Post on 13-Feb-2021
Evidence for the Interactions Occurring between
Ionic Liquids and Tetraethylene Glycol in Binary
Mixtures and Aqueous Biphasic Systems
Luciana I. N. Tomé‡, Jorge F. B. Pereira‡,†, Robin D. Rogers†, Mara G. Freire‡, José R. B.
Gomes‡ and João A. P. Coutinho
‡*
‡CICECO, Departamento de Química, Universidade de Aveiro, 3810-193 Aveiro, Portugal
† Center for Green Manufacturing and Department of Chemistry, The University of Alabama,
Tuscaloosa, AL, 35487, USA
This Supporting Information contains: the densities for binary mixtures of water and TEG calculated from
the MD simulations (Table S1); full set of electrostatic charges for the ILs and TEG model (Tables S2 to S6);
compositions (wt%) of the mixtures at which the MD calculations and the 1H NMR experiments were
performed (Table S7); compositions of the biphasic region of the [C4mim]Cl/PEG/water phase diagram at
which the additional MD simulations were performed (Table S8); comparison of the experimental and
calculated densities for binary mixtures of water and TEG (Figure S1); compositions of the experimental
phase diagrams of the ABS composed of PEG 1500 and [C4mim]Cl at which the 1H NMR experiments and
the MD simulations were performed (Figure S2); 1H NMR chemical shifts deviations between PEG-200 and
[C4mim]Cl (Figures S3 and S4); radial distribution functions between the anion and cation of [C2mim]Cl and
the hydrogen and carbon atoms of TEG (Figures S5 and S6); snapshot from a simulation of
([C4mim]Cl+TEG) (Figure S7); radial distribution functions between the anions and selected atoms of the
cations of [C1mim]Cl/[C4mim]Cl/[C6mim]Cl and different molecular regions of TEG for the binary systems
(Figures S8 to S13); comparison of the radial distribution functions for the interactions of selected groups of
TEG with the anions (Figure S14) and with selected atoms of the cations (Figures S15 to S18) for the binary
systems and with water (Figure S19) for the different ternary systems; radial distribution functions between
the anion and cation of [C4mim]Cl and the hydrogen and carbon atoms of TEG for (TEG + [C4mim]Cl +
water) ternary mixtures (Figures S20 and S21); radial distribution functions between the anions and selected
atoms of the cations of [C1mim]Cl/[C2mim]Cl//[C6mim]Cl and different molecular regions of TEG for the
ternary systems (Figures S22 to S27), and the references complete author list.
Table S1. Densities (ρ) for binary mixtures of water (1) + TEG (2) at T = 298.15 K calculated
from the MD simulations.
xwater ρ / (kg·m-3)
0.00 1124.17 0.09 1125.21 0.20 1124.63 0.50 1124.72 0.60 1123.98 0.70 1122.14 0.80 1115.41 0.90 1093.16 1.00 999.35
Table S2. Atomic charges used in the MD simulations for [C1mim]Cl. Atom numbering
corresponds to the adjacent diagram.
Atom numbering Electrostatic
Charges / e
1 N 0.179
2 C -0.140
3 C -0.140
4 N 0.179
5 C -0.117
6 C -0.230
7 H 0.141
8 C -0.230
9 H 0.219
10 H 0.219
11 H 0.215
12 H 0.141
13 H 0.141
14 H 0.141
15 H 0.141
16 H 0.141
Table S3. Atomic charges used in the MD simulations for [C2mim]Cl. Atom numbering
corresponds to the adjacent diagram.
Atom numbering Electrostatic Charges
/ e 1N 0.065
2 C -0.142
3 C -0.135
4 N 0.191
5 C -0.109
6 C -0.224
7 H 0.138
8 C 0.118
9 H 0.221
10 H 0.206
11 H 0.225
12 H 0.052
13 H 0.052
14 H 0.138
15 H 0.138
16 C -0.120
17 H 0.062
18 H 0.062
19 H 0.062
Table S4. Atomic charges used in the MD simulations for [C4mim]Cl. Atom numbering
corresponds to the adjacent diagram.
Atom numbering Electrostatic
Charges / e
1 C -0.118
2 N 0.161
3 C -0.117
4 C -0.203
5 N 0.214
6 C -0.223
7 C -0.229
8 C 0.162
9 C 0.169
10 C -0.267
11 H 0.205
12 H 0.237
13 H 0.226
14 H 0.139
15 H 0.139
16 H 0.139
17 H 0.112
18 H 0.112
19 H -0.022
20 H -0.022
21 H -0.018
22 H -0.018
23 H 0.074
24 H 0.074
25 H 0.074
Table S5. Atomic charges used in the MD simulations for [C6mim]Cl. Atom numbering
corresponds to the adjacent diagram.
Atom numbering Electrostatic
Charges / e
1 C -0.124
2 C -0.175
3 N 0.133
4 C -0.081
5 N 0.164
6 C -0.131
7 C 0.228
8 C -0.039
9 C -0.035
10 C -0.256
11 H 0.092
12 H 0.092
13 H 0.009
14 H 0.009
15 H 0.218
16 H 0.147
17 C 0.212
18 H 0.232
19 H -0.040
20 H 0.205
21 H -0.040
22 H 0.147
23 H 0.010
24 H 0.010
25 H 0.147
26 C -0.235
27 H -0.035
28 H -0.035
29 H 0.057
30 H 0.057
31 H 0.057
Table S6. Atomic charges used in the MD simulations for TEG. Atom numbering corresponds to
the adjacent diagram.
Atom numbering Electrostatic
Charges / e
1 O -0.568
2 C 0.284
3 H 0.000
4 H 0.000
5 C 0.284
6 H 0.000
7 H 0.000
8 C 0.284
9 H 0.000
10 H 0.000
11 O -0.568
12 C 0.284
13 H 0.000
14 H 0.000
15 C 0.284
16 H 0.000
17 H 0.000
18 O -0.568
19 C 0.284
20 H 0.000
21 H 0.000
22 C 0.216
23 H 0.014
24 H 0.014
25 O -0.700
26 H 0.456
27 C 0.216
28 H 0.014
29 H 0.014
30 O -0.700
31 H 0.456
Table S7. Composition (xwt%) of the mixtures at which the MD calculations and the 1H NMR
experiments were performed.
MD [C4mim]Cl TEG water 40.3 59.7 0.0 32.4 46.5 21.1 1H NMR [C4mim]Cl PEG-200 water
1st set 17.30 0.00 74.33
17.01 1.94 73.07 16.56 4.29 71.13 16.34 6.03 70.22 15.60 10.18 67.01 13.92 20.16 59.79
2nd set 0.00 19.97 74.33
1.67 20.40 75.93 3.33 19.34 71.97 4.78 19.92 74.11 9.05 18.26 67.93 17.10 16.78 62.43
3rd set 17.37 82.63 0.00
17.14 81.53 1.84 16.77 79.73 3.54 16.40 77.97 5.59 15.77 75.01 9.25
Table S8. Compositions of the biphasic region of the [C4mim]Cl/PEG/water phase diagram [ref.
40] at which the additional MD simulations were performed.
Number of ion pairs/molecules considered in the MD simulations
Mole fraction
[C4mim]Cl TEG water [C4mim]Cl PEG1500 water Binary system 160 40 - 0.80 0.20 -
Ternary system 160 40 40 0.67 0.17 0.17 160 40 80 0.57 0.14 0.29 160 40 190 0.41 0.10 0.49
Figure S1. Experimental (ref. 80) and calculated (this work) densities (ρ) for binary mixtures of
water (1) + TEG (2) at T = 298.15 K.
0.98
1.00
1.02
1.04
1.06
1.08
1.10
1.12
1.14
0.00 0.20 0.40 0.60 0.80 1.00 1.20
ρρ ρρ(g/cm
3)
x1
experimental (ref 80)
MD simulations (this work)
Figure S2. Experimental phase diagrams for the ABS composed of PEG 1500 and [C4mim]Cl at
323.15 K (red squares) and 333.15 K (black dots) [ref. 40]. The blue triangles represent the
compositions at which the MD simulations were performed and the green triangles represent the
compositions at which the 1H NMR experiments were performed.
Figure S3. 1H NMR chemical shifts deviations between PEG-200 and [C4mim]Cl in deuterated
aqueous solutions and that of pure [C4mim]Cl (1.0 mol·kg-1) in heavy water as a function of
PEG-200 molality.
-0.08
-0.06
-0.04
-0.02
0.00
0.02
0 0.2 0.4 0.6 0.8 1
∆δH/ pp
m CPEG200 / (mol.kg-1)
H2
H5
H4
HB1
Htm
HB2
HB3
Htb
-
0.0033.035.037.039.041.0
CD2O / (mol.Kg-1)
Figure S4. 1H NMR chemical shifts deviations between PEG-200 and [C4mim]Cl in deuterated
aqueous solutions and that of pure PEG-200 (1.0 mol·kg-1) in heavy water as a function of
[C4mim]Cl molality.
0.00
0.01
0.02
0.03
0.04
0 0.2 0.4 0.6 0.8 1
∆δH/ p
pm
C[C4mim]Cl / (mol.kg-1)
Hc
Hb
Ha
0.0033.035.037.039.041.0
CD2O / (mol.Kg-1)
Figure S5. Radial distribution functions between the anion of [C2mim]Cl and the hydrogen
atoms of TEG.
(a)
(b)
(c)
(d)
Figure S6. Radial distribution functions between selected atoms of the cation of [C2mim]Cl and
the hydrogen and carbon atoms of TEG.
Figure S7. Snapshot from a simulation of ([C4mim]Cl+TEG) showing the preferential
conformations adopted by the TEG molecules and the distances (Å) between selected atoms.
Red, white and green spheres represent oxygen atoms, hydrogen atoms and chloride ions,
respectively.
Figure S8. Radial distribution functions between the anion of [C1mim]Cl and different
molecular regions of TEG.
(a)
(b)
(c)
Figure S9. Radial distribution functions between selected atoms of the cation of [C1mim]Cl and
different molecular regions of TEG.
Figure S10. Radial distribution functions between the anion of [C4mim]Cl and different
molecular regions of TEG.
(a)
(b)
(c)
(d)
Figure S11. Radial distribution functions between selected atoms of the cation of [C4mim]Cl and
different molecular regions of TEG.
Figure S12. Radial distribution functions between the anion of [C6mim]Cl and different
molecular regions of TEG.
(a)
(b)
(c)
(d)
Figure S13. Radial distribution functions between selected atoms of the cation of [C6mim]Cl and
different molecular regions of TEG.
Figure S14. Comparison of the RDFs for the interactions of TEG protons and the anion of
[C1mim]Cl, [C2mim]Cl, [C4mim]Cl and [C6mim]Cl.
Figure S15. Comparison of the RDFs for the interactions of the oxygen atom of the hydroxyl
group of TEG and the H4 atom of the imidazolium ring of the cation of [C1mim]Cl, [C2mim]Cl,
[C4mim]Cl and [C6mim]Cl.
Figure S16. Comparison of the RDFs for the interactions of the O1 atom of TEG and the H2
atom of the imidazolium ring of the cation of [C1mim]Cl, [C2mim]Cl, [C4mim]Cl and
[C6mim]Cl.
Figure S17. Comparison of the RDFs for the interactions of the oxygen atom of the hydroxyl
group of TEG and the terminal carbon atom of the cation of [C1mim]Cl, [C2mim]Cl, [C4mim]Cl
and [C6mim]Cl.
Figure S18. Comparison of the RDFs for the interactions of the ether oxygens of TEG and the
terminal carbon atom of the cation of [C1mim]Cl, [C2mim]Cl, [C4mim]Cl and [C6mim]Cl.
Figure S19. Comparison of the RDFs for the interaction of the hydrogen atoms of water with the
O1 and O(OH) atoms of TEG, for the systems (TEG + IL + water).
Figure S20. Radial distribution functions between the anion of [C4mim]Cl and the hydrogen and
carbon atoms of TEG for (TEG + [C4mim]Cl + water) ternary mixtures.
(a)
(b)
(c)
(d)
(e)
(f)
(g)
Figure S21. Radial distribution functions between selected atoms of the cation of [C4mim]Cl and
different regions of TEG, for (TEG + [C4mim]Cl + water) ternary mixtures.
Figure S22. Radial distribution functions between the anion of [C6mim]Cl and different
molecular regions of TEG, for (TEG + [C6mim]Cl + water) ternary mixtures.
(a)
(b)
(c)
(d)
(e)
(f)
(g)
(h)
Figure S23. Radial distribution functions between selected atoms of the cation of [C6mim]Cl and
different molecular regions of TEG, for (TEG + [C6mim]Cl + water) ternary mixtures.
Figure S24. Radial distribution functions between the anion of [C2mim]Cl and different
molecular regions of TEG, for (TEG + [C2mim]Cl +water) ternary mixtures.
(a)
(b)
(c)
(d)
Figure S25. Radial distribution functions between selected atoms of the cation of [C2mim]Cl and
different molecular regions of TEG, for (TEG + [C2mim]Cl + water) ternary mixtures.
Figure S26. Radial distribution functions between the anion of [C1mim]Cl and different
molecular regions of TEG, for (TEG + [C1mim]Cl + water) ternary mixtures.
(a)
(b)
Figure S27. Radial distribution functions between selected atoms of the cation of [C1mim]Cl and
different molecular regions of TEG, for (TEG + [C1mim]Cl + water) ternary mixtures.
References: Complete author list
(84) Frisch, M.; Trucks, G. W.; Schlegel, H. B.; Scuseria, G. E.; Robb, M. A.; Cheeseman, J. R.; Scalmani, G.; Barone, V.; Mennucci, B.; Petersson, G. A.; Nakatsuji, H.; Caricato, M.; Li, X.; Hratchian, H. P.; Izmaylov, A. F.; Bloino, J.; Zheng, G.; Sonnenberg, J. L.; Hada, M.; Ehara, M.; Toyota, K.; Fukuda, R.; Hasegawa, J.; Ishida, M.; Nakajima, T.; Honda, Y.; Kitao, O.; Nakai, H.; Vreven, T.; Montgomery Jr., J. A.; Peralta, J. E.; Ogliaro, F.; Bearpark, M.; Heyd, J. J.; Brothers, E.; Kudin, K. N.; Staroverov, V. N.; Kobayashi, R.; Normand, J.; Raghavachari, K.; Rendell, A.; Burant, J. C.; Iyengar, S. S.; Tomasi, J.; Cossi, M.; Rega, N.; Millam, J. M.; Klene, M.; Knox, J. E.; Cross, J. B.; Bakken, V.; Adamo, C.; Jaramillo, J.; Gomperts, R.; Stratmann, R. E.; Yazyev, O.; Austin, A. J.; Cammi, R.; Pomelli, C.; Ochterski, J. W.; Martin, R. L.; Morokuma, K.; Zakrzewski, V. G.; Voth, G. A.; Salvador, P.; Bannenberg, J. J.; Dapprich, S.; Daniels, A. D.; Farkas, O.; Foresman, J. B.; Ortiz, J. V.; Cioslowski, J.; Fox, D. J. Gaussian 09, Revision A.02; Gaussian, Inc.: Wallingford CT, 2009.