - 125.5

γ−γ′ - - - 29.1, 25.6, 22.6.

- - - -

δ′ - - - 14.1 - - - -

119Sn - 154 -129 -163 - - - -

Chemical shifts (δ) in ppm. nJ[117/119Sn, 13C] in Hz are listed in square brackets.

Number in accordance with Figs. 3.62 and 3.63.

79

Table 3.24: 13C and 119Sn NMR data of 3-[(3′, 5′-dimethylphenylamido)]propenoic acid and its organotin(IV) complexes.

Carbon atom


HL2 8 9 10 11 12 13

C1 131.9 136.2 133.2 132.8 132.7 132.7 135.1

C2/6 117.7 125.1 124.9 124.9 119.4 119.5 125.0

C3/5 138.3 138.6 138.6 138.6 138.3 138.3 138.3

C4 125.9 126.0 126.2 129.0 126.1 129.7 126.1

C7/8 21.5 21.6 22.1 21.9 21.2 21.6 21.5

C9 163.5 163.7 163.6 170.2 170.5 170.5 166.8

C10 138.8 139.1 139.5 139.1 139.4 139.3 138.9

C11 131.2 132.1 131.5 131.8 131.8 131.8 131.8

C12 167.3 168.4 170.5 170.4 170.8 170.8 170.5

R

α - 138.1 1J[640, 662] 29.5 -2.7

1J[394, 376] 29.4 29.2 137

β - 136.8 2J[43]

27.9 2J[27] - 27.3 - 131

γ - 136.5 3J[70]

26.91 3J[77] - 26.7 - 126.1

δ - 128.3 14.04 - 14.1 - 125.4

119Sn - -64 155 -184 - - -



80

Table 3.25: 13C and 119Sn NMR data of 3-[(2′-fluorophenylamido)]propanoic acid and its organotin(IV) complexes.

Carbon atoms


HL3 14 15 16 17 18 19

C1 122.6 123.2 123.1 123.4 123.3 123.1 123.2

C2 154.4 151.2 (243)

155.3 152.1 (243)

155.4 152.2 (243)

155.3 152.1 (243)

155.3 152.0 (243)

154.9 151.6 (243)

154.8 151.6 (243)

C3 114.9 114.7 (18.8)

115.6 115.4 (18.8)

115.7 115.5 (18.8)

115.6 115.4 (18.8)

115.6 115.3 (18.8)

115.2 114.9 (18.8)

114.9 114.6 (18.8)

C4 124.2 124.1 (11.2)

124.5 124.4 (11.2)

124.4 124.3 (11.2)

124.3 124.2 (11.2)

124.5 124.4 (11.2)

124.6 124.5 (11.2)

124.7 124.5 (11.2)

C5 127.1 127.9 127.5 127.1 127.1 127.7 127.2

C6 127.0 127.0 127.2 126.9 126.9 127.0 127.0

C7 170.4 171.1 171.0 171.1 171.6 171.1 170.8

C8 29.7 30.2 30.2 29.8 31.4 29.8 30.6

C9 31.06 31.77 31.04 31.83 32.70 32.05 32.54

C10 173.2 175.6 174.3 174.4 175.3 175 175.1

R

α - 33.2 130.5 29.2 29.1 137.6 -2.3

1J[396, 378]

β - 31.9 126.7 27.9 28.1 2J[27]

136.3 2J[45] -

γ - 30.2 125.4 26.6 26.9 3J[77] 135.9 -

δ - 29.4 125.3 14.5 14 138.7 -

γ−γ′ - 29.2, 24.8, 22.5.

- - - - -

δ′ - 14.4 - - - - -

119Sn - - - 155 -46 -



81

Table 3.26: 13C and 119Sn NMR data of 3-[(3′,4′-dichlorophenylamido)]propanoic acid and its organotin(IV) complexes.

Carbon atoms


HL4 20 21 22 23 24

C1 139 139.5 137.5 137.9 139.5 139

C2 120 121.2 121.5 121.4 121 121.8

C3 131 132 132 132 132.4 132

C4 125 128 126 126.5 128 126

C5 130 130.7 130.2 130 131 131

C6 118 118.5 119.5 118.6 120 119

C7 170 171 170.9 171 171 172

C8 29.8 31.9 30.3 30.3 30.35 30.5

C9 29.5 30.8 29.7 30.0 30.0 30.0

C10 173 175 178 178 175 175

R

α - 31.1 29.7 1J[349,332] 29.3 138.9 -2.3

β - 31.9 27.9 2J[20.25] 27.9 137.2 -

γ - 31.8 3J[70.5]

26.8 3J[64.5] 26.6 136.2 -

δ - 29.6 14.4 14.2 129.4 -

γ−γ′ - 29.5, 29.2, 25.3.

- - - -

δ′ - 14.1 - - - -

119Sn - - 140 -149 - 129



82

Table 3.27: 13C and 119Sn NMR data of 3-[(3′,5′-dichlorophenylamido)]propanoic acid and its organotin(IV) complexes.

Carbon atoms


HL5 25 26 27 28 29 30

C1 141.3 142.1 142.2 141.6 140.2 141.9 141.5

C2/6 117.2 117.6 117.4 117.6 117.5 117.8 117.6

C3/5 134.6 135.2 136.5 136.5 134.9 135.1 135.1

C4 122.5 124.0 123.2 123.7 123.5 124.0 123.7

C7 170.7 170.2 171.0 171.2 171.1 171.4 171.0

C8 29.8 31.8 31.2 31.3 30.4 30.0 30.6

C9 31.3 31.9 32.0 32.3 32.3 31.9 32.5

C10 173.5 175.3 176.0 174.6 174.9 175.3 175.4

R

α - 34.2 137.1 30.1 29.3 1J[351,335] 29.7 -2.4

1J[398,380]

β - 31.9 136.7 27.6 27.9 2J[20.25] - -

γ - 29.7 129.2 26.4 26.8 3J[65.28] - -

δ - 29.6 128.6 14.2 14.5 - -

γ−γ′ - 29.4, 25.8, 25.3.

- - - - -

δ′ - 14.7 - - - - -

119Sn - - -48 - - -180 -



83

Table 3.28: 13C and 119Sn NMR data of 3-[(3′, 5′-dimethylphenylamido)]propanoic acid and its organotin(IV) complexes.

Carbon atoms


HL6 31 32 33 34 35 36 37

C1 138.0 138.9 138.8 138.2 138.0 138.0 138.0 138.0

C2/6 117.2 117.2 117.2 117.1 117.8 117.4 118.2 117.2

C3/5 139.6 139.7 139.8 139.8 139.7 139.7 139.6 139.6

C4 124.9 125.0 125.0 125.0 124.8 125.2 124.9 124.9

C7/8 21.5 21.6 21.6 21.6 21.9 21.6 21.6 21.5

C9 170.4 170.1 171.0 170.9 170.7 170.4 170.4 170.4

C10 29.3 31.5 30.1 31.8 30.3 29.3 30.0 29.3

C11 31.5 33.1 33.6 33.0 33.4 32.3 31.5 31.5

C12 174.34 176.39 176.38 176.28 177.4 175.25 177.43 177.5

R

α - -2.7 1J[396, 378]

31.5 1J[349, 333]

137.9 1J[635, 652] 29.6 29.3 138.2 33.2

β - - 28.3 2J[27.75] 137.3 - 27.1 133.1 31.7

γ - - 27.4 3J[75.5, 73.5]

136.7 - 26.2 130. 30.2

δ - - 14.2 129.2 - 13.9 125.2 29.4

γ−γ′ - - - - - - - 29.2, 28.8, 22.6.

δ′ - - - - - - - 14.4

119Sn - - 140 -48 - -136 - -



84

Table 3.29: 13C NMR data of [(E)-4-((2-hydroxybenzylideneamino)methyl) cyclohexane Carboxylic acid and its organotin(IV) complexes

Carbon atoms


HL7 38 39 40 41 42 43 44

C1 138.2 138.3 138.4 138.8 138.2 138.3 138.4 138.4

C2 129.3 129.2 129.2 129.3 129.1 129.4 129.2 129.2

C3 125.2 125.1 125.4 125.4 125.3 125.4 125.4 125.4

C4 120.6 120.7 120.5 120.4 120.3 120.6 120.7 120.5

C5 129.2 129.4 129.1 129.3 129.2 129.2 129.3 129.1

C6 137.8 137.7 137.5 137.6 137.5 137.1 137.7 137.5

C7 122.6 122.8 122.7 122.8 122.6 122.2 122.5 122.2

C8 31.2 31.5 31.4 31.5 31.6 31.5 31.3 31.4

C9 38.2 38.5 38.3 38.3 38.2 38.3 38.4 38.3

C10 34.8 34.6 34.5 34.6 34.6 34.5 34.6 34.6

C11 34.2 34.4 34.3 34.1 34.2 34.3 34.3 34.3

C12 33.6 33.5 33.5 33.5 33.4 33.2 33.3 33.6

C13 180.1 182.7 182.4 182.3 182.3 182.7 182.6 182.9

R

α - -2.2 1J[641, 664] 28.6 138.4 37.6

1J[555, 580] -2.3

1J[377,397] 29.2 138.8

β - - 27.4 2J[22]

137.7 2J[48]

31.3 2J[37] - 27.3

2J[22] 137.9 2J[47]

γ - - 26.8 3J[63] 136.5 30.5

3J[91] - 26.4 3J[63] 136.9

δ - - 14.5 130.2 29.8 - 14.6 130.8

γ−γ′ - - - - 29.3, 26.4, 22.1.

- - -

δ′ - - - - 14.8 - - -



85

Table 3.30: 13C NMR data of 4, 5-dimethoxy-2-nitrobenzoic acid and its organotin(IV) complexes.

Carbon atoms


HL8 45 46 47 48 49 50 51

C1 118.0 124.4 125.70 127.3 127.9 126.9 120.2 119.3

C2 138.8 1341.4 140.5 143.7 148.9 143.5 143 139.1

C3 104.0 110.9 110.5 112.2 110.5 111.7 111.3 104.4

C4 151.4 152.0 152.4 151.5 152.5 151.7 152.1 149.6

C5 148.9 149.5 149.2 150.9 151.9 151.2 150.9 147.8

C6 105.4 112.7 106.6 127.4 126.7 119.9 106.9 108.4

C7 55.0 56.5 56.6 55.1 56.5 55.5 56.7 54.1

C8 56.2 56.5 56.5 55.0 56.4 55.2 56.4 54.0

C9 169.0 170.5 176.5 173.1 174.0 175.3 179.4 176.0

R

α - 14.2 1J[394]

29.6 1J[360] 138.5 29.6 29.3 129.9 37.2

1J[566]

β - - 27.4 2J[22] 137.4 - 27.7

2J[21] 127.5 31.2 2J[36]

γ - - 26.8 2J[63] 136.30 - 26.5 126.4 30.0

δ - - 14.5 130.7 - 14.6 125.3 29.3

γ−γ′ - - - - - - - 29.1, 26.7, 22.4.

δ′ - - - - - - - 14.1



86

Table 3.31: 13C NMR data of 2, 4, 6-trichlorobenzoic acid and its organotin(IV) complexes.

Carbon atoms


HL9 52 53 54 55 56 57

C1 131.3 131.5 131.4 131.4 131.6 131.7 131.9

C2/6 134.9 135.5 135.6 135.9 135.8 135.6 135.6

C3/5 128.5 129.9 129.3 129.4 129.3 129.3 129.2

C4 134.6 135.2 135.2 135.4 135.2 135.3 135.2

C7 169 171 170.9 171.2 170.9 170.8 170.2

R

α - 138.2 1J[629,650] 129 30.2 29.3

1J[350,334]28.2

1J[355] -1.6

1J[395,376]

β - 137.5 128 29.2 28.3 2J[20.25]

27.8 2J[21] -

γ - 134.9 127 29.1 26.6 3J[66]

26.1 3J[60] -

δ - 130.8 126 27.6 14.8 14.1 -

γ−γ′ - - - 26.5, 26.0, 23.1.

- - -

δ′ - - - 14.8 - - -



87

Table 3.32: 13C NMR data of 3, 4-dimethoxybenzoic acid and its organotin(IV) complexes.

Carbon atoms


HL10 58 59 60 61 62 63 64

C1 123.0 123.2 124.0 123.6 124.0 124.4 123.6 123.0

C2 112.0 112.3 112.5 112.2 112.5 112.2 112.3 112.0

C3 148.0 148.6 148.5 148.6 148.6 148.5 148.7 148.0

C4 153.0 153.6 154.2 154.3 153.9 153.9 153.9 153.0

C5 111.0 111.4 111.2 111.2 111.3 111.4 111.3 111.0

C6 123.0 123.4 123.6 123.4 123.5 123.8 123.4 123.0

C7/8 55.0 56.2 55.3 55.9 56.1 56.4 55.7 55.0

C9 167.0 167.2 167.6 167.5 168.0 168.5 167.6 167.0

R

α - 138.5 30.8 30.9 -2.1 29.3 137.0 32.7

β - 136.7 27.3 28.2 - - 131.0 31.7

γ - 136.4 26.0 27.5 - - 126.1 31.4

δ - 127.2 13.8 19.5 - - 125.4 29.9

γ−γ′ - - - - - - - 28.8, 27.4, 22.5.

δ′ - - - - - - - 14.6



88

Table 3.33: 13C NMR data of 3, 5-dimethylbenzoic acid and its organotin(IV) complexes.

Carbon atoms


HL11 65 66 67 68 69 70

C1 131 133.2 134 133 133 132 132.5

C2/6 127 129.2 127.3 128 128.3 127.4 127.9

C3/5 138 140.2 139.4 142.8 139.6 138.4 138.8

C4 127 129.2 128 131 127.6 129.4 129

C7/8 40 41.5 41.2 41.9 41.5 41.2 40.3

C9 167 169.3 170.5 172 172 171.8 171.3

R

α - 137.21 32.7 -2.3 29.3 29.2 29.4

β - 136.4 31.9 - 27.9 - 27.1

γ - 135.2 31.7 - 26.8 - 26.7

δ - 129 30.9 - 14.2 - 13.5

γ−γ′ - - 28.9, 24.5, 22.5.

- - - -

δ′ - - 14.4 - - - -



89

3.4 Mass spectrometry The electron impact method was used to obtain the mass spectral data at 70 eV for the

synthesized complexes (Tables 3.34-3.44). The observed mass fragmentation patterns for

the di and tri-organotin(IV) carboxylates are shown in Schemes 3.1 and 3.2. The

observed fragments were in good agreement with the expected structure of the

complexes. The mass spectral data for the complexes showed the rich ion distribution

and characteristic pattern were observed for tin. The tin containing fragments were

important for the characterization of the synthesized complexes because they provided

information about the metal-ligand bond. As complexes of different structure had

different fragmentation patterns [8] the base peak of each di and tri-organotin(IV)

compound was derived by adopting a different pattern.

Three fragmentation rout were proposed for all synthesized complexes. In

triorganotin(IV) carboxylates, the fragmentation on route I started with the elimination of

R’ which was followed by CO2 elimination and subsequent fragmentation of the ligand.

On the second and third route, R3Sn and RCO2 were removed with the formation of

[RCO2H] and [R3Sn] as primary fragments. [Sn+] was obtained for most of the

complexes of fragmentation routes I and III. A molecular ion peak was usually not

observed in the case of organometallic compounds [9]. The molecular ion peak [M+˙] of

low intensity was observed in some of the triorganotin(IV) complexes, i.e. in complex

21, 31, 33 and 65. It was absent in all diorganotin(IV) dicarboxylates.

The diorganotin(IV) derivatives followed the fragmentation path by loss of the R group

in a first step and then manifested slightly different patterns for the rest of fragmentation.

As Sn has 10 naturally occurring isotopes, this effect was pronounced in the mass spectra

of the complexes. In all of spectra of the complexes, an isotopic characteristic pattern

was observed due to the isotopic effect of the M+ ion and this pattern was used for the

qualitative identification of tin containing fragment peaks.

90

[R3Sn(O2CR')]+ [R2Sn(O2CR')]+

[R2Sn]+

[R2SnR']+

Sn+

[R'CO2H]

[O2CR']

[OCR')]

R'

[R3Sn]+

[R2Sn]+

[RSn]+

-CO2

-R

[RSn]+

-R

[R3Sn]

-H

-O

-CO

-R

-R

-R-R

-R-[R'CO2]

R = CH3, C4H9, C6H5; R’ = Organic moiety of ligands

Scheme 3.1: General mass fragmentation pattern of R3Sn (O2CR′)

[R2Sn(O2CR')2]+ [RSn(O2CR')2]+

[R'2SnR]+

[RSn(O2CR')R']+

Sn+

[R'CO2H)]

[O2CR']

[OCR')]

R'

[R2SnR']+

[R2Sn]+

[RSn]+

-CO2

[RSnR']+

-R'

[R2Sn(O2CR')]

-H

-O

-CO

-R

-R

[SnR']+

[R2Sn(O2CR')]+

-R

-R

-CO2

-R

-CO2

-R-O2CR'

R = CH3, C4H9, C6H5; R’ = Organic moiety of ligands

Scheme 3.2: General mass fragmentation pattern of R2Sn (O2CR′)2

91

Table 3.34: Mass spectral data of the organotin(IV) complex 3-[(2′-fluorophenylamido)]propenoic acid

Fragments Ion HL1

m/z(%) 1

m/z(%) 2

m/z(%) 3

m/z(%) 4

m/z(%) 5

m/z(%) 6

m/z(%) 7

m/z(%)

[R2SnCOOL] - 442(4) - - - - 358(18) -

[C10H8O3NSn]+ - 310(18) - 310(8) 310(12) 310(4) 310(5) 310(32)

[C9H8ONSn]+ - 266(6) - 266(10) 266(2) - - 266(10)

[SnO2]+ - 152(3) 152(26) 152(4) 152(25) 152(8) 152(4) 152(100)

[R3Sn]+ - - - - - 350(12) 165(100) -

[R2Sn]+ - 234(4) - - 150(13) - 150(18) -

[RSn]+ - 177(56) 233(12) 135(26) 197(10) 135(42) 197(22)

[Sn]+ - 120(40) 120(21) 120(13) 120(3) 120(22) 120(25) 120(18)

[C6H5NF]+ 110(100) 110(38) 110(17) 110(11) 110(36) 110(16) 110(5) 110(9)

[C4H3O2]+ 83(22) 83(16) 83(20) 83(5) 83(28) 83(4) 83(22) 83(14)

[C4H4O2N]+ 98(25) - 98(7) 98(5) 98(11) 98(4) - 98(3)

[C3H3O]+ 55(4) 55(100) 55(68) 55(100) 55(74) 55(54) 55(5) 55(11)

[C10H7O2NF]+ 192(9) 192(45) 192(100) 192(26) 192(100) 192(100) 192(4) 192(17)

[C10H8O3NF]+ 209(11) 209(5) 209(2) 209(4) 209(11) - 209(4) -

R = CH3+, n-C4H9

+, C6H5+

92

Table 3.35: Mass spectral data of the organotin(IV) complex 3-[(3′, 5′-dimethylphenylamido)]propenoic acid

Fragment Ion HL2

m/z(%) 8

m/z(%)9

m/z(%)10

m/z(%) 11

m/z(%) 12

m/z(%) 13

m/z(%)

[R2SnCOOL] - - 451(22) 367(22) - - -

[C12H12NO2Sn]+ - 322(8) 322(2) 322(20) 322(18) 322(18) 322(8)

[R3Sn]+ - - 297(38) 165(100) - - -

[R2Sn]+ - - 234(16) 150(23) - 150(15) -

[RSn]+ - 197(5) 177(39) 135(67) 177(9) 135(67) -

[Sn]+ - 120(21) 120(49) 120(46) 120(7) 120(38) 120(28)

[C12H12NO2]+ 202(65) 202(16) 202(78) 202(55) 202(29) 202(68) 202(4)

[C11H12NO]+ 174(12) 174(4) 174(37) 174(18) 174(10) 174(10) 174(50)

[C10H11NO]+ 161(9) 161(4) 161(4) 161(75) 161(100) 161(100) 161(4)

[C8H9]+ 105(21) 105(16) 105(28) 105(31) 105(32) 105(35) 105(24)

[C6H5]+ 77(49) 77(87) 77(91) 77(58) 77(40) 77(52) 77(100)

[C4H9]+ 57(100) 57(100) 57(100) 57(6) 57(22) 57(15) 57(20)

R = CH3+, n-C4H9

+, C6H5+

93

Table 3.36: Mass spectral data of the organotin(IV) complex 3-[(2′-fluorophenylamido)]propanoic acid

Fragments Ion HL3

m/z (%) 14

m/z (%) 15

m/z (%) 16

m/z (%) 17

m/z (%) 18

m/z (%) 19

m/z (%)

[R2SnCOOL] - - - - 444 (99) - 360 (78)

[C8H10NOFSn]+ - 275 (4) 275 (6) 275 (10) 275 (12) - 275 (30)

[C10H10NO3Sn]+ - - 312(28) 312(41) 312 (6) 312(68) 312(15)

[C5H4O2Sn]+ - 216 (18) 216 (15) 216 (40) 216 (28) 216 (22) 216 (52)

[R3Sn]+ - - - - - - 165 (100)

[R2Sn]+ - - - - - 274 (3) 150 (8)

[RSn]+ - - - - 177 (48) 197 (35) 135 (36)

[Sn]+ - 120 (8) 120 (15) 120 (35) 120 (39) 120 (22) 120 (4)

[C7H5NOF]+ 138 (2) 138 (31) 138 (16) 138 (40) 138 (24) - 138 (9)

[C6H5NF]+ 110 (100) 110 (55) 110 (23) 110 (100) 110 (100) 110 (18) 110 (58)

[C4H5O3]+ 101 (7) - 101 (4) 101 (3) 101 (2) 101 (2) -

[C6H5]+ 77 (8) 77 (18) 77 (100) 77 (2) 77 (3) 77 (100) -

[C3H3O]+ 55 (11) 55 (100) 55 (15) 55 (76) 55 (67) 55 (28) 55 (22)

R = CH3+, n-C4H9

+, C6H5+

94

Table 3.37: Mass spectral data of the organotin(IV) complex 3-[(3′,4′-dichlorophenylamido)]propanoic acid

Fragments Ion HL4 m/z (%)

20 m/z (%)

21 m/z (%)

22 m/z (%)

23 m/z (%)

24 m/z (%)

[C14H13N2O6Cl2Sn]+ - 496 (25) 496 (100) 496 (18) - -

[C6H4Cl2Sn]+ - 267(38) 267(12) 267(65) 267(3) 267(13)

[C7H3ClSn]+ - 242(98) 242(20) 242(38) 242(98) 242(10)

[SnCOO]+ - 164(18) 164(18) 164(6) 164(96) 164(80)

[SnL] - - 341(8) 341(45) - 341(2)

[R3Sn]+ - - 291(8) - 350(8) 165(100)

[R2Sn]+ - - 234(5) - - 150(18)

[RSn]+ - - 177(30) 177(8) 197(25) 135(40)

[Sn]+ - 120(65) 120(7) 120(12) 120(4) 120(12)

[C10H8NO2Cl2]+ 245(11) 245(62) 245(8) 245(38) 245(92) 245(10)

[C7H4NOCl2]+ 189(6) 189(56) 189(15) 189(22) 189(90) 189(2)

[C6H4NCl2]+ 161(11) 161(40) 161(19) 161(7) 161(98) 161(63)

[C6H3Cl2]+ 146(3) 146(5) 146(5) 146(14) 146(20) 146(6)

[C6H3Cl]+ 110(59) 110(5) 110(2) 110(7) 110(14) 110(2)

[C6H3]+ 75(7) 75(12) 75(2) - 75(3) -

[C4H9]+ 57(100) 57(100) 57(25) 57(100) 57(100) 57(12)

R = CH3+, n-C4H9

+, C6H5+

95

Table 3.38: Mass spectral data of the organotin(IV) complex 3-[(3′, 5′-dichlorophenylamido)]propanoic acid

Fragments Ion HL5

m/z (%) 25

m/z (%) 26

m/z (%) 27

m/z (%) 28

m/z (%) 29

m/z (%) 30

m/z (%)

[R2SnCOOL] - - - - 495 (25) - 411(22)

[RSnCOOL2]+ - - - 700 (3) - - -

[C10H8NO3ClSn]+ - 345 (2) 345 (25) - - 345 () -

[C9H8NOClSn]+ - - 301 (5) - 301 (2) 301 (11) -

[C8H6NOClSn]+ - - 287 (12) - 287(8.22) - -

[C8H6NOSn]+ - 252 (6) 252 (4) - 252(8.57) - -

[SnL] - 380 (38) - 380 (2) 380 (12) 380 (15) -

[R3Sn]+ - - 350 (38) - 391 (2) - 164 (96)

[R2Sn]+ - - - - 234 (12) 150(45) 150 (20)

[RSn]+ - 233 (8) 196 (42) 177 (6) 177 (3) 135 (15) 134 (54)

[Sn]+ - 120 (9) 120 (25) 120 (10) 120 (16) 120 (45) 120 (18)

[C3H3O]+ 55 (100) 55 (15) 55 (20) 55 (6) 55 (100) 55 (100) 55 (100)

[C3H5O]+ 57 (21) 57 (100) 57 (62) 57 (100) 57 (2) 57 (8) 57 (16)

[C6H5]+ 77 (15) 77 (13) 77 (100) 77 (8) 77 (4) 77 (14) 77 (9)

[C5H3]+ 63 (71) 63 (16) 63 (8) 63 (6) 63 (15) 63 (22) 63 (22)

[C3H5NO]+ 71 (46) 71 (58) 71 (7) 71(9) 71(4) 71(28) -

[C10H8NO3Cl2]+ 261 (8) - 261 (2) - 261 (10) 261 (21) 261 (3)

[C6H4NCl2]+ 161 (85) - 161 (9) 161 (6) 161 (21) 161 (14) 161 (22)

[C7H4OCl2N]+ 189 (4) 189 (4) 189 (8) 189 (8) 189 (15) 189 (20) 189 (16)

R = CH3+, n-C4H9

+, C6H5+

96

Table 3.39: Mass spectral data of the organotin(IV) complex 3-[(3′, 5′-dimethylphenylamido)]propanoic acid

Fragment Ion HL6

m/z(%) 31

m/z(%) 32

m/z(%) 33

m/z(%) 34

m/z(%) 35

m/z(%) 36

m/z(%) 37

m/z(%)

[R2SnCOOL] - 370 (99) 454(100) 496 (20) - 617 (6) - 673 (6.1)

[RSnCOOL2] - - - - - 457 (38) - 566 (20)

[SnL] - - 340 (9) - 340 (6) 340 (40) - 340 (16)

[C11H14ONSn]+ - - 296 (13) 296 (18) 296 (8) 296 (12) 296 (6) -

[R3Sn]+ - 165(93) 291(20) 351(85) - - - -

[R2Sn]+ - 150(95) 234(18) 274(18) 150(8.4) 234(8) 274(11) 346(14)

[RSn]+ - 135(28) 177(60) 197(57) 135(11.4) 177(20) - 23(5.5)

[Sn]+ - 120 (25) 120 (13) 120 (25) 120 (10) 120 (8) 120(14.5) 120 (12)

[C8H10 N]+ 120(100) 120(70) 120(30) 120(38) 120(25) 120(19) 120(100) 120(38)

[C12H14O2 N]+ 204 (68) 204(100) 204 (46) 204 (100) 204(100) 204(100) 204(59) 204(100)

[C10H12ON]+ 162 (29) 162 (42) 162 (16) 162 (22) 162 (43) 162 (29) 162 (24) 162 (53)

[C8H9]+ 105 (20) 105 (28) 105 (8) - 105 (12) 105 (13) 105 (30) 105 (6)

[C6H5]+ 77 (22) 77 (30) - 77 (18) 77 (6) 77 (9) 77 (22) 77 (10)

[C4H9]+ 57 (6) 57 (19) 57 (47) 57 (6) 57 (6) 57 (33) 57 (98) 57 (19)

R = CH3+, n-C4H9

+, C6H5+

97

Table 3.40: Mass spectral data of the organotin(IV) complex [(E)-4-((2-hydroxybenzylidene amino)methyl)cyclohexane Carboxylic acid

Fragments Ion HL7

m/z (%) 38

m/z (%) 39

m/z (%) 40

m/z (%) 41

m/z (%) 42

m/z (%) 43

m/z (%) 44

m/z (%)

[C8H12O2Sn]+ - 260 (25) 260 (88) 260 (70) 260 (35) 260(100) 260 (25) 260 (55)

[C5H4O2Sn]+ - 216 (42) 216 (45) 216 (32) 216 (17) 216 (65) 216 (18) 216 (29)

[R3Sn]+ - - - - - 165 (22) 291 (31) 351 (24)

[R2Sn]+ - 150 (11) 234 (21) 274 (15) 346 (14) 150 (13) 234 (17) 274 (1)

[RSn]+ - 135 (6) 177 (14) 197 (7) 233 (11) 135 (4) 177 (9) 197 (10)

[SnH]+ - 121 (25) 121 (20) 121 (25) 121 (55) 121 (20) 121 (18) 121 (20)

[C15H19NO3]+ 261 (45) 261 (90) 261 (87) 261 (90) 261 (15) 261 (38) 261 (21) 261 (92)

[C14H18NO]+ 216 (23) 216 (70) 216 (45) 216 (70) 216 (18) 216 (60) 216 (50) 216 (40)

[C11H12NO]+ 174 (65) 174 (35) 174 (39) 174 (65) 174 (18) 174 (10) 174 (10) 174 (30)

[C8H8NO]+ 134 (40) 134 (100) 134 (100) 134 (100) 134 (55) 134 (45) 134 (20) 134 (48)

[C4H9]+ 57(72) - 57 (44) - 57 (24) - 57 (64) -

[C6H5]+ 77 (100) 77 (18) 77 (18) 77 (35) 77 (100) 77 (8) 77 (100) 77 (100)

R = CH3+, n-C4H9

+, C6H5+

98

Table 3.41: Mass spectral data of the organotin(IV) complex 4, 5-dimethoxy-2-nitrobenzoic acid

Fragment Ion HL8 m/z (%)

45 m/z (%)

46 m/z (%)

47 m/z (%)

48 m/z (%)

49 m/z (%)

50 m/z (%)

51 m/z (%)

[R2SnCOOL] - - 460 (8) 500 (100) - 460 (8) - 572 (8)

[SnL] - 302 (100) 302 (12) 302 (25) 302 (4) 302 (100) 302 (13) 302 (70)

[R3Sn]+ - 165 (12) 291 (8) 348 (18) - - - -

[R2Sn]+ - 150 (17) 234 (10) 272 (8) 150 (12) 234 (9) 272 (11) 346 (8)

[RSn]+ - 135 (38) 177 (8) 196 (82) 135 (28) 177 (12) 196 (12) 233 (4)

[Sn]+ - 120 (8) 120 (80) 120 (65) 120 (12) 120 (10) 120 (52) 120 (7)

[C9H8NO6]+ 226 (86) 226 (65) 226 (82) 226 (15) 226 (12) 226 (38) 226 (100) 226 (73)

[C10H6O2]+ 86 (10) 86 (12) 86 (100) 86 (32) 86 (100) 86 (2) 86 (67) 86 (32)

[C4H9]+ 57 (5) 57 (60) 57 (50) 57 (3) 57 (14) 57 (50) 57 (45) 57 (100)

[C4H11O2NSn]+ - 225 (9) 225 (8) 225 (8) 225 (8) 225 (8) 225 (8) 225 (8)

[C9H8O4]+ 180 (23) 180 (21) 180 (27) 180 (6) 180 (24) 180 (8) 180 (21) 180 (18)

[C7H8O2]+ 124 (100) 124 (41) 124 (3) 124 (10) 124 (51) 124 (19) 124 (45) 124 (36)

[C6H5O]+ 93 (76) 93 (16) 93 (32) 93 (12) 93 (26) 93 (11) 93 (16) 93 (18)

R = CH3+, n-C4H9

+, C6H5+

99

Table 3.42: Mass spectral data of the organotin(IV) complex 2, 4, 6-trichlorobenzoic acid

Fragments ion

HL9

m/z (%) 52

m/z (%) 53

m/z (%) 54

m/z (%) 55

m/z (%) 56

m/z (%) 57

m/z (%)

[R2SnCOOL] - 496 (30) 496 (12) - 436 (2) 459 (82) 328 (48)

[RSnCOOL2] - - 644 (8) 680 (6) 624 (8) - -

[SnCOOL]+ - 345 (3) 345 (4) 345 (7) 345 (8) 345 (12) -

[SnL] - 301 (10) 301 (6) 301 (9) 301 (7) 301 (44) 301 (10)

[SnC6H2Cl2]+ - 265 (3) - 265 (5) - 265 (13) -

[R2Sn]+ - - - - - 234 (12) 150 (27)

[RSn]+ - 197 (44) 197 (16) - 177 (8) 177 (32) 135 (53)

[Sn]+ - 120 (38) 120 (19) 120 (3) 120 (3) 120 (33) 120 (12)

[C7H2OCl3]+ 208 (100) 208 (16) 208 (100) 208 (37) 208 (29) 208 (18) 208 (54)

[C6H4Cl3]+ 182 (21) 182 (7) 182 (15) 182 (7) 182(7) 182(10) 182(35)

[C8H2Cl]+ 133 (49) 133 (8) 133 (31) 133 (17) 133 (10) 133 (10) 133 (43)

[C7H2]+ 86 (8) 86 (3) 86 (8) 86 (9) 86 (6) - 86 (100)

[C4H9]+ 57 (17) - 57 (7) 57 (100) 57 (100) 57 (100) 57 (33)

[C6H5]+ 77 (5) 77 (100) 77 (16) 77 (14) 77 (4) - 77 (13)

R = CH3+, n-C4H9

+, C6H5+

100

Table 3.43: Mass spectral data of the organotin(IV) complex 3, 4-dimethoxybenzoic acid

Fragments Ion HL10

m/z (%) 58

m/z (%) 59

m/z (%) 60

m/z (%) 61

m/z (%) 62

m/z (%) 63

m/z (%) 64

m/z (%)

[R2SnCOOL] - 455(3) - 415 (48) 331 (8) - - -

[RSnCOOL2] - - 539 (12) - - 497 (23) - 595 (42)

[SnL] - 301(27) 301 (45) 301 (37) - 301 (38) 301 (52) 301 (65)

[C8H10O2Sn]+ - 257(62) 257 (32) 257 (39) 257 (5) 257 (43) 257 (10) 257 (35)

[R3Sn]+ - 351(25) - - 165 (24) - - -

[R2Sn]+ - - 234 (3) 234 (5) 150 (3) 150 (6) - -

[RSn]+ - 197(45) - 177 (7) 135 (4) 135 (9) 197(15) 233(3)

[Sn]+ - 120 (19) 120 (13) 120 (6) 120 (28) 120 (29) 120 (31) 120 (11)

[C9H9O4]+ 181 (100) 181 (79) 181 (28) 181 (3) 181 (73) 181 (88) 181 (26) 181 (28)

[C8H9O2]+ 137 (18) 137 (7) 137 (10) 137 (10) 137 (10) 137 (21) 137 (28) 137 (15)

[C4H6O2]+ 86 (3) 86 (13) - - 86 (3) 86 (3) 86 (45) 86(3)

[C6H5]+ 77 (10) 77 (19) 77 (31) 77 (19) 77 (41) 77 (49) 77 (100) 77 (23)

[C4H9]+ 57 (4) 57 (24) 57 (48) 57 (100) 57 (3) 57 (11) 57 (70) 57 (100)

R = CH3+, n-C4H9

+, C6H5+

101

102

Table 3.44: Mass spectral data of the organotin(IV) complex 3, 5-dimethylbenzoic acid

Fragment Ion HL11

m/z (%) 65

m/z (%) 66

m/z (%)67

m/z (%) 68

m/z (%) 69

m/z (%) 70

m/z (%)

[R2SnCOOL] - 426 (56) - 299 (32) 383 (52) 433 (17) -

[RSnCOOL2] - - 527 (18) - - - 475 (12)

[SnL] - 269 (11) 269 (47) 269 (3) 269 (48) 269 (16) 269 (69)

[C8H9sn]+ - 225 (28) 225 (18) 225 (24) 225 (47) 225 (23) 225 (28)

[R3Sn]+ - 351 (8) - 165 (12) - - -

[R2Sn]+ - - - 150 (22) 234 (5) 150 (13) -

[RSn]+ - 197 (49) - 135(12) 177 (12) 135 (15) -

[Sn]+ - 120 (46) 120 (8) 120 (38) 120 (14) 120 (8) 120 (5)

[C9H9O2]+ 149 (5) 149 (27) 149 (3) 149 (20) 149 (3) 149 (18) 149 (23)

[C9H9O]+ 133 (27) 133 (61) 133 (45) 133 (21) 133 (95) 133 (69) 133 (71)

[C8H9]+ 105 (100) 105 (100) 105 (65) 105 (100) 105 (100) 105 (100) 105 (100)

[C7H2]+ 86 (2) 86 (3) 86 (3) 86 (12) 86 (3) 86 (5) 86 (6)

[C6H5]+ 77 (42) 77 (98) 77 (100) 77 (91) 77 (42) 77 (53) 77 (52)

[C4H9]+ 57 (3) 57 (7) 57 (60) 57 (5) 57 (75) 57 (2) 57 (41)

R = CH3+, n-C4H9

+, C6H5+

3.5 Biological Activity 3.5.1 Antibacterial activity The solution of each free ligand and the synthesized organotin(IV) carboxylate, 1 mg/mL

in DMSO, were used to determine antibacterial activities by the agar well diffusion

method [10]. Four different types of microbes having several clinical implications were

selected for this purpose: Escherichia coli, infection of wounds, urinary tract and

dysentery; Bacillus subtilis food poisoning; shigella flexenari, blood diarrhea with fever

and severe prostration; pseudomonas aeruginosa, infection of wounds, eyes and

septicemia. The antibacterial activity for each free ligand and its complexes were

measured as a zone of inhibition in millimeter for 24h. Results are given in Table 3.45.

The results of the present study are summarized below:

All free ligands except 3,4-dimethoxy- 2-nitrobenzoic acid (HL8) were found to be

inactive against the used strains of bacteria. The ligand 3,4-dimethoxy-2-nitrobenzoic

acid was found to be more active for bacillus subtilis and shigella flexenari.

In case of the complexes, the antibacterial action varied from strain to strain but in

general they were found to be good antibacillus subtilis agents.

Complexes 5 and 24 showed significant inhibition action against bacillus subtilis.

Complex 5 also showed higher antibacterial potential than other complexes against

shigella flexenari. Compounds 27 and 42 showed the highest potential against P.

aeroginosa. Complex 28 showed higher antiescherichia coli activity than other

complexes.

The complexes synthesized with 3-[(3′,5′-dimethyl phenyl amido)]propenoic acid (HL2)

were found to be inactive against bacillus subtilis.

Complexes 40, 46, 51, 50, 54, 57 and 61 showed no antibacterial activities against the

tested strains of bacteria.

The present study, in general, shows that triorganotin(IV) complexes are more active

than diorganotin(IV) complexes.

The inhibitory action of organotin(IV) compounds can be attributed to their ability to

interact with DNA and protein. The mode of action is to enter the bacterium cell and to

block special enzymes. These enzymes are no more active to perform their actions. The

loss of enzyme activity affects important system performances necessary for the survival

103

of the life; e.g organotin(IV) carboxylates effect the ATPase, which damage the

respiratory process. In some strains of bacteria, organotin(IV) carboxylates affect the role

of cystolic enzymes. Organotin(IV) carboxylates affect the enzyme activity by

coordinating directly with proteins or to remain close in the vicinity of proteins. In

different strains of bacteria, organotin(IV) carboxylates affect different types of

enzymes. Organotin(IV) carboxylates attack the cell wall, damage it and finally kill the

bacteria. They also effect on the cell wall functions like transduction, solute transport,

retention and oxidation of substrate [11].

Table: 3.45: Antibacterial data of ligands and their organotin(IV) derivatives a,b.

Compound Zone of Inhibition (mm) E. coli B. subtilis S. flexenari P. aeruginosa

HL1 0 0 0 0 1 22 25 29 18 2 12 18 20 19 3 11 14 16 18 4 19 17 15 14 5 20 28 30 22 6 8 18 12 11 7 14 18 18 10

HL2 0 0 0 0 8 12 0 12 0 9 18 0 20 22 10 17 0 13 0 11 13 0 15 15 12 0 0 11 20 13 12 0 10 16

HL3 0 0 0 0 14 12 18 14 12 15 18 17 11 15 16 18 20 18 15 17 22 20 24 20 18 18 24 23 18 19 18 14 10 12

HL4 0 0 0 0 20 10 16 14 10 21 16 28 24 18 22 12 14 16 0 23 0 0 0 0 24 8 12 12 10

HL5 0 0 0 0 25 16 12 20 18 26 23 26 13 18 27 20 18 15 18 28 24 27 23 23 29 15 13 12 12 30 19 20 20 18

HL6 0 0 0 0 31 10 11 0 0

104

32 17 19 17 12 33 0 16 0 10 34 11 14 10 14 35 12 0 12 14 36 0 11 9 16 37 15 10 13 0

HL7 0 0 0 0 38 15 0 0 12 39 22 24 17 14 40 0 0 0 12 41 0 0 0 0 42 0 0 0 23 43 12 12 12 12 44 12 12 12 15

HL8 0 11 12 0 45 13 15 15 15 46 0 0 0 0 47 0 0 0 15 48 0 0 0 13 49 0 0 0 11 50 0 0 0 0 51 0 0 0 0

HL9 0 0 0 0 52 19 21 20 13 53 16 0 0 16 54 0 0 0 0 55 14 13 0 10 56 23 10 16 19 57 0 0 0 0

HL10 0 0 0 0 58 10 0 12 0 59 0 12 0 10 60 10 0 14 12 61 15 20 18 10 62 0 10 11 0 63 0 10 12 12

HL11 0 0 0 0 64 10 16 13 10 65 15 14 10 12 66 18 19 0 0 67 0 0 0 0 68 0 12 0 12 69 0 13 0 0 70 9 10 0 0

Imipenum 30 37 36 32 aIn vitro, agar well diffusion method, conc. 1 mg/mL of DMSO, inhibition zone in mm. bReference drug, Imipenum.

105

Figure 3.1: Antibacterial activity of organotin(IV) derivatives against E. coli.

Figure 3.2: Antibacterial activity of organotin(IV) derivatives against B. subtilis.

106

Figure 3.3: Antibacterial activity of organotin(IV) derivatives against S. flexenari.

Figure 3.4: Antibacterial activity of organotin(IV) derivatives against P. aeroginosa.

107

3.5.2 Antifungal activity The synthesized organotin(IV) carboxylates were screened for their antifungal activities

using four fungal strains: Trichophyton longifusus (22397), Aspergillus flavis (1030),

Candida glaberata (90030), and Candida albicans (2192) [10]. The activity is reported

as percentage inhibition in Table 3.46 using standard drugs: Miconazole and

amphotericin B.

The results for antifungal activity are summarized below:

The fungicidal data shows that the antifungal activity of the synthesized complexes was

significant and higher than the activity of the free ligand.

The organotin(IV) derivatives obtained from 3-[(2′-fluorophenylamido)]propenoic acid

(HL1) showed higher activities as compared to the rest of the synthesized complexes.

The complexes of 2,4,6-trichlorobenzoic acid (HL9) showed no potential against the four

strains of fungi except complexes 54 and 55 which were found to be active only against

aspergillus flavis (1030).

As a general rule, triorganotin(IV) derivatives were found to be more active against

selected fungal strains than the diorganotin(IV) derivatives.

Among all synthesized organotin(IV) carboxylates, tributyltin(IV) derivatives of 3,5-

dimethylbenzoic acid (HL11) was found to be the best antifungal agent. It showed 97%

activity against trichophyton longifusus.

Complexes 44 and 47 were very active against C. glaberata and C. albicans.

Although it is difficult to explain the observed antifungal activities fully on the basis of

the structure of the organotin(IV) carboxylates, some correlations can be concluded from

the results obtained. Triorganotin(IV) carboxylates are more active against the tested

fungal strains than the diorganotin(IV) dicarboxylates. In the former case the central tin

metal is penta coordinated and has a vacant site for the interaction with biological

systems but in the later case, the central tin metal is hexa coordinated and has no more

vacant site for the interaction or rather it is difficult for the central tin metal to interact

with biological systems. This reduces the activity of diorganotin(IV) dicarboxylates. The

importance of the corresponding ligand cannot be negated as it plays a role in antifungal

activities. Organotin(IV) carboxylates of HL1 showed a higher activity than other

108

complexes. It may be due to its good ability to transport the organotin(IV) species to site

of the action.

Table 3.46: Antifungal activitiesa-c (% inhibition) of free ligands and their organotin(IV) complexes

Compound Inhibition (%) T. longifusus A. flavis C. glaberata C. albicans

HL1 0 0 0 0 1 81 80 81 79 2 10 17 15 23 3 65 23 24 29 4 13 16 15 11 5 71 72 76 63 6 26 18 13 15 7 26 37 44 43

HL2 0 0 0 0 8 3 0 4 0 9 83 0 74 0 10 23 0 38 0 11 71 0 62 0 12 73 0 71 0 13 51 0 55 0

HL3 0 0 0 0 14 21 73 56 73 15 68 59 22 45 16 78 76 38 45 17 81 72 88 83 18 43 15 17 75 19 11 8 7 5

HL4 0 3 4 0 20 0 0 0 35 21 10 0 0 30 22 0 0 0 70 23 0 0 0 0 24 10 0 80 0

HL5 0 0 0 0 25 78 68 54 71 26 92 92 60 76 27 20 41 44 50 28 12 38 24 27 29 24 52 65 23 30 44 90 76 85

HL6 0 0 0 0 31 73 52 50 43 32 81 71 73 76 33 53 59 56 51 34 31 78 71 70 35 0 0 0 11 36 32 12 51 70 37 0 0 12 0

HL7 0 0 0 0 38 30 0 0 0 39 0 0 0 0

109

40 80 0 0 0 41 0 0 0 0 42 80 50 20 20 43 20 50 20 0 44 80 90 90 90

HL8 0 0 0 0 45 80 90 0 0 46 80 40 0 0 47 80 0 90 90 48 0 0 0 0 49 0 0 0 0 50 0 0 0 0 51 0 0 0 0

HL9 0 0 0 0 52 0 0 0 0 53 0 0 0 0 54 0 85 0 0 55 0 85 0 0 56 0 0 0 0 57 0 0 0 0

HL10 0 0 0 0 58 51 78 68 53 59 53 39 33 36 60 80 80 87 85 61 24 23 26 28 62 0 0 0 0 63 26 43 44 68 64 7 6 17 19

HL11 0 0 0 0 65 76 67 53 23 66 29 31 41 65 67 30 33 14 52 68 97 87 63 60 69 84 67 23 71 70 73 64 55 56

Standard Drug

Miconazole Amphotericin B Miconazole Miconazole

MIC (µg/ml) 70.0 20.0 110.8 110.8 DMSO - - - -

aConcentration: 200 μg/mL of compound bMIC: Minimum inhibitory concentration cPercent inhibition (standard drug) = 100

110

Figure 3.5: Antifungal activity of organotin(IV) derivatives against T. longifuses.

Figure 3.6: Antifungal activity of organotin(IV) derivatives against A. flevus.

111

Figure 3.7: Antifungal activity of organotin(IV) derivatives against C. glabrata.

Figure 3.8: Antifungal activity of organotin(IV) derivatives against C. albicans

112

3.6 Anti-viral studies A group of novel organotin(IV) carboxylates were synthesized and tested against

Hepatitis C virus (HCV). The dose–response curves are shown in Figures 3.9-3.12.

Based on the luciferase assay results, the compounds were divided into three ranges: The

first range was between 5-10nM (complexes 1, 5 and 18); the second one was between

10-1000nM (complexes 9, 21, 45, 51, 55, 56 and 61); the third range was in between

500-5000nM (complex 14, 19, 37 and 39).

The obtained data shows that the viral inhibition depends upon the nature, structure and

coordination number of the central tin atoms of the complex used [12]. Compounds 1, 5

and 18 showed a high potential at low concentrations against HCV. All three complexes

were triorganotin(IV) derivatives and their high potential was due to the availability of

coordination positions at Sn [13] and higher lipophilicity of triorganotin(IV)

carboxylates. Triorganotin(IV) compounds displayed a higher biological activity than the

diorganotin(IV) analogues, which can be related to their ability to bind to proteins [14-

17].

For complexes 14, 19, 37 and 39 lower activity was observed as compared to 1, 5 and 18.

In case of complexes 14 and 37, both compounds are diorganotin(IV) complexes.

For complexes 14, 18 and 19 the ligand was the same but the organotin(IV) derivatives

were different. The data suggest that the alkyl groups attached to the tin atom were

responsible for the activity. The results conclude that methyl and octyl substituted

complexes displayed lower activities than tributyl and triphenyl substituted complexes

which are in agreement with the literature [18].

In the case of complexes 61, 45 and 51, the alkyl groups were methyl and octyl.

Therefore, they showed lower activities. But in complexes 21, 55 and 56 the alkyl groups

were butyl and showed a lower potential than complexes 18, 1 and 5 due to chloride

groups on the ligands. The chloride groups greatly affects the biological activity of

complexes and this is in agreement with literature data [19,20]. Different positions of the

substituted groups on the complex change the anti-viral activity of complexes [21]. The

chloride groups impart high polarity and lower the lipophilicity. The polarity of the

complexes is a great hindrance for the complexes to pass through cell membranes [21].

113

0 2000 4000 6000 8000 10000

0.00E+000

2.50E+007

5.00E+007

7.50E+007

1.00E+008

1.25E+008

1.50E+008

5 6 7 8 9 10 11 12

0

500000

1000000

1500000

2000000

2500000

3000000

3500000

Lucif

eras

eDrug Concentration

Luci

fera

se

Drug Concentration

0118 02

Figure 3.9: Dose-response curve of organotin(IV) carboxylates in the range

of 5-10nM

0 20000 40000 60000 80000 100000

0.00E+000

3.00E+007

6.00E+007

9.00E+007

1.20E+008

1.50E+008

1.80E+008

0 1000 2000 3000 4000 50000.00E+000

5.00E+007

1.00E+008

1.50E+008

Lucif

eras

e

Drug Concentration

Luci

fera

se

Drug Concentration

39 14 19 37


of 500-5000nM

The chlorides form ion pairs with the nitrogen of amino acids in proteins of cell

membrane and thus lower the penetration of inhibitors in to the cell. Therefore, a less

number of molecules enter into the cell as compared to complex 1. This takes a longer

time of delivery to the site of action. The reason for the variation of the toxicity of

114

organotin compounds with different ligands is suggested by Garrod et al., [22] and it

depends either on the impermeability of the cell. The effect of ligands on the antiviral

activity is further elaborated in Figure 3.12. The dose–response curves of different

tributyltin(IV) complexes having different ligands. The role of the ligand in delivering

organotin(IV) is further studied in detail and is discussed in Section 3.7.

The HCV inhibition assay data predicts that it interfers with a virus after the penetration

in the replication stage and inhibits the virus replication cycle. There are two possible

modes of anti-viral activity. Firstly, the tin metal ion has an appropriate hard-soft

character and abundant valence shell orbitals for an electrovalent bonding with DNA’s

oxygen sites and covalent bonds with nitrogen sites on purine and pyrimidine [23]. The

anti-viral activity may be due to the interaction of organotin(IV) complexes with the

RNA’s oxygen sites and covalent bonds with nitrogen sites on purine and pyrimidine to

prevent its replication. The tin metal atom is directly attached with the oxygen of the

phosphate and affects its replication. This idea is supported by literature reports [24-27].

Secondly, the antiviral activity may stem from affecting cellular enzymes which require

metal ions. The organotin complexes directly complexed with the metalloenzyme

through the metal of the enzyme inhibit cellular and viral activities. The dose–response

curves support the first possibility as complexes 55, 56, and 21 show almost the same

activities although complex 21 has a good chelating ligand compared with complexes 55

and 56. Also complex 18 should a have different activity than complexes 1 and 5 as it

has different chelating capacities. Nevertheless, further experiments are required to

elucidate the mode of action for organotin(IV) carboxylate compounds in detail. These

compounds represent the mode for synthesis of new anti-viral agents.

115

0 2000 4000 6000 8000 10000

0.00E+000

2.00E+007

4.00E+007

6.00E+007

8.00E+007

1.00E+008

0 100 200 300 400 500

0.00E+000

5.00E+007

1.00E+008

1.50E+008

Lucif

eras

e

Drug Concentration

Luci

fera

se

Drug Concentration

55 56 21 09 45 61 51


of 10-1000nM

0 20 40 60 80 100 120 140

0.00E+000

3.00E+007

6.00E+007

9.00E+007

1.20E+008

1.50E+008

1.80E+008

0 20

0.00E+000

3.00E+007

6.00E+007

9.00E+007

1.20E+008

1.50E+008

1.80E+008

Lucif

eras

e

Drug Concentration

Luci

fera

se

Drug Concentration

1 9 46 21 56

Figure 3.12: Dose-response curve of But3SnL

116

3.7 Surfactant-organotin(IV) carboxylate interaction studies To interact with biological systems or to bind with cell organelles, the organotin(IV)

carboxylates have to pass through cell membrane and their interaction with cell

membrane are of prime importance directing the organotin(IV) carboxylates to the target.

Surfactant- organotin(IV) carboxylate interaction studies are one of the best systems that

reflect the idea of physical and chemical behavior of organotin(IV) carboxylates and to

measure various parameters of interactions with biomembranes. The Biological activity

of organotin(IV) carboxylate complexes is mainly dependent on their interactions with

cell membranes which are the main passages for their way to the cell. The hydrophobic

core of the cell membrane is the main site for most of the biological reactions. Cell

membrane are in the form of double layers of phospholipids and charged head groups of

lipids which are responsible for interactions of polar groups of drugs. Surfactant micell

act as cells and the vesicles behave as cell membranes. The extent and type of interaction

is responsible for adsorption, bioavailability and excretion of organotin(IV) carboxylate

molecules through the urinary tract. This type of interaction includes electrostatic force

of interaction, H-bonding, van der Waals forces and hydrophobic forces. Conductometry,

UV-Vis spectroscopy and fluorescence spectroscopy are the most efficient tools to study

the interaction of a drug with a biological systems/ surfactant.

3.7.1 Conductometry Conductometry is one of the best techniques to study the interaction of organotin(IV)

carboxylates with cetyl N,N,N-trimethyl ammonium bromide (CTAB). Specific

conductances of organotin(IV) carboxylate solutions (1mM) in the presence of various

concentrations of CTAB are measured. The conductance of compound 9, 17, 21 and 32

are plotted against concentrations of CTAB as shown in Fig. 3.13-3.16. The conductance

of the solution increases with the increase of CTAB and at a certain concentration of

CTAB an inflection is observed. This point of inflection is known as the CMC of CTAB.

At this point premicellar and postmicellar regions intersect each other. Free energy of

micellization, ∆Gm, can be calculated by using the following equation,

∆Gm= 2.303 (1+ β) RT log Xcmc (3.1)

Where β is the degree of the counter ion binding which is given as

β = 1- α (3.2)

117

α is the degree of dissociation or the degree of ionization calculated from the ratio of

plots before and after cmc.

α = S2/S1 (3.3)

S2 and S1 are slopes of conductivity-concentration plots after and before cmc. Xcmc is

cmc in terms of mole fractions and in case of aqueous solution

Xcmc = cmc/55.55 (3.4)

β, α, Xcmc and ∆Gm for complexes 9, 17, 21 and 32 are given in Table 3.47. In case of all

four organotin(IV) complexes, the addition of CTAB enhanced the conductance as it

disturb the surface tension and its monomers ionizes and generats CTAB+ and Br- ions

[28]. These ions are small in size, free to move and have little interaction among

themselves. After cmc the monomer is used in the micelle formation and the number of

free monomers decreases and the rate of conductance increase is low. After cmc the

conductance is mainly due to the movement of Br- from the surface of one micelle to

another [29].

0.000 0.001 0.002 0.003 0.004 0.005 0.006 0.007 0.0080

50

100

150

200

250

Spec

ific

Con

duct

ivity

(μS

/cm

)

C[CTAB] M

cmc=0.0019 M

Figure 3.13: Specific conductivity curves of CTAB in the presence of 21 in water.

118

0.000 0.001 0.002 0.003 0.004 0.005 0.006 0.007 0.0080

50

100

150

200

250

Spec

ific

Con

duct

ivity

(μS

/cm

)

C [CTAB] M

cmc=0.0016 M


0.000 0.001 0.002 0.003 0.004 0.005 0.006 0.007 0.0080

50

100

150

200

Spe

cific

Con

duct

ivity

(μS

/cm

)

C[CTAB]mM

cmc=0.0015 M


119

0.000 0.001 0.002 0.003 0.004 0.005 0.006 0.007 0.0080

20

40

60

80

100

120

140

160

180

200

cmc=0.0010 M

Spe

cific

Con

duct

ivity

(μS

/cm

)

C [CTAM] M


Table 3.47: Organotin(IV)carboxylate and CTAB interaction parameters determined by conductometery.

α β 1+β R T cmc Xcmc lnXcmc

ΔGp = (1+β)RTlnXcmc

-ΔG(kJ/mol) Compound

0.819177 0.180823 1.180823 8.314 298 0.001 1.80E-05 -10.93 31.98 9

0.697486 0.302514 1.302514 8.314 298 0.0015 2.70E-05 -10.52 33.95 32

0.45932 0.54068 1.54068 8.314 298 0.0016 2.88E-05 -10.33 39.43 17

0.41633 0.58367 1.58367 8.314 298 0.0019 3.60E-05 -10.23 40.14 21

120

3.7.2 Electronic absorption spectra of the complexes UV-Vis spectroscopy studies are used to measure the various interacting parameters of

organotin(IV) carboxylates with CTAB. To calculate various thermodynamic parameters

like the water-micelle partition coefficient Kx, the solubility and standard free energy

change for the transfer of organotin(IV) molecules from bulk water to CTAB micelles,

UV-Vis spectrum of an organotin(IV) carboxylate solution is recorded in the absence

and presence of various concentrations of CTAB. For simple UV-Vis spectroscopy,

distilled water is used as a reference, while for differential UV-Vis spectroscopy, a blank

solution of organotin(IV) solution is used.

Four compounds 9, 17, 21 and 32 selected for the present spectroscopic studies showed

an increase in the absorbance of organotin(IV) carboxylates solutions with the addition

of CTAB. This increase in absorbance was small in premicellar concentration regions

that showed the interaction of the complex with CTAB monomers which also increased

the solubility of organotin(IV) carboxylates in aqueous media.

At the cmc, a sharp increase in hyperchromic shifts was observed which showed the

partition of a greater number of molecules from aqueous media to micellear regions. In

the cmc region CTAB monomers gathered and formed an assembly called micelles. As

the micelles had a large available surface area for interaction, a greater number of

organotin(IV) carboxylate molecules moved towards the micelles region and an increase

in solubility was observed. Organotin(IV) carboxylate molecules absorbed light

preferably in micelles than in aqueous media. In the postmicellar region, the absorbance

became almost constant which showed that additional CTAB monomers were utilized for

the formation of more micelles.

In the presence of organotin(IV) carboxylate, the cmc of CTAB increased. The electrons

on the organotin(IV) carboxylate molecule rearranged and partial negative charge

appeared on carbonyl oxygen atoms, which interacted with the positively charged

nitrogen atoms of the ionized CTAB+ through electrostatic force. This interaction

resulted in an ion pair, which contributed to the stabilization of CTAB+ and increased in

cmc [30].

121

NHC

O

C

O

O

Sn

But

But

But

R

R

NH+

C

O-

C

O-

O+

Sn

But

But

But

R

R

Figure 3.17: Delocalization of electrons in organotin(IV) carboxylate molecules.

The absorption spectra (Fig. 3.24, 3.30, 3.36, and 3.42) for all four organotin(IV)

compounds show that the cmc value of CTAB increased in the presence of the

compound as compared to its aqueous solution. This was due to the reason that the

organotin(IV) carboxylate molecules were tightly bound to the monomers of CTAB

which reduced the repulsion between the positively charged nitrogen atoms of CTAB

molecules as a result the rate of self assembling of CTAB monomers become lower by

decreasing its charge density and enhancing the entropy of mixing.

N+

NH+

C

O-

H2C

H2C

C

O-

O+

Sn But

But

But

R

R

H2CH2C CH3

14

Figure 3.18: Interaction of organotin(IV) carboxylate with CTAB.

The interaction between CTAB and organotin affects Δλmax of all four complexes

selected for the present study as shown in Fig. 3.23, 3.29, 3.35 and 3.41. The change in

Δλmax becomes significant at the cmc of CTAB. Depending on the nature of the

chromophores of the organotin molecules, bathochromic or hypsochromic shifts can take

place. Compounds 17, 21 and 32 showed bathochromic shifts while compound 40

showed a hypsochromic shift. The reason for a bathochromic shift is due the

delocalization of negative charge on the oxygen atom of the carbonyl group. This shift

was prominent in the cmc region which was due to the reason that a greater number of

122

organotin(IV) carboxylate molecules moved from the bulk to CTAB micelles, and the

microenvironment around these molecules was changed. Further, due to the greater

polarity of the organotin(IV) carboxylates and the strength of electrostatic forces

between organotin(IV) molecules and CTAB+, organotin(IV) carboxylate molecules

remained on the peripheral charged core of CTAB micelles, as shown in Figure 3.19.

The position organotin(IV) carboxylate molecules was confirmed by the rise of Kx value

[31].

Figure 3.19: Adsorption of organotin(IV) complex at the surface of CTAB

micelles

In case of an adsorbtion more organotin(IV) molecules is associated with micelles than

in solubilization (in the hydrophophic region) as more surface area will be available for

organotin(IV) molecules. The polarity of the organotin(IV) molecules was mainly

responsible for their release time and place and thus it controls their specifity. A change

in free energy and binding constant depends upon the polarity and the position of

solubilisation in the micelle.

For complex 9, the case is different and a red shift is followed by a blue shift. The π

electrons are resonating in the structure as shown in Figure 3.20.

Due to the presence of the positive charge on the CTAB monomer, the organotin(IV)

carboxylate molecules were attracted towards CTAB and the organotin(IV) carboxylate

molecules moved towards the CTAB monomers. This interaction of organotin(IV)

carboxylate and CTAB resulted in an increase of absorbance as a well as red shift of

Δλmax. At cmc a greater number of molecules interacted with the CTAB micelles due the

greater surface area of spherical shaped micelle which resulted in a sudden increase of

absorbance and a red shift of λmax. The interaction is shown in Figure 3.20.

123

C

HC CH

C

-O -O

N+

+

Figure 3.20: Interaction of CTAB with complex 9

Due to the delocalization of pi electrons in complex 9 (as shown in Fig.3.21) its polarity

decreases.

C

HC CH

C

O O

C

C C

C

O O

Figure 3.21: Diagram showing the resonance of pi electrons in the complex

Moreover, the hydrophobic interaction balance the hydrophilic interaction and the

organotin(IV) carboxylate are pulled into the palisade layer of CTAB micelles and the

hydrophobic butyl chain is incorporated deep into the hydrophobic region of the micelle.

Due to this interaction, organotin(IV) carboxylates no more remain at the surface of a

micelle but enter into the inner core of a micelle. After a certain concentration the

micelles are no longer able to accommodate more organotin(IV) molecules.

In case of complex 9 the surface is not occupied with organotin(IV) molecules and the

structural change of CTAB micelle from spherical to rod like took place. A rod like

structured micelle is compact and has less space for organotin(IV) molecules resulting in

a decreased solubility of complex 9. The decreased solubility results in a blue shift of

Δλmax and lowers the absorbance. As a limited number of organotin(IV) carboxylate

molecules can be accommodated in the palisade layer of CTAB micelle as compared to

peripheral layers, the net absorbance of the solution decreases. The blue shift of λmax

shows that a less number of organotin(IV) molecules are accommodating within the

micelle and a change of the environment around the chromophore [32].

124

Solubilizate

Figure 3.22: Adsorption in the palisade layer of CTAB micelle (up to 2-3 carbons)

Differential absorbance spectroscopy (Figure 3.25, 3.31, 3.37, and 3.43), in the

postmiceller concentration region, is carried out to determine the extent of interactions of

organotin(IV) carboxylates with CTAB, as a function of change in the differential

absorbance with CTAB concentration. The addition of CTAB increases the differential

absorbance. Interaction parameters like water-micelle partition coefficient (Kc) and

Standard free energy change (ΔG) for the transfer of organotin(IV) molecules from bulk

water to CTAB micelle were calculated by using spectroscopy. The measured change in

differential absorbance is negligible before cmc showing that small amount of

organotin(IV) carboxylate is solubalized. After cmc, there is an increase in adsorption as

a higher number of molecules is adsorbed on the surface of a micelle [33,34]. The

partition coefficient Kc for the distribution of organotin(IV) carboxylates between

aqueous media and a micelle can be calculated using the Kawamura Equation:

αα ACCAKA mosac Δ

++Δ

=Δ

1)(

11 (3.5)

Where, Ca is the concentration of the organotin(IV) carboxylate, Csmo represents the

concentration of micellized CTAB i.e., Cs-CMCo (CMCo is the cmc of surfactant in

water) and ΔAα is the ΔA at infinity of CTAB. Kc is obtained from the plot of l/ΔA

versus)(

1mosa CC +

for the complexes 9, 17, 21 and 32 as shown in Figure 3.27, 3.33,

3.39, and 3.45. This Kc is used for the calculation of Kx.

Kx = Kc.nw (3.6)

nw is the number of moles of water per liter i.e. 55.5 mol/L. The slope of the Eq. (3.6)

gives Kc and the intercept gives ΔAα. The values of Kc for all four systems are

125

summarized in Table 3.48. A higher value of Kx indicates higher electrostatic

interactions due to the polar nature of the organotin(IV) complexes. The positively

charged nitrogen atom of CTAB creates a type of charge density in the outer periphery of

the micelle that attract the organotin(IV) complex molecules. This higher value of Kx

also reflects the idea about the position of the organotin(IV) complexes in the micelle of

CTAB, i.e. the organotin(IV) carboxylate molecules are present in the outer polar core of

micelle and their n-butyl group is pulled inward by lateral forces. The standard free

energy change is accompanied by the partition of organotin(IV) carboxylate molecules

and it is given by;

(3.7) xop KRTG ln−=Δ

Where R is the ideal gas constant, T is the absolute temperature. The amount of -ΔGºp

gives us an information about the phenomenon of solubilization. The negative value of

the Standard free energy change for the process of the transfer of organotin(IV)

molecules from bulk water to CTAB micelle shows that the process is spontaneous.

The relative solubility of the complexes 9, 17, 21 and 32 is calculated by using equation;

St/So = 1+KxvM (3.8)

Figures 3.15, 3.21, 3.27 and 3.33 show the relative solubility of the studied complexes. v

is the partial molar volume of the CTAB micelle, Kx is the partition coefficient of the

water- micelle system and M. The micellar concentration is obtained by using the

equation;

M = Cs-CMCo/N (3.9)

Cs is the concentration of micelles and CMCo is the critical micelle concentration.

126

230 240 250 260 270 280 2900.10

0.15

0.20

0.25

0.30

0.35

0.40

0.45

0.50

0.55

0.60

0.65

0.70

0.75

228229

230231

232233

234

235

236

237

238

239

240

241

242243

244245

246247

248249250251252253254255

256257

258259

260261

262263

264265

266267

268269270271272273274275

767

HTHU

HVHW

HXHY

HZ

IA

IB

IC

ID

IE

IF

IG

IHII

IJIK

ILIM

INIOIPIQIRISITIU

IVIW

IXIY

IZJA

JBJC

JDJE

JFJG

JHJIJJJKJLJMJNJO

P

hthu

hvhw

hxhy

hz

ia

ib

ic

id

ie

if

ig

ihii

ijik

ilim

inioipiqirisit

iuiv

iwix

iyiz

jajb

jcjd

jejf

jgjh

jijjjkjljmjnjop

Abso

rban

ce

Wave length (nm)

0.00 mM CTAB 7.0 mM CTAB 5.6mM CTAB 4.5 mM CTAB 3.6 mM CTAB 2.9 mM CTAB 2.3 mM CTAB 1.8 mM CTAB 1.5 mM CTAB 1.2 mM CTAB 0.90 mM CTAB 0.75 mM CTAB 0.60 mM CTAB 0.48 mM CTAB 0.39 mM CTAB

1 0.31 mM CTABA 0.25 mM CTABa 0.19 mM CTAB

0.16 mM CTAB 0.13 mM CTAB

CTAB

Figure 3.23: Absorption of 21 in pre and postmicellar concentration of CTAB (Ca =7.5х10-6mM)

0.000 0.001 0.002 0.003 0.004 0.005 0.006 0.007 0.008

0.62

0.64

0.66

0.68

0.70

0.72

0.74

Abs

orba

nce

C [CTAB] M

Figure 3.24: Effect of CTAB concentration on absorbance of 21

127

250 260 270 280 290-0.10

-0.05

0.00

0.05

0.10

0.15

0.20

0.25 7 mMCTAB5.6 mMCTAB4.5 mMCTAB3.6 mMCTAB2.9 mMCTAB2.3 mMCTAB1.8 mMCTAB1.5 mMCTAB1.2 mMCTAB0.9 mMCTAB

Diff

eren

tial A

bsor

banc

e

Wave length(nm)

CTAB

Figure 3.25: Differential absorption spectra of 21 in the postmicellar concentrations of CTAB (Ca = 7.5х10-6mM)

0.000 0.001 0.002 0.003 0.004 0.005 0.006 0.0070.05

0.10

0.15

0.20

0.25

0.30

Diff

eren

tial A

bsor

banc

e

C [CTAB] M

Figure 3.26: Effect of CTAB concentration on differential absorbance of 21

128

500 1000 1500 2000 2500 3000 3500 40003

4

5

6

7

8

9

10

1/D

iff. A

bsor

banc

e

1/Ca+C

smo

Figure 3.27: Relationship between 1/ΔA and 1/(Ca+Csmo) for 21

0.001 0.002 0.003 0.004 0.005 0.006 0.007

100

200

300

400

500

St/S

o

M [M]

Figure 3.28: Effect of CTAB concentration on relative solubility of 21

129

230 240 250 260 270 280 290 300

0.2

0.3

0.4

0.5

0.6

0.7

129130131132133134135136137138139140141142143144145

146147

148149

150151

152153

154155

156157

158159

160161

162163

164165

166167168169170171172173174175767

DZEAEBECEDEEEFEGEHEIEJEKELEMENEO

EPEQ

ERES

ETEU

EVEW

EXEY

EZFA

FBFC

FDFE

FFFG

FHFI

FJFKFLFMFNFOFPFQFRFSFT

dzeaebecedeeefegeheiejekelemeneo

epeq

eres

eteu

evew

exey

ezfa

fbfc

fdfe

fffg

fhfifjfkflfmfnfofpfqfrfsft

Abs

orba

nce

Wave length (nm)

0.00 mM CTAB7 mM CTAB5.6 mM CTAB4.5 mM CTAB3.6 mM CTAB2.9 mM CTAB2.3 mM CTAB1.8 mM CTAB1.5 mM CTAB1.2 mM CTAB0.9 mM CTAB0.76 mM CTAB0.60 mM CTAB0.48 mM CTAB0.39 mM CTAB

1 0.31 mM CTABA 0.25 mM CTABa 0.19 mM CTAB

0.16 mM CTAB0.13 mM CTAB0.10 mM CTAB

CTAB

Figure 3.29: Absorption of 17 in pre and postmicellar concentration of CTAB (Ca = 6.9х10-6mM)

0.000 0.001 0.002 0.003 0.004 0.005 0.006 0.0070.54

0.56

0.58

0.60

0.62

0.64

0.66

0.68

0.70

Abs

orba

nce

C [CTAB] M


130

230 240 250 2600.00

0.02

0.04

0.06

0.08

0.10

0.12

0.14

0.16

0.18

0.20

Diff

eren

tial A

bsor

banc

e

Wave length (nm)

7 mM CTAB 5.6 mM CTAB 4.5 mM CTAB 3.6 mM CTAB 2.9 mM CTAB 2.3 mM CTAB 1.8 mM CTAB 1.5 mM CTAB 1.2 mM CTAB 0.9 mM CTAB

CTAB


0.001 0.002 0.003 0.004 0.005 0.006 0.0070.00

0.05

0.10

0.15

0.20

Diff

eren

tial A

bsor

banc

e

C [CTAB] M


131

200 400 600 800 1000 12004

5

6

7

8

9

10

11

12

1/D

iff. A

bsor

banc

e

1/Ca+Csmo


0.001 0.002 0.003 0.004 0.005 0.006 0.007

100

200

300

400

St/S

o

M [M]


132

230 240 250 260 270 280 290 300 310

0.1

0.2

0.3

0.4

0.5

0.6

226229

232

235

238

241

244

247

250

253256259

262

265

268

71

HRHU

HX

IA

ID

IG

IJ

IM

IP

ISIVIY

JB

JE

JH

K

hrhu

hx

ia

id

ig

ij

im

ip

isiviy

jb

je

jh

k

CTAB

7 mMCTAB 5.6 mMCTAB 4.5 mMCTAB 3.6 mMCTAB 2.9 mMCTAB 2.3 mMCTAB 1.8 mMCTAB 1.5 mMCTAB 1.2 mMCTAB 0.9 mMCTAB 0.76 mMCTAB 0.60 mMCTAB 0.48 mMCTAB 0.38 mMCTAB

1 0.31 mMCTABA 0.25 mMCTABa 0.19 mMCTAB

0.16 mMCTAB 0.13 mMCTAB 0.10 mMCTAB 0.08 mMCTAB 0.00 mMCTAB

Abs

orba

nce

Wave length (nm)


0.000 0.001 0.002 0.003 0.004 0.005 0.006 0.007

0.48

0.50

0.52

0.54

0.56

0.58

Abs

orba

nce

C [CTAB] M


133

240 250 260 270 280

0.00

0.05

0.10

0.15


Diff

eren

tial A

bsor

banc

e

wave length (nm)

CTAB


0.001 0.002 0.003 0.004 0.005 0.006 0.0070.00

0.02

0.04

0.06

0.08

0.10

0.12

0.14

0.16

0.18

Diff

eren

tial A

bsor

banc

e

C [CTAB] M


134

0 200 400 600 800 1000 12000

2

4

6

8

10

12

14

16

18

20

22

24

1/D

iff. A

bsor

banc

e

1/Ca+Csmo


0.001 0.002 0.003 0.004 0.005 0.006 0.007200

400

600

800

1000

1200

1400

1600

1800

St/S

o

M [M]


135

260 270 280 290 300 310 320 330 340 350 360 370 380

0.05

0.10

0.15

0.20

0.25

0.30

0.35

135155

175

195

215

235

Abs

orbt

ion

Wave length (nm)

7 mM CTAB 5.6 mM CTAB 4.5 mM CTAB 3.6 mM CTAB 2.9 mM CTAB 2.3 mM CTAB 1.8 mM CTAB 1.5 mM CTAB 1.2 mM CTAB 0.9 mM CTAB 0.76 mM CTAB 0.60 mM CTAB 0.48 mM CTAB 0.39 mM CTAB 0.31 mM CTAB 0.25 mM CTAB

1 0.00 mM CTAB

CTAB


0.000 0.001 0.002 0.003 0.004 0.005 0.006 0.007

0.26

0.28

0.30

0.32

0.34

Abso

rban

ce

C [CTAB] M


136

270 280 290 300 310 320 330 340 350 360 370 380-0.10

-0.05

0.00

0.05

0.10


CTAB

Diff

eren

tial A

bsor

banc

e

Wave length(nm)


0.001 0.002 0.003 0.004 0.005 0.006 0.007

0.0

0.2

0.4

0.6

Diff

eren

tial A

bsor

banc

e

C [CTAB] M


137

0 100 200 300 400 500 6006

8

10

12

14

16

18

20

22

24

26

1/D

iff. A

bsor

banc

e

1/Ca+C

smo

Figure 3.45: Relationship between 1/ΔA and 1/ (Ca+Csmo) for 9

0.001 0.002 0.003 0.004 0.005 0.006 0.00710

15

20

25

30

35

40

45

50

55

60

65

70

75

80

St/S

o

M [M]


138

Table 3.48: The binding constants and Gibbs free energies of organotin(IV) carboxylates calculated by using UV-Visible Spectroscopy

Compound Kx(L/mol) -ΔG(kJ/mol)

21 1.9х105 30.17

17 3.4х105 25.84

32 1.1х104 23.08

9 9.4х103 22.67

3.7.3 Fluorescence Spectroscopy Fluorescence spectroscopy is used to measure various binding parameters of

organotin(IV) carboxylates with CTAB as a function of emission intensity versus wave

length (nm). In the present fluorescence study, different amounts of CTAB (in the region

of postmicellar concentration) are added to the solution of an organotin(IV) carboxylate

and the spectra are recorded. The data obtained from the spectra recorded at the different

postmicellar concentrations is processed to measure various interaction parameters like

the binding constant, the binding energy and the number of binding sites of

organotin(IV) carboxylates to which CTAB interacts.

The Fig. 3.48, 3.51, 3.54 and 3.57 show the fluorescence emission spectra for the

organotin(IV) carboxylates 9, 17, 21 and 32. The emission intensity of the organotin(IV)

carboxylate complexes decreases with the increase of the CTAB concentration. This

decrease in intensity is due to the interaction of the carboxylate with CTAB. The

fluorescence behavior of organotin(IV) carboxylate molecules at different concentrations

of CTAB shows that organotin(IV)carboxylate molecules residue on the outer positively

charged surface of CTAB micelles [35]. This spectral pattern also shows the closeness of

bromide ions to the partially charged oxygen atoms of the ligand carbonyls and is

supportive about the position of organotin(IV) molecules in the periphery of CTAB

molecules. At the surface of the micelle organotin(IV) carboxylate molecules stable ion

pairs with CTAB+ in solution are formed [36]. In the ion pair formation, a change of

energy states on a molecular level in organotin(IV) carboxylate molecule occurs and the

transitions take place between new energy states formed due to ion pair formation.

However, there is no change observed in the position of the emission spectra.

139

The quenching constant for the complexes is calculated by plotting (Io- I)/I against

[CTAB] as shown in Fig. 3.49, 3.53, 3.56 and 3.59 for complexes using the following

equation:

(Io- I)/I = Kq [CTAB] (3.11)

Where Io and I are the fluorescence intensities of organotin(IV) carboxylates without

CTAB and with CTAB. Kq is the quenching constant and [CTAB] is the concentration

of CTAB. The value for Kq is obtained from the slope of the plot (Io- I)/I versus

[CTAB]. High values show that the interaction is electrostatic as well as hydrophobic

between the organotin(IV) carboxylate and the CTAB micelle, which is responsible for a

decreasing fluorescence intensity. The so obtained data from Fig. 3.50, 3.52, 3.55 and

3.58 is used for the determination of binding constant, binding capacity and binding

energy using given equation;

log (Io- I)/I = log Kb + n log [CTAB] (3.12)

In a plot of log (Io- I)/I vs log [CTAB] in (Fig. 3.50, 3.52, 3.55 and 3.58), the Intercept

gives us the value of the log of the binding constant, and the slope gives the number of

binding sites of the organotin(IV) carboxylate with CTAB. The binding energy of CTAB

with organotin(IV) carboxylate molecules is calculated by using the given equation;

ΔG= -RT lnKb (3.13)

The high value of the binding energy is given in Table 3.69 and it shows that the

organotin(IV) carboxylate has a high binding capacity with CTAB micelles due to the

electrostatic interaction besides the hydrophobic interaction of n-Butyl chains attached

with the tin atom and the alkyl chain of CTAB. Organotin(IV) carboxylate molecules

form ion pairs with CTAB due to electrostatic forces between the negatively charged

carbonyl oxygen atoms and positively charged nitrogen atom of CTAB.

This model explains the antiviral trends of the tested complexes that the complexes with

higher number of electronegative atoms remain attached with the cell membrane and

cannot pass easily through cell membrane to inhibit HCV.

This study also help us in predicting the mode of the organotin(IV) complexes. During

the passage of organotin(IV) molecules in to the cell, organotin(IV) molecules interact

with the contents of cell memberane and remain embedded at different levels in lipid

bilayers, as evidenced by alterations in a membrane fluidity [37]. Differing ligand types

140

influence both the polarity and structural characteristics of each organotin(IV)

compound, and result in different actions at the phospholipid membrane level.

N+

N+

N+

N+

N+

N+

N+

N+

N+

N+

N+

N+

N+N+ N+

NH+

C

O-

H2C

H2C

C

O-

O+

SnBut

But

But

R

R

Figure 3.47: Interaction of organotin(IV) carboxylates with micelles

141

SnHN C C

O

O O

Cl

Cl

300 350 400 450 500 550 600 6500

200

400

600

800

Wave length(nm)

Inte

nsity

(I)

0.00mMCTAB 0.79mMCTAB 0.85mMCTAB 0.90mMCTAB 0.95mMCTAB 1.00mMCTAB 1.05mMCTAB 1.11mMCTAB 1.18mMCTAB 1.25mMCTAB 1.33mMCTAB 1.43mMCTAB

CTAB

Figure 3.48: Plot of I versus wave length for postmicellar concentrations

of CTAB for 21 (Ca= 1.0х10-9)

142

0.0010 0.0012 0.0014 0.0016 0.0018 0.0020

0.2

0.3

0.4

0.5

0.6

0.7

0.8

k=585

(Io-I)

/I

C [CTAB] mM

Figure 3.49: Plot of [I-Io)I] versus (Cs) for 21

-3.05 -3.00 -2.95 -2.90 -2.85-0.8

-0.7

-0.6

-0.5

-0.4

-0.3

log(

Io-I)

/I

logC [CTAB] mM

n=2.3log k=6.19

Figure 3.50: Plot of log [I-Io)I] versus log (Cs) for 21

143

SnHN C C

O

O OF

300 350 400 450 500 550 600 6500

200

400

600

800

Inte

nsity

(i)

Wave length(nm)

PURE DRUG 2.0mMCTAB 1.8mMCTAB 1.6mMCTAB 1.5mMCTAB 1.4mMCTAB 1.3mMCTAB 1.25mMCTAB 1.1mMCTAB 0.900mMCTAB

CTAB

Figure 3.51: Plot of I versus wave length for postmicellar concentrations of CTAB for 17 (Ca= 1.0х10-9 M)

144

-2.95 -2.90 -2.85 -2.80

-1.1

-1.0

-0.9

-0.8

-0.7

-0.6

-0.5

-0.4

n=2.3log k=6.097

log[

Io-I/

I]

log C [CTAB] mM

Figure 3.52: Plot of log [I-Io)1] versus log (Cs) for 17

0.0012 0.0014 0.0016 0.0018 0.0020

0.10

0.15

0.20

0.25

0.30

0.35

K=311

Io-I/

I

C [CTAB] mM


145

SnHN C C

O

O O

H3C

CH3

300 350 400 450 500 550 6000

200

400

600

800

1000

Inte

nsity

(i)

Wave length(nm)

PURE DRUG 0.77mMCTAB 0.80mMCTAB 0.85mMCTAB 0.89mMCTAB 0.90mMCTAB 1.00mMCTAB 1.07mMCTAB 1.14mMCTAB 1.22mMCTAB 1.31mMCTAB 1.42mMCTAB 1.55mMCTAB

CTAB

Figure 3.54: Plot of I versus wave length for postmicellar concentrations of CTAB for 32 (Ca= 1.0х10-9M)

146

-3.05 -3.00 -2.95 -2.90 -2.85 -2.80 -2.75

-1.1

-1.0

-0.9

-0.8

-0.7

-0.6

-0.5

log[

Io-I/

I]

log C [CTAB]

n=2.3log k=6.068


0.0008 0.0010 0.0012 0.00140.05

0.10

0.15

0.20

0.25

0.30

Io-I/

I

C [CTAB] mM

K=315


147

SnHN C C

O

O O

H3C

CH3

300 320 340 360 380 400 420 440 460 480 5000

200

400

600

800

Inte

nsity

(i)

Wave length(nm)

0.00mMCTAB0.90mMCTAB1.00mMCTAB1.05mMCTAB1.11mMCTAB1.20mMCTAB1.25mMCTAB1.33mMCTAB1.43mMCTAB1.54mMCTAB1.67mMCTAB1.82mMCTAB2.00mMCTAB

CTAB

Figure 3.57: Plot of I versus wave length for postmicellar concentrations of CTAB for 9 (Ca= 1.0х10-9 M)

148

-3.05 -3.00 -2.95 -2.90 -2.85 -2.80 -2.75

-0.9

-0.8

-0.7

-0.6

-0.5

-0.4

-0.3

-0.2

log[

Io-I/

I]

log C [CTAB] mM

n=2.1log k=5.53


0.0010 0.0012 0.0014 0.0016 0.0018 0.0020

0.1

0.2

0.3

0.4

0.5

Io-

I/I

C [CTAB] mM

k=419


149

Table 3.49: The binding constants, binding sites and Gibbs free energies of organotin(IV)carboxylates calculated by using Flouresence Spectroscopy.

Compound n Kb(L/mol) -ΔGb(kJ/mol)

21 2.3 1.54х106 35.3

17 2.3 1.25х106 34.8

32 2.3 1.17х106 34.6

9 2.1 3.4х105 31.6

3.8 Thermal Studies Thermogravimetric analyses were performed on 50 selected compounds. Thermal

decomposition patterns of selected organotin(IV) compounds are given in Table 3.50

while the thermal behavior of the selected compounds based on calculated and actual

values are given in Table 3.51. The calculated fragment weights of each step were

compared with the weight of the obtained fragment. The comparison of calculated and

the obtained weights at each step showed no significant differences. The kinetics

parameters, i.e., order of reaction, enthalpy, entropy and activation energy, for each step

of the TG curves were calculated using Horowitz and Coats methods [38,39]. Thermal

degradation patterns of compounds obtained from the ligand the HL7 and HL8 are given

in Figures 3.48 and 3.49, as representative of all studied compounds.

The organotin(IV) complexes showed different patterns of decomposition depending on

nature of the ligand. The stability and bulkiness of ligands affected the patterns of

decomposition. All organotin(IV) complexes of HL7 showed decomposition pathways in

more than one step due to the presence of the cyclohexane moiety which imparted the

stability to the ligand and decomposed in several steps.

The number of the decomposition steps for the triorganotin(IV) derivatives are less than

in the diorganotin(IV) derivatives. Probably, it occurs due to one and two carboxylate

groups.

The final step of decomposition in all tested organotin(IV) complexes corresponded to

the formation of SnO2. The formation of SnO2 lies in the different temperature ranges for

different complexes. Organotin(IV) complexes are decomposed by the following pattern.

150

Table 3.50: Thermal decomposition pattern of selected organotin(IV) carboxylates

Complex No. Formula Temp. range Fragment

evolved Fragment

residue 1 C22H34NO3FSn 108-238 C22H34NOF SnO2

2 C28H36N2O6F2Sn 107-254 257-353 357-457

C12H10NO4F2 C14H16 C2H8N

SnO2

3 C36H52O6N2F2Sn 121-321 C36H52O4N2F2 SnO2 4 C22H20O6N2F2Sn 140-383 C22H20O4N2F2 SnO2 6 C13H18O3NFSn 106-246 C13H18ONF SnO2

7 C32H24O6N2F2Sn 140-280 290-350 361-535

C13H10O4NF C4H4N

C15H10F SnO2

14 C36H52O6N2F2Sn 176-570 C36H52O4N2F2 SnO2

15 C32H28O6N2F2Sn 137-256 260-539

C21H22O4N2F2 C11H5

SnO2

16 C28H36O6N2F2Sn 91-285 C28H36O4N2F2 SnO2

17 C22H36O3NFSn 100-247 250-539

C10H19ONF C12H17

SnO2

18 C28H24O3NFSn 189-274 383-349

C24H22ONF C4H2

SnO2

19 C13H18O3NFSn 143-247 C13H18ONF SnO2 20 C36H50O6N2Cl4Sn 189-343 C36H50O4N2Cl4 SnO2 21 C22H35O3NCl2Sn 208-291 C22H35ONCl2 SnO2 22 C28H34O6N2Cl4Sn 175-317 C28H34O4N2Cl4 SnO2 23 C28H23O3NCl2Sn 190-327 C28H23ONCl2 SnO2 24 C13H17O3NCl2Sn 175-337 C13H17ONCl2 SnO2

25 C36H50O6N2Cl4Sn 100-273 273-330

C19H23O4N2Cl4 C17H27

SnO2

26 C28H23O3NCl2Sn 193-283 286-383

C22H17ONCl2 C6H6O

SnO2

27 C28H39O6N2Cl4Sn 158-328 C28H34O4N2Cl4 SnO2 28 C22H35O3NCl2Sn 206-328 C22H35ONCl2 SnO2

29 C13H17O3NCl2Sn 172-298 300-370

C13H12O4NCl2 C9H10NCl2

SnO2

30 C13H17NO3Cl2Sn 238-309 C13H17NOCl2 SnO2

31 C15H23NO3Sn 160-203 220-261

C2H4NO C13H19 SnO2

32 C24H41NO3Sn 125-316 C24H41NO SnO2 33 C30H29NO3Sn 197-318 C30H29NO SnO2

34 C26H34N2O6Sn 142-224 224-424

C5H16NO4 C21H18N

SnO2

35 C32H32N2O6Sn 188-294 C32H32N2O4 SnO2

36 C36H38N2O6Sn 165-229 232-342 345-464

C23H28N2O4 C5H2 C8H8

SnO2

151

37 C40H62N2O6Sn

126-258 258-345 347-410 410-480

C9H10NO C4H8O2 C8H10N C19H34O

SnO2

38 C32H42N2O6Sn 160-330 330-520

C17H22N2O3 C15H20O SnO2

39 C38H54N2O6Sn 170-330 330-400 400-510

C7H6O C16H19N2O3

C15H29 SnO2

40 C42H46N2O6Sn 140-230 230-320 350-510

C23H27O4 C14H16 C5H3N

SnO2

41 C46H70N2O6Sn 100-340 370-570 570-630

C9H9NO C19H28O3

C16H33 SnO2

42 C18H27NO3Sn 220-310 310-460

C6H5O C12H22N SnO2

43 C27H45NO3Sn 146-223 223-728

C10H8N C17H37O SnO2

44 C33H33NO3Sn 127-260 260-406 406-787

C7H6O C15H23N

C11H4 SnO2

45 C12H17NO6Sn 100-220 220-400

C4H6O2 C8H11O2

SnO2

46 C21H35NO6Sn 120-400 C21H35NO5 SnO2 47 C27H23NO6Sn 140-400 C27H23NO5 SnO2

48 C20H22N2O12Sn 140-260 260-320 320-540

C4H2O4 C3H7O6

C13H11N2 SnO2

49 C26H34N2O12Sn 160-300 300-700

C9HNO6 C17H33NO4 SnO2

50 C30H26N2O12Sn 120-240 240-730

C8H12O6 C22H14NO4 SnO2

51 C34H50N2O12Sn 100-280 280-329 329-700

C7H5NO3 C8H15O6

C19H30NO

SnO2

52 C25H17O2Cl3Sn 100-300 310-450

C10H10 C15H7Cl3 SnO2

53 C26H14O4Cl6Sn 130-300 300-344 344-450

C12H2 CCl

C13H12O2Cl5 SnO2

54 C30H38O4Cl6Sn 230-370 C30H38O2Cl6 SnO2 55 C22H22O4Cl6Sn 170-360 C22H22O2Cl6 SnO2 56 C19H29O2Cl3Sn 160-360 C19H29Cl3 SnO2 57 C10H11O2Cl3Sn 200-370 C10H11Cl3 SnO2

152

The order of reaction for the thermal decomposition of the tested complexes was one.

The activation energy (Ea) value for step I is lower than the second and third step

because of a greater stiric hindrance initially in the complexes. At higher temperatures a

rearrangement of molecules occur and moieties with more stable configuration are

formed which results in higher activation energies in the second, third and fourth step as

compared to the first step of decomposition. The apparent activation enthalpy has a

positive value for all complexes. Hence, thermal degradation of these complexes is a

spontaneous process.

Table 3.51: Kinetics parameters obtained from TGA of selected organotin(IV) carboxylates

Compound Temp. (°C)

Order (n)

E* (kJ/mol)

ΔS* (J/mol.K)

ΔH* (kJ/mol)

% wt loss

Cal. Obs.

1 108-238 0.9 15.9 -123.0 14.1 96.5 30.5

94.4 32.6

2 107-254 257-353 357-457

0.9 0.9 1.1

19.7 34.4 40.2

-85.6 -31.1 -81.1

17.8 31.8 37.2

41.0 28.5 7.3 23.2

39.5 28.3 9.5 22.7

3 121-321 0.94 21.4 -129.2 18.9 80.0 20.0

78.2 21.8

4 140-383 1.0 10.9 -198.4 8.8 73.1 26.9

72.0 28.0

6 106-246 0.8 27.0 1.9.0 25.1 59.3 40.7

61.1 38.9

7 140-280 290-350 361-535

1.0 0.9 1.0

17.4 61.5 88.9

-115.0 159.0 160.9

15.4 58.8 85.3

37.9 9.8 30.4 21.9

35.2 7.5 32.1 25.2

14 176-570 0.94 19.2 -137.0 16.8 80.2 19.8

81.2 18.8

15 137-256 260-539

1.0 1.0

26.1 30.1

-21.0 -134.0

24.3 26.5

58.4 19.7 21.9

57.9 18.9 23.2

16 91-285 1.0 23.2 -82.0 21.2 76.8 23.2

75.6 24.4

17 100-247 250-539

0.9 1.0

19.4 20.5

-96.0 -120.0

17.4 18.2

35.5 34.2 30.3

35.6 33.9 31.5

18 189-274 383-349

0.9 1.1

39.9 44.1

88.9 65.0

37.8 41.7

63.9 8.9 27.2

62.6 10.3 27.1

153

19 143-247 0.9 24.7 -32.1 22.8 59.5 40.5

57.4 42.6

20 189-343 1.0 22.8 -102.0 20.5 82.5 17.5

83.2 16.8

21 208-291 0.9 44.9 96.8 42.6 72.5 27.5

71.9 28.1

22 175-317 0.9 29.2 -57.3 2.6 79.9 20.1

79.5 20.5

23 190-327 0.9 37.2 2.1 34.7 75.2 24.8

74.9 25.1

24 175-337 1.0 24.2 -101.3 2.7 82.5 17.5

81.6 18.4

25 100-273 273-330

0.9 0.9

24.1 81.9

-63.8 402.0

21.9 79.6

60.0 22.5 17.5

61.5 21.8 17.7

26 193-283 286-383

0.8 0.8

12.2 23.3

-195.7 -125.6

9.9 20.6

59.8 15.4 24.8

58.5 15.1 26.4

27 158-328 1.0 28.7 -61.0 26.6 79.9 20.1

78.4 21.6

28 206-328 0.9 36.6 2.3 34.8 72.5 27.5

73.1 26.9

29 172-298 300-370

0.8 0.8

23.1 81.2

-77.3 283.9

21.5 78.4

47.1 30.3 22.6

45.7 31.1 23.2

30 238-309 0.8 42.8 75.9 40.5 64.3 35.7

63.5 36.5

31 160-203 220-261

1.0 0.8

43.6 58.6

266.0 272.0

42.1 56.5

15.1 45.4 39.4

15.8 44.9 39.3

32 125-316 1.0 25.7 -75.0 23.3 70.2 29.8

69.4 30.6

33 197-318 1.0 40.5 49.0 38.2 73.4 26.6

73.1 26.9

34 142-224 224-424

0.9 1.0

22.3 54.8

-33.6 186.1

20.6 52.5

47.2 27.1 25.8

46.7 28.0 25.3

35 188-294 1.0 42.3 91.0 40.1 77.0 23.0

76.2 23.8

36 165-229 232-342 345-464

0.8 1.0 1.1

30.3 36.3 44.8

46.8 43.8 -44.2

28.5 34.2 41.2

55.5 8.7 14.6 21.2

54.6 7.9 14.3 23.2

154

37

126-258 258-345 347-410 410-480

0.9 0.9 0.8 0.9

15.3 54.1 64.0 640.9

-143.1 135.2 61.6 294.0

13.3 51.6 60.3 63.7

23.6 14.4 17.0 20.7 24.3

23.1 15.0 17.9 21.2 22.8

38 160-330 330-520

0.9 1.0

23.7 29.2

-107.1 -36.9

21.2 45.4

45.1 32.2 22.7

46.0 32.8 21.2

39 170-330 330-400 400-510

0.8 0.8 1.0

18.8 61.8 96.6

-153 109

182.6

16.3 58.7 92.6

14.0 37.9 28.0 20.1

13.7 36.4 30.6 19.3

40 140-230 230-320 350-510

0.8 0.7 0.9

16.6 33.7 38.4

-111.2 -18.42 -84.94

14.8 31.3 34.8

47.9 23.5 9.6 19.0

48.0 23.9 10.0 18.1

41 100-340 370-570 570-630

0.9 0.9 1.0

14.7 33.7 210.2

-189 -117 557

12.1 29.9 205.3

16.9 43.7 21.9 17.5

17.0 43.1 21.0 18.9

42 220-310 310-460

0.8 0.8

39.3 40.8

33.8 -120.4

36.9 25.5

21.9 42.3 35.8

21.0 41.9 37.1

43 146-223 223-728

0.8 0.8

8.4 12.4

-219 -227

6.5 16.5

25.8 46.5 27.6

25.8 47.2 27.0

44 127-260 260-406 406-787

0.8 0.8 1.0

28.6 45.5 64.9

39.9 -10.3 -18.8

26.9 42.3 60.2

17.4 35.7 22.0 24.9

17.9 35.1 21.8 25.2

45 100-220 220-400

1.0 1.0

17.9 22.3

-48.1 -110.8

16.5 19.9

21.9 39.2 38.9

20.1 40.7 39.2

46 120-400 1.1 17.0 -169.8 14.4 70.6 29.4

71.5 28.5

47 140-400 1.0 11.7 -225.5 8.9 73.7 26.3

71.3 28.7

48 140-260 260-320 320-540

0.8 0.9 1.0

18.3 19.6 37.0

-119.6 -125.6 -107.7

16.3 17.3 33.1

19.1 23.3 32.3 25.3

20.9 24.0 30.1 25.0

49 160-300 300-700

0.8 0.9

33.4 34.1

-16.7 -84.24

30.9 30.9

32.1 45.8 23.1

32.0 46.1 21.9

155

50 120-240 240-730

0.9 1.0

12.6 22.0

-158.9 -210.0

10.8 19.4

30.1 49.0 20.9

32.3 48.6 19.1

51 100-280 280-329 329-700

0.9 0.9 1.0

14.4 96.1 173.2

-169.2 463.0 826.0

12.2 93.6 170.1

18.9 26.2 35.9 19.0

18.1 26.6 36.2 19.1

52 100-300 310-450

0.8 0.9

66.9 98.8

262.0 274.0

64.5 91.4

22.4 51.2 26.4

21.9 50.5 27.6

53 130-300 300-344 344-450

0.8 0.9 1.1

14.9 106.4 107.5

-162.0 462.0 390.0

12.7 103.6 104.4

20.2 6.5 52.3 21.0

19.8 6.2 52.1 21.9

54 230-370 1.0 57.3 96.0 54.3 77.8 22.2

78.1 21.9

55 170-360 0.8 41.8 4.8 39.0 77.7 22.3

76.9 23.1

56 160-360 1.0 30.4 -39.6 28.4 70.5 29.5

69.1 30.9

57 200-370 0.9 40.3 0.9 37.6 60.9 39.1

61.2 38.8

0 100 200 300 400 500 600 70010

20

30

40

50

60

70

80

90

100

Wei

ght (

%)

Temperature oC

Compound 45 Compound 46 Compound 47 Compound 48 Compound 49 Compound 50 Compound 51

Figure 3.60: Thermal decomposition pattern of organotin(IV) complexes of HL7

156

100 200 300 400 500 600 700

20

30

40

50

60

70

80

90

100

Wei

ght (

%)

Temperature oC

Compound 44Compound 43Compound 42

Compound 41 Compound 40 Compound 39 Compound 38

Figure 3.61: Thermal decomposition pattern of organotin(IV) complexes of HL8

Sn CH3

α

Sn

α

CH3β

γδ

Sn αβ γ

δ

Fig. 3.62: Numbering scheme of the organic moiety attached to the Sn atom.

157

HL1

F

NH

O O

O-

78 9 10

1

2

4

3

5 6

HL7

OH

CH

-OOC1

2

3

45

67

9 N81011

12

13

HL2 1112

NH

O

C

O

O-

1

7

8

910

H3C

H3C

5 6

23

4

HL8

COO-

NO2

H3CO

OCH3

1

2

45

6

7

8

9

3

HL3

F

NH

O OCOO-

O-

78 9 10

1

2

4

3

5 6

HL9

Cl

Cl

Cl 1

2

34

5

6

7

HL4

23

4NH

O

C

O

O-78 9

10

Cl

5 6

Cl1

HL10

COO-

OCH3

OCH3

12

4

5

6

78

9

3

HL5

23

41

NH

O

C

O

O-78 9

Cl

10

Cl

5 6

HL11

COO-

CH3H3C

12

3

45

6

78

9

HL6

23

41

1112

NH

O

C

O

O-

7

8

910

H3C

H3C

5 6

Fig. 3.63: Numbering scheme of free ligands

158

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[18] M Gielen, R Willem, M Biesemans., Appl. Organomet. Chem., 6 (1992) 287.

[19] Q. L. Xie, X. H. Xu, H. G. Wang, X. K. Yao, R. J. Wang, Z. G. Zhang and J. M. Hu, Acad. Chim. Sin., 49 (1991)1085.

[20] C. Vatsa, V. K. Jain, T. Kesavadas and E. R. T. Tiekink, J. Organomet. Chem., 410 (1991) 135.

[21] M. Tonelli, I. Vazzana, B. Tasso, V. Boido, F. Sparatore, M. Fermeglia, M. S. Paneni, P. Posocco, S. Pricl, P. LaColla, C. Ibba, B. Secci, G. Collu and R. Loddo; Bioorg. & Med. Chem., 17 (2009) 4425.

[22] L. P. Garrod, H. P. Lambert and F. O. Grady, Antibiotic and Chemotherapy. 5 ed. Edinburgh, Scotland: Churchill Livingstone, (1981).

[23] P. Yang, M. Guo, Metal-Based Drugs, 5 (1998) 43.

[24] S. Shigeta, S. Mori, T. Yamase, N. Yamamoto and N. Yamamoto, Biomed. & Pharmacother, 60 (2006) 211.

159

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[25] S. Ikeda, J. Neyts, N. Yamamoto, B. Murrer, The B. obald, G. Bossard. Antivir Chem Chemother., 4 (1993) 253.

[26] D. L. Barnard, C. L. Hill, T. Gage, J. E. Matheson, J. H. Huffman, R. W. Sidwell, Antivir Res., 34 (1997) 27.

[27] J. H. Huffman, R. W. Sidwell, D. L. Barnard, A. Morrison, M. J. Otto Hill, Antivir Chem Chemother., 8 (1997) 75.

[28] T. Q. LI U, R. GUO, Chin. J. Chem., 24 (2006) 620.

[29] S. S. Shah, A. Saeed, Q. M. Sharif, J. Colloids Surf. A, 155 (1999) 405.

[30] T. Farias, L. C. de Menorval, J. Zajac and A. Rivera J. Physicochem. Eng. Aspects, 345 (2009) 51.

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Chapter−4

CRYSTALLOGRAPHIC ANALYSIS

4.1 Crystal structures of free ligands (HL1, HL3, HL4, HL5, and HL6)

Crystal data and structure refinements of the free ligands HL1, HL3, HL4, HL5, and HL6

are given in Tables 4.1-4.5. Selected bond angles and distances are listed in Tables 4.6-

4.10. Figures 4.1-4.5 show the molecular structure along with the atomic numbering

scheme. The bond lengths and bond angles in almost all ligand precursors are similar to

those found in the literature [1,2]. The molecular structure shows that the two hydrogen

atoms in ligand L1 are in cis position to each other. HL1 and HL3 containing C-F bonds,

which show normal values as observed [3]. There are C-H-F interactions in HL1 and HL3

which stabilize the title molecule. It is interesting to note that in all ligands containing F

and Cl substituted on the benzene ring as planer. In all ligand acids there are H-

interactions between the amino and carbonyl groups. The ORTEP diagram shows that

the carboxyl groups adopt an antiplanar conformation. In both HL4 and HL5, benzene is

substituted with Cl groups. Their positions on benzene ring are different and they

influence the packing and the interaction parameters. In the HL4 structure there does not

exist any kind of π interaction but in HL5 due to the change of chloro substitution, the

packing of the title compound has been changed and a single C--CI--π interaction is

observed. In HL4, an intramolecular H-bond of C-H-O type exists and completes a six-

member heterocyclic ring adjacent to the benzene ring. In HL1, HL3, HL4 and HL5 the

benzene ring is substituted with halogen groups which are involved in hydrogen bonding.

In all ligand acids the intermolecular H-bonding has been observed. The C-N bond

distances are comparable within experimental errors.

161

Figure 4.1: ORTEP drawing of 3-[(2′-fluorophenylamido)]propenoic acid (HL1)

Figure 4.2: ORTEP drawing of 3-[(2′-fluorophenylamido)]propanoic acid (HL3)

Figure 4.3: ORTEP drawing of 3-[(3′,4′-dichlorophenylamido)]propanoic acid(HL4)

Figure 4.4: ORTEP drawing of 3-[(3′,5′-dichlorophenylamido)]propanoic acid (HL5)

162

163

Figure 4.5: ORTEP drawing of 3-[(3′,5′-dimethylphenylamido)]propanoic acid (HL6)

Table 4.1: Crystal data and structure refinement parameters for HL1, HL3, HL4, HL5 and HL6

HL1 HL3 HL4 HL5 HL6

Empirical formula C10 H8 FNO3 C10 H10 FNO3 C10H9Cl2NO3 C10H9Cl2NO3 C12 H15 N O3

Formula mass 209.176 211.19 262.08 262.08 221.25

Crystal system orthorhombic' Monoclinic Monoclinic Triclinic Monoclinic

Space group, no. P 2c -2n' P 21/c P 21/n P1 P 21/n

a (Å) 20.282(2) 4.8054(3)A 4.8441(4) 4.8568(2) 14.355(2)

b (Å) 3.8025(4) 19.0399(13)A 10.3388(10) 8.6677(4) 5.0170(10)

c (Å) 11.8183(8) 11.0429(8)A 22.457(2) 13.9038(8) 17.858(4)

α (◦) 90.00 90.00 90 74.467(3) 90.00

β (◦) 90.00 101.821(3) 90.613(3) 80.495(2) 111.980(15)

γ (◦) 90.00 90.00 90 82.712(3) 90.00

V (Å3) 911.47(15) 988.94(12) 1124.62(17) 554.09(5) 1192.6(4)

Z (Z’) 4 4 4 2 4

Crystal habit Plate Needles Block Needles Block

Crystal size (mm) 0.57х0.21х0.06 0.25 x 0.15 x 0.10 0.25 x 0.12 x0.10 0.25 x 0.12 x 0.10 0.28 x 0.22 x 0.18

T (K) 299 296(2) 296(2) 296(2) 295(2)

164

165

µ(Mo Kα ) (cm-1) 0.71073 0.12mm 0.71073 0.71073 1.54178

Total reflections 1075 11668 11915 12157 2332

Independent reflections All 799 2550 2912 2971 2263

R(F) = (||Fo| - |Fc||) / ∑ ∑ |Fo | For Fo > 4.0 σ (Fo) 0.0418 0.0388 0.065 0.040 0.0391

wR(F2) = [ [w(Fo2 - Fc

2)2] / [w(Fo2)2]]1/2 ∑ ∑ 0.0992 0.144 0.182 0.125 0.097

Goodness-of-fit 1.105 1.01 1.05 1.07 1.038

θ range for data collections (◦) 4.58-27.51 2.1-28.7 2.7-28.9 1.5-29.2 3.4-70.1

Table 4.2: Selected bond lengths (Å) and bond angles (o) for HL1, HL3, HL4, HL5 and HL6

Comp. Code

Bond Lengths

HL1 C1-C2 1.377(5) C7-O1 1.237(4)

C1-N1 1.421(4) C10-O2 1.210(4)

C2-F1 1.353(4) C10-O3 1.302(4)

C2-C1-C6 117.3(3) C1-C6-C5 120.6(3)

C2-C1-N1 117.5(3) O1-C7-N1 122.7(3)

C6-C1-N1 125.1(3) O1-C7-C8 123.1(3)

O2-C10-C9 117.9(3) N1-C7-C8 114.2(3)

O2-C10-O3 121.5(3) C7-N1-C1 127.0(3)

Bond lengths

HL3 F-C6 1.351(2) C1-C2 1.484(3)

O1-C1 1.300(2) C2-C3 1.513(3)

O2-C1 1.215(2) C3-C4 1.502(3)

O3-C4 1.223(2) C5-C6 1.370(3)

N-C4 1.350(2) N-C5 1.415(2)

C1-O1-H1 111.6(16) F1 -C6- C5 117.86(17)

C4-N1-C5 124.00(15) N1- C5- C6 120.67(17)

O1-C1-O2 122.59(18) O3- C4- N1 122.74(17)

O1- C1- C2 114.01(17) C6- C7-C8 119.6(2)

Bond lengths

HL4 Cl1-C3 1.730(4) N1-C7 1.346(4)

O1-C10 1.286(4) C5-C6 1.384(5)

O2-C10 1.236(3) C9-C10 1.495(4)

O3-C7 1.214(3) C7-C8 1.518(4)

N1-C1 1.414(4) C8-C9 1.497(5)

C10-O1-H10 112(3) C1-N1-C7 126.1(2)

N1-C1-C6 122.5(3) Cl1-C3-C2 118.0(3)

C2-C3-C4 120.4(3) O3-C7-N1 123.5(3)

O3-C7-C8 122.6(3) O2-C10-C9 121.9(3)

O1-C10-O2 123.3(3) O1-C10-C9 114.8(2)

166

HL5 Bond lengths

Cl1-C7 1.737(2) N1-C4 1.343(3)

O1-C1 1.295(3) N1-H1A 0.84(3)

O1-H1 0.92(4) C1-C2 1.488(3)

O2-C1 1.219(3) C5-C6 1.394(3)

C1-O1-H1 113(2) O2-C1-O1 123.4(2)

C4-N1-C5 125.67(16) O2-C1-C2 123.1(3)

O3-C4-C3 121.8(2) O1-C1-C2 113.5(2)

C10-C9-C8 121.8(2) O3-C4-N1 122.7(2)

C8-C7-Cl1 118.42(18)

Bond lengths

HL6 N1-C4 1.3409(12) O3-C4 1.2391(11)

N1-C5 1.4117(14) C9-C12 1.5138(17)

C7-C11 1.5086(18) C7-C8 1.3896(17)

O2-C1 1.3245(12)

C4-N1-C5 129.78(9) O3-C4-N1 122.24(10)

C6-C7-C11 119.64(12) O3-C4-C3 122.62(9)

O2-C1-C2 117.34(8) N1-C4-C3 115.13(8)

C6-C5-C10 119.40(11) O1-C1-O2 118.77(11)

C6-C5-N1 124.03(9) O1-C1-C2 123.87(9)

4.2 X-ray crystal structure of triorganotin(IV) carboxylates Crystal data and structure refinement parameters for triorganotin(IV) carboxylates are

given in Table 4.3 while the bond lengths and bond angles which define the coordination

sphere around the tin centre were selected in Table 4.4.

ORTEP diagrams for triphenyltin(IV) complexes show that these complexes molecules

exist in monomeric forms as shown in Figure 4.6, 4.7 and 4.10. The tin atom is

coordinated to only one ligand. The ligand is coordinated through one oxygen atom (O1)

and the second oxygen (O2) remains uncoordinated. In triorganotin(IV) carboxylates, the

tin atom is normally penta coordinated but in triphenyltin(IV) complexes the tin atom is

tetracoordinated due to the bulky groups (phenyl) attached to the tin atom. These bulky

groups create steric hindrance and prevent the approach of another ligand. The bond

167

angles and bond lengths obtained from crystallographic data suggest tetrahedral

geometry.

Due to the electrostatic effect of an uncoordinated oxygen atom (O2), the phenyl group

(of C31in complex 18, of C17 in case of complex 26 and of C19 in complex 33) is pulled

towards O1 and away from the other two phenyls. Thus the angles around the central tin

atom are deviated from the normal 109⁰ in all three cases. ( in case of complex 18, O1-

Sn1-C31 decreases to 95.54⁰, C31-Sn1-C21 angle increases to 115.01(8), in case of complex

26, C17-Sn-O1 decreases to 94.99°, C11-Sn1-C23 increases to 118.77° and in complex 33,

O2-Sn1-C19 decreases to 93.3(7)⁰, C17-Sn1-C18 angle increases to 118.1(7). All these

deviations distorted the geometry around the tin atom from normal tetrahedral to

distorted tetrahedral.

ORTEP diagrams (Figure 4.8, 4.9, 4.11 and 4.12) for tributyl/methyltin(IV) complexes

show that the molecule exists in a zigzag chain polymeric structure due to intermolecular

C=O and Sn coordination in compounds in which the organotin species are associated

via a bridging carboxylate. The central tin atom is penta-coordinated i.e. the tin atom is

coordinated to 3-α carbon atoms of alkyl groups and 2 oxygen atoms of the ligands. The

crystal structure shows that each ligand is coordinated to two different organotin species

in different coordination modes. Similarly, each organotin species is bonded to two

ligands through the oxygen atoms. Owing to this type of coordination, the compound

exists in polymeric forms. Sn-O bond lengths suggest that the two Sn-O bonds are not

identical. The geometry around Sn is mainly defined by angles around the tin metal

atom. The complexes shows a trans-R3SnO2 trigonal-bipyramidal coordination in which

the three alkyl groups are in equatorial positions while the two oxygen atoms from two

different ligands are occupying the axial positions. According to the literature [4] the

geometry around the Sn atom can be characterized by τ = (β-α)/60, where β is the largest

of the basal angles around the Sn atom and α is the second largest angle of the basal

angles around the Sn atom. The angle values (β = α) = 180° correspond to a square-

pyramidal geometry, and the value α = 120° corresponds to a perfect trigonal

bipyramidal geometry. Thus, the x value is equal to zero for a perfect square-pyramidal

and one for perfect trigonal-bipyramidal. The calculated τ values for complexes are given

in Table 4.3. The calculated τ value for complex 28, 31, 33, 46 and 67 indicate a slightly

distorted trigonal-bipyramidal arrangement around the Sn atom. The sum of the

168

equatorial C-Sn-C angles is in the range of 359.8°‐339.1°. The bond lengths are in

agreement with those of reported triorganotin (IV) carboxylates [5-8].

Figure 4.6: ORTEP drawing of complex 18 with atomic numbering scheme.

Figure 4.7: ORTEP drawing of complex 26 with atomic numbering scheme

169



170



171

172


Table 4.3: Crystal data and structure refinement parameters for compound 18, 22, 28, 31, 33, 46 and 67.

(18) (26) (28) (31) (33) (46) (67)

Emp. formula C28 H24 F N O3Sn 'C28H23Cl2NO3 Sn' 'C44H70Cl4N2O6Sn2' C15H23NO3 Sn' 'C30H29NO3Sn' 'C21H35NO6 Sn' 'C24H36O4Sn2'

Formula weight 560.17 611.06 1102.20 384.03 570.23 516.19 625.91

Crystal system Triclinic Monoclinic Monoclinic Monoclinic - Monoclinic Monoclinic

τ - - 0.11 0.16 0.04 0.079 0.11

Space group P-1 'P 21/c' 'P 21/c' 'P 21/c' - 'P 1 21/a 1' 'P 21/c'

a (Å) 8.8162(3) 10.361(3) 47.1867(14) 17.168(8) 10.420(3) 10.6065(2) 12.041(3)

b (Å) 11.3193(4) 27.083(5) 10.1593(3) 10.925(6) 27.227(7) 18.9480(4) 11.466(3)

c (Å) 12.8973(5) 9.692(2) 25.3842(8) 9.623(7) 9.707(3) 12.1146(3) 20.435(5)

α (◦) 76.7590(10). 90.00 90.00 90.00 90.00 90 90.00

β (◦) 73.7580(10).� = 86.3970(10) � =

86.3970(10)°. 97.902(7) 120.001(2) 101.48(5) 97.021(5) 94.7700(10) 99.367(4)

γ (◦) 86.3970(10). 90.00 90.00 90.00 90.00 90 90.00

V (Å3) 1202.84(8) 2693.8(11) 10538.4(6) 1768.8(18) 2733.3(14) 2426.26(9) 2783.7(12)

Z (Z’) 2 4 8 4 4 4 4

Crystal size (mm) 0.29 x 0.16 x 0.11 0.22 x 0.17 x 0.12 0.51 x 0.31 x 0.22 0.14x0.10 x0.08 - 0.40 x 0.25 x 0.18 0.18х 0.10х 0.07

Crystal habit Colorless wedges Block Block Prism - prism Block

T (K) 299(2) 293(2) 293(2) 295(2) 293(2) 150(2) 294(2)

173

174

µ(MoKα ) (cm-1) 0.71073 0.71073 0.71073 0.71073 0.71073 0.71073 0.71073

Total reflections 14794 5563 9719 3498 20001 30439 25358

Independent reflections All 7508 4850 48303 3285 5243 5535 5023

Final R indices [I>2σ (I)]

R1 =0.0317 wR2 =0.0740

R1 =0.0397 wR2 =0.1039

R1 =0.0463 wR2 =0.1036

R1 =0.0545 wR2 =0.1247

R1 =0.1828 wR2 =0.4481

R1 =0.033 wR2 =0.0676

R1 = 0.0341 wR2 =0.0768

R indices (all data) R1 = 0.8886 wR2 =0.7409

R1 = 0.0510 wR2 =0.1116

R1 = 0.0864 wR2 =0.1315

R1 =0.0922 wR2 =0.1350

R1 = 0.2081 wR2 =0.4531

R1 =0.0531 wR2 =0.0748

R1=0.0879 wR2 =0.0697

Goodness-of-fit 1.038 1.062 1.035 1.004 2.907 1.044 0.838

θ range for data collections (◦) 1.69-31.91 3.01-25.25 2.39-25.50 4.2- 23.6 1.50-25.94 0.99-27.48 3.12-50.51

Data/restraints/parameters 7508/36/346 4850/1/320 9719/1.061/530 3285/0/185 5243/0/149 5535/1.044/291 5023/0/271

Table 4.4: Selected bond lengths (Å) and bond angles (˚) for 18, 26, 28, 31, 33, 46 and 67

Ph3SnL (18)

Bond lengths

Sn1-O1 2.0733(15) O2-C1 1.233(2)

Sn1-C11 2.124(2) C1-C2 1.506(3)

Sn1-C31 2.1271(19) O1-C1 1.299(2)

Sn1-C21 2.128(2)

O1-Sn1-C11 106.44(7) O2-C1-O1 121.37(19)

O1-Sn1-C31 95.54(7) O2-C1-C2 122.43(18)

O1-Sn1-C21 115.43(7) C4-N1-C5 127.61(18)

C11-Sn1-C31 109.71(8) C31-Sn1-C21 115.01(8)

C11-Sn1-C21 113.16(8) Ph3SnL (26)

Bond lengths

Sn1-C11 2.119(4) O1- C1 1.307(4)

Sn1-C23 2.121(3) O2-C1 1.213(4)

Sn1-C17 2.136(3) O3-C4 1.231(4)

Sn1- O1 2.069(2) C1-C2 1.510(5)

C2-C3 1.519(5)

O1-Sn1-C11 113.54(11) C11-Sn1- C17 110.90(14)

O1-Sn1-C23 105.38(11) C23-Sn1-C17 110.61(13)

O1-Sn1-C17 94.99(10) C1-O1-Sn1 108.5(2)

C11-Sn1-C23 118.77(13) C24-C23-Sn1 119.3(3) Bu3SnL (28)

Bond lengths

Sn2-C37 2.115(6) O5-C11 1.219(6)

Sn2-C33 2.121(7) O6-C14 1.199(8)

Sn2-C41 2.126(6) Sn2-O4 2.122(4)

O4-C11 1.288(6)

C37-Sn2-C33 124.0(3) C37-Sn2-O4 101.5(2)

C37-Sn2-C41 117.3(3) O5-C11-O4 123.0(5)

C33-Sn2-C41 111.9(3)

175

Me3SnL (31)

Bond lengths

Sn1-C15 2.109(8) Sn1-O2 2.358(5)

Sn1-C14 2.112(8) O1-C1 1.274(8)

Sn1-C13 2.120(7) O2-C1 1.246(8)

Sn1-O1 2.203(4) O3-C4 1.209(8)

C15-Sn1-C14 126.3(3) C15-Sn1-O2 86.2(3)

C15-Sn1-C13 116.1(3) C14-Sn1-O2 88.1(3)

C14-Sn1-C13 116.9(3) C13-Sn1-O2 87.4(2)

C15-Sn1-O1 97.0(3) O1-Sn1-O2 176.1(18)

C14-Sn1-O1 91.8(3) C1-O1-Sn1 115.2(4)

C13-Sn1-O1 89.2(2) O2-C1-O1 121.8(6) Ph3SnL

(33)

Bond lengths

Sn1-C17 2.06(2) Sn1-O2 2.091(13)

Sn1-C19 2.15(2) C14-O1 1.25(2)

Sn -C18 2.105(18) C31-O2 1.23(2)

C17-Sn1-C18 118.1(7) C18-Sn1-C67 125.9(7)

C17-Sn1-C19 108.8(9) C19-Sn1-C67 18.0(7)

C18-Sn1-C19 112.2(8) O2-C31-O3 128.0(2)

O2-Sn1-C18 106.5(6) O2-Sn1-C67 98.7(7)

O2-Sn1-C17 115.4(6) O2-Sn1-C19 93.3(7)

C17-Sn1-C67 91.0(8) O2-Sn1-C67 98.7(7) Bu3SnL

(46)

Bond lengths

Sn-C31 2.133(7) Sn-O1 2.4158(1) Sn-C11 2.137(3) O1-C1 1.250(3) Sn-C21 2.137(3) O2-C1 1.268(3) Sn-O2 2.2031(1) C31-Sn-C11 126.2(2) C31-Sn-O1 84.74(19) C31-Sn-C21 116.3(2) C11-Sn-O1 90.63(9) C11-Sn-C21 117.30(11) C21-Sn-O1 89.70(9) O1-C1-O2 124.6(2) O2-Sn-O1 170.02(6) C31-Sn-O2 85.32(19)

176

Me3SnL (67)

Bond lengths

Sn2-C24 2.097(5) O3-C13 1.232(6)

Sn2-C23 2.098(5) Sn2-O4 2.135(3)

Sn2-C22 2.101(6) Sn2-O1 2.515(4)

O4-C13 1.278(6)

C24-Sn2-C23 116.7(3) O1-C1-O2 122.6(5)

C24-Sn2-C22 117.3(3) C24-Sn2-O1 82.31(18)

C23-Sn2-C22 124.0(2) C23-Sn2-O1 86.62(18)

C24-Sn2-O4 90.26(18) C22-Sn2-O1 86.97(19)

C23-Sn2-O4 99.29(19) O4-Sn2-O1 172.06(13)

C22-Sn2-O4 94.00(19)

4.3 X-ray structure of diorganotin(IV) dicarboxylates The crystallographic data including crystal data and structure refinement parameters,

bond angles and bond lengths are shown in Tables 4.5 and 4.6. The molecular structures

for diorganotin(IV) dicarboxylates along with numbering schemes are shown in Figure

4.13-4.15.

In the case of complex 49, the structure is composed of an endo- and exocyclic ring. The

endocyclic ring comprises of tetranuclear centrosymmetric dimer of the oxoditin unit

with a central four membered ring defined by Sn1-O13 and Sn1_2-O13_2. In the endocyclic

ring the bond distance of Sn1-O13 is equal to that of Sn1_2-O13_2 and the bond distance of

Sn1-O13_2 is equal to Sn1_2-O13. The tin atom in the endocyclic ring is attached with two

butyl groups and three oxygen atoms. The tin atom is bonded to two oxygen atoms in

endocyclic ring and coordinating to one of the oxygen atoms of ligand involved in the

exocyclic ring. The tin metal in the endocyclic ring is pentacoordinated and has a

trigonal bipyramidal geometry [9-17]. Similarly, in the exocyclic ring the tin atom is

attached with two butyl groups and three oxygen atoms. Here, the tin metal atom is

attached with one of the oxygen atoms from the endocyclic ring and two of the oxygen

atoms from different ligands. The structure also shows the dual behavior of the ligand. In

the exocyclic ring, one of the ligands acts as bidentate as it is coordinated to the tin atom

through both oxygen atoms but the other ligand is coordinated only through one of its

oxygen atoms and behaves as monodentate ligand.

177

The ORTEP diagrams for complexes 69 and 70 in Fig 4.14 and 4.15 show that the tin

metal is hexa-coordinated. The metal is coordinated to two alkyl groups and two ligands.

Each ligand is coordinated through both of its oxygen atoms in an anisotropic way. The

bond lengths of Sn-O and C-O show that each ligand has adopted different coordination

modes. The bond lengths of Sn1-O1 and Sn1-O3 are greater than Sn1-O2 and Sn1-O4. Main

plans are defined by four oxygen atoms of two ligands. The O3-Sn1-O1 angle is smaller

than the O2-Sn1-O4 angles as the two alkyl groups sterically and electronically affect the

O2-Sn1-O4 angle. The four oxygen atoms and the tin atom are nearly in one plane. The

bond angle of C19-Sn1-C20 (148.66) shows that the two methyl groups are in semi-trans

positions and are bent towards the larger bond angles of O2-Sn1-O4. The Sn1-O1 and Sn1-

O3 values show that these are true covalent bond while the Sn1-O4 and Sn1-O2 values

indicated that the bonds are coordinate covalent bonds in nature. The Sn1-O4 and Sn1-O2

bond length values are smaller than the sum of van der waal’s radii (3.68 Å) [18];

therefore the coordination number six is assigned unambiguously to the central tin. The

C-Sn-C angle (148.66(11)° for complex 69 and 148.51(16)° for complex 70) is not

exactly 180° but falls in the range of 122-156° specified for skew-trapezoidal [19,20].

The Sn-O and Sn-C distances and the C-Sn-C, C-Sn-O and O-Sn-O values suggest the

skew-trapezoidal geometry for the said compound [20,21].

Figure 4.13: ORTEP drawing of complex 49 with the atomic numbering

scheme.

178

Figure 4.14: ORTEP drawing of complex 69 with the atomic numbering scheme.

Figure 4.15: ORTEP drawing of complex 70 with the atomic numbering scheme.

179

Table 4.5: Crystal data and structure refinement parameters for compound 49, 69 and 70.

(49) (69) (70)

Emp. formula 'C68.5H105.5N4O26.25Sn4' 'C20H24O4Sn' 'C26H36O4Sn'

Formula weight 1879.91 447.08 531.24

Crystal system Triclinic monoclinic triclinic

Space group 'P -1' 'P 21/c' 'P -1'

a (Å) 12.1263(5) 11.540(4) 9.566(3)

b (Å) 13.1212(5) 7.298(2) 11.892(5)

c (Å) 15.7825(6) 24.778(8) 13.438(5)

α (◦) 72.1720(5) 90.00 104.257(6)

β (◦) 72.9468(6) 102.918(5) 99.468(6)

γ (◦) 64.1866(5) 90.00 109.702(8)

V (Å3) 2114.24(14) 2034.0(11) 1342.6(9)

Z (Z’) 1 4 2

Crystal size (mm) 0.17х0.12х 0.11 0.22х0.16х0.07 0.21 x 0.18 x 0.06

Crystal habit Prism Plate Plate

T (K) 293(2) 295(2) 295(2)

µ(MoKα

Data/restraints/parameters 11487/0.0390/515 4664/0/232 7824/18/ 292

) (cm-1) 0.71073 0.71073 0.71073

Total reflections 11487 23345 7837

Independent reflections All 8343 4664 7824

Final R indices [I>2σ (I)] R1 =0.0215

wR2 =0.0488

R1 = 0.0284

wR2 =0.0747

R1 = 0.0422

wR2 =0.1027

R indices (all data) R1 =0.039

wR2 =0.0547

R1 = 0.0329

wR2 =0.0776

R1 = 0.0618

wR2 =0.1057

Goodness-of-fit 1.000 1.050 1.042

θ range for data collections (◦) 1.76-29.52 23.4-4.8 8.30- 20.42

180

Table 4.6: Selected b nd bo ) for 49

But(49)

ond lengths (Å) a nd angles (˚ , 69 and 70

2SnL2

Bond lengths

Sn1-O13 2.0437(11) O1-C7 1.259(2)

2.1560(10) O2-C7 1.246(2)

)

)

C14 31-Sn2-C27 38.44(9)

1

1

But2SnL2 (69) .096(3) 3-C10 .293(3)

)

)

-C20 O2

)

Sn1_1-O13

Sn1-O2 2.2789(11) O7-C24 1.220(2)

Sn1-C10 2.0978(17) O8-C24 1.281(2)

Sn1-C14 2.130(2) Sn2-O13 2.0410(11

Sn1-Sn1 3.2963(2) Sn2-O8 2.1613(11

Sn2-C31 2.112(2) Sn2-O1 2.2756(12)

Sn2-C27 2.136(2)

O13-Sn1-C10 104.09(6) O13-Sn2-C27 113.66(7)

O13-Sn1- 114.54(7) C 1

C10-Sn1-C14 140.63(9) O13-Sn2-O8 80.54(4)

O13-Sn1-O13_1 76.61(5) C31-Sn2-O8 101.40(7)

C10-Sn1-O13_1 100.96(6) Sn2-O13-Sn1 132.78(5)

C10-Sn1-O2 87.69(6) Sn2-O13-Sn1_ 123.62(5)

O13-Sn2-C31 106.81(8) Sn1-O13-Sn1_ 103.39(5)

O2-C7-O1 126.23(16) O7-C24-O8 125.13(16)

Bond lengths

Sn1-C19 2.094(3) Sn1-O4 2.5482(19)

Sn1-C20 2 O 1

Sn1-O3 2.1126(17 O4-C10 1.236(3)

Sn1-O1 2.1350(15 O1-C1 1.288(2)

Sn1-O2 2.4822(17) O2-C1 1.245(3)

C19-Sn1 148.66(11) O1-Sn1- 55.83(5)

O3-Sn1-O1 83.31(6) O2-C1-O1 119.04(18)

O2-Sn1-O4 165.69(5) O3-Sn1-O4 55.16(6)

C19-Sn1-O1 102.34(10 O1-Sn1-O4 138.46(5)

C20-Sn1-O1 103.03(10) O3-Sn1-O2 139.13(6)

C20-Sn1-O3 101.00(9) C20-Sn1-O4 86.05(9)

C19-Sn1-O2 89.96(9) C19-Sn1-O4 87.07(9)

C20-Sn1-O2 89.27(9) C19-Sn1-O3 99.95(9)

181

Bond lengths Me2SnL2

(70)

Sn1-C19 2.103(4) Sn1-O2 2.509(3)

Sn1-C23 2.125(4) O1-C1 1.289(4)

Sn1-O1 2.140(2) O2-C1 1.252(4)

Sn1-O3 2.141(2) O3-C10 1.273(4)

Sn1-O4 2.480(2) O4-C10 1.255(3)

C19-Sn1-C23 148.51(16) O1-Sn1-O2 55.77(8)

C19-Sn1-O1 99.44(13) O1-Sn1-O3 84.64(8)

C19-Sn1-O4 89.81(12) O3-Sn1-O2 140.40(8)

C19-Sn1-O3 103.53(12) O4-Sn1-O2 163.78(8)

C23-Sn1-O3 102.00(13) O1-Sn1-O4 140.43(8)

C23-Sn1-O1 101.01(13) O3-Sn1-O4 55.81(7)

C23-Sn1-O4 89.49(13) C19-Sn1-O2 85.22(13)

C23-Sn1-O2 86.77(14 O2-C1-O1 119.7(3)

182

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183

CONCLUSIONS

• Novel di- and triorganotin(IV) derivatives have been synthesised in good yields

by refluxing free oxygen donor [O,O] ligands, triethylamine and the respective

organotin(IV) chlorides/ dioctyltin(IV) oxides in dry toluene for 8-10 hours.

• The appearance of new bands for Sn-O, Sn-C and disappearance of the OH band

in the IR spectra indicated the formation of organotin(IV) carboxylates. The

values of Δν for the complexes predict the bidentate nature of the free ligands in

the solid state.

• Multinuclear NMR (1H, 13C and 119Sn) data suggested that in solution the

coordination number of Sn changed from five to four for triorganotin(IV)

derivatives and from six to five in diorganotin(IV) compounds, in most cases.

• Mass spectral data also supported the observations obtained from other

spectroscopic techniques.

• Single crystal X-ray analysis of organotin(IV) complexes illustrated that the

carboxylate moiety chelate the Sn atom in an isobidentate fashion with one

shorter Sn-O bond and one longer Sn-O bond, generating trigonal bipyramidal

geometry for triorganotin(IV) and an octahedral geometry for diorganotin(IV)

derivatives in the solid state. In case of diorganotin(IV) carboxylates, the

asymmetric nature of the two bonded ligands is dissimilar.

• The synthesised complexes were screened for their antibacterial and antifungal

activities. The results showed that the complexes have more potential against

different strains of bacteria and fungi than the corresponding free ligands. In

general, the triorganotin(IV) complexes were found to be better antibacterial and

antifungal agent than diorganotin(IV) complexes.

• Selected organotin(IV) complexes were tested against HCV and some of these

complexes showed high potential against HCV. Compounds 1, 5 and 18 are good

inhibitors against HCV and reduce the viral load up to 80%, at low

concentrations. The tributyl compounds with more electronegative atoms show

lower HCV potential.

• The interaction of tributyltin(IV) complexes having different ligands, i.e. L = 3-

[(2′-fluorophenylamido)]propanoic acid, 3-[(3′,5′- dimethylphenylamido)]

propenoic acid, 3-[(3′,4′-dichlorophenylamido)]propanoic acid and 3-[(3′,5′-

184

185

dimethylphenylamido)]propanoic acid) with cetyl N,N,N-trimethyl ammonium

bromide (CTAB), was measured and an increasing order of binding strength of

tributyltin(IV) complexes and CTAB was found as: 21> 17> 32> 9. All three

techniques (conductometery, UV and steady state fluorescence spectroscopy)

employed were in agreement with each other.

• The organotin(IV) complexes and CTAB interaction studies support the antiviral

study results that complexes with higher electronegative atoms has more sites for

interactions and greater binding strengths, which lower their permeability through

the cell membranes.

• The negative values of the standard free energy changes as the partition ΔG

designates the spontaneity of the complex - CTAB binding and increase in

solubility with addition of CTAB.

• Thermal decomposition results showed that the order of reaction for the thermal

decomposition of the tested complexes was one and the final product of

decomposition in all the tested organotin(IV) complexes was SnO2. The

activation energy value for step I was lower than the second and third step and

the apparent activation enthalpy values were found to be positive for all

complexes.

Documents

ORGANOTIN(IV) COMPLEXES WITH OXYGEN DONOR LIGANDS: …prr.hec.gov.pk/jspui/bitstream/123456789/1753/1/1335S.pdf · 2018-07-23 · The bioassay results of the synthesized complexes