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Electronic supplementary information (ESI)

Zinc(II) and cadmium(II) metal-organic frameworks with 4-imidazole

containing tripodal ligand: sorption and anion exchange properties†

Shui-Sheng Chen,a,b

Peng Wang,a Satoshi Takamizawa,

c Taka-aki Okamura,

d Min Chen

a and

Wei-Yin Sun*a

a Coordination Chemistry Institute, State Key Laboratory of Coordination Chemistry, School

of Chemistry and Chemical Engineering, Nanjing National Laboratory of Microstructures,

Nanjing University, Nanjing 210093, China. E-mail: [email protected]; Fax: +86 25

83314502

b School of Chemistry and Chemical Engineering, Fuyang Teachers College, Fuyang 236041,

China

c International Graduate School of Arts and Sciences, Yokohama City University,

Kanazawa-ku, Yokohama, Kanagawa 236-0027, Japan

d Department of Macromolecular Science, Graduate School of Science, Osaka University,

Toyonaka, Osaka 560-0043, Japan

Table S1. Selected bond lengths [Å] and bond angles [º] for complexes 1 and 2

1

Zn(1)-N(1) 2.008(2) Zn(1)-N(2)#1 1.970(2)

Zn(1)-N(6)#2 1.979(2) Zn(1)-N(4)#3 2.015(2)

N(2)#1-Zn(1)-N(6)#2 111.57(10) N(2)#1-Zn(1)-N(1) 115.18(10)

N(6)#2-Zn(1)-N(1) 110.64(10) N(2)#1-Zn(1)-N(4)#3 107.69(10)

N(6)#2-Zn(1)-N(4)#3 111.62(10) N(1)-Zn(1)-N(4)#3 99.51(10)

2

Cd(1)-N(12) 2.337(4)

N(12)-Cd(1)-N(12)#4 88.86(15)

Symmetry transformations used to generate equivalent atoms: #1 -y+5/4,x+3/4,z-1/4, #2

-x+1,-y+2,-z+2, #3 -x+1/2,-y+2,z+1/2, #4 -z+1/2,-x+1,y+1/2-1.

Electronic Supplementary Material (ESI) for Dalton TransactionsThis journal is © The Royal Society of Chemistry 2014

mailto:[email protected]

2

Computational Details.

In the simulations, atomic partial charges for the frameworks are computed from the

ChelpG method as Yang et al.1 DFT calculations using the UB3LYP functional were carried

out to compute the charge distributions, and the basis set LANL2DZ was used for the metal

atoms Co and Zn, while 6-31+G* was used for the remaining atoms. All the calculations were

performed using the GAUSSIAN 03 programs.2 ChelpG charge is listed by the atomic label

given in Scheme 1 and Table S2.

The adsorption isotherms were simulated with grand canonical Monte Carlo (GCMC)

simulations with Towhee Code.3 Detailed descriptions of the simulation method are given in

the references.4 In the grand canonical ensemble, the chemical potential of each component,

temperature, and volume are kept constant as in adsorption experiments. For the sorbate

molecules as well as for the frameworks 1′, 3' and 4', atomistic models were employed.

Interactions beyond 0.75, 0.74 and 0.495 nm were neglected for 1′, 3' and 4', respectively.

The Lorentz-Berthelot (LJ) mixing rules were used to calculate mixed LJ parameters.5 For

methane, the van der Waals interactions between the sorbate molecules themselves as well as

between the sorbate molecules and the frameworks were described with the LJ potential only.

Methane was described with a united atom description, with the potential parameters for

methane were taken from Goodbody et. al.6 (σCH4 = 0.373 nm, εCH4/kB = 148 K). A

combination of the LJ and Coulombic potentials was used to describe the van der Waals

interaction for other sorbate molecules except methane. Hydrogen was treated as a diatomic

molecule modeled with parameters (σH = 0.2958 nm, εH/kB = 36.7 K).7 CO2, N2 were

described by the TraPPE potential (σC = 0.305 nm, εC/kB = 79.0 K, σO = 0.280 nm, εN/kB = 27

K).8 All the potential parameters have been successfully employed to describe the adsorption

of alkanes in zeolites quantitatively. The LJ parameters for the C, H and N atoms from the

frameworks were taken from the DREIDING force field,9 and Co atom was taken from the

all-atom UFF force field,10

which is missed in DREIDING force field. The atoms of the

frameworks were held fixed at their crystallographic coordinates. The excess adsorption

values were conversed from absolute adsorption values, the outputs of GCMC simulations, by

the method of Myers et. al.11

Isosteric heat of adsorption is another interest in our research,

which was obtained from the fluctuation theory.12

While in the limit of zero converge, Qst

was derived from the (NVT) MC calculations.13


3

Scheme 1. Model systems used in the ChelpG charge calculations. The atom labels used in

Table S2 are included in the figure.

Table S2. ChelpG charges calculation for 1′, 3' and 4'

1′ 3' 4'

Atom label q/e Atom label q/e Atom label q/e

Zn1 0.864 Co1 0.864 Co1 0.834

C1 0.142 C1 0.119 C1 0.147

C2 -0.193 C2 -0.193 C2 -0.171

C3 0.119 C3 0.142 C3 0.101

C4 -0.183 C4 -0.187 C4 -0.19

C5 0.135 C5 0.135 C5 0.115

C6 -0.187 C6 -0.183 C6 -0.205

C7 0.134 C7 0.145 C7 0.215


4

C8 -0.023 C8 -0.008 C8 0.005

C9 0.185 C9 0.265 C9 0.308

C10 0.205 C10 0.134 C10 0.106

C11 0.041 C11 -0.023 C11 -0.002

C12 0.269 C12 0.185 C12 0.165

C13 0.145 C13 0.205 C13 0.169

C14 -0.008 C14 0.041 C14 0.015

C15 0.255 C15 0.259 C15 0.252

H 0.349 H 0.349 H 0.368

H2 0.106 H2 0.106 H2 0.097

H4 0.046 H4 0.1 H4 0.143

H6 0.1 H6 0.046 H6 0.037

H8 0.101 H8 0.098 H8 0.142

H9 0.066 H9 0.095 H9 0.144

H11 0.162 H11 0.101 H11 0.116

H12 0.149 H12 0.066 H12 0.085

H14 0.098 H14 0.162 H14 0.11

H15 0.095 H15 0.149 H15 0.091

N1 -0.471 N1 -0.532 N1 -0.498

N2 -0.536 N2 -0.545 N2 -0.603

N3 -0.545 N3 -0.536 N3 -0.529

N4 -0.532 N4 -0.471 N4 -0.463

N5 -0.594 N5 -0.494 N5 -0.544

N6 -0.494 N6 -0.594 N6 -0.56


5

Table S3. Adsorption enthalpies of gases simulated by GCMC calculation

Adsorbent adsorbate Qst (kJ/mol) (sim/exp)

1′

Methane 17.43

H2 7.80/ 7.32

N2 14.51

CO2 32.69/ 33.63

3'

Methane 16.16

H2 7.59/ 7.27

N2 14.60

CO2 32.17/ 33.22

4'

Methane 4.31

H2 3.62

N2 8.38

CO2 22.86


6

Figure S1. The coordination environment of Zn(II) atom with thermal ellipsoids at 30%

probability for 1. The free water molecules and hydrogen atoms were omitted for clarity.

Figure S2. a) The 1D helical channel formed by the coordination of Zn(II) and two imidazolyl

groups. b) The 3D porous framework constructed from the connection of imidazolyl group

with adjacent opposite 1D helical channels.


7

Figure S3. Schematic representations of the (4, 4)-connected ecl framework of 1 with (4·63·8

2)

topology; turquiose balls represent the Zn(II) atoms, and red balls represent the centers of

benzene rings of H3L ligands.

Figure S4. The coordination environment of Cd(II) atom with thermal ellipsoids at 30%

probability for 2. The free water molecules, perchlorate ions and hydrogen atoms were

omitted for clarity.


8

Figure S5. Schematic representations of the (3, 6)-connected pyr framework of 2 with

(63)2(6

12·8

3) topology; green balls represent the Cd(II) atoms, and yellow balls represent the

centers of benzene rings of H3L ligands.

0 100 200 300 400 500 600 700

20

40

60

80

100

Weig

ht

(%)

Temperature (°C)

Figure S6. The TGA curve of complex 1.


9

10 20 30 40 50

c

b

2 theta (degree)

a

Figure S7. The X-ray powder diffractions of complex 1: a - simulated; b - as-synthesized; c

- activated.


10

Calculation of CO2/N2 selectivity

The methods are applied to estimate the CO2/N2 selectivity according to the literature (J. Am.

Chem. Soc., 2010, 132, 38). The ratios of these initial slopes of the CO2 and N2 adsorption

isotherms were applied to estimate the adsorption selectivity for CO2 over N2.

0 2 4 6 8 10 12 14 16 18 20

0.0

0.1

0.2

0.3

0.4

0.5

0 2 4 6 8 10 12 14 16 18 20

0.0

0.1

0.2

0.3

0.4

0.5

y = 0.09869x +0.01055

R = 0.99972

y = 0.00222x - 0.00357

R = 0.9995

Ga

s U

pta

ke (

mm

ol/

g)

Pressure (KPa)

Figure S8. The fitting initial slope for CO2 and N2 isotherms collected at 273K (CO2:

red squares; N2: green triangles).

0.0 0.2 0.4 0.6 0.8 1.0

0

20

40

60

80

100

120

P/P0

Va

ds/

cm

3g

-1(S

TP

)

1' exp

1' sim

3' exp

3' sim

4' exp

4' sim

Figure S9. Experimental and simulated hydrogen adsorption isotherm at 77 K


11

0.0 0.2 0.4 0.6 0.8 1.0

-20

0

20

40

60

80

100

120

140

160

180

P/P0

Va

ds/

cm

3g

-1(S

TP

)

1' exp

1' sim

3' exp

3' sim

4' exp

4' sim

Figure S10. Experimental and simulated CO2 adsorption isotherm at 195 K

0.0 0.2 0.4 0.6 0.8 1.0

0

20

40

60

80

100

120

140

160

Va

ds/

cm

3g

-1(S

TP

)

P/P0

1' exp

1' sim

3' exp

3' sim

4' exp

4' sim

Figure S11. Experimental and simulated N2 adsorption isotherm at 195 K.


12

0.0 0.2 0.4 0.6 0.8 1.0

0

20

40

60

80

100

120

Va

ds/

cm

3g

-1(S

TP

)

P/P0

1' exp

1' sim

3' exp

3' sim

4' exp

4' sim

Figure S12. Experimental and simulated CH4 adsorption isotherm at 195 K

0 1 2 3 4 5 6-3

-2

-1

0

1

2

3

4

5

-0.5 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.02

3

4

5

6

7

8

9

10

77 K

87 K

y=ln(x)+1/T*(a0+a

1*x+a

2*x

2)+(b

0)

R^2 = 0.99968

a0 -876.36592 ? 1.39133

a1 44.72317 ? .64729

a2 2.52633 ? .31029

b0 10.46489 ? .13916

n / mmol g-1

ln(p

/ k

Pa

)

uptake (mmol/g)

Iso

ste

ric

He

at

of

Ad

so

rpti

on

(k

J/m

ol)

Figure S13. H2 isotherm for 1′ with fitting by virial method. (inlet. Isosteric heat of adsorption

with mount of adsorbed H2)


13

0 1 2 3 4 5 6-3

-2

-1

0

1

2

3

4

5

-0.5 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.02

3

4

5

6

7

8

9

10

77 K

87 K

y=ln(x)+1/T*(a0+a

1*x+a

2*x

2)+(b0)

R^2 = 0.99968

a0 -876.36592 ±11.39133

a1 44.72317 ±1.64729

a2 2.52633 ±0.31029

b0 10.46489 ±0.13916

n / mmol g-1

ln(p

/ k

Pa

)

uptake (mmol/g)

Iso

ste

ric

He

at

of

Ad

so

rpti

on

(k

J/m

ol)

Figure S14. H2 isotherm for 3' with fitting by virial method. (inlet. Isosteric heat of adsorption

with mount of adsorbed H2.)

0.0 0.5 1.0 1.5 2.0-6

-4

-2

0

2

4

6

-0.5 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.010

15

20

25

30

35

40

45

50

273 K

298 K

n / mmol g-1

ln(p

/ k

Pa

)

y=ln(x)+1/T*(a0+a

1*x+a

2*x

2)+(b0)

R^2 = 0.9983

a0 -4054.25515 ±3.72486

a1 169.40076 ±5.05419

a2 59.38549 ±.67006

b0 16.76954 ±.22756

uptake (mmol/g)

Iso

ste

ric

He

at

of

Ad

so

rpti

on

(k

J/m

ol)

Figure S15. CO2 isotherm for 1′ with fitting by virial method.(inlet. Isosteric heat of

adsorption with mount of adsorbed CO2.)


14

0.0 0.5 1.0 1.5 2.0 2.5-6

-4

-2

0

2

4

6

-0.5 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.010

15

20

25

30

35

40

45

50

ln(p

/ k

Pa

)

n / mmol g-1

y=ln(x)+1/T*(a0+a

1*x+a

2*x

2)+(b0)

R^2 = 0.99936

a0 -4000.14059 ±38.83034

a1 78.04655 ±8.14792

a2 73.27012 ±3.55494

b0 16.45262 ±0.1387

273 K

298 K

uptake (mmol/g)

Iso

ste

ric

He

at

of

Ad

so

rpti

on

(k

J/m

ol)

Figure S16. CO2 isotherm for 3' with fitting by virial method.(inlet. Isosteric heat of

adsorption with mount of adsorbed CO2.)


15

2000 1500 1000 500

Wavelength(cm-1

)

2

2A

2C

1618

1485

1271

1128

1092992

949

827758626

Figure S17. IR spectra of 2, exchanged product 2A and 2C (reversed exchanged product from

2A to 2C).

2000 1500 1000 500

Wavelength(cm-1

)

2

2B

2D

1621

1571

13821318

11251096

993

945

827758

647

686

Figure S18. IR spectra of 2, exchanged product 2B and 2D (reversed exchanged product from

2B to 2D).


16

2000 1500 1000 500

Wavelength(cm-1

)

2

H3L

1617

14951448

1141

11141089

992949

870831

759

626

Figure S19. IR spectra of 2 and ligand H3L.

10 20 30 40 50

d

c

b

2 theta (degree)

a

Figure S20. The X-ray powder diffractions of complex 2: a - simulated; b - as-synthesized;

and exchanged products: c - the exchanged product 2A; d - the exchanged product 2B.


17

2000 1500 1000 500

Wavelength(cm-1

)

2A

2B

2A

1618

1570

1488

1452

1271

11251096

992945

827758 648

1390

Figure S21. IR spectra of 2A, exchanged product 2B and 2A (reversed exchanged product

from 2B to 2A).

2000 1500 1000 500

Wavelength(cm-1

)

2B

2A

2B

1618

1568

14881452

1271

11251094

990948

825 756 649

1382

1318

Figure S22. IR spectra of 2B, exchanged product 2A and 2B (reversed exchanged product

from 2A to 2B).


18

References

1. Q. Yang, C. Zhong, J. Phys. Chem. B 2008, 110, 1562.

2. M. J. Frisch, G. W. Trucks, H. B. Schlegel, et al. GAUSSIAN 03, rev B.1; Gaussian, Inc.:

Pittsburgh, PA, 2003.

3. http://towhee.sourceforge.net

4. D. Frenkel, B. Smit, Understanding of Molecular Simulations: from Algorithms to

Applications, 2nd ed.; Academic Press: San Diego, CA, 2002.

5. D. Marx, P. Nielaba, Phys. Rev. A. 1994, 45, 8968.

6. S. J. Goodbody, K. Watanabe, D. Macgowan, J. P. R. B. Walton, N. Quirke, J. Chem. Soc.,

Faraday Trans. 1991, 87, 1951.

7. F. Darkrim, A. Aoufi, P. Malbrunot, D. Levesque, J. Chem. Phys. 2000, 112, 5991.

8. J. J. PotQff, J. SiePmann, I. AIChE J. 2001, 47, 1676.

9. S. L. Mayo, B. D. Olafson, W. A. Goddard, J. Phys. Chem. 1990, 94, 8897.

10. A. K. Rappi, C. J. Casewit, K. S. Colwell, W. A. Goddard, W. M. Skid, J. Am. Chem. Soc.

1992, 114, 10024.

11. A. L. Myers, P. A. Monson, Langmuir 2002, 18, 10261.

12. D. D. Do, H. D. Do, J. Phys. Chem. B 2006, 110, 17531.

13. R. Babarao, Z. Hu, J. W. Jiang, S. Chempath, S. I. Sandler, Langmuir 2007, 23, 659.


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