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Construction, Structural Diversity and Properties of Seven Zn(II)-Coordination Polymers Based on 3,3#,5,5#Azobenzenetetracarboxylic Acid and Flexible Substitute Bis(imidazole) linkers Mürsel Ar#c#, Okan Zafer Yesilel, Murat Ta#, Hakan Demiral, and Hakan Erer Cryst. Growth Des., Just Accepted Manuscript • DOI: 10.1021/acs.cgd.6b00912 • Publication Date (Web): 25 Jul 2016 Downloaded from http://pubs.acs.org on July 26, 2016

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Crystal Growth & Design

66x29mm (300 x 300 DPI)

ACS Paragon Plus Environment


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1

Construction, Structural Diversity and Properties of Seven Zn(II)-Coordination

2

Polymers Based on 3,3′,5,5′-Azobenzenetetracarboxylic Acid and Flexible Substitute

3

Bis(imidazole) linkers

4

Mürsel Arıcıa,*, Okan Zafer Yeşilela, Murat Taşb, Hakan Demiralc, Hakan Erera

5

a

6

26480 Eskişehir, Turkey

7

b

8

Samsun, Turkey

9

c

Department of Chemistry, Faculty of Arts and Sciences, Eskişehir Osmangazi University,

Department of Science Education, Education Faculty, Ondokuz Mayıs University, 55139,

Department of Chemical Engineering, Faculty of Engineering and Architecture, Eskişehir

10

Osmangazi University, 26480 Eskişehir, Turkey

11

ABSTRACT: Flexible bis(imidazole) linkers incorporating methyl-, ethyl and isopropyl-

12

groups on imidazole rings were synthesized and their seven Zn(II)-coordination polymers,

13

namely

14

bmeipe)]·2DMA}n (2), {[Zn2(µ8-ao2btc)(µ-1,5-beipe)]·DMA}n (3), {[Zn4(µ8-ao2btc)(µ-1,5-

15

bisoipe)2]·2DMF}n (4), {[Zn2(µ4-ao2btc)(µ-1,6-bih)1.5(DMA)]·2DMA}n (5), {[Zn2(µ8-abtc)(µ-

16

1,6-bmeih)]·DMF}n (6) and {[Zn2(µ8-ao2btc)(µ-1,6-beih)]·DMF}n (7) (ao2btc= di-oxygenated

17

form of 3,3′,5,5′-azobenzenetetracarboxylate, 1,5-bipe: 1,5-bis(imidazol-1-yl)pentane, 1,5-

18

b(x)ipe: 1,5-bis(2-x-imidazol-1-yl)pentane (x = methyl-, ethyl-, isopropyl-), 1,6-bih: 1,6-

19

bis(imidazol-1-yl)hexane, 1,6-b(x)ih = 1,6-bis(2-y-imidazol-1-yl)hexane (y = methyl-, ethyl-

20

)) were obtained with azobenzenetetracarboxylic acid to investigate the effect of substitute

21

groups of bis(imidazole) ligands on structural diversity and characterized by elemental

22

analyses, IR spectra, single-crystal X-ray diffraction, powder X-ray diffractions (PXRD) and

23

thermal analyses (TG/DTA). X-ray results demonstrated that complex 1 had 2D structure

24

while the other complexes were 3D coordination polymers. For complexes 1-4,

25

dimensionality increased with the steric hindrance on imidazole rings. Complexes 2-7 were

{[Zn2(µ4-ao2btc)(µ-1,5-bipe)2]·4DMF}n

(1),

1 ACS Paragon Plus Environment

{[Zn2(µ6-ao2btc)(µ-1,5-

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26

3D frameworks with 1D channels and their 1D channel sizes decreased with the change of

27

substitute groups from –CH3 to –CH(CH3)2. For complexes 3, 4, 6 and 7, paddlewheel

28

Zn2(CO2)4 binuclear SBUs occurred with the increase of steric hindrance of substitute groups

29

on imidazole rings. CO2 adsorption results of the complexes showed that uptake capacities

30

decreased with the increase of length of substitute alkyl groups from methyl- to isopropyl- in

31

channels. Furthermore, photoluminescence and topological properties of the complexes were

32

studied.

33 34

Keywords:

Azobenzentetracarboxylate;

35

bis(imidazole) linker; CO2 uptake.

Zn(II)-coordination

36 37


polymer;

Substitute


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1. INTRODUCTION

39

In recent years, a great deal of attention has focused on the rational design and

40

construction of coordination polymers owing to their diverse application areas e.g. gas

41

adsorption/separation,

42

adsorption/degradation, drug delivery, etc., and their fascinating architectures 1-19. Up to now,

43

although a large number of coordination polymers have been synthesized and characterized, it

44

has still been challenge to rationally synthesize targeted structures. There are several factors

45

(organic ligands, metal ions, pH, solvents, temperature) directing the final structures of

46

coordination polymers in the self-assembly process20-22. In the rational design and synthesis of

47

coordination polymers, the selection of appropriate organic ligand from the above factors is

48

the most important parameter. In the construction of coordination polymers, polycarboxylates

49

(di-, tri- tetra- carboxylates) have been widely employed as bridging ligands due to their

50

versatile coordination modes. In this study, 3,3′,5,5′-azobenzenetetracarboxylic acid (H4abtc),

51

easily oxidized to generate mono and di-oxygenated azoxy-structures, can bind to metal ions

52

with four carboxylate groups in diverse coordination modes and is a symmetric rigid ligand

53

which enhances the thermal stability when coordinated to metal ions

54

incorporation of polycarboxylates and ancillary N-donor ligands has become an effective way

55

for construction of coordination polymers with desired structures24,

56

flexible and rigid bis(imidazole) derivative ligands have been extensively used as auxiliary N-

57

donor ligands for the connection of metal ion in the syntheses of mixed-ligand coordination

58

polymers29, 30. Especially, flexible bis(imidazole) ligands have been widely preferred due to

59

free rotation of imidazole rings around -CH2- groups23,

60

conformations to connect to metal ions easily. In the literature, although some coordination

61

polymers were synthesized with 3,3′,5,5′-azobenzenetetracarboxylic acid (H4abtc) and

62

flexible bis(imidazole) derivatives, there were no systematic investigations with

catalyst,

luminescence,

iodine

31, 32


encapsulation,

dye

23-25

. Recently, the

26-28

. Flexible, semi-

and have adopted different

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azobenzenetetracarboxylic acid and flexible bis(imidazole) ligands. Moreover, the systematic

64

study related to the effect of substitute groups of bis(imidazole) ligands on the final structures

65

of coordination polymers has been rare. In this study, two -methyl, -ethyl and -isopropyl

66

groups were inserted into the bis(imidazole) linkers to systematically investigate the effect of

67

substitute groups on structural diversities of coordination polymers.

68

Taking all the above into account, seven flexible bis(imidazole) derivative ligands,

69

namely, 1,5-bis(imidazol-1-yl)pentane (1,5-bipe), 1,5-bis(2-methylimidazol-1-yl)pentane

70

(1,5-bmeipe), 1,5-bis(2-ethylimidazol-1-yl)pentane (1,5-beipe), 1,5-bis(2-isopropylimidazol-

71

1-yl)pentane (1,5-bisoipe), 1,6-bis(imidazol-1-yl)hexane (1,6-bih), 1,6-bis(2-methylimidazol-

72

1-yl)hexane (1,6-bmeih) and 1,6-bis(2-ethylimidazol-1-yl)hexane (1,6-beih) were prepared

73

and serially, their Zn(II)-coordination polymers, ({[Zn2(µ4-ao2btc)(µ-1,5-bipe)2]·4DMF}n (1),

74

{[Zn2(µ6-ao2btc)(µ-1,5-bmeipe)]·2DMA}n (2), {[Zn2(µ8-ao2btc)(µ-1,5-beipe)]·DMA}n (3),

75

{[Zn4(µ8-ao2btc)(µ-1,5-bisoipe)2]·2DMF}n

76

bih)1.5(DMA)]·2DMA}n (5), {[Zn2(µ8-abtc)(µ-1,6-bmeih)]·DMF}n (6) and {[Zn2(µ8-ao2btc)(µ-

77

1,6-beih)]·DMF}n (7) were synthesized with 3,3′,5,5′-azobenzenetetracarboxylic acid to

78

investigate the effect of substitute groups of bis(imidazole) ligands on the structural diversity.

79

They were structurally characterized by elemental analysis, IR spectra, single crystal X-ray

80

diffraction and powder X-ray diffraction (PXRD) and thermal analysis techniques.

81

Furthermore, photoluminescence, topological and CO2 adsorption properties were studied.

82

2. MATERIALS AND PHYSICAL MEASUREMENTS

(4),

{[Zn2(µ4-ao2btc)(µ-1,6-

83

All reagents were purchased commercially and were used without further purification.

84

H4abtc33, 1,5-bipe34, 1,5-bmeipe35, 1,6-bih36, 1,6-bmeih37 ligands were synthesized according

85

to literatures. Bruker Tensor 27 FT−IR spectrometer was used for IR spectra (using KBr

86

pellets in the range of 400−4000 cm−1). Elemental analyses (C, H and N) were acquired with a

87

Perkin-Elmer 2400C Elemental Analyzer. 1H NMR spectra were recorded on Varian 500



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88

MHz spectrometer using DMSO-d6. Powder X-ray diffraction (PXRD) patterns were

89

collected by a Rikagu Smartlab X-ray diffractometer with Cu-Kα radiation (λ= 1.5406 nm) in

90

the range 10-50o 2θ. A Perkin Elmer Diamond TG/DTA Thermal Analyzer was used to record

91

thermal curves with a heating rate of 10 °C/min in the static air atmosphere. The

92

photoluminescence spectra of the solid and suspension samples were recorded on a Perkin-

93

Elmer LS-55 spectrophotometer. Topological analyses were performed using ToposPro

94

software38. Sorption isotherms for N2 and CO2 were acquired with Quantachrome Autosorb 1-

95

C device at 77 K and 273, respectively. Diffraction data of 1, 3-7 and 2 were collected on a

96

Bruker Smart Apex II CCD and a STOE IPDS diffractometer equipped with MoKα (0.71073

97

Å), respectively. The structures were solved by SHELXS and refined by full-matrix least-

98

squares on all F2 data using SHELXL in conjunction with the OLEX2 graphical user interface

99

39, 40

. For all complexes, the anisotropic thermal parameters were refined for non-hydrogen

100

atoms and hydrogen atoms were calculated and refined with a riding model. The most

101

noticeable features of the determination of the structures for 2-7 are the ratios of the residual

102

electron densities that are slightly different under -1 and +1. These peaks lie in positions that

103

are neither chemically sensible, nor fit to any discernible disorder pattern. One obvious

104

possible cause for such peaks are disorders for 2-7. Molecule drawings were carried out with

105

Mercury program 41.

106

2.1. Syntheses of the ligands

107

1,5-bis(2-ethyl-1H-imidazol-1-yl)pentane (1,5-beipe) and 1,5-bis(2-isopropyl-1H-imidazol-1-

108

yl)pentane (1,5-bisoipe)

109

A mixture of 2-ethylimidazole (5.77 g, 60 mmol) or 2-isopropylimidazole (6.61 g, 60

110

mmol) and NaOH (2.40 g, 60 mmol) was stirred in 30 mL DMSO at 60 ºC until obtaining

111

clear mixture. Afterwards, 1,5-dibromopentane (6.44 g, 28 mmol) was added into reaction

112

mixture and stirred at 60 ºC for 16 h. After the solution was cooled to room temperature,


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113

DMSO was evaporated. The crude product was stirred in 100 ml CH2Cl2 and filtered. The

114

filtration was extracted twice with 200 ml of water. The separated organic phase was filtered

115

over Na2SO4 and evaporated to give a clear yellow oily product.

116

For 1,5-beipe; Yield: 77 %. Anal. Calcd. for C15H24N4: C, 69.19; H, 9.29; N, 21.52 %.

117

Found: C, 69.74; H, 9.36; N, 21.06 %. FT-IR (KBr, cm-1): 3376 w, 3109 w, 2976 m, 2935 m,

118

2872 w, 1672 m, 1493 s, 1459 s, 1374 m, 1274 s, 1153 m, 1046 m, 731 m, cm-1. 1H NMR

119

(500 MHz, DMSO-d6): δ=6.985-6.709 (m, 4H, Im–H), 3.811-3.806 (m, 4H, 2×–N–CH2),

120

2.567-2.484 (m, 4H, 2×–CH2), 1.63 (t, 2H, -CH2), 1.17 (m, 6H, 2×–CH3).

121

For 1,5-bisoipe; Yield: 71 %. Anal. Calcd. for C17H28N4: C, 70.79; H, 9.78; N, 19.42

122

%. Found: C, 70.18; H, 10.03; N, 19.36 %. FT-IR (KBr, cm-1): 3283 w, 3109 w, 2971 m,

123

2932 m, 2872 w, 1674 m, 1487 s, 1440 s, 1371 m, 1272 s, 1162 m, 1070 m, 930 w, 726 m,

124

cm-1. 1H NMR (500 MHz, DMSO-d6): δ=6.97-6.73 (m, 4H, Im–H), 3.84 (m, 4H, 2×–N–

125

CH2), 2.99 (m, 2H, -CH), 1.66 (m, 2H,–CH2), 1.23-1.17 (m, 12H, 4×–CH3).

126

1,6-bis(2-ethyl-1H-imidazol-1-yl)hexane (1,6-beih)

127

The synthetic procedure of 1,6-beih was similar to that of 1,5-beipe, except that 1,6-

128

dibromohexane (6.83 g, 28 mmol) was used instead of 1,5-dibromopentane. Clear oily

129

product was obtained. Yield: 81 %. Anal. Calcd. for C16H26N4: C, 70.03; H, 9.55; N, 20.42 %.

130

Found: C, 69.93; H, 10.04; N, 20.47 %. FT-IR (KBr, cm-1): 3288 w, 3109 w, 2977 m, 2938 m,

131

2863 w, 1669 m, 1567 w, 1495 s, 1459 s, 1374 m, 1272 s, 1150 m, 1046 m, 924 w, 728 m,

132

cm-1. 1H NMR (500 MHz, DMSO-d6): δ=6.99-6.72 (m, 4H, Im–H), 3.80 (m, 4H, 2×–N–

133

CH2), 2.57-2.485 (m, 4H, 2×–CH2), 1.605 (m, 4H, 2×–CH2), 1.23 (4H, 2×–CH2), 1.17 (m,

134

6H, 2×–CH3).

135

2.2 Syntheses of the complexes

136

{[Zn2(µ4-ao2btc)(µ-1,5-bipe)2]·4DMF}n (1)



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137

A mixture of H4abtc (0.1 g, 0.279 mmol), Zn(NO3)2·6H2O (0.166 g, 0.558 mmol) and

138

1,5-bipe (0.056 g, 0.279 mmol) was stirred at 50 oC in DMF (10 mL) for 30 min. Then, HNO3

139

(6.0 M) was added into the mixture to obtain a clear solution. The clear solution was placed in

140

a vial (25 mL) and heated at 95 oC for 3 days to obtain yellow crystals. Yield: 0.095 g, 56 %

141

(based on H4abtc). Anal. Calcd. for C25H33N7O7Zn: C, 49.31; H, 5.46; N, 16.10 %. Found: C,

142

49.28; H, 5.83; N, 16.24 %. IR (KBr, cm–1): 3122 w, 3056 w, 2926 w, 1659 vs, 1633 vs, 1576

143

m, 1437 m, 1346 vs, 777 s, 746 m, cm-1.

144

{[Zn2(µ6-ao2btc)(µ-1,5-bmeipe)]·2DMA}n (2) and {[Zn2(µ8-ao2btc)(µ-1,5-beipe)]·DMA}n

145

(3)

146

A mixture of H4abtc (0.1 g, 0.279 mmol), Zn(NO3)2·6H2O (0.166 g, 0.558 mmol) and

147

1,5-bmeipe (0.064 g, 0.279 mmol) (for 2) or 1,5-beipe (0.073 g, 0.279 mmol) (for 3) was

148

stirred at 50 oC in the mixture of DMA:H2O (10:2, v:v) for 30 min. After, HNO3 (6.0 M) was

149

added into the mixture until clear solution was obtained. The resulting solution was placed in

150

a vial (25 mL) and heated at 95 oC for 2 days to obtain yellow crystals.

151

For 2; Yield: 0.182 g, 71 % (based on H4abtc). Anal. Calcd. for C37H44N8O12Zn2: C,

152

48.12; H, 4.80; N, 12.13 %. Found: C, 48.69; H, 4.45; N, 12.91 %. IR (KBr, cm–1): 3041 w,

153

2935 m, 2866 m, 1670 s, 1622 vs, 1577 s, 1437 m, 1392 s, 1354 s, 781 m, 717 m, cm-1.

154


155


156

2974 w, 2933 w, 1654 vs, 1502 m, 1446 s, 1384 vs, 785 m, 717 s, cm-1.

157

{[Zn4(µ8-ao2btc)(µ-1,5-bisoipe)2]·2DMF}n (4)

158

A mixture of H4abtc (0.1 g, 0.279 mmol), ZnCl2 (0.076 g, 0.558 mmol) and 1,5-bisoipe

159

(0.080 g, 0.279 mmol) was stirred at 50 oC in the mixture of DMF:H2O (10:2, v:v) for 30 min.

160

After, HNO3 (6.0 M, 3 drops) was added into the mixture. The clear solution was placed in a

161

vial (25 mL) and heated at 100 oC for 2 days to obtain orange crystals. Yield: 0.156 g, 54 %


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162

(based on H4abtc). Anal. Calcd. for C47H63N7O11Zn2: C, 49.07; H, 5.59; N, 12.26 %. Found:

163

C, 49.71; H, 5.09; N, 11.44 %. IR (KBr, cm–1): 3126 w, 2964 w, 2932 w, 1657 vs, 1485 m,

164

1444 s, 1384 s, 785 m, 717 s, cm-1.

165

{[Zn2(µ4-ao2btc)(µ-1,6-bih)1.5(DMA)]·2DMA}n (5)

166

The synthetic procedure of 5 was similar to that of 2, except that 1,6-bih (0,061 g, 0.279

167

mmol) was used instead of 1,5-beipe. After three days, yellow crystals of 5 were obtained.

168

Yield: 0.104 g, 34 % (based on H4abtc). Anal. Calcd. for C46H60N11O13Zn2: C, 49.96; H, 5.47;

169

N, 13.93 %. Found: C, 49.37; H, 5.20; N, 13.12 %. IR (KBr, cm–1): 3130 m, 2935 m, 2864 w,

170

1631 vs, 1573 s, 1440 s, 1363 vs, 781 m, 727 m, cm-1.

171

{[Zn2(µ8-abtc)(µ-1,6-bmeih)]·DMF}n (6) and {[Zn2(µ8-ao2btc)(µ-1,6-beih)]·DMF}n (7)

172

The procedures for the syntheses of 6 and 7 were similar to that used for 4, except that 1,5-

173

bmeih (0.069 g, 0.279 mmol) for 6 and 1,6-beih (0.076 g, 0.279 mmol) for 7 were used

174

instead of 1,5-bisoipe.

175


176


177

3066 w, 2935 w, 2858 w, 1651 vs, 1582 m, 1444 s, 1387 s, 785 m, 721 m, cm-1.

178


179


180

2978 w, 2933 w, 1649 vs, 1504 m, 1442 s, 1383 s, 785 m, 719 m, cm-1.

181 182

3. RESULTS AND DISCUSSION

183

3.1. Synthesis and Characterization

184

3,3′,5,5′-azobenzenetetracarboxylic acid and systematic substitue bis(imidazole)

185

derivative ligands (Scheme 1) were synthesized and their Zn(II)-coordination polymers were

186

obtained in acidic medium in the similar solvent mixtures. The complexes were characterized



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 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

187

by single crystal X-ray diffraction, powder X-ray diffraction, IR spectra, thermal analysis

188

techniques as well as elemental analysis. Elemental analysis results are agreed with single

189

crystal X-ray results. IR spectra of the complexes were given in Fig. S1. In the IR spectra of

190

complexes 1-7, the weak bands observed between 3134 and 2866 cm-1 are assigned to

191

aromatic and aliphatic ν(C-H) stretching vibrations, respectively. The asymmetric and

192

symmetric stretching vibrations of carboxylate groups of H4abtc ligand are observed at 1710

193

and 1278 cm-1, respectively. The asymmetric stretching vibration observed at 1710 cm-1 of

194

H4abtc is shifted to lower frequency after conversion to complexes 1-7, indicating the full

195

deprotonation of carboxylate groups of H4abtc. The asymmetric and symmetric stretching

196

vibrations for 1-7 are appeared in the range 1657-1622 cm-1 and 1387-1346 cm-1, respectively.

197

Description of structures

198 199

The crystal data and the refinement details of complexes are given in Tables 1 and 2. Selected bond distances and angles are listed in Tables S1-7, respectively.

200

{[Zn2(µ4-ao2btc)(µ-1,5-bipe)2]·4DMF}n (1). The X-ray single crystal structural analysis

201

reveals that complex 1 is 2D ladder-like coordination polymer. Complex 1 crystallizes in the

202

monoclinic system with space group P21/c. The asymmetric unit of 1 contains one Zn(II) ion,

203

half ao2btc anion, one 1,5-bipe ligand and two DMF molecules. Each Zn(II) ion in 1 exhibits a

204

distorted tetrahedral environment (τ4 = 0.918) 42, composed of two carboxylic O atoms from

205

two different ao2btc anions [Zn1−O1 = 1.9766(15); Zn1−O4i = 1.9863(16) Å] and two N

206

atoms from two different 1,5-bipe ligands [Zn1−N2 = 2.008(2); Zn1−N5ii = 2.017(2) Å], as

207

shown in Fig. 1a. The Zn(II) ions are bridged by O1 and O4 atoms of ao2btc ligands to

208

generate 26-membered ring. The combination of 26-membered rings produces 1D chain

209

structures of the complex (Fig. S2a). Adjacent 1D chains are linked by nitrogen atoms (N2

210

and N5) of 1,5-bipe ligands with a Zn···Zn distance of 10.513 Å to generate 2D structures,

211

with the pore dimension of 14.187 × 15.11 Å2 (defined by Zn···Zn distances) (Fig. S2b). 2D


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212

layers of the complex adopt –AAA– stacking to form 3D supramolecular network (Fig. 1b).

213

The free void volume of 1 after the removal of DMF molecules is 1110.2 Å3 which represents

214

38.5 % per unit cell volume, according to a calculation performed with PLATON43 (Fig. 1b).

215

Topologically, complex 1 is (3,4)-connected binodal net with the point symbol of

216

{4.62}2{42.62.82} (Fig. 1c).

217

{[Zn2(µ6-ao2btc)(µ-1,5-bmeipe)]·2DMA}n (2). To further examine the influence of the

218

auxiliary ligand which has substituted with −CH3 group on the imidazole ring on the

219

structure, we used 1,5-bmeipe instead of 1,5-bipe ligand. When 1,5-bmeipe ligand was used

220

as an auxiliary ligand, a 3D framework was obtained. Single-crystal X-ray diffraction analysis

221

reveals that the complex 2 crystallizes in the monoclinic system with the C2/c space group.

222

The asymmetric unit of complex 2 contains one Zn(II) ion, half ao2btc anion, half 1,5-bmeipe

223

ligand and one DMA molecules. As shown in Fig. 2a, the environment around Zn(II) ion can

224

be described as a distorted square pyramidal geometry (τ5 = 0.142)44, in which it is

225

coordinated by three oxygen atoms from two ao2btc ligands and one nitrogen atom from 1,5-

226

bmeipe ligand in an equatorial plane and one oxygen atom from ao2btc ligand occupies the

227

axial position. Each ao2btc ligand acts an octadentate ligand in which 3,3′-carboxyl groups

228

display bidentate bridging modes and 5,5′-carboxyl groups exhibit bidentate chelating modes,

229

connecting to six metal centers. Zn(II) ions are bridged by 3,3′,5,5′-carboxylate oxygen atoms

230

of the ao2btc ligand to form 1D double zig-zag chains with the 28-membered rings (Fig. S3a).

231

Adjacent 1D double chains are linked by 3,5′-carboxyl groups of ao2btc with a Zn···Zn

232

distance of 4.158 Å to generate 2D structures (Fig. S3b). 2D structures are extended to a 3D

233

porous structure by the coordination of ao2btc ligand (Fig. 2b and 2c). The free void volume

234

of 2 after the removal of DMA molecules is 1323.7 Å3 which represents 33% per unit cell

235

volume, according to PLATON analysis. Topologically, complex 2 is 3D (3,6)-connected

236

sqc5381 net with the point symbol of {42.6}2{44.66.85} (Fig. 2d).



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 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

237

{[Zn2(µ8-ao2btc)(µ-1,5-beipe)]·DMA}n

(3)

Page 12 of 41

and

{[Zn4(µ8-ao2btc)(µ-1,5-

238

bisoipe)2]·2DMF}n (4). The X-ray single crystal study shows that complexes 3 and 4 have 3D

239

coordination polymer. The crystallographic analyses reveal that complexes 3 and 4 appear to

240

be very similar. The asymmetric unit of 3 contains two Zn(II) ion, one ao2btc anion, one 1,5-

241

beipe ligand and one DMA molecule (Fig. 3a), while the asymmetric unit of 4 contains one

242

Zn(II) ion, half ao2btc anion, one 1,5-beipe ligand and one DMF molecule (Fig. 4a). Each

243

Zn(II) ion is coordinated by four carboxylate oxygen atoms from four different ao2btc ligands

244

and one nitrogen atom from 1,5-beipe or 1,5-bisoipe ligands, thus showing a distorted square

245

pyramidal geometry (τ5 = 0.0012 for 3). All carboxylate oxygen atoms of four different

246

ao2btc ligands coordinate eight Zn(II) ions to form a paddle-wheel [Zn2(COO)4] secondary

247

building unit (SBU) with the Zn···Zn distances of 3.101 Å for 3 and 3.110 Å for 4. The ao2btc

248

ligand displays µ8-η1:η1:η1:η1:η1:η1:η1:η1 coordination mode with the inter-isophthalate

249

dihedral angle of 161.95º (through C3–C7–C9–C13) for 3 and 180º (through C3–C7–C7x–

250

C3x) for 4. Paddlewheel type Zn2 clusters are connected together by ao2btc linkers to generate

251

3D framework (Figs. 3b and Fig. 4b). 1,5-beipe and 1,5-bisoipe ligands have contributed to

252

the stabilities of the structures by completing the fifth coordination site. The structures have

253

1D hexagonal channels, with the pore dimensions of approximately 10 × 10 Å2 for 3 and 7.93

254

× 9.46 Å2 (defined by Zn···Zn distances) for 4 (Figs. S4a and S5a). The free void volumes of

255

complexes after the removal of solvent molecules are 740.6 Å3 for 3 and 576.2 Å3 for 4 which

256

represent 19.6% for 3 and 1 5% for 4 per unit cell volume, according to PLATON analysis.

257

Topologically, complexes are 3D (3,6)-connected sqc5381 net with the point symbol of

258

{42.6}2{44.66.85} like 2 (Figs. S4b and S5b).

259

{[Zn2(µ4-ao2btc)(µ-1,6-bih)1.5(DMA)]·2DMA}n (5). The crystal structure of 5 with

260

atom numbering scheme is shown in Fig. 5a. X-ray single-crystal diffraction analysis

261

demonstrates that complex 5 crystallizes in the triclinic system with the space group of P-1.


Page 13 of 41

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262

The asymmetric unit of 5 consists of two Zn(II) ions, one ao2btc, one and half bih and one

263

coordinated DMA and two uncoordinated DMA molecules. Although Zn(II) centers adopt

264

distorted tetrahedral geometry in the structure, they have different coordination environments.

265

Zn1 atom is coordinated by two carboxylate O atoms from two different ao2btc ligands and

266

two imidazole N atoms from two different 1,6-bih ligands while Zn2 atom is coordinated by

267

two O atoms from two different ao2btc ligands and one N atom from one 1,6-bih ligand and

268

one N atom from coordinated DMA molecule. Zn(II) ions are bridged by 3,3′ and 5,5′-

269

carboxylate oxygen atoms of ao2btc ligand as a monodentate to form 2D structure, which are

270

further coordinated to 1,6-bih ligand to generate 3D framework (Fig. 5b). Four ao2btc ligands

271

connect to four Zn(II) ions to form 52- and 32-membered rings. In complex 5, there are two

272

types of bih ligands which display trans conformations. In 1,6-bih connected to Zn1 center,

273

the two imidazole rings are parallel with a distance of 10.761 Å while in other 1,6-bih

274

connected to Zn2 center, the two imidazole rings are parallel with a distance of 8.458 Å.

275

According to PLATON analysis, 5 has voids of 590.2 Å3 which represents 24 % per unit cell

276

volume. Topologically, complex 5 is 3D 4-nodal 3,4,4,4-connected net with the point symbol

277

of {72.83.10}{72.8}{73.83} (Fig. 5c).

278

{[Zn2(µ8-abtc)(µ-1,6-bmeih)]·DMF}n (6) and {[Zn2(µ8-ao2btc)(µ-1,6-beih)]·DMF}n

279

(7). X-ray analysis studies reveal that complexes 6 and 7 are similar structures (isomorphous).

280

When methyl- and ethyl- substitute (imidazol-1yl)hexane ligands were used instead of non-

281

substitute bis(imidazol-1-yl)hexane, {Zn2(CO2)4}-type binuclear SBU based 3D frameworks

282

of 6 and 7 were obtained. Both complexes crystallize in the monoclinic space group C2/c. In

283

7, abtc ligand oxidized to di-oxygenated ao2btc in reaction medium. As shown in Fig. 6, there

284

are one Zn(II) ion, half abtc (ao2btc for 7), half neutral ligand and one DMF molecule in the

285

asymmetric units of 6 and 7. In the complexes, each Zn(II) ion which has distorted square

286

pyramid geometry is coordinated by four carboxylate O atoms from four abtc ligands and two



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 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

287

imidazole N atoms from two different neutral ligands. A pair of Zn(II) ions are connected by

288

four carboxylate O atoms to generate paddlewheel {Zn2(CO2)4} binuclear SBUs with the

289

Zn···Zn distances of 3.058 Å for 6 and 3.066 Å for 7. Each {Zn2(CO2)4} binuclear SBU is

290

connected by four different abtc ligand to form 3D framework (Fig. 7). Each abtc ligand acts

291

an octadentate ligand in which 3,3′,5,5′-carboxyl groups display bidentate bridging modes to

292

connect to eight metal centers in 6 and 7. In the complexes, two Zn(II) ions are bridged by

293

neutral ligand and 3,3′-carboxylate oxygen atoms to form 1D hexagonal channels, with the

294

pore dimensions of approximately, 10.343 × 8.206 Å2 for 6, and 10.246 × 8.223 Å2 for 7,

295

respectively (Fig. 7). According to PLATON analysis, the solvent-accessible volumes for 6

296

and 7 are 23.8 % and 20.9, respectively. Topologically, complexes 6 and 7 have 3,6-

297

connected sqc5381 net with the point symbol of {42.6}2{44.66.85} like complexes 2-4.

298

3.2. Structural comparison

299

All Zn(II)-complexes were synthesized about at 95 oC in acidic medium using 3,3′,5,5′-

300

azobenzenetetracarboxylate as an anionic ligand and series of methyl-, ethyl- and isopropyl-

301

substituted bis(imidazole) derivatives as neutral ligands to investigate the effect of substitute

302

groups on structural diversity. In all complexes, azo-groups of abtc are oxidized to generate

303

di-oxygenated forms (ao2btc) except complex 6. The abtc or ao2btc ligands display various

304

coordination modes to connect to Zn(II) ions (Scheme 2). Complex 1 synthesized with abtc

305

and non-substitue 1,5-bipe exhibits 2D structure while complexes 2-4 obtained with abtc and

306

substitute bis(imidazole) linkers are 3D frameworks. In the series of non- and substitute-

307

bis(imidazole-1yl)pentane, dimension was increased with the increase of steric hindrance on

308

imidazole rings. Complexes 5-7 synthesized using non- or substitute bis(imidazol-1yl)hexane

309

have 3D structures. There are no effect of substitute groups of bis(imidazole) linkers on the

310

dimensionalities of complexes 5-7. Complexes 2-7 are 3D frameworks with 1D channels and

311

their 1D channel sizes reduce as alkyl groups change from –CH3 to –CH(CH3)2.

312

Bis(imidazole) linkers having flexible long methylene skeleton tend to display

313

interpenetration or polycatenation. In literature studies used abtc and flexible neutral ligands,

314

{[Zn(abtc)0.5(bip)]·H2O}n and {[Zn(abtc)0.5(bib)]·3H2O}n complexes prepared by using abtc

315

and 1,3-bis(imidazol-1yl)propane (bip) or 1,4-bis(imidazol-1yl)butane (bib) were synthesized

316

at 165 oC in the mixture of H2O:DMF in basic medium and they displayed two-fold 13 ACS Paragon Plus Environment

Page 14 of 41

Page 15 of 41

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and

self-penetrating

3D

frameworks45.

317

interpenetrating

318

[Co3(H2abtc)3(btb)(H2O)6]n synthesized with bis(triazol-1-yl)butane at 120

Furthermore, o

C in H2O

27

319

containing NaOH was 3-fold interpenetrating 3D pillar-layered framework . Interpenetration

320

or polycatenation were observed in the above complexes prepared by using abtc and flexible

321

bis(imidazole) linkers in neutral or basic mediums at high temperature. Although flexible

322

bis(imidazole) linkers were utilized in this study, complexes 1-7 which were synthesized at

323

low temperature and acidic medium did not show interpenetration or polycatenation. Hence,

324

reaction conditions are important to control the final structures of coordination polymers.

325

Complexes 1-4 and 6, 7 had binodal net while complex 5 exhibited 4-nodal 3,4,4,4-connected

326

net. Complexes 2-4 and 6, 7 exhibited 3,6-connected 3D sqc5381 net with the point symbol of

327

{42.6}2{44.66.85}. Moreover, as seen in crystal section, complexes displayed paddlewheel

328

Zn2(CO2)4 binuclear SBUs with the increase of length of substitute alkyl groups from methyl-

329

to isopropyl- on imidazole rings in channels. Hence, substitute bis(imidazole) linkers having

330

steric hindrance in channels can be used to obtain paddlewheel SBUs in the synthesis of

331

coordination polymers with abtc ligand. Moreover, there are weak C-H···O interactions

332

between the encapsulated solvent molecules and frameworks in all complexes.

333 334

3.3. Powder X-ray Diffraction and Thermal analysis Results

335

Powder X-ray diffraction (PXRD) measurements were performed to check the phase

336

purity of the bulk materials. (Fig. S6). PXRD patterns of the complexes are consistent with

337

the simulated patterns obtained from their single-crystal structures, indicating the phase

338

purities of the complexes. PXRD patterns of complexes were recorded three month later and

339

PXRD patterns of the complexes have still been good agreement with consistent with the

340

simulated patterns obtained from their single-crystal structures. Therefore, complexes showed

341

stability at room temperature in air.

342

The thermal behaviors and stabilities of complexes 1-7 were investigated by thermal

343

analysis techniques in a static air atmosphere with a heating rate of 10 oC/min in the

344

temperature range 30-700 oC (Figs. S7-13). For complexes 1 and 4, the first weight losses of

345

24.93 % in the temperature range of 55-200 oC for 1 and 8.6 % in the temperature range of



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 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

346

66-192 oC correspond to removal of DMF molecules, respectively (calcd.: 7.98 % for 1,

347

calcd.: 7.08 % for 4). After this steps, complexes 1 and 4 are stable up to 299 and 323 oC,

348

respectively. For complexes 2 and 3, the weight losses of 20.74 % from 38 to 148 oC and 10

349

% from 66 to 206 oC correspond to release of DMA molecules, respectively (calcd.: 18.86 %

350

for 2 and calcd.: 10.07 % for 3). After removal of DMA molecules, complexes 2 and 3 are

351

stable up to 243 and 334 oC, respectively. For 5-7, the first weight losses correspond to

352

removal of uncoordinated DMA and DMF molecules placed in pores (obsd.: 14.80 %, calcd.:

353

15.77 % for 5; obsd.: 13.40 %, calcd.: 13.36 % for 6; obsd.: 11.33 %, calcd.: 11.71 % for 7).

354

For all complexes, on further heating, frameworks are decomposed with exothermic picks.

355

The final residual products of complexes 1-7 are possible ZnO (obsd.: 14.69 %, calcd.: 13.30

356

% for 1; obsd.: 9.67 %, calcd.: 8.77 % for 2; obsd.: 18.76 %, calcd.: 18.74 % for 3; obsd.:

357

16.29 %, calcd.: 15.69 % for 4; obsd.: 13.05 %, calcd.: 14.66 % for 5; obsd.: 18.39 %, calcd.:

358

19.74 % for 6; obsd.: 18.69 %, calcd.: 18.74 % for 7).

359

3.4. Gas adsorption studies

360

As seen from the crystal structures of synthesized complexes, pores with one

361

dimensional channels encouraged us for gas sorption measurements. Prior to the gas

362

adsorption measurements, the complexes were immersed in methanol for four days (MetOH

363

was changed with a new one for every day) at room temperature. After that, they were heated

364

to 100 oC for one day for fully activation under a vacuum to obtained complexes 1a-7a. After

365

activations, PXRD patterns of activated complexes 1a-7a are similar to as-synthesized PXRD

366

patterns of complexes 1-7 except 2. For 2, PXRD pattern after activation shows that

367

framework losses the crystallinity and may be collapsed or partial decomposition with the

368

removal of solvent molecules in the pores. PXRD patterns of 1a and 3a-7a demonstrate that

369

frameworks are robust after activations. Hence, gas adsorption properties of all complexes

370

except 2 were studied.


Page 16 of 41

Page 17 of 41

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371

N2 adsorption isotherms of the activated complexes were recorded at 77 K and 1.0 bar.

372

BET surface areas are 172.90 m2/g for 1a, 159.0 m2/g for 3a, 100.84 m2/g for 4a, 7.33 m2/g

373

for 5a, 434.43 m2/g for 6a and 411 m2/g for 7a, respectively. When compared to BET values

374

of complexes which had similar SBU structures, for 3a and 4a and for 6a and 7a, surface

375

areas decreased with the increase of length of substitute groups (or steric hindrance) on

376

imidazole rings in channels.

377

CO2 adsorption-desorption isotherms for complexes all complexes except 2 were

378

recorded volumetrically at 273 K and 1.0 bar (Fig. 8). The CO2 adsorption measurements of

379

the complexes exhibit type-I isotherms with the characteristic of microporous structures.

380

Desorption isotherm of complex 7a displays significant hysteresis loop which demonstrate a

381

small of mesoporosity. The CO2 uptake capacities are 21.24 (4.17 %) for 1a, 47.64 (9.36 %)

382

for 3a, 28.71 (5.64 %) for 4a, 15.29 cm3/g (3.0 %) for 5a, 42.85 (8.42 %) for 6a and 32.52

383

cm3/g (6.39 %) for 7a, respectively. As seen from crystal section, complexes 3 and 4 have

384

similar bis(imidazole) linkers containing pentane chain. Only, substitute groups (ethyl- and

385

isopropyl-) on imidazole rings are different. According to PLATON analysis, the solvent-

386

accessible volume of complex 4 is lower than that of complex 3 because of the increase of

387

steric hindrance on imidazole rings in channels. CO2 adsorption values of complexes 3 and 4

388

confirm the PLATON analysis results. Again, the similar results are observed for complexes 6

389

and 7. CO2 uptake capacity of complex 7 is lower than complex 6 due to the increase of

390

length of substitute alkyl groups from methyl- to ethyl- in channels. Complexes 3a and 6a has

391

highest CO2 adsorption values in the other complexes. Moreover, CO2 adsorption values of

392

complexes 3a and 6a are higher than some MOFs, like MOF-5 (6.2 %), MOF-602 (5.0 %)

393

and SNU-15 (7.0 %) at 273 K and 1 bar46-50.

394

3.5. Photoluminescent Properties



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 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

395

The solid state photoluminescence spectra of free ligand H4abtc and complexes 1-7

396

were obtained under the same conditions at room temperature (Figs. 9 and 10). The emission

397

bands of free ligand H4abtc were observed at 410, 420, 463, 487 and 532 nm upon excitation

398

at 344 nm. These emissions can be assigned to π*→n or π*→π transitions of H4abtc. As seen

399

in Figs. 11 and 12, complexes 1-7 and H4abtc have similar emissions. Complexes 1-7

400

displayed emissions at 407, 419, 463 and 486 nm (1), 408, 421, 463 and 486 nm (2), 406, 421,

401

463 and 487 nm (3), 407, 420, 463 and 486 nm (4), 406, 421, 463 and 487 (5), 399, 463 and

402

487 (6) and 405, 420, 462 and 487 (7) upon excitation at 344 nm, respectively. The emissions

403

of as-synthesized complexes are neither ligand to metal charge transfer nor metal to ligand

404

charge transfer. Since, reduction or oxidation of Zn(II) ions are difficult owing to d10

405

configurations of them. Therefore, the emissions of complexes 1-7 can be attributed to intra-

406

ligand transitions of H4abtc51.

407

Moreover, in order to determine photoluminescence properties of as-synthesized

408

complexes in different organic solvents (DMF, MetOH and CH2Cl2), solvent-dependent

409

photoluminescence studies were carried out. Before the measurements, the complexes (4.0

410

mg) were finely grounded and immersed in solvents (3.0 mL) and then stirred for 24 h to

411

obtain suspensions. The photoluminescence spectra of as-synthesized complexes dispersed in

412

organic solvents were recorded under the same conditions with the solid state

413

photoluminescence spectra (Figs. S14-S16). As seen in Fig. S14-S16, the emissions of the

414

complexes dispersed in organic solvents are similar with those of the solid-state samples. The

415

shifts in the wavelengths are observed and the emission intensities for the complexes

416

dispersed in different organic solvents are different due to solvent effect. The emission

417

intensities of the complexes dispersed in organic solvents increased with the decrease of

418

polarities of solvents. Furthermore, for all complexes, in CH2Cl2 solvent, the intensity of

419

emission picks at about 408 nm increased.


Page 18 of 41

Page 19 of 41

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420 421

4. CONCLUSIONS

422

Flexible bis(imidazole) linkers including -methyl, -ethyl and -isopropyl groups on

423

imidazole rings were prepared and serially, their seven 2D and 3D Zn(II)-coordination

424

polymers were synthesized with abtc ligand to determine the effect of substitute groups on

425

imidazole rings of bis(imidazole) ligands. Complexes 2-7 were 3D frameworks with 1D

426

channels while complex 1 displayed 2D structure. Dimensionality increased with the increase

427

of steric hindrance on imidazole rings for complexes 1-4. 1D channel sizes of 3D frameworks

428

decreased when alkyl groups was changed from –CH3 to –CH(CH3)2 on imidazole rings. This

429

study can provide promising way to obtain paddlewheel Zn2(CO2)4 binuclear SBUs with the

430

increase of length of substitute alkyl groups on imidazole rings in channels with abtc ligand.

431

CO2 adsorption results showed that CO2 uptake capacities of the complexes decreased with

432

the increase of length of substitute alkyl groups in channels. Furthermore, photoluminescence

433

properties of complexes 1-7 were due to intraligand transitions.

434 435

Acknowledgments This work has been supported by The Scientific and Technological Research Council

436 437

of Turkey (TUBĐTAK) (Project No: 113Z313).

438 439

Supporting Information

440

TG and PXRD curves and tables for bond distances and angles of complexes 1-7.

441

Crystallographic data for the structural analysis have been deposited with the Cambridge

442

Crystallographic Data Centre, CCDC No. 1042637-1042640 for 1-4 and 1043707-1043709

443

for 5-7. Copies of this information may be obtained free of charge from the Director, CCDC,

444

12

445

[email protected] or www: http://www.ccdc.cam.ac.uk).

Union

Road,

Cambridge

CB2

1EZ,

UK

(fax:


+44-1223-336033;

e-mail:


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 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

446

This material is available free of charge via the Internet at http://pubs.acs.org.

447

*Corresponding Author:

448

E–mail: [email protected]

449

Tel: +902222393750, Fax: +902222393578

450 451


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Arıcı, M.; Yeşilel, O. Z.; Tas, M., Cryst. Growth Des. 2015, 15, 3024-3031.

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Fan, L.; Fan, W.; Li, B.; Liu, X.; Zhao, X.; Zhang, X., Dalton Trans. 2015, 44, 2380-

492

2389.

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Zhang, S.; Ma, J.; Zhang, X.; Duan, E.; Cheng, P., Inorg. Chem. 2014, 54, 586-595.

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Zhang, C.-L.; Qin, L.; Shi, Z.-Z.; Zheng, H.-G., Dalton Trans. 2015, 44, 4238-4245.

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Zhao, J.; Li, D.-S.; Ke, X.-J.; Liu, B.; Zou, K.; Hu, H.-M., Dalton Trans. 2012, 41,

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2015, 5, 16190-16198.

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Sun, D.; Xu, M.-Z.; Liu, S.-S.; Yuan, S.; Lu, H.-F.; Feng, S.-Y.; Sun, D.-F., Dalton

Wang, S.-L.; Hu, F.-L.; Zhou, J.-Y.; Zhou, Y.; Huang, Q.; Lang, J.-P., Cryst. Growth

Yan, Z.-H.; Wang, W.; Zhang, L.; Zhang, X.; Wang, L.; Wang, R.; Sun, D., RSC Adv.

Fan, L.; Fan, W.; Li, B.; Liu, X.; Zhao, X.; Zhang, X., RSC Adv. 2015, 5, 14897-

Erer, H.; Yeşilel, O. Z.; Arıcı, M., Cryst. Growth Des. 2015, 15, 3201-3211.


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505

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506

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516

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Dalton Trans. 1984, 1349-1356.

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527

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531

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535


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Page 25 of 41

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 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


536

Figure and Table Captions

537

Fig. 1. (a) The molecular structure of 1 showing the atom numbering scheme ((i) 1+x, y, z;

538

(ii) 1-x, 1-y, 2-z) (b) space-filling mode of 2D structure viewed along the c-axis (c) a

539

schematic representation of 3,4-connected binodal net in 1

540

Fig. 2. (a) The molecular structure of 2 showing the atom numbering scheme ((i) x, -y+1, z-½;

541

(ii) -x+½, y-½, -z+½) (b) 3D framework of 2 viewed along the b-axis (c) space-filling mode of

542

3D structure in 2 (d) a view of 3D (3,6)-connected sqc5381 net

543

Fig. 3. (a) The molecular structure of 3 showing the atom numbering scheme ((i) x+½, -y+½,

544

-z; (ii) -x−½, -y+1, z-½; (iii) –x-1, y+½, -z+½) (b) 3D framework of 3 in the ac plane

545

Fig. 4. (a) The molecular structure of 4 showing the atom numbering scheme (b) 3D

546

framework of 4 (ac plane)

547

Fig. 5. (a) The molecular structure of 5 showing the atom numbering scheme (b) space-filling

548

mode of 3D structure in 5 (c) a topological view of 3D 3,4,4,4-connected 4-nodal net

549

Fig. 6. The molecular structures of (a) 6 ((i) -x+½, -y+½, -z; (ii) -x+½, y-½, -z+½; (iii) x, -

550

y+1, z-½) and (b) 7 ((i) x, -y+2, z-½; (ii) -x-½, y-½, -z+3/2; (iii) -x-½, -y+3/2, -z+1)) showing

551

the atom numbering scheme

552

Fig. 7. Space-filling modes of 3D structures in (a) 6 and (b) 7 viewed along the c*-axis

553

Fig. 8. CO2 adsorption-desorption isotherms for 1a-7a at 273 K and 1 bar

554

Fig. 9. Photoluminescence spectra of complexes 1-4 and free ligand H4abtc

555


556

Fig. S1. IR spectra of complexes 1-7

557

Fig. S2. (a) 1D structure along the c- axis (b) 2D structure of 1

558

Fig. S3. (a) 1D structure and (b) 2D layer formed by abtc ligand in 2 along the b-axis.

559

Fig. S4. (a) Space-filling mode of 3D structure in 3 (b) A topological view of 3D (3,6)-

560

connected sqc5381 net.



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 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

561

Fig. S5. (a) Space-filling mode of 3D structure in 4 viewed along the b-axis (b) A topological

562

view of 3D (3,6)-connected sqc5381 net.

563

Fig. S6. PXRD patterns of simulated, as-synthesized and activated complexes

564

Fig. S7. TG, DTG and DTA curves of complex 1

565


566


567


568


569


570


571

Fig. S14. The photoluminescence spectra of as-synthesized complexes dispersed in DMF

572

Fig. S15. The photoluminescence spectra of as-synthesized complexes dispersed in MetOH

573

Fig. S16. The photoluminescence spectra of as-synthesized complexes dispersed in CH2Cl2

574

Table 1. Crystal data and structure refinement parameters for complexes 1-4

575


576

Table S1. Selected bond lengths and angles for 1 (Å, º)

577


578


579


580


581


582


583 584


Page 26 of 41

Page 27 of 41

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 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


585 586

Scheme 1. Schematic representation of H4abtc and bis(imidazole) derivative ligands, 1,5-

587

bipe, 1,5-bmeipe, 1,5-beipe, 1,5-bisoipe, 1,6-bih, 1,6-bmeih, 1,6-beih

588



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 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 28 of 41

(a) complexes 1 and 5

(b) complex 2

(c) complexes 3, 4 and 7

(d) complex 6

589 590

Scheme 2. Coordination modes of azobenzenetetracarboxylate observed in this paper

591 592


Page 29 of 41

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 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60



593

1 Empirical formula

2

3

4

C25H33N7O7Zn

C37H44N8O12Zn2

C35H39N7O11Zn2

C47H63N7O11Zn2

608.95 Monoclinic

923.54 Monoclinic

864.47 Orthorhombic

1032.28 Orthorhombic

P21/c

C2/c

P212121

Pnma

a (Å)

10.211(2)

28.947(14)

10.373(5)

24.063(6)

b (Å)

19.216(3)

8.332(5)

15.088(5)

15.192(5)

c (Å)

14.786(2)

18.328(10)

24.126(5)

10.487(4)

α(º)

90.00

90.00

90.00

90.00

β (º)

96.447(1)

114.792(4)

90.00

90.00

γ(º)

90.00

90.00

90.00

90.00

2882.81(6)

4013.2(4)

3776(2)

3833.33(17)

4

4

4

4

1.403

1.529

1.521

1.789

296 0.91

293 1.27

293 1.34

293 1.34

2.5–31.8

1.6-27.3

2.4-27.5

1.6-27.3

Measured refls.

30673

12649

65056

31016

Independent refls.

5898

4254

8620

3886

Rint

0.020

0.098

0.029

0.106

S

1.02 0.043/ 0.138

1.03 0.088/ 0.263

1.03 0.075/ 0.205

1.03 0.084/ 0.228

0.69/ -0.78

2.17/ -1.90

2.16/ -2.25

1.35/ -1.86

Formula weight Crystal system Space group

V (Å3) Z Dc (g cm-3) T (K) µ (mm-1) θ range (º)

R1/wR2 -3

∆ρmax/∆ρmin (eÅ )

594



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 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

595

Page 30 of 41

Table 2. Crystal data and structure refinement parameters for complexes 5-7 5 Empirical formula

6

7

C46H60N11O13Zn2

C33H35N7O10Zn2

C35H39N7O11Zn2

1105.79 Triclinic

820.42 Monoclinic

864.47 Monoclinic

P -1

C2/c

C2/c

a (Å)

10.482(14)

27.519(10)

27.621(7)

b (Å)

12.424(4)

10.425(5)

10.512(3)

c (Å)

19,804 (5)

14.866(6)

14.761(4)

α(º)

75.229(14)

90.00

90.00

β (º)

81.277(14)

117.541(2)

117.048(1)

γ(º)

82.936 (12)

90.00

90.00

V (Å3)

2455.35(11)

3781.3(2)

3817.30(18)

2

4

4

1.496

1.441

1.504

120 1.05

296 1.33

296 1.33

2.4-27.4

2.9-29.6

2.8-33.3

Measured refls.

42001

27982

15685

Independent refls.

11320

7035

3835

Rint

0.033

0.045

0.020

S

1.04 0.065/ 0.191

1.06 0.095/ 0.277

1.08 0.1/ 0.271

1.43/ -1.15

4.65/ -4.66

4.15/ -4.27

Formula weight Crystal system Space group

Z Dc (g cm-3) T (K) µ (mm-1) θ range (º)

R1/wR2 -3

∆ρmax/∆ρmin (eÅ )

596 597


Page 31 of 41

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 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


(a)

(b)

(c)

598 599

Fig. 1. (a) The molecular structure of 1 showing the atom numbering scheme ((i) 1+x, y, z;

600

(ii) 1-x, 1-y, 2-z) (b) space-filling mode of 2D structure viewed along the c-axis (c) a

601

schematic representation of 3,4-connected binodal net in 1

602



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 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 32 of 41

(a)

(b)

(c)

(d)

603

Fig. 2. (a) The molecular structure of 2 showing the atom numbering scheme ((i) x, -y+1, z-½;

604

(ii) -x+½, y-½, -z+½) (b) 3D framework of 2 viewed along the b-axis (c) space-filling mode of

605

3D structure in 2 (d) a view of 3D (3,6)-connected sqc5381 net

606 607


Page 33 of 41

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 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


(a)

(b)

608

Fig. 3. (a) The molecular structure of 3 showing the atom numbering scheme ((i) x+½, -y+½,

609

-z; (ii) -x−½, -y+1, z-½; (iii) –x-1, y+½, -z+½) (b) 3D framework of 3 in the ac plane

610 611



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 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

612 613

(a)

614 615 616 617

Fig. 4. (a) The molecular structure of 4 showing the atom numbering scheme (b) 3D

618

framework of 4 (ac plane)

(b)

619


Page 34 of 41

Page 35 of 41

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 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


(a)

(b)

(c)

620 621

Fig. 5. (a) The molecular structure of 5 showing the atom numbering scheme (b) space-filling

622

mode of 3D structure in 5 (c) a topological view of 3D 3,4,4,4-connected 4-nodal net

623 624



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 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

625 626

(a)

627 628

(b)

629

Fig. 6. The molecular structures of (a) 6 ((i) -x+½, -y+½, -z; (ii) -x+½, y-½, -z+½; (iii) x, -

630

y+1, z-½) and (b) 7 ((i) x, -y+2, z-½; (ii) -x-½, y-½, -z+3/2; (iii) -x-½, -y+3/2, -z+1)) showing

631

the atom numbering scheme

632 633


Page 36 of 41

Page 37 of 41

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 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


(a) 634

(b)

Fig. 7. Space-filling modes of 3D structures in (a) 6 and (b) 7 viewed along the c*-axis

635



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 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

636 637

Fig. 8. CO2 adsorption-desorption isotherms for 1a-7a at 273 K and 1 bar

638


Page 38 of 41

Page 39 of 41

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 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

639 640 641



642



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 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

643 644 645



Page 40 of 41

Page 41 of 41

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 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

646 647


For Table of Contents Use Only

648 649

Seven novel Zn(II)-coordination polymers with flexible substitute bis(imidazole)

650

linkers and 3,3′,5,5′-azobenzenetetracarboxylic acid to investigate the effect of substitute

651

groups of bis(imidazole) ligands on the structural diversity and characterized. Paddlewheel

652

Zn2(CO2)4 binuclear SBUs were observed with the increase of length of substitute alkyl

653

groups from methyl- to isopropyl- on imidazole rings in channels. CO2 adsorption results

654

showed that uptake capacities of complexes were decreased with the increase of length of

655

substitute alkyl groups from methyl- to isopropyl- in channels.

656 657

Construction, Structural Diversity and Properties of Seven Zn(II)-Coordination

658

Polymers Based on 3,3′,5,5′-Azobenzenetetracarboxylic Acid and Flexible Substitute

659

Bis(imidazole) linkers

660

Mürsel Arıcıa,*, Okan Zafer Yeşilela, Murat Taşb, Hakan Demiralc, Hakan Erera

661


Construction, Structural Diversity, and Properties of ... - ACS Publications

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