deep eutectic solvent: physicochemical behaviour and

Reciprocal Binary Mixture of Protic/Aprotic Ionic Liquids as

Deep Eutectic Solvent: Physicochemical Behaviour and

Application towards Agarose Processing

Pankaj Bharmoria,1 Krishnaiah Damarla,1 Tushar J. Trivedi,1 Naved I Malek2 and Arvind

Kumar*1,3

1Academy of Scientific and Innovative Research, CSIR-Central Salt and Marine Chemicals

Research Institute, Salt and Marine Chemicals Division, G. B. Marg, Bhavnagar-364002,

India,

2Applied Chemistry Department, S.V. National Institute of Technology, Surat- 395 007, India.

3Salt and Marine Chemicals Division, CSIR-Central Salt and Marine Chemicals Research Institute, G. B. Marg, Bhavnagar-364002, India.

.

Fig. S1. 1H-NMR spectra of [HEA][HCOO] ionic liquid. The absence of 1H-

NMR peak of the O-H of formic acid at 2 ppm and NH2 of ethanolamine at 5

ppm in the prepared IL confirms the absence of any free acid or base.

Electronic Supplementary Material (ESI) for RSC Advances.This journal is © The Royal Society of Chemistry 2015

HONH3 O H

O

2

13

External solvent (C6D6)

2(CH2 ―OH) 1(CH2 ―NH3+)3(CH― of formate ion)

Fig. S2. 13C-NMR spectra of [HEA][HCOO] ionic liquid.

m/z50 54 58 62 66 70 74 78 82 86 90 94 98 100

%

0

HOEAF 1 (0.017) 1: TOF MS ES+ 29662.10

58.1056.0953.325.84 61.96 72.0963.1071.1069.0964.10 88.1383.1281.1274.11 79.12 85.76 89.1290.12 92.10 95.11 96.12 98.05

100

NH3

HOChemical Formula: C2H8NO+

Exact Mass: 62.06Molecular Weight: 62.09

m/z: 62.06 (100.0%), 63.06 (2.6%)

Fig. S3. LCMS spectra of [HEA][HCOO] ionic liquid.

CHNS Analysis of [HOA][HCOO]

Theoretical Experimental

C=33.64% C =35±0.5%

H=8.47% H = 8%±0.5%

N=13.08% N=14.50±0.5%

1 (CH3)

2 (CH2)

3 (CH2)

6 (CH3)

4 (CH2)7, 8 (HC═CH)

5 (HC═N+)

Fig. S4. 1H-NMR spectra of [C4mim][Cl] ionic liquid.

N+ NCl- 1

24

3

56

7 8

1: TOF MS ES+

2.15e3

83.1357.13

56.1180.1278.21

58.14 139.0384.13 124.1896.15 106.0999.10 118.18

140.23

141.24 153.25 155.19 171.29 184.95173.26 194.32

M/z50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200

%

0

100BMIMCL 2 (0.024) 139.23

NNCl

Chemical Formula: C8H15N2+

Exact Mass: 139.12Molecular Weight: 139.22

m/z: 139.12 (100.0%), 140.13 (8.8%)

1 (CH3)

2 (CH2)

3 (CH2)4 (CH2)

6 (CH3)

7, 8 (HC═CH)

2 (HC═N+)

Fig. S5. 13C-NMR spectra of [C4mim][Cl] ionic liquid.

N+ NCl- 1

24

3

56

7 8

Fig. S6. LCMS Spectra of [C4mim][Cl] ionic liquid.

Fig. S8. DSC thermograms (A) Pure [HEA][HCOO]

(B-F) [C4mim][Cl]+[HEA][HCOO] mixtures at

different mixture compositions (G) pure [C4mim][Cl].

Fig. S7. Visual Images of [C4mim][Cl]+[HEA][HCOO] eutectic mixtures at different mixture compositions

BCl+HEAF

20 30 40 50 60 70 80 90 100

-0.24

-0.21

-0.18

-0.15

-0.12

-0.09

-0.06(G)

65 oC

Pure [C4mim][Cl]

DSC

/ m

W.m

g-1

T / oC

Exo

-135 -120 -105 -90 -75 -60 -45-0.5

-0.4

-0.3

-0.2

-0.1

0.0

0.1

(D)

Cp =0.962 J/g.K

Exo

-101 oC

DSC

/ (m

W/m

g)

T / oC

5:5 [C4mim][Cl]:[HEA][HCOO]

-120 -100 -80 -60 -40 -20 0-0.4

-0.3

-0.2

-0.1

0.0

0.1

(E)

Cp =0.605 J/g.K

-90 oC

Exo

DSC

/ (m

W/m

g)

T / oC


-140 -120 -100 -80 -60 -40 -20 0

-0.32

-0.24

-0.16

-0.08

0.00

0.08

(F)

Cp =0.757 J/g.K

-97.24 oC

Exo

DSC

/ (m

W/m

g)

T / oC


-140 -120 -100 -80 -60 -40 -20 0-0.45

-0.30

-0.15

0.00

0.15

Cp=0.778 J/g.K

(B)-94.96 oC

Exo

DSC

/ (m

W/m

g)

T/ 0C


-140 -120 -100 -80 -60 -40 -20 0

-0.3

-0.2

-0.1

0.0

0.1

(C)

CP =0.777 J/g.K

-91.67 oC

Exo

DSC

/ (m

W/m

g)

T / oC


-140 -120 -100 -80 -60 -40 -20-0.30

-0.25

-0.20

-0.15

-0.10

-0.05

0.00

0.05Exo

(A)

Cp =0.984 J/g.K

Pure [HEA][HCOO]

-88.5 oCDSC

/ (m

W/m

g)

T / oC

0.0 0.2 0.4 0.6 0.8 1.0

1.08

1.10

1.12

1.14

1.16

1.18

/ (

g.cm

-3)

x1

298.15 K 308.15 K 318.15 K

Fig. S10. Plots of variation in density of [HEA][HCOO]

(x1)+[C4mim][Cl] (x2) mixture at different mole fractions at

298.15 K, 308.15 K, and 318.15 K.

[C4mim][Cl] 9:1 7:3 5:5 3:7 1:9[HEA][HCOO]-120-100-80-60-40-20

020406080

T m /o C

[C4mim][Cl]+[HEA][HCOO]

Fig. S9. Plots showing the melting points of [C4mim][Cl] +

[HEA][HCOO] mixtures and native [C4mim][Cl] and

[HEA][HCOO].

0.0 0.2 0.4 0.6 0.8 1.0

75

150

225

300

375

450 298.15 K 308.15 K 318.15 K

/ (m

Pa.s)

x1

0.0 0.2 0.4 0.6 0.8 1.01740

1750

1760

1770

1780

1790

1800

u / (

m.s

-1)

x1

298.15 K 308.15 K 318.15 K

Fig. S11. Variation in speed of sound (u) of [HEA][HCOO]


298.15 K, 308.15 K, and 318.15 K.

Fig. S12. Variation in viscosity (η) of [HEA][HCOO]


298.15 K, 308.15 K, and 318.15 K.

0.0 0.2 0.4 0.6 0.8 1.0265

270

275

280

285

290

295

300

298.15 K 308.15 K 318.15 K

s /

(T.P

a-1)

x1

0.00318 0.00324 0.00330 0.00336 0.00342

2.5

3.0

3.5

4.0

4.5

5.0

5.5

6.0 x1

1 0.7901 0.62589 0.49391 0.38551 0.29491 0.21804 0.152 0.094660.04441

ln

/ (m

Pa.s

)

T-1 / (K-1)

Fig. S13. Variation in isentropic compressibility ( s ) of

[HEA][HCOO](x1)+[C4mim][Cl](x2) at different mole

fractions at 298.15 K, 308.15 K and 318.15 K.

Fig. S14. Arrhenius plots (lnη vs T-1) showing variation in

viscosity as a function of temperature for [HEA][HCOO](x1) +

[C4mim][Cl](x2) mixtures at different mole fractions

Polarity Parametersx1 (kCal.)30(TE

mol-1)

TNE

(kCal.mol-1)

*

0.04441 51.33 0.6309 1.11 0.49 0.83

0.152 54.05 0.71398 1.08 0.69 0.79

0.29491 56.28 0.78231 1.02 0.87 0.76

0.49391 57.76 0.82751 1.04 0.94 0.71

0.7901 58.11 0.83828 1.06 0.95 0.67

1 58.35 0.84553 1.08 0.96 0.62

λmax (nm)x1RD 4NA DENA

0.04441 557 398 417

0.152 529 394 415

0.29491 508 390 412

0.49391 495 389 413

0.7901 492 388 414

1 490 387 415

Table S1. Experimental Kamlet-Taft parameters of [HEA][HCOO](x1)+[C4mim][Cl]

(x2) mixtures at various mole fractions of [HEA][HCOO] at 298.15 K.

Table S2. Experimental values of wavelengths corresponding to

absorption maximum of nitroaniline (4NA), Reichardt’s dye (RD) and N-

N-diethylnitoaniline (DENA) [HEA][HCOO](x1) + [C4mim][Cl] (x2)

mixtures at various mole fractions of [HEA][HCOO] at 298.15 K.

350 400 450 500 550 600 650

0.0

0.1

0.2

0.3

0.4

0.5Pure [HEA][HCOO]

Abso

rban

ce

/ nm

4NA RD DENA

350 400 450 500 550 600 650

0.0

0.1

0.2

0.3

0.4

0.5

Abso

rban

ce / nm

4NA RD DENA

0.7901 [HEA][HCOO]

350 400 450 500 550 600 650

0.0

0.1

0.2

0.3

0.4

0.50.4939 [HEA][HCOO]

4NA RD DENA

Abso

rban

ce

/ nm350 400 450 500 550 600 650

0.0

0.1

0.2

0.3

0.4

0.5

Ab

sorb

ance

/ nm

4NA RD DENA

0.2946 [HEA][HCOO]

350 400 450 500 550 600 650 700

0.0

0.1

0.2

0.3

0.4

0.50.152 [HEA][HCOO]

Abso

rban

ce

/ nm

4NA RD DENA

350 400 450 500 550 600 650

0.0

0.1

0.2

0.3

0.4

0.50.044 [HEA][HCOO]

Abso

rban

ce

/ nm

4NA RD DENA

Fig. S15. UV-Vis spectra of the dyes, nitroaniline (4NA), Reichardt’s dye (RD) and

N-N-diethylnitoaniline (DENA) in the [HEA][HCOO](x1)+[C4mim][Cl] (x2)

mixtures at various mole fractions.

Fig. S17. Plot showing dynamic storage (G') and loss

moduli (G'') vs temperature profiles of ionogels prepared

by dissolving 5% agarose in different mixture

compositions of [C4mim][Cl]+[HEA][HCOO]. The

crossing point of G' and G'' indicating the melting

temperature.

Fig. S16. (A) Ionosols of agarose dissolved in native

[HEA][HCOO](x1)+[C4mim][Cl] mixtures and native ILs at 70oC. (B)

Agarose ionogels prepared by cooling the ionosols to room temperature.

(A)

(B)

30 40 50 60 70 80 900

100

200

300

400

500

600

700

70oC

(D)


G'G

" / P

a

T / oC

G' G"

30 40 50 60 70 80 90

0

120

240

360

480

600

720

840 (A)Native [C4mim][Cl]

G' G''

G'G

'' / P

a

T / oC

82 oC

30 40 50 60 70 80 900

150

300

450

600

750

900(B)


G'G

" / P

a

T / oC

G' G"

86oC

30 40 50 60 70 80 900

150

300

450

600

750

900

1050 (C)


G'G

" / P

a

T / oC

G' G"

79.7oC

30 40 50 60 70 80 900

150

300

450

600

750

900

1050

60oC

1:9 [C4mim][Cl]+[HEA][HCOO]

G'G

'' / P

a

T / oC

G' G"

(F)

30 40 50 60 70 80 900

500

1000

1500

2000

2500

3000

73.4oC

Pure [HEA][HCOO]

G'G

" / P

a

T / oC

G' G"

(G)

30 40 50 60 70 80 90

0

100

200

300

400

500

600(E)

3:7 [C4mim][Cl]+[HEA][HCOO]

G' G''

G'G

'' / P

a

T / oC

50.4oC

0 20 40 60 80 100 120-0.6

-0.5

-0.4

-0.3

-0.2

-0.1

0.0(A) Native [C4mim][Cl]

Tg =33.95 oC

Tm = 100.5 oC

T / oC

DSC

/ m

W.m

g-1

Exo

20 40 60 80 100 120

-0.35

-0.30

-0.25

-0.20

-0.15

-0.10

-0.05

0.00

T / oC

DSC

/ m

W.m

g-1

Tg = 38.2 oC

(C) 7:3 [C4mim][Cl]:[HEA][HCOO]

Tm = 89 oC

Exo

20 40 60 80 100 120-0.30

-0.25

-0.20

-0.15

-0.10

-0.05

0.00

Tg = 44.43 oC

Tm = 92.5

5:5 [C4mim][Cl]:[HEA][HCOO]D

SC /

mW

.mg-1

T / oC

(D)Exo

20 40 60 80 100 120

-0.6

-0.5

-0.4

-0.3

-0.2

-0.1

0.0

Tm = 88oC

Tg = 33.1 oC


DSC

/ m

W.m

g-1

T / oC

(E)Exo

20 40 60 80 100 120

-0.40

-0.35

-0.30

-0.25

-0.20

-0.15

-0.10

-0.05

0.00

Tg = 30.32 oC

Tm = 83.5 oC

(F)

DSC

/ m

W.m

g-1

T / oC

1:9 [C4mim][Cl]:[HEA][HCOO]Exo

20 40 60 80 100 120-0.35

-0.30

-0.25

-0.20

-0.15

-0.10

-0.05

0.00 (G) Pure [HEA][HCOO]

Tg = 29.72 oC

Tm = 83 oC

T / oC

DSC

/ m

W.m

g-1

Exo

20 40 60 80 100 120

-0.35

-0.30

-0.25

-0.20

-0.15

-0.10

-0.05

0.00

Tg = 34.01 oC

Tm = 94.75 oC

(B) 9:1 [C4mim][Cl]:[HEA][HCOO]

DSC

/ m

W.m

g-1

T / oC

Exo

Fig. S18. Plot showing DSC

thermograms of agarose ionogels

prepared in different composition of

[C4mim][Cl]+[HEA][HCOO].

5% Agarose Gels in the Ionic Liquid Mixtures

Glass transitionTemp. DSC

(Tg / oC)

Melting Temp.DSC

(Tm / oC)

Melting Temp.Rheology(Tm / oC)

Native [C4mim][Cl] 33.95 100.5 82.009:1 [C4mim][Cl]+[HEA][HCOO] 34.01 94.75 86.007:3 [C4mim][Cl]+[HEA][HCOO] 38.20 89.00 79.705:5 [C4mim][Cl]+[HEA][HCOO] 44.43 92.50 70.003:7 [C4mim][Cl]+[HEA][HCOO] 33.10 88.00 56.801:9 [C4mim][Cl]+[HEA][HCOO] 30.32 83.50 60.00

9:1 [HEA][HCOO] 29.72 83.00 73.40

Fig. S19. Comparative plot of the G' and G'' of ionogels formed at

different mole fractions at an angular frequency of 98 rad.s-1

20 40 60 80 1000

400

800

1200

1600

2000

G' /

Pa

BCl 9:1 7:3 5:5 3:7 1:9 HEAF

(A)

0 20 40 60 80 100

100

200

300

400

500

600(B)

G" /

Pa

BCl 9:1 7:3 5:5

3:7 1:9

HEAF

Table S3. Glass transition (Tg) and Meting temperatures (Tm) of agarose ionogels

measured from DSC and temperature dependent rheology measurements.

[C4mim][Cl] 9:1 7:3 5:5 3:7 1:9[HEA][HCOO]0

500

1000

1500

2000

2500

G' G''

G'G

'' / P

a

Mixture Composition

At = 98 rad.s-1

Fig. S20. Strain ( ) dependence of (A) dynamic storage (G') and (B) %

loss moduli (G'') of agarose ionogels (5%) at different compositions of

[C4mim][Cl]+[HEA][HCOO].

O

OO

O

OO

OHO

O

OO

n

o

O

O

N+

OO

O-

H H

HN+

O

O

O-

HH

H

H

H H

H

HH

N+

OO

O-H H

H

HH

N+

OH

OO-H

H

H H

O H Inter-molecular hydrogen bondingbetween agarose and [HEA][HCOO]

Fig. S21. Schematic showing inter-molecular hydrogen bonding between

agarose and [HEA][HCOO].

deep eutectic solvent: physicochemical behaviour and

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