BL 06/2007 Page 1
Water – Ionic Liquid Interaction Studiesby MIR and THz
New Definition ofProcess Gas
Chromatography
Probing intermolecular interactions in water/ionic
liquid mixtures by THz spectroscopy
Introduction
Ionic Liquids
MIR Studies
2DCoS
MCR -ALS
FIR Studies
MCR-ALS
Conclusions
Bernhard Lendl
Institute of Chemical Technologies and Analytics, TU Vienna, Austria
BL 06/2007 Page 2
Water – Ionic Liquid Interaction Studiesby MIR and THz
Introduction / Motivation
Ionic Liquids – molten salts at room temperature
Flow Injection System – to generate spectra
Data Analysis Techniques
- MCR
- 2DCoS
Results
MIR Studies
THz (FIR) Studies
Outline
Introduction
Ionic Liquids
MIR Studies
2DCoS
MCR -ALS
FIR Studies
MCR-ALS
Conclusions
BL 06/2007 Page 3
Water – Ionic Liquid Interaction Studiesby MIR and THz
Ionic Liquids
Properties of Ionic Liquids
Salts containing organic cations and inorg. or organic anionsMolten salts at or slightly above room temperature (max.
100°C)Good solvation powerGood thermal stability (ca. 300ºC)Negligible volatilityGood electrical conductivity
Typical Building Blocks
Introduction
Ionic Liquids
MIR Studies
2DCoS
MCR -ALS
FIR Studies
MCR-ALS
Conclusions
BL 06/2007 Page 4
Water – Ionic Liquid Interaction Studiesby MIR and THz
Ionic Liquids Under Study
Selected Ionic Liquids
tetrafluoroborate hexafluorophosphate
1-ethyl-3-methylimidazolium
“emim+”
1-butyl-3-methylimidazolium
“bmim+”
Liquid at room temperature
Liquid at room temperature
Liquid at room temperature
Solid at room temperature
Introduction
Ionic Liquids
MIR Studies
2DCoS
MCR -ALS
FIR Studies
MCR-ALS
Conclusions
BL 06/2007 Page 5
Water – Ionic Liquid Interaction Studiesby MIR and THz
MIR Spectra of Ionic Liquids Under Study
ATR (1 bounce) spectra of dry Ionic Liquids
3500 3000 2500 2000 1500 1000 500
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8Ab
sorb
ance
Wavenumber, 1/cm
emimBF4 bmimBF4 bmimPF6
3400 3200 3000 2800 26000.00
0.01
0.02
0.03
0.04
0.05
0.06
0.07
Abso
rban
ce
Wavenumber, 1/cm
Introduction
Ionic Liquids
MIR Studies
2DCoS
MCR -ALS
FIR Studies
MCR-ALS
Conclusions
BL 06/2007 Page 6
Water – Ionic Liquid Interaction Studiesby MIR and THz
FIR Spectra of Ionic Liquids Under Study
600 500 400 300 200 100
0,0
0,5
1,0
1,5
2,0 emimBF4 bmimBF4 bmimPF4
Abso
rban
ce u
nits
Wavenumber (cm-1)
25 µm transmission cell (PE windows)
Introduction
Ionic Liquids
MIR Studies
2DCoS
MCR -ALS
FIR Studies
MCR-ALS
Conclusions
BL 06/2007 Page 7
Water – Ionic Liquid Interaction Studiesby MIR and THz
Motivation
Traces of co-solvents change properties of ionic liquids
Get fundamental understanding on formation of small water clusters
Fun
Results
MIR Studies
THz (FIR) Studies
Water - Ionic Liquid Interaction
Introduction
Ionic Liquids
MIR Studies
2DCoS
MCR -ALS
FIR Studies
MCR-ALS
Conclusions
BL 06/2007 Page 8
Water – Ionic Liquid Interaction Studiesby MIR and THz Type of anion influence position of OH-stretch vibrations
Water - Ionic Liquid Interaction
0,000,02
0,040,060,08
0,100,120,140,16
0,180,20
325033503450355036503750
Wavenumber 1/cm
Abs
orba
nce
emimBF4
bmimBF4
bmimPF6
Introduction
Ionic Liquids
MIR Studies
2DCoS
MCR -ALS
FIR Studies
MCR-ALS
Conclusions
BL 06/2007 Page 9
Water – Ionic Liquid Interaction Studiesby MIR and THz Change in ν-OH-stretch region as function of water
concentration
Water - Ionic Liquid Interaction
0,00
0,20
0,40
0,60
0,80
1,00
1,20
325033503450355036503750
Wavenumber 1/cm
Arb
itrar
y U
nits
high concentration
low concentration
Introduction
Ionic Liquids
MIR Studies
2DCoS
MCR -ALS
FIR Studies
MCR-ALS
Conclusions
BL 06/2007 Page 10
Water – Ionic Liquid Interaction Studiesby MIR and THz
Water - Ionic Liquid Interaction
Pure IL
in out
Sample
Holding coil500μl
Syringe pump1000μl
Waste
ThermostatedFlow cell
Bruker IFS 88Sagitarius V3
Introduction
Ionic Liquids
MIR Studies
2DCoS
MCR -ALS
FIR Studies
MCR-ALS
Conclusions
BL 06/2007 Page 11
Water – Ionic Liquid Interaction Studiesby MIR and THz
H2O in emim+[BF4]- and bmim+[BF4]-
3300340035003600370038000
0.2
0.4
0.6
0.8
1
Wavenumber / cm-1
Abs
orba
nce
3640
3564
3450
3640
Set of spectra covering 0-5% m/m of H2O in [BF4]- based ionic liquids
Introduction
Ionic Liquids
MIR Studies
2DCoS
MCR -ALS
FIR Studies
MCR-ALS
Conclusions
BL 06/2007 Page 12
Water – Ionic Liquid Interaction Studiesby MIR and THz
2DCoS - Concept
( ) ( )2121 ,, νννν Ψ+Θ i
( ) ( )ϖϖπ 2
01
1 YiYT
+= ∫∞
Time resolved spectra Time/pressure/Temperature,..
Correlation analysis
Spectral Variable
I. Noda Lecture 2DCoS-3, 2005
Looking for correlation in the experimental output D
Introduction
Ionic Liquids
MIR Studies
2DCoS
MCR -ALS
FIR Studies
MCR-ALS
Conclusions
BL 06/2007 Page 13
Water – Ionic Liquid Interaction Studiesby MIR and THz
2DCoS - Output
I. Noda Lecture 2DCoS-3, 2005
Correlation Maps
Spectral variable, ν1
Spe
ctra
lvar
iabl
e, ν
2
Spectral variable, ν1
Spe
ctra
lvar
iabl
e, ν
2
Synchronous map Asynchronous mapIntroduction
Ionic Liquids
MIR Studies
2DCoS
MCR -ALS
FIR Studies
MCR-ALS
Conclusions
BL 06/2007 Page 14
Water – Ionic Liquid Interaction Studiesby MIR and THz
Asynchronous Correlation Map : H2O in emim+[BF4]- and bmim+[BF4]-
Peaks in asynchronous correlation map:3640 – 3610 cm-1; 3640 - 3450 cm-1; 3610 - 3560 cm-1 and 3560 - 3450 cm-1
No correlation between 3610 - 3450 cm-1 and 3640 - 3560 cm-1
=> presence of 2 different species 1st Specie: Bands at 3640 - 3560 cm-1
2nd Species: Bands at 3610 and 3450 cm-1W
aven
umbe
r / c
m-1
Wavenumber / cm-1340036003800
3300
3400
3500
3600
3700
3800
Wav
enum
ber /
cm
-1
Wavenumber / cm-1340036003800
3300
3400
3500
3600
3700
3800
3640
3610 3450 3560
36103560
3450
Introduction
Ionic Liquids
MIR Studies
2DCoS
MCR -ALS
FIR Studies
MCR-ALS
Conclusions
BL 06/2007 Page 15
Water – Ionic Liquid Interaction Studiesby MIR and THz
Multivariate Curve Resolution (MCR-ALS)
Concept: Modeling of experimental data matrix D
D = CST + E
D(r × c) is the original data matrix C(r × n) and ST(n×c) contain pure response profiles related to the data variation in the row (r) and column (c) direction of D(r × c)E(r × c) is the error matrix
• Multi-component systems can be often be described witha simple model consisting of the composition-weightedsum of signals of their pure components
• Only condition: linear structure of data set
Introduction
Ionic Liquids
MIR Studies
2DCoS
MCR -ALS
FIR Studies
MCR-ALS
Conclusions
BL 06/2007 Page 16
Water – Ionic Liquid Interaction Studiesby MIR and THz
Multivariate Curve Resolution:
ci...concentration profiles with time si...spectra of pure substances
= ++c1
s1T
c3
s3T
c2
s2T
=C
ST
exp. dataD
ν
t =
ci...concentration profiles with time si...spectra of pure substances
= ++c1
s1T
c1
s1T
c3
s3T
c2
s2T
=C
ST
exp. dataD
exp. dataD
exp. dataD
ν
t = + E
+ E
Graphical Representation
Introduction
Ionic Liquids
MIR Studies
2DCoS
MCR -ALS
FIR Studies
MCR-ALS
Conclusions
BL 06/2007 Page 17
Water – Ionic Liquid Interaction Studiesby MIR and THz
2DCoS vs. MCR-ALS
Two complementary approaches which help to gain understanding of dynamic processes
2DCoS: Looking for correlation in the data set
Output: synchronous and asynchronous correlation mapsrequires some art to read the maps
MCR-ALS: Modeling of the data set
Output: spectra and concentration profiles of compounds requires definition of compounds rather objective criteria whether modeling was successful
Introduction
Ionic Liquids
MIR Studies
2DCoS
MCR -ALS
FIR Studies
MCR-ALS
Conclusions
BL 06/2007 Page 18
Water – Ionic Liquid Interaction Studiesby MIR and THz
0 100 200 3000
1
2
3
4
5
Time / sec
Arb
itrar
y U
nits
0 100 200 3000
1
2
3
4
5
6
Time / sec
Arb
itrar
y U
nits
3 3 0 03 4 0 03 5 0 03 6 0 03 7 0 03 8 0 00
0 .0 3
0 .0 6
0 .0 9
0 .1 2
0 .1 5
W a v e numbe r / c m-1A
rbitr
ary
Uni
ts
bmim+[BF4]- emim+[BF4]-
[BF4]-
Spectra of encountered compounds
Concentration of encountered compounds
Introduction
Ionic Liquids
MIR Studies
2DCoS
MCR -ALS
FIR Studies
MCR-ALS
Conclusions
Results of MCR-ALS
BL 06/2007 Page 19
Water – Ionic Liquid Interaction Studiesby MIR and THz
Influence of the Cation
0 100 200 3000
0.5
1
1.5
2
2.5
3
3.5
Time / sec
Arb
itrar
y U
nits
0 100 200 3000
1
2
3
4
5
Time / sec
Arb
itrar
y un
itsbmim+ emim+
Theory of FIA explains the form of the FIA peaks as a result ofconvection (dominating) and diffusionUpon increasing viscosity, radial diffusion is less pronounced => higher dispersion
radial diffusion convection
Cation determines the dispersion profile of the FIA peaks
0 100 200 3000
0.5
1
1.5
2
2.5
Time / sec
Arb
itrar
y U
nits bmim+
Introduction
Ionic Liquids
MIR Studies
2DCoS
MCR -ALS
FIR Studies
MCR-ALS
Conclusions
BL 06/2007 Page 20
Water – Ionic Liquid Interaction Studiesby MIR and THz
Only type present in PF6- based I.F.
as well as first water species in BF4-
containing I.L. is monomeric water:
First Water Species
3300340035003600370038000
0.03
0.06
0.09
0.12
0.15
Pastor et al. J Phys Chem. B 110 (2006) 10896-10902
Water species as resolved by MCR - ALS
Introduction
Ionic Liquids
MIR Studies
2DCoS
MCR -ALS
FIR Studies
MCR-ALS
Conclusions
BL 06/2007 Page 21
Water – Ionic Liquid Interaction Studiesby MIR and THz
Second Water Spezie
• Bands at 3610 cm-1 and 3450 cm-1
• Literatur: (Koeddermann et al.Absorptionen in CCl4):Water dimer at 3553 cm-1
Cyclic water trimer at 3409 cm-1330034003500360037003800
0
0.03
0.06
0.09
0.12
0.15
Our data suggest the following structure:
Pastor et al. J Phys Chem. B 110 (2006) 10896
Introduction
Ionic Liquids
MIR Studies
2DCoS
MCR -ALS
FIR Studies
MCR-ALS
Conclusions
BL 06/2007 Page 22
Water – Ionic Liquid Interaction Studiesby MIR and THz
Water - Ionic Liquid Interaction in the FIR
Pure IL
in out
Sample
Holding coil500μl
Syringe pump1000μl
Waste
ThermostatedFlow cell
Bruker IFS 66vSagitarius V3
Pure IL
in out
Sample
Holding coil500μl
Syringe pump1000μl
Waste
ThermostatedFlow cell
Bruker IFS 66vSagitarius V3
Introduction
Ionic Liquids
MIR Studies
2DCoS
MCR -ALS
FIR Studies
MCR-ALS
Conclusions
BL 06/2007 Page 23
Water – Ionic Liquid Interaction Studiesby MIR and THz
FIR (THz) Spectra Recorded at Bessy
500 400 300 200 1000,0
0,2
0,4
0,6 emimBF4 bmimBF4 emimPF6
Abso
rban
ce u
nits
Wavenumber (cm-1)
500 400 300 200 1000,0
1,0
2,0
3,0
Wavenumber (cm-1)
Inte
nsity
uni
ts
H HO
BF4-Single Beam Spectrum H H
O
FIR Spectra of 2% (w/w) of H2O in Ionic Liquids
Dominguez et al. J. Phys. Chem. B 11 (2007) 4446-4452
Introduction
Ionic Liquids
MIR Studies
2DCoS
MCR -ALS
FIR Studies
MCR-ALS
Conclusions
BL 06/2007 Page 24
Water – Ionic Liquid Interaction Studiesby MIR and THz
Matrix Augmentation in MCR Analysis
Simultaneous Analysis of Several Experiments
blank
emimBF45% H2O
Exp. withEnzymebmimBF45% H2O
Introduction
Ionic Liquids
MIR Studies
2DCoS
MCR -ALS
FIR Studies
MCR-ALS
Conclusions
BL 06/2007 Page 25
Water – Ionic Liquid Interaction Studiesby MIR and THz
Results of Matrix Augmentation
0 100 200 300 400 5000,0
1,0
2,0
3,0
4,0C
once
ntra
tion
(AU
)
Time (s)0 200 400 600 800 1000
0,0
1,0
2,0
3,0
4,0
Time (s)
350 300 250 200 150 100 50
0,00
0,05
0,10
0,15
0,20
Wavenumber (cm-1)
Abs
orba
nce
(AU
)
0 200 400 600 800 10000,0
1,0
2,0
3,0
4,0
Time (s)
Blank bmimBF4 emimBF4
148 cm-1
202 cm-1
H HO
BF 4-
O H O
Dominguez et al. J. Phys. Chem. B 11 (2007) 4446-4452
Introduction
Ionic Liquids
MIR Studies
2DCoS
MCR -ALS
FIR Studies
MCR-ALS
Conclusions
BL 06/2007 Page 26
Water – Ionic Liquid Interaction Studiesby MIR and THz
Conclusions
Spectra of Ionic Liquids from the MIR-FIRspectral region
Flow Injection Analysis very suitable for generate of binary mixtures of ionic liquids and water
In emimBF4 water dimers can be found and a cyclicstructure can be proposed
In bmimPF6 only water monomers could be detected
Successful use of 2DCoS and MCR-ALS ascomplementary techniques to resolve overlappingfeatures and components
Introduction
Ionic Liquids
MIR Studies
2DCoS
MCR -ALS
FIR Studies
MCR-ALS
Conclusions
BL 06/2007 Page 27
Water – Ionic Liquid Interaction Studiesby MIR and THz
Acknowledgements
Maria JoseAyora Canada
Ana Dominguez Vidal Mercedes Lopez Pastor
Nina Kaun - Ulli Schade
Introduction
Ionic Liquids
MIR Studies
2DCoS
MCR -ALS
FIR Studies
MCR-ALS
Conclusions