Supporting Information

Charge Transfer Liquid: A Stable Donor-Acceptor

Interaction in Solvent-free Liquid State

Vivek C. Wakchaure,a,b

Lekshmi V. Pillai,c

Goudappagouda,a,b

Kayaramkodath

C. Ranjeesh,a,b

Suman Chakrabarty,d Sapna Ravindranathan,

b,e Pattuparambil R.

Rajamohanan,b,e

Sukumaran S. Babu*a,b

a. Organic Chemistry Division, National Chemical Laboratory (CSIR-NCL), Dr. Homi

Bhabha Road, Pune-411008, India. b.

Academy of Scientific and Innovative Research (AcSIR), Ghaziabad-201 002, India. c. Amrita Vishwa Vidyapeetham University, Amritapuri, Kerala-690525, India.

d. S. N. Bose National Centre for Basic Sciences, JD Block, Sector-III, Salt Lake City,

Kolkata - 700 106, India e. Central NMR Facility, National Chemical Laboratory (CSIR-NCL), Dr. Homi Bhabha

Road, Pune-411008, India.

Content

1. Experimental Page S2

2. Synthesis Page S5

3. Figures S1 to S21 Page S10

4. References Page S23

Electronic Supplementary Material (ESI) for ChemComm.This journal is © The Royal Society of Chemistry 2019

S-2

Experimental

Materials

All chemicals, 12-tricosanone, 1-bromo-2-ethylhexane, 1,8-naphthalic anhydride,

naphthalene-1,4,5,8-tetracarboxylic dianhydride (TCI), 2-ethylhexyl amine, ammonium

acetate (Spectrochem), sodium cyanoborohydride, dithranol (Aldrich), 2,6-

dihydroxynaphthalene (Alfa Aeser) and hydrochloric acid (Spectrochem) were used as

received. The solvents such as dichloromethane, methanol, dimethylformamide (Finar) were

used as received without further purification. Thin layer chromatography was carried out

using Aluchrosep Silica Gel 60/UV254 purchased from Merck Specialities Pvt Ltd and

visualized either by UV Fluorescence or by iodine chamber. Column chromatography was

performed using silica gel (100-200 mesh), bed was made by using 60-120 mesh silica

purchased from Spectrochem Pvt. Ltd. India and mixtures of dichloromethane-PET used for

elution were distilled before use.

General

All the reactions were carried out in oven dried round bottom flasks under argon atmosphere

unless otherwise mentioned. The 1H,

13C NMR spectra were recorded on a Bruker-400 MHz

NMR spectrometer. NOESY and ROESY NMR experiments were carried out on a Bruker

700 MHz spectrometer while diffusion experiments were carried out on a Bruker 500 MHz

spectrometer equipped with a broad band diffusion probe (DIFF60) generating a maximum

gradient of 1700 Gauss/cm. The chemical shift values for 1H (TMS as internal standard) and

13C NMR are recorded in CDCl3. The value of coupling constant (J) is stated in Hertz (Hz).

MALDI-TOF MS spectrum was recorded using dithranol as the inert matrix on AB SCIEX

MALDI TOF/TOF™ 5800. FT-IR spectra were recorded using Bruker Alpha FT-IR

spectrometer and reported in frequency of absorption (cm-1

). UV-Vis absorption spectra were

recorded with a Shimadzu 1800 spectrophotometer, while all emission spectra were

performed using PTI Quanta Master™ Steady State Spectrofluorometer. The Powder X-ray

diffraction patterns were recorded on a Rigaku, MicroMax-007HF equipped with high

intensity Micro focus rotating anode X-ray generator. The data was collected with the help of

Control Win software. A Rigaku, R-axis IV++ detector was used for the wide-angle

experiments using Cu K (1.54 Å) radiation outfitted with a Ni filter and Aluminium holder

was used as sample holder. DSC Q 10 differential scanning calorimeter connected to Q Series

S-3

PCA (TA Instruments, USA) was used to determine the phase transition temperatures of

molecule. TGA data was collected in METTLER TOLEDO, TGA/SDTA851 instrument.

Rheology experiment was carried out using a MCR dynamic oscillatory Cup and Bob

Frequency Sweep at 20 oC by using about 5 g of the liquid samples.

Preparation of liquid CT complex

The donor 1 and acceptor 2 with different equivalents in glass vials (1.5 mL) were either

stirred well with spatula or heated gently to become a homogeneous mixture.

UV-VIS spectrum of neat liquids

UV-Vis spectra of all neat liquids were recorded in the transmittance mode and the samples

are prepared by making a uniform transparent coating of 5 mg sample on 1 x 1 cm2 area of

quartz plate. The consistency of each spectrum was confirmed by repeated trails.

NMR experiments

NMR spectra in n-hexane were recorded using DMSO-d6 as the external reference. All the

NMR spectra in the neat condition (1, 2 and 1+2 CT liquids) were recorded by placing the

compounds (~ 200 mg) in a 3 mm NMR tube and inserting it in an outer 5 mm NMR tube

containing DMSO-d6 as an external lock. After mixing, samples were allowed to homogenize

at the measurement temperature before carrying out the experiments. The actual ratios of 1

and 2 were estimated by integration of peak areas of the aromatic protons.

Molecular dynamics (md) simulations

All MD simulations were performed using Gromacs 5.0.7 software. Molecule 3 with short

branched alkyl chain has been chosen for facile MD simulations. The GAFF force field

parameters for compound 1 and 3 were generated using the antechamber utility of

AmberTools 18. A cubic simulation box containing 10 acceptor and 100 donor molecules

(D:A = 1:0.1) was prepared with periodic boundary conditions. The system was energy

minimized using steepest descent algorithm. All the systems were equilibrated for 2 ns in

NPT ensemble using a velocity rescale thermostat and Parrinello-Rahman barostat at 300 K

and 1 bar. Long-range electrostatic interactions were calculated with the particle mesh Ewald

(PME) summation method with a grid spacing of 0.16 nm and fourth-order cubic

interpolation. For short range electrostatics and van der Waals interaction, a cut-off distance

of 1 nm was used. The integration time step was set to 2 fs. The production run was further

continued for 100 ns and coordinates were saved every 20 ps for further analysis. Radial

distribution functions (RDF) captures the statistical distribution of the distance between

chosen pairs.

S-4

Synthesis

Molecules1 and 2 are synthesized as shown in Scheme S1.

Scheme S1. Synthesis of 1and 2.

Procedure for synthesis of 2,6-bis((2-ethylhexyl)oxy)naphthaleneS1

Potassium carbonate 8.6 g (5 eq.) was suspended in 50 ml of acetonitrile and sonicated for 30

min followed by degassing N2 for 30 minutes. 12 g (5 eq.) of 2-ethylhexyl bromide was

added into above reaction mixture. Separately 2 g (1 eq.) of 1,5-dihydroxynaphthalene

suspended in acetonitrile and added via a dropping funnel to the reaction mixture. After

completion of addition, the reaction mixture was refluxed under N2 for 24 h. The progress of

reaction was monitored by TLC. After completion of reaction, the reaction mixture was

filtered, the filtrate collected and solvent removed under reduced pressure. The residue

obtained was dissolved in chloroform and washed with 1M hydrochloric acid, water and

brine. The organic layer was dried over sodium sulphate and the solvent was removed under

reduced pressure. The crude product was purified by silica gel column chromatography by

using 10% dichloromethane in petroleum ether as an eluent (Rf = 0.8). Combined organic

layer was concentrated under reduced pressure and dried under vacuo to yield a colourless

liquid (3.94 g, 82%).

S-5

1H-NMR (400 MHz, CDCl3, 25

oC): δ = 7.63 (2H, d, J = 8.7 Hz), 7.14-7.12 (2H, dd, J = 8.7

and 2.26 Hz), 7.10 (2H, d, J = 2.26 Hz), 3.95-3.93 (4H, m), 1.79 (2H, m), 1.55-1.38 (8H, m),

1.37-1.34 (8H, m), 0.98-0.91 (12H, m) ppm.

13C-NMR (100 MHz, CDCl3, 25

oC): δ = 155.76, 129.66, 127.91, 119.24, 106.88, 70.55,

39.41, 30.60, 29.11, 23.94, 23.06, 22.9, 14.09, 11.14 ppm.

MALDI-TOF MS: calcd. for C26H40O2 = 384.6040, found 384.2239.

Tricosan-12-amineS2

1,2-Tricosanone, ammonium acetate (NH4OAc) and sodium cyanoborohydride (NaBH3CN)

were dissolved in 40 ml methanol (HPLC grade) and stirred at RT for 56 h (3 days). After a

clear solution was observed in the reaction mixture, it was quenched by adding conc.

hydrochloric acid dropwise. The solution was then concentrated with rotatory evaporator.

The solid thus obtained was dispersed in 250 ml of water and adjusted to pH = 10 with KOH.

The obtained latex solution was extracted by using 150 ml of dichloromethane two times.

Combined organic layer was dried over sodium sulphate and the solvent was removed under

reduced pressure to give pale yellow liquid in quantitative yield. The amine obtained was

used further without purification.

2,7-di(tricosan-12-yl)benzo[lmn][3,8]phenanthroline-1,3,6,8(2H,7H)-tetraoneS3

Naphthalene-1,4,5,8-tetracarboxylic dianhydride (200 mg, 1 eq.) and tricosan-12-amine (633

mg, 2.5 eq.) were suspended in DMF (20 mL) in 100 ml round bottom flask. The reaction

mixture was stirred for 6 h at 140°C. The progress of reaction was monitored by TLC. After

completion of reaction, the reaction mixture was allowed to cool to RT and it was quenched

by addition of hydrochloric acid (2N, 40 mL). Reaction mixture was extracted with

dichloromethane (3 × 200 mL). The organic layer was dried over sodium sulphate and the

solvent was removed under reduced pressure. The crude product was purified by silica gel

S-6

column chromatography by using 50% dichloromethane in petroleum ether as an eluent (Rf =

0.6). Combined organic layer was concentrated under reduced pressure and dried under vacuo

to yield a light brown colour solid (584 mg, 86%).

1H-NMR (500 MHz, CDCl3, 25

oC): δ = 8.73 (4H, s), 5.21-5.12 (2H, m), 2.24-2.17 (4H, m),

1.87-1.78 (4H, m), 1.33-1.19 (72H, m), 0.85 (12H, t, J = 6.8 Hz) ppm.

13C-NMR (125 MHz, CDCl3, 25

oC): δ = 164.1, 162.9, 131.3, 130.6, 126.8, 55.2, 32.3, 31.9,

29.6, 29.5, 29.3, 26.9, 22.7, 14.1 ppm.

MALDI-TOF MS: calcd. for C60H98N2O4 = 911.4540, found 911.5922.

1H NMR spectra of 2,6-bis((2-ethylhexyl)oxy)naphthalene 1.

VW_Dye_01022019.001.001.1r.esp

7.7 7.6 7.5 7.4 7.3 7.2 7.1 7.0

Chemical Shif t (ppm)

2.012.032.04

7.1

07

.10

7.1

2

7.1

37

.14

7.2

7

7.6

17

.63

VW_Dye_01022019.001.001.1r.esp

7.5 7.0 6.5 6.0 5.5 5.0 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0

Chemical Shif t (ppm)

12.258.308.102.054.072.012.032.04

0.9

10

.92

0.9

60

.98

1.3

41

.35

1.3

51

.37

1.4

71

.56

1.5

91

.78

1.7

91

.80

3.9

33

.94

3.9

43

.95

7.1

07

.10

7.1

27

.27

7.6

17

.63

S-7

13

C NMR spectra of 2,6-bis((2-ethylhexyl)oxy)naphthalene 1.

MALDI-TOF MS of 2,6-bis((2-ethylhexyl)oxy)naphthalene 1.

13C.jdf

180 160 140 120 100 80 60 40 20 0

Chemical Shif t (ppm)

CHLOROFORM-d

11

.14

14

.09

23

.06

23

.94

29

.11

30

.60

39

.41

70

.55

77

.00

10

6.8

8

11

9.2

4

12

7.9

11

29.6

6

15

5.7

6

S-8

1H NMR spectra of naphthalene-1,4,5,8-tetracarboxylic dianhydride 2.

13

C NMR spectra of naphthalene-1,4,5,8-tetracarboxylic dianhydride 2.

Tue3av2#183_11682.001.001.1r.esp

9 8 7 6 5 4 3 2 1 0

Chemical Shif t (ppm)

12.0472.044.024.022.003.96

0.0

00.8

20

.85

0.8

8

1.1

91

.25

1.5

91

.78

1.8

11

.85

1.8

72

.17

2.1

92

.21

2.2

4

5.1

15

.13

5.1

65

.18

5.2

07.2

7

8.7

3

Tue3av2#183_11682.001.001.1r.esp

9.0 8.5 8.0 7.5 7.0 6.5 6.0 5.5 5.0

Chemical Shif t (ppm)

2.003.96

5.1

25

.135

.16

5.1

95

.21

7.2

7

8.7

3

13C.001.1r.esp

180 160 140 120 100 80 60 40 20 0

Chemical Shif t (ppm)

CHLOROFORM-d

14

.09

22

.65

26

.88

29

.29

29

.53

29

.57

31

.88

32

.27

55

.16

77

.00

12

6.3

11

26.7

9

13

0.6

11

31.3

4

16

2.9

81

64.1

3

S-9

MALDI-TOF MS of naphthalene-1,4,5,8-tetracarboxylic dianhydride 2.

Synthesis and characterization of molecules 3S3

, 4S4

, and 5S5

are conducted according to the

reported procedures.

S-10

Figures

Figure S1. a) absorption and b) steady state emission spectra of 1 and 2 in dichloromethane

solution and in neat thin film (λex = 342 nm for 1 and 353 nm for 2). Inset of Figure S1-b

shows the photograph of 1 under UV light (365 nm). c, d) DSC thermograms in the heating

trace at a scanning rate of 10 ˚C/min and e, f) TGA of 1 and 2, respectively.

Absorption spectra show that both the compounds absorb in the range of 300 to 400 nm

(Figure S1-a) and there is no absorption peak between 400 to 600 nm for both the molecules.

Both 1 and 2 exhibits almost similar absorption features in solution and thin film. Compound

1 shows an enhanced deep blue emission ranging from 350 to 450 nm with λmax located at

372 nm (Figure S1-b). NDI derivative 2 exhibited a comparatively broad emission from 370

to 550 nm, which is nearly 30 nm red shifted to that of 1. However, in the neat form only

compound 1 is found to be emissive (Inset; Figure S1-b).

400 500 600

In

ten

sit

y (

No

rm)

Wavelength (nm)

1 sol

1 Thin film

2 sol

300 400 500

A

bso

rban

ce (

No

rm)

Wavelength (nm)

1 sol

1 Thin film

2 sol

2 Thin film

100 200 300 400 500

0

50

100

50% at 303 oC

Wt

loss / %

Temperature (oC)

1

5% at 234 oC

100 200 300 400 500

0

50

100

Wt

los

s / %

Temperature (oC)

2

5% at 281 oC

50% at 421 oC

-50 0 50 100

-2

0

2

En

do

the

rmic

Temperature (oC)

Cooling

1

-60.1 oC

Heating

c)

e)

-100 -50 0 50 100 150-4

-2

0

2

4

Temperature (oC)

2-15.68

oC

9.62 oC

46.84 oC

Cooling

HeatingEn

do

therm

ic

d)

f)

a) b)

S-11

Figure S2. a) Variation of storage modulus (Gʹ) (■), loss modulus (Gʺ) () and complex

viscosity (ŋ*) (■) versus angular frequency on double logarithmic scale, of 1. b) Comparison

of PXRD pattern of 1 and 2.

We prepared a series of acceptor molecules (even donor and acceptor with same branched

alkyl chain) and except molecules 2, none found as RT liquid. Molecule 2 with long branched

chain is a low melting solid giving diffraction peaks in PXRD at RT, not a free flowing liquid.

However, we found that 2 is a free flowing liquid above 46 oC.

Figure S3. a) Variation in absorption spectra of 1 in n-hexane (25 mM) with increasing

equivalents of 2 in n-hexane at 25 ˚C, b) corresponding variation of absorbance at 497 nm

with increasing equivalents of 2. c) Photographs of the CT complex with varying equivalents

(0 to 3) of acceptor 2.

0 10 20 30 40 50

Inte

nsit

y

2

2 (degree)

1

10 10010

-2

100

102

*

(Pa.s

)

G,

G'' (

Pa)

(rad s-1)

G'

G''

a) b)

0 1 2 3

0.0

0.5

1.0

1.5

Ab

so

rba

nc

e a

t 4

97

nm

Equivalents of 2450 500 550 600 650

0.0

0.5

1.0

1.5 0.0

0.2

0.4

0.6

0.8

1.0

1.5

2.0

2.5

3.0

Ab

so

rban

ce

Wavelength (nm)

0 0.2 0.4 0.6 0.8 1.0 1.5 2.0 2.5 3.0

a)

c)

b)

S-12

Figure S4. a) Variation in absorption spectra of 1 in dichloromethane (25 mM) with

increasing equivalents of 2 in dichloromethane at 25 ˚C, b) corresponding variation of

absorbance at 497 nm with increasing equivalents of 2. c) Photographs of the CT complex

with varying equivalents (0 to 3) of acceptor 2.

450 500 550 600 650

0.0

0.1

0.2

0.0

0.2

0.4

0.6

0.8

1.0

1.5

2.0

2.5

3.0

Ab

so

rban

ce

Wavelength (nm)

0 0.2 0.4 0.6 0.8 1.0 1.5 2.0 2.5 3.0

0 1 2 3

0.0

0.1

0.2

Ab

so

rba

nc

e a

t 4

97

nm

Equivalents of 2

a)

c)

b)

S-13

Figure S5. Photographs of the 1+2 (1:1) CT complex in various solvents at different

concentrations.

5 mM

10 mM

20 mM

25 mM

Tetr

ahyd

rofu

ran

Dic

hlo

rom

eth

ane

Ch

loro

form

Tolu

en

e

Cyc

loh

exan

e

n-H

exan

e

S-14

Figure S6. a) UV-Vis absorption spectra of 1+2 (1:1) CT complex in various solvents (25

mM) and the corresponding variation of absorbance at λ = 497 nm against refractive index of

the solvents. Photographs of the 1+2 (1:1) CT complex in various solvents (25 mM) showing

the variation of CT complex colour.

A clear decrease in the CT band intensity shows that the complexation is primarily due to

electrostatic interaction between the donor-acceptor. It has to be noted that polar solvents

can efficiently disrupt the electrostatic attraction unlike nonpolar solvents. Hence, n-hexane

and cyclohexane stabilize the CT complex compared to other polar solvents.

450 500 550 600 6500.0

0.5

1.0A

bso

rban

ce

Wavelength (nm)

n-Hexane

Cyclohexane

Toluene

Chloroform

Dichloromethane

Tetrahydrofuran

1.35 1.40 1.45 1.500.0

0.5

1.0

Dichloromethane

ChloroformTetrahydrofuranToluene

n-Hexane

Ab

so

rban

ce a

t 49

7 n

m

Refractive index

Cyclohexane

a) b)

c)

Tetr

ahyd

rofu

ran

Dic

hlo

rom

eth

ane

Ch

loro

form

Tolu

en

e

Cyc

loh

exan

e

n-H

exan

e

S-15

Figure S7. Absorption spectral variation of 1+2 CT liquid with increasing equivalents of 2

ranging from a) 1:0.0 to 1:0.01, b) 1:0.02 to 1:0.1 and c) 1:0.2 to 1:1.0 in the solvent-free

condition. d) Relative variation of λmax at 495 nm with respect to neat donor as a function of

acceptor concentration at RT.

420 480 540 600 6600.000

0.027

0.054

1:0.01

1:0.005

1:0.001

1:0.0

Ab

so

rban

ce

Wavelength (nm)450 500 550 600 650

0.0

0.2

0.4

0.6 1:0.1

1:0.09

1:0.08

1:0.07

1:0.06

1:0.05

1:0.04

1:0.03

1:0.02

Ab

so

rban

ce

Wavelength (nm)

450 500 550 600 6500

1

2

3 1:1.0

1:0.9

1:0.8

1:0.7

1:0.6

1:0.5

1:0.4

1:0.3

1:0.2

Ab

so

rba

nce

Wavelength (nm)

a) b)

c) d)

[A], moles/Kg

l4

95

nm

Y = b*K*x / (1+k*x)

K = 2.024 0.20 Ml-1

b = 1.48 0.08

S-16

Figure S8. a) Absorption spectral variation of 1+2 CT liquids with increasing equivalents of

2 ranging from 0.0002 to 0.001 equivalents and b) corresponding photographs of CT liquids

of 1 and 2.

Figure S9. DSC thermograms in the heating trace of 1+2 CT liquids with varying equivalents

of 2 at a scanning rate of 10 ˚C/min.

450 500 550 600 6500.00

0.01

0.02

0.03 0.001

0.0005

0.00033

0.00025

0.0002

0.0A

bso

rban

ce

Wavelength (nm)

1:0.001 1:0.0005 1:0.00033 1:0.00025 1:0.0002 0:0

a)

b)

1:0.1

1:0.25

1:0.5

1:0.75

25 50 75 100

Exo

therm

ic

Temperature (oC)

1:1

S-17

Figure S10. DSC thermograms of 1+2 CT liquid with varying acceptor ratio, a) 1:0.1 and b)

1:0.25 at a scanning rate of 10 ˚C/min.

-50 0 50 100-2

0

2

37.9 oC

1:1 (1:0.25)11.8

oC

Temperature (oC)

En

do

the

rmic

-50 0 50 100

-2

0

2

4

-60.3 oC

0.7 oC 1:2 (1:0.1)

30.5 oC

Temperature (oC)

En

do

therm

ic

b)

a)

S-18

Figure S11. DSC thermograms of 1+2 CT liquid with varying acceptor ratio, a) 1:0.5, b)

1:0.75 and c) 1:1 at a scanning rate of 10 ˚C/min.

0 20 40 60 80 100

0

2

47.4 oC

Cooling

1:1

Heating

22.4 oC

En

do

the

rmic

Temperature (oC)

0 20 40 60 80 100

-2

0

2

44.9 oC

Cooling

1:0.75

Heating

20.2 oC

En

do

the

rmic

Temperature (oC)

0 20 40 60 80 100

-4

-2

0

2

4

42.2 oC

Cooling

1:0.5

Heating

17.9 oC

En

do

the

rmic

Temperature (oC)

a)

b)

c)

S-19

Figure S12. TGA analysis of 1, 2 and 1+2 (1:1) CT liquid.

Figure S13. Photographs of the 1+2 CT liquids with varying D-A ratio stored at three

different temperatures, a) -20 ˚C (freezer), b) 30 ˚C (RT) and c) 90 ˚C (oven) for two months.

100 200 300 400 500

0

50

100

Wt

los

s (

%)

Temperature (oC)

1

2

1+2 (1:1)

5% Wt loss

1 234 oC

2 281 oC

1+2 256 oC

-20 oC

30 oC

90 oC

1:0.001 1:0.01 1:1

S-20

Figure S14. a) Photograph of the 3 mm NMR tube containing 1+2 CT liquid inside the 5 mm

NMR tube with DMSO-d6 as an external lock used for all NMR studies. b) Comparison of 1H

NMR spectra of 1 as neat and in CDCl3 solution.

Comparison of the 1H NMR spectra of the donor molecule in CDCl3 and in the neat state

(external reference DMSO-d6), show that all signals shift upfield. The proton Ha at 7.63 (2H,

d, J = 8.7 Hz) shift to 6.78 (2H, d, J = 8.9 Hz) and becomes broad compared to spectrum in

CDCl3. The Hb proton showing doublet of doublets at δppm 7.14 with large ortho coupling

8.7 Hz and small meta coupling 2.26 Hz, shifts to 6.35 showing a doublet with coupling

constant 8.9 Hz. Proton Hc which shows a doublet (J = 2.26 Hz) at δppm 7.10 appears as a

broad singlet at δppm 6.26.

DAN.001.001.1r.esp

2.021.982.00

6.26

6.336.35

6.76

6.78

1H.001.001.1r.esp

7.5 7.0 6.5Chemical Shift (ppm)

2.001.991.99

7.10

7.10

7.12

7.13

7.14

7.27

7.61

7.63

1H.001.001.1r.esp

2.001.99

7.10

7.10

7.12

7.127.

137.

14

Neat

In CDCl3

Ha

Hb Hc

b)a)

S-21

Figure S15. Expansion of 1H NMR titration spectra recorded at 318 K, showing donor 1

proton signals in the aromatic region.

Figure S16. NOESY spectrum of the 1+2 (1:0.98) CT liquid at 318 K. Mixing time is 30 ms,

for which spin diffusion effects are minimal.

HcHbHa

1:0.04

1:0.07

1:0.15

1:0.23

1:0.29

1:0.37

1:0.45

1:0.57

1:0.69

1:0.78

1:0.98

1:1.53

1:0.00

S-22

Figure S17. ROESY spectrum of the 1+2 (1:0.98) CT liquid at 318 K. Spin-lock strength and

duration is 2.5 KHz and 100 ms, respectively.

Figure S18. 2D NMR spectra a) NOESY and b) ROESY of 1+2 (1:1) CT complex in n-

hexane (25 mM) at 318 K.

b)a)

S-23

Figure S19. Two Preferred orientations in the D-A complex obtained from MD simulation.

A near perpendicular stacking is more populated/stable in the MD simulation possibly due to

less steric repulsion between the long alkyl chains. In parallel stack, due to repulsion

between the chains stacking may be a bit distorted. Also, the two aromatic rings of donor

need to align above the four rings of acceptor, hence a staggered alignment of the central

axis of the molecules is likely.

Figure S20. a) Temperature dependent absorption spectral changes of the 1+2 (1:1) CT

complex in cyclohexane (3 mM) and b) the corresponding variation of absorbance at 497 nm

with temperature.

450 500 550 600 650

0.00

0.02

0.04

0.06

0.08 40

oC

45 oC

50 oC

55 oC

60 oC

65 oC

70 oC

5 oC

10 oC

15 oC

20 oC

25 oC

30 oC

35 oC

Ab

so

rban

ce

Wavelength (nm)0 20 40 60 80

0.02

0.04

0.06

Ab

so

rba

nc

e a

t 4

97

nm

Temperature oC

a) b)

S-24

References

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