1

Supporting Information

Pressure-induced remarkable emission enhancement based on

intermolecular charge transfer in halogen bond-driven

dual-component co-crystals

Aisen Li,1,2

Jing Wang,1 Yingjie Liu,

1 Shuping Xu,

1 Ning Chu,

1 Yijia Geng,

1 Bao Li,

1

Bin Xu, 1

Haining Cui,2* and Weiqing Xu

1*

1. State Key Laboratory of Supramolecular Structure and Materials, Institute of

Theoretical Chemistry, Jilin University, Changchun, 130012, P. R. China

2. College of Physics, Jilin University, Changchun 130012, P. R. China

*Email: xuwq@jlu.edu.cn

cuihn@jlu.edu.cn

Content

1. Raman spectra of pure BIPY and co-crystals. ............................................................................... 2

2. IR spectra of pure BIPY and co-crystals. ...................................................................................... 2

3. Single crystal data. ........................................................................................................................ 5

4. Analysis of intermolecular interactions of co-crystals. ................................................................. 6

5. Hirshfeld surface analysis of co-crystals. ...................................................................................... 8

6. Fluorescent spectra of BIPY-IPFB under UV irradiation. ............................................................ 9

7. Fluorescent spectra properties of BIPY-IFB. .............................................................................. 10

8. The calculated results of BIPY-DITFB. ...................................................................................... 11

9. Raman spectra of co-crystals under high pressure. ..................................................................... 12

References ....................................................................................................................................... 14

Electronic Supplementary Material (ESI) for Physical Chemistry Chemical Physics.This journal is © the Owner Societies 2018

2

1. Raman spectra of pure BIPY and co-crystals.

Fiugre S1. The Raman spectra of BIPY, BIPY-IPFB, BIPY-DITFB, and BIPY-IFB in

the ranges of 100-1800 cm-1

(A) and 2800-3200 cm-1

(B), respectively.

2. IR spectra of pure BIPY and co-crystals.

Fiugre S2. The IR spectra of BIPY (black line), IPFB (red line) and co-crystal

BIPY-IPFB (blue line) in the ranges of 1200-2000 cm-1

(A) and 400-1200 cm-1

(B),

respectively.

500 1000 15000

10k

20k

BIPY-IFB

BIPY-DITFB

BIPY-IPFB

BIPY

Inte

nsity (

a.u

.)

Raman shift (cm-1)

2800 3000 32000

1k

2k

3k

4k

5k

BIPY-IFB

BIPY-DITFB

BIPY-IPFB

BIPY

Raman shift (cm-1)

Inte

nsity (

a.u

.)

(A) (B)

2000 1800 1600 1400 12000.0

0.2

0.4

0.6

0.8

1.0

1507

1484

1513

1491

BIPY-IPFB

IPFB

BIPY

Tra

nsm

itta

nce

Wavenumber(cm-1)

1487

1200 1000 800 600 4000.0

0.3

0.6

0.9

1.2

1.5BIPY-IPFB

IPFB

BIPY1074

1062

1084

1075

804

808

609

Tra

nsm

itta

nce

Wavenumber(cm-1)

606

(A) (B)

3

Fiugre S3. The IR spectra comparison of BIPY (black line), DITFB (red line) and

co-crystal BIPY-DITFB (blue line) of 2000 cm-1

-3600 cm-1

(A) and 400 cm-1

-2000

cm-1

(B).

Fiugre S4. The IR spectra comparison of BIPY (black line), IFB (red line) and

co-crystal BIPY-IFB (blue line) of 2000 cm-1

-3600 cm-1

(A) and 400 cm-1

-2000 cm-1

(B).

As displayed in Figure S2, for the pristine BIPY, the characteristic ring breathing

vibration bands of pyridine group appear at 1075 cm-1

and 1487 cm-1

, and the peak

located at 606 cm−1

and 808 cm−1

can be assigned to ring bending vibration and C-H

out-of-plane bending vibration, respectively. And upon assembly with the co-former

IPFB, the vibration bands experienced an obvious shift and were located at 1062 cm−1

(Δ = 13 cm−1

), 1484 cm-1

(Δ = 3 cm−1

), 609 cm−1

(Δ = 3 cm−1

) and 804 cm-1

(Δ = 4

cm−1

). At the same time, C-F stretching vibration at 1084 cm-1 of IPFB shifted

towards to 1074 cm-1 in BIPY-IPFB, while the bands at 1491 cm-1

and 1513 cm-1

assigned to ring stretching vibration shifted to 1484 cm-1

and 1507 cm-1

. Similarly, in

Figure S3, the bands at 606 cm−1

, 808 cm−1

and 1075 cm-1

also showed obvious

3000 2500 20000.0

0.2

0.4

BIPY

DITFB

BIPY-DITFB

Wavenumber(cm-1)

Tra

nsm

itta

nce

3072

(A) (B)

2000 1500 1000 5000.0

0.2

0.4

0.6

0.8BIPY-DITFB

1059

1075

808

1456

990

939

939

725

753

759

BIPY

DITFB

Wavenumber(cm-1)

Tra

nsm

itta

nce

733

988

1465

606

611

801

3000 2500 20000.0

0.1

0.2

0.3

0.4

3072

BIPY-IFB

IFB

BIPY

Wavenumber(cm-1)

Tra

nsm

itta

nce

2000 1500 1000 5000.0

0.3

0.6

0.9

1075

1064 702

808

799

702

1561

1591

1556

1591

610

650

650

BIPY-IFB

IFB

BIPY

Wavenumber(cm-1)

Tra

nsm

itta

nce

606

(A) (B)

4

change to 611 cm-1

(Δ = 5 cm−1

), 801 cm-1

(Δ = 7 cm−1

) and 1056 cm-1

(Δ = 19 cm−1

)

upon assembly with DITFB. Besides, the C-H out-of-plane bending vibration at 733

cm-1

shifted towards to 725 cm-1

, and the C-H out-of-plane bending vibration at 3072

cm-1

disappeared. Moreover, the C-F symmetrical deformation vibration of DITFB at

1465 cm-1

appeared in the IR spectra of co-crystals at 1456 cm-1

. As described in

Figure S4, the bands at 606 cm−1

, 808 cm−1

and 1075 cm-1

also showed obvious

change to 610 cm-1

(Δ = 4 cm−1

), 799 cm-1

(Δ = 9 cm−1

) and 1064 cm-1

(Δ = 11 cm−1

)

upon assembly with IFB. The band at 3072 cm-1

also disappeared and the obvious

bands at 650 cm-1

and 702 cm-1

attributed to C-F stretching vibration from IFB can be

observed in the BIPY-IFB co-crystal. All the spectroscopic changes described above

demonstrate the formation of the relative strong halogen bonding interaction (XB)

between the co-former and N atoms in the pyridine group.

5

3. Single crystal data.

Table S1. Crystal data and refinement parameters of BIPY-IPFB, BIPY-DITFB and

BIPY-IFB.

BIPY-IPFB BIPY-DITFB BIPY-IFB

Moiety formula C6 F5 I, 0.5(C10 H8 N2) C6 F4 I2, C10 H8 N2 C6 F3 I3, C10 H8 N2

Sum formula C11 H4 F5 I N C16 H8 F4 I2 N2 C16 H8 F3 I3 N2

Formula wt 372.05 558.04 665.94

T,K 293 K 293 K 273 K

Space group P 21/c P 21/c P n

A, Å 10.102(2) 8.3599(3) 4.1475(3)

B, Å 7.6653(15) 5.7208(2) 9.1050(6)

C, Å 14.953(3) 17.7679(7) 24.1464(17)

α, deg 90 90 90

β, deg 93.24(3) 96.344(1) 91.273(3)

γ, deg 90 90 90

Volume, Å3

1156.0(4) 844.55(5) 911.62(11)

Z 4 2 2

Density, Mg / m3

2.138 2.194 2.426

μ(M0 K α) , mm

-1

2.815 3.764 5.172

R(reflections) 0.0317( 2039) 0.0321( 1777) 0.0768( 2872)

wR2(reflections) 0.0702( 2637) 0.0791( 2096) 0.1929( 2887)

Goodness of fit 0.998 0.998

CCDC 1869982 1869981 1869998

6

4. Analysis of intermolecular interactions of co-crystals.

Fiugre S5. The molecular stacking mode of BIPY-IPFB (A), BIPY-DITFB (B), and

BIPY -IFB (C) along a axis (1) and b axis (2).

Figure S6. The analysis of intermolecular interactions of BIPY-IPFB (A),

BIPY-DITFB (B) and BIPY-IFB (C).

(A1)) (B1))

(A2))

(C1))

(B2)) (C2))

(A1)) (A2)) (A3))

(B1) (B2)) (B3))

(C1) (C2)) (C3))

7

Table S2. The analysis of intermolecular interactions of BIPY-DITFB.

Donor Hydrogen Acceptor DH(Å) HA(Å) DA(Å) DHA(deg)

C2 H2 F2 0.9302 2.6211 3.5269 164

C4 H4 F2 0.9294 2.6712 3.5846 167

C1 H1 F1 0.9302 3.9627 4.6668 135

C2 H2 F1 0.9302 3.9809 4.6661 133

C5 H5 I1 0.9303 3.4192 4.1840 141

Table S3. The analysis of intermolecular interactions of BIPY-IFB.

Donor Hydrogen Acceptor DH(Å) HA(Å) DA(Å) DHA(deg)

C8 H8 F2 0.9298 4.4152 4.9310 118.801

C13 H13 F2 0.9305 2.7405 3.4109 129.701

C10 H10 F3 0.9312 2.9957 3.3434 103.866

C16 H16 F3 0.9307 3.1308 4.0168 159.709

C5 I3 F1 2.0939 3.1000 5.0668 154.102

Firstly, they show different stacking modes because of the difference in co-formers

(Figure S5). It should be noted that the BIPY in BIPY-IPFB and BIPY-DITFB show

excellent planarity, while it does not for BIPY-IFB, which results from different

microenvironments in crystal aggregate state. Moreover, all the co-crystals show

parallel stacking and the expected π…π interactions are observed for BIPY-IPFB and

BIPY-IFB with the distance between the conjugated ring centroids from 3.98 Å to

4.15 Å, respectively (Figure S6A2, S6C1 and S6C2). Additionally, the CH…F

hydrogen bonds can be observed between the BIPY and fluorine-containing units in

the BIPY-DITFB and BIPY-IFB co-crystals (Figure S6B3, S6C3) and the detailed

measurements are summarized in Table S2 and Table S3. As illustrated in Figure

S6C3, a zig-zag halogen-bonding chain is produced for BIPY-IFB and connected with

the adjacent one by I…F close contacts (dI⋯F = 3.1000 Å in Table S3). And the

C-F…F-C weak noncovalent interactions are also shown in Figure S6A3 and S6B2

for BIPY-IPFB and BIPY-DITFB, which are known to be stabilizing and give

significant energy contributions for structures, as Pauling’s principle states that the

8

attractive interatomic dispersion forces would be low because of the low polarizability

of fluorine.1,2

Therefore, the introduction of electron withdrawing substituents (such

as -F) on the co-formers affords 3D architectures due to their ability to simultaneously

participate in additional intermolecular interactions besides the enhanced I…N

interactions.

5. Hirshfeld surface analysis of co-crystals.

Figure S7. Distribution of individual intermolecular interactions of each part in

BIPY-IPFB co-crystal of on the basis of Hirshfeld surface analysis.

Figure S8. Distribution of individual intermolecular interactions of each part in

BIPY-DITFB co-crystal of on the basis of Hirshfeld surface analysis.

7.50%

5.90%3.00%

22.70% 3.30%

13.30%

26.50%

45.10%

7.40%

5.10%

3.60%

5.20%

12.60%

7%

16.40%

15.40%

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

IPFB

BIPY

C…C H…H F…F C…H H…F I…H I…N I…F H…N others

5.20%

5.70% 23.60%

4.50% 7.30%

13.80%

22.50%

19.70%

20.00%

7.90%

6.20%

4.80%

14.70%

10%

19.60%

14.50%

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

DITPB

BIPY

C…C H…H F…F C…H H…F I…H I…N I…F H…N others

9

Figure S9. Distribution of individual intermolecular interactions of each part in

BIPY-IFB co-crystal of on the basis of Hirshfeld surface analysis.

6. Fluorescent spectra of BIPY-IPFB under UV irradiation.

Figure S10. The variation of in situ fluorescent spectra of BIPY-IPFB after UV

irradiation as UV irradiation time increasing.

7.00%

10.60% 17.60%

1.60%

1.30%

14.00%

20.30%

20.00%

29.80%

17.70%

7.30%

5.20%

13.50%

9%

19.20%

5.90%

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

IFB

BIPY

C…C H…H F…F C…H H…F I…H I…N I…F H…N others

500 600 700 8000

10k

20k

30k

40k

50k

60kAfter UV irradiation

Inte

nsity(a

.u.)

Wavelength(nm)

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

30

60

Time/min

10

7. Fluorescent spectra properties of BIPY-IFB.

Figure S11. (A) The fluorescent spectra of BIPY-IFB co-crystal during compression

and corresponding photos (B) via DAC device. Excitation wavelength was 365 nm.

The scale is 100 μm.

Figure S12. The fluorescent spectra recovery properties of BIPY-IFB co-crystal via

DAC. Excitation wavelength was 365 nm.

500 600 700 8000.0

4.0k

8.0k

12.0k

16.0k

Inte

nsity (

a.u

.)

Wavelength (nm)

0 GPa

0.50 GPa

1.04 GPa

1.22 GPa

1.95 GPa

2.43 GPa

2.91 GPa

3.64 GPa

4.16 GPa

5.00 GPa

5.92 GPa

6.68 GPa

7.36 GPa

7.79 GPa

8.31 GPa

(A) (B)0GPa 0.50GPa 1.04GPa 1.22GPa 1.95GPa

2.43GPa

5.92GPa

5.00GPa 4.16GPa 3.64GPa 2.91GPa

7.36GPa 7.79GPa 8.31GPa6.68GPa

500 600 700 8000.0

2.0k

4.0k

6.0k

8.0k

release

Wavelength (nm)

Inte

nsity (

a.u

.)

0 GPa

release

0 GPa

11

8. The calculated results of BIPY-DITFB.

Figure S13. Calculated stacking structure of BIPY-DITFB under different pressure

and the detailed measurement of distances between adjacent BIPY molecules or

DITFB molecules for comparison.

4.520

3.3303.366

3.447

3.442

3.560

3.394

3.352

4.440

3.249

3.3343.397

3.214

3.290

3.192

3.209

3.183

3.245

0GPa 2GPa

6GPa 7GPa 8GPa

3GPa 4GPa 5GPa

1GPa

12

9. Raman spectra of co-crystals under high pressure.

Figure S14. Raman spectra of BIPY-DITFB co-crystal at different pressure values via

DAC up to 9.16 GPa. Excitation wavelength was 633 nm.

200 400 600 800 1000 1200 1600 18000.0

4.0k

8.0k

12.0k

16.0k

0.44 GPa

Inte

nsity (

a.u

.)

Raman shift (cm-1)

0 GPa

0.91 GPa

1.56 GPa

1.97 GPa

2.39 GPa

2.74 GPa

0.0

4.0k

8.0k

12.0k

16.0k

3.33 GPa

Inte

nsity (

a.u

.)

9.16 GPa

8.28 GPa

7.47 GPa

6.42 GPa

5.20 GPa

3.97 GPa

13

Figure S15. (a) Raman spectra of BIPY-IFB co-crystal at different pressure values via

DAC up to 3.72 Gpa, and the recovered Raman spectra of the BIPY-IFB co-crystal

after the decompression. Excitation wavelength was 633 nm.

Figure S16. Raman spectra of the BIPY-DITBF co-crystal upon the decompression

process (a) and the recovery of the BIPY-DITBF (b). Excitation wavelength was 633

nm.

Figure S17. Pressure dependence of Raman shifts 168 cm-1

(A), 1002 cm-1

(B), 1220,

1239, 1295 and 1301 cm-1

(C) in BIPY-IFB co-crystal.

300 600 900 1200 1600 18000.0

2.0k

4.0k

6.0k

0.25 GPa

3.72 GPa

3.04 GPa

2.59 GPa

1.99 GPa

1.30 GPa

0.82 GPa

0.65 GPa

Inte

nsity (

a.u

.)

Raman shift (cm-1)

0 GPa

(a) (b)

300 600 900 1200 1600 18000

300

600

900

1200

Inte

nsity (

a.u

.)

Raman shift (cm-1)

0 GPa

release

200 400 600 800 10001200 1600 1800

Inte

nsity (

a.u

.)

Raman shift (cm-1

)

25000

release

9.16 GPa

6.25 GPa

5.43 GPa

4.72 GPa

4.15 GPa

3.15 GPa

200 400 600 800 1000 1200 1600 18000.0

3.0k

6.0k

9.0k

In

tensity (

a.u

.)

Raman shift (cm-1)

0 GPa

release

(a) (b)

0 1 2 3 4

168

169

170

171

172

Ram

an

shift (c

m-1)

Pressure (GPa)

0 1 2 3 4

1220

1240

1260

1280

1300

1320

Pressure (GPa)

Ram

an

shift (c

m-1)

0 1 2 3 41000

1004

1008

1012

1016

Ram

an

shift (c

m-1)

Pressure (GPa)

(A) (B)

(C)

14

Table S4. Assignment and frequencies (cm-1

) of observed Raman internal modes of

BIPY-DITFB co-crystal in comparison with DFT simulation results.

Experimental value

(cm-1

)

Theoretical value

(cm-1

)

Vibrational mode

150 149 C-I stretching vibration

1007 1009 Triangular ring breathing vibration of BIPY

1216 1235 C-H rocking vibration in plane

1236 1240 C-H rocking vibration in plane

ring breathing vibration of DITFB

1284 1305 C-C stretching vibration

ring breathing vibration of BIPY

C-H rocking vibration in plane

1597 1621 C=C=C antisymmetric stretching vibration of

DITFB

1609 1628 C=C=C antisymmetric stretching vibration of

BIPY

C-C stretching vibration

1612 1637 C=C=C antisymmetric stretching vibration of

BIPY

C-C stretching vibration

Table S5. Assignment and frequencies (cm-1

) of observed Raman internal modes of

BIPY-IFB co-crystal in comparison with DFT simulation results.

Experimental value

(cm-1

)

Theoretical value

(cm-1

)

Vibrational mode

168 165 C-I stretching vibration

1002 1003 Triangular ring breathing vibration of BIPY

1220 1238 C-H rocking vibration in plane

1295 1305 C=C=C antisymmetric stretching vibration of IFB

C-H rocking vibration in plane

C-C stretching vibration

References

1. V. G. Saraswatula and B. K. Saha, New J. Chem., 2014, 38, 897-901. .

2. K. Reichenbacher, H. I. Suss and J. Hulliger, Chem. Soc. Rev., 2005, 34, 22-30.