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Ca
Borderless Science Publishing 24
Canadian Chemical Transactions Year 2014 | Volume 2 | Issue 1| Page 24-35
ISSN 2291-6458 (Print), ISSN 2291-6466 (Online)
Research Article DOI:10.13179/canchemtrans.2014.02.01.0062
Ligational, Spectroscopic (Infrared and Electronic) and
Thermal Studies on the Mn(II), Co(II), Fe(II) and Cu(II)
Complexes with Analgesic Drugs
Moamen S. Refat
1,2*, Sabry A. El-Korashy
3 and Mostafa A. Hussien
1
1 Chemistry Department, Faculty of Science, Port-Said University, Port-Said, Egypt
2 Chemistry Department, Faculty of Science, Taif, Taif University, 888 Taif, Kingdom Saudi Arabia
3 Chemistry Department, Faculty of Science, Suez Canal University, Ismailia, Egypt
*Corresponding Author, E-mail: msrefat@yahoo.com
Received: November11, 2013 Revised: December 1, 2013 Accepted: December2, 2013 Published: December 3, 2013
Abstract: The goal of this paper is to get a wide understanding of the structural and spectral properties as
well as microbial activities of ibuprofen and paracetamol and their Mn(II), Co(II), Fe(II) and Cu(II) metal
ion complexes. Metallo-ibuprofen/paracetamol complexes were investigated by spectral and thermal
techniques. The IR spectral data suggested that the paracetamol ligand behaves as a neutral bi-dentate
ligand coordinated to the metal ions via the lone pair of electrons of nitrogen and carbonyl-O atoms of the
amide group. On the other hand, ibuprofen liganed behaves as a monobasic bi-dentate ligand coordinated
to the metal ions via the deprotonated carboxylate O atom. From the micro-analytical data, the
stoichiometry of the complexes reacts with Mn(II), Co(II), Fe(II) and Cu(II) by molar ratios (2:1)
(drug:metal ion). The thermal behavior (TG/DTG) of the complexes was studied.
Keywords: Paracetamol; Ibuprofen; Transition Metal; Thermal Analysis; Antimicrobial Activity
1. INTRODUCTION
A number of drugs and potential pharmaceutical agents also contain metal-binding or metal-
recognition sites, which can bind or interact with metal ions and potentially influence their bioactivities,
and might also cause damages on their target biomolecules. Numerous examples these ‘‘metallodrugs’’
and ‘‘metallopharmaceuticals’’ and their actions can be found in the literature, for instance: (a) several
anti-inflammatory drugs, such as aspirin and its metabolite salicylglycine [1-4], suprofen [5], are known
to bind metal ions and affect their antioxidant and anti-inflammatory activities; (b) the potent histamine-
H2-receptor antagonist cimetidine [6] can form complexes with Cu+2
and Fe and the histidine blocker ,+3
antiulcer drug famotidine can also form stable complex with Cu the anthelmintic and (c) ,[7,8] +2
fungistatic agent thiabendazole, which is used for the treatment of several parasitic diseases, forms a Co+2
complex with metal:drug ratio of 1:2 [9] (d) the Ru complex of the anti-malaria agent chloroquine +2
exhibits an activity two to five times higher than the parent drug against drug-resistant strains of
Plasmodium faciparum [10].
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Canadian Chemical Transactions Year 2014 | Volume 2 | Issue 1| Page 24-35
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Figure 1. Structure of Ibuprofen and Paracetamol
O
O
O
O
O
O
OO
Fe
Fe
OH2
H2O
O
O
O
O
O
O
OO
Cu
Cu
OH2
H2O
O
O
O
O
O
O
OO
Co
Co
OH2
H2O
O
O
O
O
O
O
OO
Mn
Mn
OH2
H2O
Figure 2. Structure of the Ibuprofen complexes
An analgesic is any member of the group of drugs used to relieve pain (achieve analgesia).
Analgesic drugs act in various ways on the peripheral and central nervous systems, they include
paracetamol (para-acetylaminophenol, also known in the US as acetaminophen), the non-steroidal anti-
inflammatory drugs (NSAIDs) such as the salicylates, narcotic drugs such as morphine, synthetic drugs
with narcotic properties such as tramadol. Complexes of ketoprofen, another NSAID, with lighter and
heavier lanthanides were synthesized and characterized [11, 12]. The motivation for the preparation of
lanthanide complexes with NSAIDs is the structural similarity with other lanthanide complexes already
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Canadian Chemical Transactions Year 2014 | Volume 2 | Issue 1| Page 24-35
ISSN 2291-6458 (Print), ISSN 2291-6466 (Online)
reported in the literature that showed pharmacological, diagnostic and therapeutic applications [13].
[Ru2(dNSAID)4Cl] and novel [Ru2(dNSAID)4(H2O)2]PF6 complexes, where dNSAID =
deprotonated carboxylate from the non-steroidal anti-inflammatory drugs (NSAIDs), respectively:
ibuprofen, aspirin, naproxen and indomethacin, have been prepared and characterized by optical
spectroscopic methods. All of the compounds exhibit mixed valent Ru2(II, III) cores where metal–metal
bonds are stabilized by four drug-carboxylate bridging ligands in paddlewheel type structures [14]. Three
new vanadyl(IV) complexes with non-steroidal anti-inflammatory drugs, ibuprofen, naproxen, and
tolmetin, were synthesized and characterized by means of elemental analysis, UV–vis, diffuse reflectance
and IR spectroscopies as well as their magnetic behavior [15]. The biological activity of these vanadium
compounds was tested on two osteoblast-like cells in culture through a proliferation bioassay. Complexes
of Zn(II), Cd(II) and Pt(II) metal ions with the anti-inflammatory drugs, tolmetin, ibuprofen, naproxen
and indomethacin have been synthesized and characterized [16]. The kinetics of the oxidation of
ruthenium(III)- and osmium(VIII)-catalysed oxidation of paracetamol by diperiodatoargentate(III) (DPA)
in aqueous alkaline medium at a constant ionic strength of 0.10 mol dm-3
was studied
spectrophotometrically [17]. The reaction between DPA and paracetamol in alkaline medium exhibits 2:1
stoichiometry in both catalysed reactions (DPA:Par). The main products were identified by spot test, IR,
NMR and GC–MS. Probable mechanisms are proposed and discussed. The activation parameters with
respect to the slow step of the mechanism are computed and discussed and thermodynamic quantities are
also calculated.
In this paper the complexes of Mn(II), Co(II), Fe(II) and Cu(II) with ibuprofen or paracetamol
drug were synthesized and characterized by elemental analysis, conductivity, UV–Vis, IR spectroscopy
and thermal analysis, as well as screened for antimicrobial activity.
2. EXPERIMENTAL
2.1 Materials
All chemicals used were of the purest laboratory grade Merck and both of ibuprofen and
paracetamol (Fig. 1) were presented from Egyptian international pharmaceutical industrial company
(EIPICo.).
2.2 Preparation of solid complexes
For all preparations, doubly distilled water employed as solvent. All used reagents were of
analytical grade and employed without further purifications. Cu(II) chloride, Fe(II) chloride, Mn(II)
chloride and Co(II) chloride (1 mmol, Fluka) were dissolved in 20 cm3 of water and then the prepared
solutions were slowly added to 25 cm3 of an aqueous solution with 1 mmol of ligand solution under
magnetic stirring. The pH of each solution adjusted to 6-8 by addition of ammonium hydroxide. The
resulting solutions heated at 50 oC and left to evaporate slowly at room temperature overnight. The
obtained precipitates were filtered-off, wash with hot water and then dried at 60 oC.
2. 3 Micro-analytical and instrumental techniques
Carbon and hydrogen contents were determined using a Perkin-Elmer CHN 2400. The metal
content found gravimetrically by converting the compounds into their corresponding oxides. The sulfate
content in the sulfate containing complexes was determined gravimetrically as barium sulphate using
BaCl2 solution as a precipitating agent. Chloride content in all prepared complexes determined
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Figure 3. Structure of the paracetamol complexes
potentiometrically by the titration against a standard AgNO3 Materials. Mn(II), Co(II), Fe(III)
and Cu(II) were determined atomic absorption technique. Molar conductivities of freshly prepared
1.0×10-3
mol/dm-3
dimethylsulfoxide ‘DMSO’ solutions measured using Jenway 4010 conductivity meter.
IR spectra were recorded on Bruker FTIR Spectrophotometer (4000–400 cm-1
) in KBr pellets. The UV–
vis, spectra were determined in the DMSO solvent with concentration (1.0×10-3
M) for the free ligands
and their complexes using Jenway 6405 Spectrophotometer with 1cm quartz cell, in the range 200–800
nm. Thermogravimetric analyses (TG) carried out in the temperature range from 25 to 800 oC in a steam
of nitrogen atmosphere by Shimadzu TGA 50H thermal analysis. The experimental conditions were:
platinum crucible, nitrogen atmosphere with a 30 ml/min flow rate and a heating rate of 10 oC/min.
2. 4 Microbiological investigation
The investigated isolates of bacteria were seeded in tubes with nutrient broth (NB). The seeded
NB (1 cm3) was homogenized in the tubes with 9 cm
3 of melted (45
oC) nutrient agar (NA). The
homogeneous suspensions were poured into Petri dishes. The discs of filter paper (diameter 4 mm) were
ranged on the cool medium. After cooling on the formed solid medium, 2×10-5
dm3 of the investigated
compounds were applied using a micropipette. After incubation for 24 h in a thermostat at 25–27 oC, the
inhibition (sterile) zone diameters (including disc) were measured and expressed in mm. An inhibition
zone diameter over 7 mm indicates that the tested compound is active against the bacteria under
investigation [18]. The antibacterial activities of the investigated compounds were tested against
Escherichia Coli (Gram -ve), Bacillus subtilis (Gram +ve) and antifungal (tricoderma and penicillium).
The concentration of each solution was 1.0×10-3
mol dm3. Commercial DMSO was employed to dissolve
the tested samples.
3. RESULTS AND DISCUSSION
3.1. Elemental analyses and conductivity data
The elemental analysis results were summarized in Tables 1 and 2. These results were in good
agreement with the proposed formulae’s. The melting points of the ibuprofen and paracetamol complexes
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Table 1. Analytical and physical data of Ibu and its metal complexes
Complex
Mwt Formula %C %H
Calc. Found Calc. Found
Mn2(Ibu)4(H2O)2 969.01 C52H74Mn2O10 64.45 64.57 7.70 7.66
Co2(Ibu)4(H2O)2 974.99 C52H74Co2O10 64.06 64.28 7.44 7.43
Fe2(Ibu)4(H2O)2 968.81 C52H74Fe2O10 64.47 64.48 7.49 7.55
Cu(Ibu)2(H2O)2 986.23 C52H74Cu2O10 63.33 63.43 7.56 7.59
Table 2. Analytical and physical data of Par and its metal complexes
Complex
Mwt Formula %C %H %N
Calc. Found Calc. Found Calc. Found
Mn(Par)2 355.25 C16H16MnN2O4 54.10 54.32 4.54 4.67 7.89 7.18
Co(Par)2 359.24 C16H16CoN2O4 53.49 54.01 4.49 4.86 7.80 7.66
Fe(Par)2(OH)(H2O) 406.17 C16H18FeN2O7 47.31 47.44 4.47 4.60 6.90 6.98
Cr(Par)2 (OH)(H2O) 402.32 C16H18CrN2O7 47.77 47.78 4.51 4.54 6.96 6.72
Table 3. IR spectra (4000-400 cm-1
) of Ibu and its metal complexes
Table 4. IR spectra (4000-400 cm
-1) of Paracetamol and its metal complexes
were higher than that of the free ligand, revealing that the complexes are much more stable than
ligand. The molar conductivity values for the ibuprofen complexes in DMSO solvent 1.00×10-3
mol were
in the range 6.50-44.40 Ω-1
cm-1
mol-1
, suggesting them to be non-electrolytes nature. Conductivity
measurements have frequently used in elucidation of structure of metal chelates (mode of coordination)
within the limits of their solubility. They provide a method of testing the degree of ionization of the
complexes, the molecular ions that a complex liberates in solution in case of presence of anions outside
the coordination sphere, the higher will be its molar conductivity and vice versa [19]. It was clear from
the conductivity data that the complexes present seem to be non-electrolytes. Paracetamol complexes
have conductance values in the range from 53-to-84 Ω-1
cm2mol
-1 at 25
oC, which indicates that the
complexes were of a non-electrolytic nature. The low conductivity values were in agreement with the low
Compound (COO)
(sym)
v(COO)
(asym.)
∆
v(M-O)
(COO) (M-O)
(H2O)
Ibuprofen 11594sh 1413sh 141 --- ---
Mn2(Ibu)4(H2O)2 1565s 1410m 154 417s 560s
Co2(Ibu)4(H2O)2 1578m 1403s 175 403w 556s
Fe2(Ibu)4(H2O)2 1592m 1403sh 189 419s 578s
Cu(Ibu)2(H2O)2 1555m 1402m 153 419w 558s
Compound v(NH) + ν(OH) ν(C=O) δ(CNH)
amide group
v(C-OH) v(M-O) (M-O) (M-O)
(H2O)
Paracetamol 3300 s 1640 vs 1540 (sh) s 1256 vs -- -- --
Mn(Par)2 3326 1655 1564 1255 489s 473s 543s
Co(Par)2 3325 1656 1562 1256 496w 466w 537s
Fe(Par)2(OH)(H2O) 3325 1654 1563 1256 496s 477w 517s
Cr(Par)2 (OH)(H2O) 3409 1623 1564 1255 486w 468w 528s
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solubility of parcetamol complexes in water, ethanol, chloroform, acetone and most organic solvents. On
the other hand, they were soluble in DMSO, dimethylformamide ‘DMF’ and concentrated acids.
3.2 Infrared spectral data
The IR spectra of the ibuprofen complexes were exhibit the characteristic pattern of the ligand
vibrational modes, which were very similar to those of the Na salts. But some notable differences can
observed in the 3500–3200 cm-1
, 1650–1300 cm-1
, and the low frequency ν(500 cm-1
) spectral regions. In
the 3500–3200 cm-1
. In the IR spectral region of metal complexes, the bands attributable to v(OH) were
broader and their intensity was weaker than that of the corresponding Na salts. This indicates that the
Metal ion coordinates fewer water molecules than the Na ion. In the 1650–1300 cm-1
spectral region the
stretching vibrations of the carboxylate ion (vas and vs) were present; these frequencies, as well as ∆v=vas -
vs, can give indications about the coordination modalities. Indeed, for metal complexes two main
structures were possible, a chelating bidentate and a bridged bidentate structure. Literature data obtained
by IR spectra of metal transition complexes with carboxylic acids with known structures (by X-ray
measurements) assign ∆v= 160 cm-1
for the bridging bidentate complexes, while chelating bidentate
complexes usually have ∆v <130 cm-1
[20]. Also, the values of vas and vs frequencies were indicative of
the complex structure, it has been reported that vas < 1570 cm-1
and vs < 1450 cm-1
were observed for the
bidentate chelate complexes of metal transition ions. The bridging bidentate complexes characterized by
vas < 1570 cm-1
[20] and vs <1400 cm-1
, Table 3, shows the IR spectra data of the metal complexes, their
vas and vs wavenumbers, and the corresponding ∆v values: in most cases, there was an Increase in both v
as and v s in comparison with the corresponding Na salt (Table 3). Moreover, the ∆ as increase was higher
than that of v s going from Na salts to metal complexes. The fact that vas was higher than the
corresponding frequencies of Na salts was in agreement with a binuclear diametric structure for the
complex [20].
From the comparative IR spectra of paracetamol and its complexes (Table 4), it has been noticed
a slight blue shift of the stretching band of the carbonyl group at 1640 cm−1
in paracetamol IR spectrum to
1654 cm−1
in the complexes spectra. A slight red shift of the in-plane bending band of the carbonyl group
of the paracetamol spectrum at 840–830 cm−1
in the complexes spectra and the disappearance of the in-
plane bending bands of CNH at the positions at 1540 cm−1
and 1260 cm−1
[20] in the IR spectra of the
complexes in addition to the disappearance or the intensity change of the out-of-plane wagging band of
NH in the amide group at 720 cm−1
in the complexes spectra. The appearance of the stretching band and
the in-plane bending band of the hydroxyl group, with respect to the phenyl moiety at positions 1240 cm−1
and 620 cm−1
[20] , respectively, excludes the contribution of the hydroxyl oxygen atom to be chelated
with the metal ion as well as the appearance of the stretching band in the hydroxyl group between oxygen
and hydrogen atom at position 3300 cm−1
verifies the assumption of exclusion of the hydroxyl oxygen
atom to be chelated with the metal ion in the complex.
3.3 Electronic spectral data
The electronic absorption spectra of the ligand and its M(ІІ) complexes in DMSO in the 200-600
nm range. It can see that free ibuprofen has two distinct absorption bands. The first one at 225 nm may be
attributed to π→π* transition of the heterocyclic moiety and benzene ring. The second band observed at
320 nm was attributed to n→π* electronic transition. It can see that free paracetamol has two distinct
absorption bands. The first one at 300 nm may be attributed to π→π* transition of the heterocyclic moiety
and benzene ring. The second band observed at 390 nm was attributed to n→π* electronic transition.
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Table 5. Thermodynamic data of the thermal decomposition of Ibu metal complexes
Complex TG range
(C)
DTGmax
(C)
Mass loss Total mass
% Found (Calcd.)
Assignment Residue
Mn2(Ibu)4(H2O)2 140-450 300 70.25(70.26) 64.65 (64.22) 2H2O+4C6H6 +6C2H2+4CO2 MnO
Co2(Ibu)4(H2O)2 140-450 300 54.60 (53.69) 45.49 (45.78) 2H2O+4C6H6+4C2H2+4CO2 CoO
Fe2(Ibu)4(H2O)2 140-450 300 70.03(70.12) 55.63 (55.63) 2H2O+4C6H6+6C2H2+4CO2 FeO
Cu(Ibu)2(H2O)2 140-450 300 69.02(69.57) 59.58 (59.21) 2H2O+4C6H6+6C2H2+4CO2 CuO
Table 6. Thermodynamic data of the thermal decomposition of Par metal complexes
Complex TG
range
(C)
DTGmax
(C)
Mass loss Total mass
% Found (Calcd.)
Assignment Metallic
residue
Mn(Par)2 30-340 300 89.34 (89.03) 19.89 (19.97) 2C6H6O+2H2O+ 2NO2 MnO
Co(Par)2
30-370
370-430
200
400
12.89 (12.81)
34.66 (34.53) 49.96 (50.94)
NO3
CH3OH+2NO2
CoO
Fe(Par)2(OH)(H2O)
30-220
220-400
100
300
8.90 (8.87)
39.53(39.41) 58.67 (58.10)
2H2O.
2H2O+2NO2+CH3OH
1/2Fe2O3
Cr(Par)2(OH)(H2O) 30-800 300 48.89 (51.26) 49.16 (48.74) 2C6H6O+H2O 1/2Cr2O3
# n = number of decomposition steps.
3.4 Mass spectral data
In the mass spectra of [Fe2(Ibu)4(H2O)2] intense mass peaks at m/z 206, 164, 107, 91 and 56
were detected. The first mass peak corresponds to the [H-Ibu]+ ion and the second one proceeds by
elimination of propane from the molecular ion at m/z 164, then the formation of 1-ethylbenzene ion at
m/z= 164. The molecular ion peak at m/z= 91 can be assigned to C7H7. In comparison between the
ibuprofen ligand and the Fe(III) complexes, the peak assigned to molecular ion m/z= 206 of ibuprofen
ligand was present complexe, and new peaks appear at m/z = 56 can be assigned to Fe(III). These results
were again consistent with the presence of direct metal-ligand bonding in the ibuprofen complexes. In the
mass spectrum of [Cr(Par)2(OH)(H2O)] intense mass peaks at m/z 151, 109, 80, 52 and 51 were detected.
The first mass peak corresponds to the [H-Par]+ ion and the second one proceeds by p-amino phenol from
the molecular ion at m/z 109 with intensity 75%, then the elimination of NO2 and OH groups leads to the
formation of Benzen ring ion at m/z= 79. In comparison between the paracetamol (ligand) and the Cr(III)
complexes, the peak assigned to molecular ion m/z= 151 of paracetamol ligand was present complexe,
and new peaks appear at m/z = 51 can be assigned to Cr(III). These results were again consistent with the
presence of direct metal-ligand bonding in the paracetamol complexes.
3.5 Thermal and kinetic studies
Thermal methods of analysis are widely used for checking thermal decomposition, thermal
stability [21–24], polymorphism [21], reactions in solid state, drug formulations [25–27], purity [28],
evolved gas analysis using simultaneous TG–FTIR [29] and other properties of solid compounds used in
pharmaceutical industry [30]. DSC was used as a screening technique to determine the compatibility of
ketoprofen with excipients [31], as well as theoretical calculations in structural investigations [23]. Owing
to the numerous issues involved, it becomes important to have a complete understanding of the properties
of pharmaceutical materials. The heating rates were controlled at 10 C min-1
under nitrogen atmosphere
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and the weight loss was measured from ambient temperature up to 1000 C. The data was listed in
Tables 5 and 6. The different thermodynamic parameters were calculated upon Coats-Redfern [32] and
Horowitz-Metzger [33] methods and listed in Tables 7 and 8.
3.5.1 Mn(II), Co(II), Fe(III) and Cu(II) Ibuprofen complexes
The thermal decomposition of Mn2(Ibu)4(H2O)2 occurs at one step. The degradation step takes
place in the range of 140-450 oC was corresponding to the loss of 2H2O, 4CO2, 6C2H2 and 4C6H6
molecules, representing a weight loss of 70.25 % and its calculated value was 70.26%.The MnO (polluted
with some carbon atoms) was the final product remains and was stable till 800 oC. The cobalt (II)
Ibuprofen complex decomposed in one-steps, occurring at 140-150 oC was corresponding to the loss of
2H2O, 4CO2, 6C2H2 and 4C6H6 molecules, representing a weight loss of 54.60 % and its calculated value
was 53.69%. The final products resulted at 800 oC contain CoO polluted with some carbon atoms. The
Fe(III) Ibuprofen complex decomposed in one steps, occurring at 140-450 oC was corresponding to the
loss of of 2H2O, 4CO2, 6C2H2 and 4C6H6 molecules, representing a weight loss of 70.03 % and its
calculated value was 70.12%. The final products resulted at 800 oC contain FeO polluted with some
carbon atoms. The thermal decomposition of Cu(Ibu)2(H2O)2 occurs in one steps. The degradation step
take place in the range of 140-450 o C and it was corresponds to the eliminated of 2H2O, 4CO2, 6C2H2 and
4C6H6 molecules due to a weight loss of 69.02% in a good matching with theoretical value 69.57%. The
CuO was the final product remains stable till 800 oC polluted with some carbon atoms. The data is
summarized in Table 7. The activation energies of decomposition found to be in the range 1.27 x104 - 9.70
x105 k J mol
-1. The high values of the activation energies reflect the thermal stability of the complexes.
The entropy of activation found to have negative values in all the complexes, which indicate that the
decomposition reactions proceed with a lower rate than the normal ones. On another meaning the thermal
decomposition process of all ibuprofen complexes were non-spontaneous, i.e, the complexes were
thermally stable. The correlation coefficients of the Arhenius plots of the thermal decomposition steps
found to lie in the range 0.9756 to 0.9991, showing a good fit with linear function.
3.5.2 Mn(II), Co(II), Fe(III) and Cu(II) paracetamol complexes
The weight losses for each paracetamol chelates calculated within the corresponding temperature
ranges (Table 6). The different thermodynamic parameters were listed in Table 8. The thermal
decomposition of Mn(Par)2 occurs in one step. The degradation step take place in the range of 30-340o C
and it was corresponds to the eliminated of 2 (C6H6O) +2H2O+ 2NO2 molecules due to a weight loss of
89.34 % in a good matching with theoretical value 89.03%. The MnO was the final product remains
stable till 800 oC. The cobalt(II) Paracetamol complex decomposed in two steps, the first one occurring at
30-370 oC and corresponding to the evolution of NO2, representing a weight loss of 12.89 % and its
calculated value was 12.81%. The second step occurring at 370-430 oC was corresponding to the loss of
CH3OH and 2NO2 molecules, representing a weight loss of 34.66 % and its calculated value was 34.53%.
The final products resulted at 900 oC contain CoO polluted with nine carbon atoms. The Fe(III)
paracetamol complex decomposed in two steps, the first one occurring at 30-220 oC and corresponding to
the evolution of 2H2O, representing a weight loss of 8.90% and its calculated value was 8.78%. The
second step occurring at 220-400 oC was corresponding to the loss of of 2H2O, 2NO2 and CH3OH
molecules, representing a weight loss of 39.53% and its calculated value was 39.41%. The final products
resulted at 900 oC contain Fe2O3 polluted with some carbon atoms. The thermal decomposition of
Cr(Par)2(OH)(H2O) occurs in one step. The degradation step take place in the range of 30-800 oC and it
was corresponds to the eliminated of (C6H6O)2 and H2O molecules due to a weight loss of 49.89 % in a
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Table 7: Thermodynamic data of the thermal decomposition of Ibu metal complexes
Complex Stage Method Parameter r
E
(kJ mol−1
)
A (s−1
) ΔS
(Jmol−1
K−1
)
ΔH
(kJmol−1
)
ΔG
(kJmol−1)
Ibu 1nd
CR
HM
average
1.72×104
1.41×104
1.57×104
4.25 ×105
7.07×105
5.66×105
-1.64 ×102
-1.53×102
-1.89×102
6.62×104
6.41×104
6.52×104
1.96×105
1.12×105
1.54×105
0.9947
0.9991
0.9969
Co 1st CR
HM
average
3.89×104
6.41×104
5.15×104
5.82 ×103
3.21×103
4.52×103
-1.50×102
-1.28×102
-1.39 ×102
5.52×104
5.14×104
5.33×104
1.72×105
1.59×105
1.66×105
0.9881
0.9895
0.9888
Cu 2st CR
HM
average
4.56 ×104
4.65×104
4.61×104
2.68×103
3.57×103
3.13×104
-1.72×102
-1.71×102
-1.72×102
2.47×104
3.69×104
3.08×104
1.14×105
1.93×105
1.55×105
0.9740
0.9771
0.9756
Fe
2nd
CR
HM
average
7.72×104
9.70×104
8.71×104
1.86×102
6.73 ×102
4.30×102
-2.93×102
-2.68×102
-2.81×102
3.21×104
1.25×104
2.23×104
1.54×105
1.52×105
1.54×105
0.9886
0.9961
0.9924
Mn 1st CR
HM
average
6.75×104
6.86×104
6.81×104
5.30×104
3.82×104
4.56×105
-1.60×102
-1.35×101
-1.48×102
5.14×104
5.74×104
5.44×104
1.70×105
1.67×105
1.69×105
0.9951
0.9959
0.9955
Table 8. Thermodynamic data of the thermal decomposition of Par metal complexes
Complex Stage Method Parameter r
E
(kJmol−1
)
A (s−1
) ΔS
(Jmol−1
K−1
)
ΔH
(kJmol−1
)
ΔG
(kJ mol−1)
Para 1st CR
HM
average
1.65×105
1.64×105
1.65 ×105
2.49×1012
1.47×1013
2.08×1013
-1.28×101
-1.01×101
-1.14 ×101
1.51×105
1.60×105
1.55×105
1.58×105
1.54×105
1.565×105
0.9998
0.9999
0.9999
Co
2nd
CR
HM
average
1.45×105
1.56×105
1.51×105
1.27×109
1.63×1010
8.79×109
-7.75×101
-6.00×101
-6.88 ×101
1.39×105
1.50×105
1.40×105
1.92×105
1.91×105
1.92×105
0.9984
0.9985
0.9985
Cr 2nd
CR
HM
average
7.40×104
5.31×104
6.36 ×104
1.71×105
3.05×106
1.61×105
-1.64×102
-1.22×102
-1.43 ×102
4.42×104
5.03×104
4.72×104
9.27×104
9.09×104
9.22×104
0.9916
0.9908
0.9912
Fe 1st CR
HM
average
4.84×104
5.19×104
5.06 ×104
7.44×105
7.33×106
4.04×106
-1.33×102
-1.14×102
-1.24 ×102
4.58×104
4.93×104
4.76×104
8.75×104
8.50×104
8.68×104
0.9899
0.9924
0.9912
Mn 1st CR
HM
average
1.25×105
1.35×105
1.30×105
8.39×108
1.37×1010
72.70×109
-7.97×101
-5.64×101
-6.80 ×101
11.2×105
1.30×105
1.25×105
1.67×105
1.63×105
1.67×105
0.9996
0.9997
0.9997
good matching with theoretical value 51.26%. The Cr2O3 was the final product remains stable
till 800 oC polluted with some carbon atoms. The data is summarized in Table 8, the activation energies of
decomposition found to be in the range 4.84x104-1.65x10
5 kJmol
-1. The high values of the activation
energies reflect the thermal stability of the complexes. The entropy of activation found to have negative
values in all the complexes, which indicate that the decomposition reactions proceed with a lower rate
than the normal ones. On another meaning the thermal decomposition process of all paracetamol
complexes were non-spontaneous, i.e, the complexes were thermally stable. The correlation coefficients
of the Arhenius plots of the thermal decomposition steps found to lie in the range 0.991 to 0.999, showing
Ca
Borderless Science Publishing 33
Canadian Chemical Transactions Year 2014 | Volume 2 | Issue 1| Page 24-35
ISSN 2291-6458 (Print), ISSN 2291-6466 (Online)
a good fit with linear function.
3.6 Microbiological studies
Antibacterial and antifungal activities of the ibuprofen and paracetamol drug ligands and its
complexes were carried out against the Escherichia Coli (Gram -ve), Bacillus subtilis (Gram +ve) and
antifungal (tricoderma and penicillium activities). The antimicrobial activity estimated based on the size
of inhibition zone around dishes. The ibuprofen complexes were found to have high activity against
Bacillus subtilis and penicillium, whereas the Cu(II) complex was more active than the Fe(III) , Mn(II)
and Co(III)complexes against tricoderma. The paracetamol complexes were found to have high activity
against Bacillus subtilis and penicillium, whereas the Fe(III) complex was more active than the Mn(II),
Co(II) and Cr(III) complexes against tricoderma.
3-7- Suggested structures of ibuprofen and paracetamol complexes
The structures of both complexes of ipuprofen and paracetamol with Cr(III), Fe(III), Mn(II) and
Co(II) ions (Fig. 2 and 3) have been confirmed from the elemental analyses, IR, molar conductance, UV-
Vis, mass and thermal analysis data.
4. CONCLUSION
Ibuprofen and paracetamol are a very interesting ligand from point of view of its applications. It
could form several complexes with metal (II) ions. In this paper, the synthesis and properties of these
types of compounds was investigated. The complexes with the empirical formulas: Mn2(Ibu)4(H2O)2,
Co2(Ibu)4(H2O)2, Fe2(Ibu)4(H2O)2, Cu(Ibu)2(H2O)2, Mn(Par)2, Co(Par)2, Fe(Par)2(OH)(H2O), and
Cr(Par)2(OH)(H2O) were prepared as a solid compounds. The structures of the complexes of Ibu and Par
with Mn(II), Co(II), Fe(III) and Cu(II) have been confirmed from the elemental analysis, FT-IR
spectroscopy and thermal analysis. Thus, from the FTIR spectrum, it is concluded that both Ibu and Par
behave as a monobasic bidentate ligand co-ordinated to the metal ion. The co-ordination water, evidenced
by FT-IR spectroscopy, was confirmed and determined by thermal analysis, in the TG curve. The thermal
investigation (studied by TG/DTG techniques) shows that obtained complex decomposes progressively,
and the first step of thermolysis is dehydration. The final product of the thermal decomposition is metal
oxides, which through its percentage confirms the empirical formulae of the new complexes prepared.
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