Synthesis, Structural Diversity, and Properties of Cd MetalâOrganic

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Synthesis, Structural Diversity and Properties of Cd– MOFs Based on 2-(5-Bromo-pyridin-3-yl)-1H-imidazole-4,5dicarboxylate and N-Heterocyclic Ancillary Ligands Ruiying Wang, Lina Liu, Lulu Lv, Xing Wang, Rui Chen, and Benlai Wu Cryst. Growth Des., Just Accepted Manuscript • Publication Date (Web): 19 May 2017 Downloaded from http://pubs.acs.org on May 22, 2017

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Crystal Growth & Design

1

Synthesis, Structural Diversity and Properties of Cd–MOFs Based on

2

2-(5-Bromo-pyridin-3-yl)-1H-imidazole-4,5-dicarboxylate and

3

N-Heterocyclic Ancillary Ligands

4

Ruiying Wang,†,‡ Lina Liu,† Lulu Lv,† Xing Wang,† Rui Chen,† and Benlai Wu*,†

5 6

†College of Chemistry and Molecular Engineering, Zhengzhou University,

7

Zhengzhou 450001, P. R. China

8

‡School of Chemical Engineering, Henan Vocational College of applied technology,

9

Zhengzhou 450042, P. R. China

10 11

Five

1‒3D

cadmium(II)

coordination

polymers,

namely,

12

ABSTRACT:

13

[Cd(HL)(DMF)]n (1), [Cd4(HL)4(H2O)6]n (2), [Cd(HL)(phen)]n (3), [Cd2(HL)2(bpy)]n

14

(4), and {[Cd3(HL)3(pbim)2]·H2O}n (5), have been synthesized and fully characterized

15

[H3L = 2-(5-bromo-pyridin-3-yl)-1H-imidazole-4,5-dicarboxylic acid, DMF =

16

N,N-dimethylformamide, phen = 1,10-phenanthroline, bpy = 4,4'-bipyridine, and

17

pbim = 1,1'-(5-methyl-1,3-phenylene)bis(1H-imidazole)]. In those complexes the

18

doubly deprotonated H3L ligands and CdII ions display versatile coordination modes

19

to construct various structures with interesting topologies. Complex 1 is a 2D helical

20

structure with (4·82) topology built up from 3-connected (HL)2‒ and CdII nodes.

21

Complex 2 containing (HL)2‒-bridged tetranuclear CdII subunits is a 3D helical

22

structure where both (HL)2‒ and CdII adopt three coordination modes to form a rare

23

3-connected network with (5·8·12)2(5·12·16)2(5·82)(82·12) topology. As substituted

24

the smaller terminal ligands DMF or water with larger terminal ligands phen, (HL)2‒

25

ligands only use their imidazoledicarboxylate groups to bis-chelate CdII into a chain

26

structure of 3. Complex 4 is a (3,4)-connected 3D network with (4·82)(4·82·103)

27

topology built up from the (HL)2‒-bridged (4,82) meso-layer observed in 1 being

28

further linked by rod-like bpy bridges replacing terminal ligands DMF. Complex 5

29

consists of (HL)2‒- and pbim-bridged macrocycle chains, and is a (3,4)-connected 2D 1

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novel network with (3·4·8)2(3·4·5·82·9)2(32·82·92) topology. As expected that the

31

strongly

32

imidazoledicarboxylate of (HL)2‒ absolutely dominates the assemblies with CdII in

33

those complexes. Intriguingly, the additional ligands, such as smaller terminal ligands

34

water and DMF, larger planar terminal ligand phen, and as well as rod-like and

35

V-shaped bridges bpy and pbim, exert obvious influence upon the coordination modes

36

of ligands (HL)2‒ and the resulting architectures. Clearly, larger terminal and bridging

37

ligands phen and pbim could limit the coordination of the pyridyl of (HL)2‒ through

38

steric hindrance. Meanwhile, the solid-state photoluminescence of those compounds

39

at room temperature was also investigated, and the results indicate that their emissions

40

are significantly influenced by the additional ligands incorporating into the networks.

bis-chelating

coordination

mode

µ-kN,O:kN′,O′

of

the

41

2-(5-Bromo-pyridin-3-yl)-1H-imidazole-4,5-dicarboxylic

acid,

42

Keywords:

43

Cadmium(II) coordination polymer, Topology, Luminescence, Mixed ligand system

44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 2


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INTRODUCTION

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Metal–organic frameworks (MOFs) as a new class of multifunctional materials have

61

greatly attracted current attention, and been extensively explored for potential

62

applications in gas storage and separation, fluorescence, heterogeneous catalysis,

63

sensing,

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4,5-imidazoledicarboxylic acid (H3IDC) as a rigid and multifunctional bridge has

65

been immensely used to construct MOFs.8‒15 Those results disclosed that H3IDC

66

ligand shew intriguing versatility of coordination modes but usually adopted the

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dominated bis-chelating coordination mode µ-kN,O:kN′,O′ to direct the construction

68

of MOFs. Of further interest is functionalized H3IDC at its 2-positon with diverse

69

substituents such as methyl, ethyl, or pyridyl, and based on this modification a series

70

of H3IDC’s derivatives have been designed, synthesized and used to construct MOFs

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with various metal ions by our and other groups.16‒24 Very interestingly, it was found

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that those derivatives not only carried forward the merits such as coordination

73

direction and diversity from H3IDC but also added tunable factors such as additional

74

coordination sites and structural constraint from the substituents which could be

75

further used to control the assemblies of MOFs. Furthermore, the functionalization at

76

the 2-positon of H3IDC could endow the resulting derivatives and MOFs with unique

77

properties. Accordingly, the derivatives of H3IDC have become a class of first-rank

78

ligands for constructing MOFs with abundant diversities in architectures and

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topologies as well, but their coordination chemistry remains largely unexplored.

magnetism,

drug

delivery,

etc.1‒7

In

the

past

decades,

80

In this context as well as further pursuing our work in this area, we designed and

81

synthesized 2-(5-bromo-pyridin-3-yl)-1H-imidazole-4,5-dicarboxylic acid (H3L),

82

another analogous to our previously reported pyridyl-containing H3IDC’s derivatives

83

(Scheme 1).16‒17 In contrast with 2-(pyridine-3-yl)-1H-4,5-imidazoledicarboxylic acid

84

ligand,24 the additional halogen atom Br in H3L not only provides halogen-related

85

interactions to extend the dimension of the resulting MOFs but also influences the

86

photoelectric properties and chemical environment of the MOFs, which has become

87

quite attractive in recent crystal engineering.25,26 In this paper, cadmium(II) ion, one 3



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of currently used metal ions for the construction of functional MOFs, has been

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selected as metal centers to incorporate into our aimed H3L-based MOFs due to its

90

labile coordination number and the interesting fluorescence of its complexes.27‒31 As

91

is well known, the combination of different ligands may result in greater tunability

92

than that present only with single ligand to construct MOFs,32‒36 and thus a series of

93

N-heterocyclic ligands such as planar chelating ligand 1,10-phenanthroline (phen),

94

rod-like

95

1,1'-(5-methyl-1,3-phenylene)bis(1H-imidazole) [pbim], are chosen as auxiliary

96

ligands in our present work (Scheme 1). By doing so, we hope to modulate the

97

structures and properties of H3L-based Cd─MOFs through the different structure

98

types and coordination tendencies of the additional ligands, and to further understand

99

the assembly principles in a mixed ligand system as well. We report herein the

100

syntheses, structural analysis, thermal stability, and photoluminescent properties of

101

five cadmium(II) complexes, namely, [Cd(HL)(DMF)]n (1), [Cd4(HL)4(H2O)6]n (2),

102

[Cd(HL)(phen)]n (3), [Cd2(HL)2(bpy)]n (4), and {[Cd3(HL)3(pbim)2]·H2O}n (5) [DMF

103

= N,N-dimethylformamide]. Interestingly, the change of the substituent in

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imidazole-based dicarboxylic ligand and the use of auxiliary ligands lead to the

105

architectural diversity of those Cd─MOFs.

bridge

4,4'-bipyridine

(bpy),

and

V-shaped

bridge

106 107

EXPERIMENTAL SECTION

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Materials and General Procedures. All chemicals purchased were of reagent

109

grade or better and used without further purification. The ligand H3L was prepared by

110

following

111

2-(pyridin-4-yl)-1H-imidazole-4,5-dicarboxylic acid,37 and the detailed synthesis and

112

characterization data were provided in the supporting information. Element analyses

113

were performed with a Carlo-Erba 1106 elemental analyzer. IR spectra (KBr pellets)

114

were recorded on a Nicolet NEXUS 470 FT–IR spectrophotometer from 400 to 4000

115

cm−1. Thermal analysis curves were scanned from 30 to 800 °C under air on a STA

116

409 PC thermal analyzer. The solid-state fluorescent spectra were determined at room

the

reported

procedure

for

4


the

synthesis

of

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117

temperature on a Hitachi F-4500 fluorophotometer with a xenon arc lamp as light

118

source. The powder X-ray diffraction (PXRD) patterns of the samples were recorded

119

by a RIGAKU-DMAX2500 X-ray diffractometer with Cu-Kα radiation.

120

Synthesis of [Cd(HL)(DMF)]n (1). A mixture of CdSO4·8H2O (0.0176 g, 0.05

121

mmol), H3L (0.0156 g, 0.05 mmol), NaOH (0.0040 g, 0.1 mmol), methanol (6 mL)

122

and DMF (2 mL) was stirred for 30 min under room temperature, and then filtered.

123

With the filtrate evaporating under room temperature without disturbance for 4 weeks,

124

colorless block crystals were obtained, washed with methanol, and dried in air. Yield

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34% (based on Cd). Anal. Calcd for C13H11BrCdN4O5 (%): C, 31.51; H, 2.24; N,

126

11.31. Found: C, 31.64; H, 2.26; N, 11.25. IR (KBr, cm−1): 3445(br), 1651(s),

127

1580(vs), 1474(m), 1381(m), 1010(m), 895(m), 864(m), 681(w), 543(w).

128

Synthesis of [Cd4(HL)4(H2O)6]n (2). A mixture of Cd(NO3)2·4H2O (0.0154 g, 0.05

129

mmol), H3L (0.0156 g, 0.05 mmol), NaOH (0.0040 g, 0.1 mmol), and deionized H2O

130

(7 mL) was sealed in a 25 mL Teflon-lined stainless autoclave and heated at 150 °C

131

for 72 h. After the mixture was cooled to room temperature at a rate of 5 °C·h−1,

132

colorless block crystals were obtained, washed with distilled water, and dried in air.

133

Yield 48% (based on Cd). Anal. Calcd for C40H28Br4Cd4N12O22 (%): C, 26.72; H, 1.57;

134

N, 9.35. Found: C, 26.51; H, 1.59; N, 9.40. IR (KBr, cm−1): 3432(br), 1613(vs),

135

1560(s), 1540(s), 1404(m), 1382(m), 1019(m), 996(m), 856(m), 785(w), 551(w).

136

Synthesis of [Cd(HL)(phen)]n (3). A mixture of Cd(NO3)2·4H2O (0.0154 g, 0.05

137

mmol), H3L (0.0156 g, 0.05 mmol), phen (0.0090 g, 0.05 mmol), NaOH (0.0040 g,

138

0.1 mmol), methanol (4 mL), and deionized H2O (3 mL) was sealed in a 25 mL

139

Teflon-lined stainless autoclave and heated at 150 °C for 72 h. After the mixture was

140

cooled to room temperature at a rate of 5 °C·h−1, colorless block crystals were

141

obtained, washed with methanol, and dried in air. Yield 54% (based on Cd). Anal.

142

Calcd for C22H12BrCdN5O4 (%): C, 43.84; H, 2.01; N, 11.62. Found: C, 43.95; H,

143

1.98; N, 11.57. IR (KBr, cm−1): 3440(br), 1583(vs), 1538(s), 1463(m), 1382(s),

144

1019(m), 937(m), 853(w), 729(m), 636(m), 516(w).

145

Synthesis of [Cd2(HL)2(bpy)]n (4). A mixture of Cd(NO3)2·4H2O (0.0154 g, 0.05

146

mmol), H3L (0.0156 g, 0.05 mmol), bpy (0.0039 g, 0.025 mmol), NaOH (0.0040 g, 5



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147


148


149

cooled to room temperature at a rate of 5 °C·h−1, colorless block crystals were

150


151

Calcd for C30H16Br2Cd2N8O8 (%): C, 35.99; H, 1.61; N, 11.19. Found: C, 36.12; H,

152

1.64; N, 11.12. IR (KBr, cm−1): 3412(br), 1604(m), 1575(vs), 1479(s), 1416(m),

153

1272(m), 1122(s), 1100(m), 700(m), 628(s), 550(w).

154

Synthesis of {[Cd3(HL)3(pbim)2]·H2O}n (5). A mixture of CdI2 (0.0183 g, 0.05

155

mmol), H3L (0.0156 g, 0.05 mmol), pbim (0.0112 g, 0.05 mmol), NaOH (0.0040 g,

156


157


158

cooled to room temperature at a rate of 5 °C·h−1, pale yellow block crystals were

159


160

Calcd for C56H37Br3Cd3N17O13 (%): C, 38.81; H, 2.15; N, 13.74. Found: C, 38.54; H,

161

2.19; N, 13.80. IR (KBr, cm−1): 3423(br), 1609(m), 1536(vs), 1508(s), 1457(m),

162

1384(s), 1251(s), 1113(m), 745(m), 618(s), 548(w).

163

X-ray Structure Determination and Structure Refinement. On an Oxford

164

diffractometer equipped with a CCD detector, single-crystal X-ray data were collected

165

at 293(2) K using graphite-monochromated Cu Kα radiation (λ = 1.5418 Å) and Mo

166

Kα radiation (λ = 0.71073 Å) for 1–2 and 3–5, respectively. Absorption corrections

167

were applied by using the multiscan program SADABS.38 Structural solutions and

168

full-matrix least-squares refinements based on F2 were performed with the

169

SHELXS-9739 and SHELXL-9740 program packages, respectively. All the

170

non-hydrogen atoms were refined with anisotropic displacement parameters during

171

the final cycles. The H atoms attached to C were generated geometrically while the H

172

atoms attached to O were located from different Fourier maps and treated as idealized

173

contributions. The crystal and refinement data are collected in Table 1, and the

174

selected bond distances and angles are given in Table S1.

175

6


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176

RESULTS AND DISCUSSION

177

Synthesis and General Characterization of Compounds 1−5. In the preparation

178

of compounds 1‒5, NaOH was used to deprotonate in a molar ratio of NaOH and H3L

179

being 2:1. In this basicity, two protons were removed from every H3L ligand, and each

180

H3L ligand acts as a divalent anion (HL)2−. In combination with the following

181

structural analysis, it can be observed that the proton dissociation from ligand H3L

182

occurred in the imidazole group and one carboxyl. But adding more alkali for further

183

deprotonation, such as in a molar ratio of NaOH and H3L being 3:1, only resulted in

184

unidentified precipitates. As the ratios of metal CdII and ligand H3L varied from 1:1 to

185

1.5:1 or to 2:1 in combination with the suitable modification of basicity, unidentified

186

precipitates were also obtained. Remarkably, those hydro/solvothermal reaction

187

systems are very sensitive to temperature: irregular polycrystals being obtained at

188

lower temperature such as 140 °C or 145 °C; but at a higher temperature such as

189

160 °C, precipitates being obtained only.

190

As for synthesis methods, compound 1 was obtained through the traditional

191

evaporation of the resulting methanol/DMF reaction solution whereas the others were

192

hydro/solvothermally synthesized at 150 °C by changing solvents from water to

193

water/methanol mixtures. Notably, 3‒5 were obtained in the presence of the auxiliary

194

ligands phen, bpy and pbim, respectively.

195

The chemical formulas of these complexes have been confirmed by satisfactory

196

elemental analysis and X-ray diffraction. In the IR spectra of 1−5, the strong and

197

broad absorption bands in a range of 3412−3445 cm−1 may be assigned to the

198

characteristic peaks of the νO–H stretching frequencies of the undeprotonated carboxyl

199

in ligand (HL)2− and water molecules, respectively. Five complexes exhibit strong

200

characteristic absorptions around 1536−1613 cm−1 [νas(COO−)] and 1382−1479 cm−1

201

[νs(COO−)], respectively. As for the strong absorption band centered at 1651 cm−1 in

202

the IR spectrum of 1, it may be attributed to the νc=o stretching frequency of the

203

coordinated DMF.

204

The phase purity of the as-synthesized crystalline products 1−5 was determined by 7



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205

powered X-ray diffraction (PXRD) measurements. As shown in Figures S1−5, the

206

calculated PXRD patterns from the single-crystal X-ray diffraction data are in good

207

agreement with the observed ones, indicating the phase purity of the polycrystalline

208

samples. Thermal stability of these complexes was investigated by the TGA technique

209

(Figure S6). The TGA curves of 1 and 2 are similar. They began weight losses at 125

210

and 120 °C, respectively. With heating, they suffered continuous weight losses until to

211

770 and 630 °C, respectively. The resulting residues of 26.34% for 1 and 28.45% for

212

2 are presumed to be CdO (calcd 25.91 and 28.57% for 1 and 2, respectively).

213

Compounds 3 and 4 are stable up to 327 and 267 °C, respectively. As overtaken by

214

their heat-resisting temperatures, the samples of 3 and 4 suffered continuous

215

decomposition processes. In the crucibles, the remains of 22.07% for 3 and 24.73%

216

for 4 may be CdO (calcd 22.49 and 25.65% for 3 and 4, respectively). The

217

dehydration process of 5 occurred from 85 to 135 °C, and a further continuous weight

218

loss followed from 178 to 715 °C with the resulting residue of 21.79% perhaps being

219

CdO (calcd 22.21%).

220

Structural Analysis and Discussion. [Cd(HL)(DMF)]n (1). Compound 1

221

crystallizes in monoclinic C2/c space group, and its asymmetrical unit contains one

222

CdII, one (HL)2−, and one DMF molecule. As shown in Figure 1, the CdII center is

223

coordinated with three N and two O atoms from three individual (HL)2− ligands and

224

one O atom from a DMF molecule, forming a sharply distorted coordination

225

octahedron with the cis- and trans-bond angle ranges of 72.4(1)−112.4(2)° and

226

149.6(2)−168.2(1)°, respectively. In the coordination octahedron, two of the three

227

(HL)2− ligands cis-chelate the CdII center with the N and O atoms from their

228

imidazoledicarboxylate groups, and the dihedral angle between the two chelating

229

rings is 79.9(2)°. Cd−N and Cd−O distances cover a range of 2.280(4)−2.346(4) Å,

230

being comparable to our reported values in the cadmium(II) complexes of H3IDC’s

231

analogues.14‒21

232

In 1 each (HL)2− ligand adopts a µ3-kN,O:kN′,O′:kN′′ coordination mode with its

233

imidazoledicarboxylate chelating two CdII and its pyridyl bonding another CdII. The

234

resulting dihedral angle between the imidazole and pyridyl groups of (HL)2− is 8


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235

37.0(3)°, which contrasts with the almost coplanar conformer of H3L found in its

236

adduct of bpy (Figure S7). Every CdII in 1 also acts as a 3-connector ligating with

237

three (HL)2− ligands. As displayed in Figure 2a, (HL)2− ligands in bis-N,O-chelating

238

modes bridge CdII centers into b axially extended left- and right-handed helixes with

239

the 21 helical pitches being 8.761(1) Å, and those adjacent left- and right-handed

240

helixes are further linked together through the coordination of the pyridyl groups of

241

(HL)2− ligands. Consequently, it forms a 3-connected meso-layer with (4·82)-topology

242

(Figure 2b). Finally, those layers stack up along a axis through interlayered

243

Br···Ocarboxyl interactions (3.002(5) Å),25,26 forming a 3D supramolecular framework

244

(Figure S8).

245

[Cd4(HL)4(H2O)6]n (2). Compound 2 crystallizes in monoclinic P21/c space group,

246

and its asymmetrical unit contains four CdII, four (HL)2−, and six coordinated H2O.

247

The four crystallographically independent CdII are bridged by the four

248

crystallographically independent (HL)2− to form a tetranuclear [Cd4(HL)4] subunit

249

(Figure S9). As shown in Figure 3, CdII centers and (HL)2− ligands in 2 have three

250

kinds of coordination geometries and modes, respectively. The Cd1 and Cd3 adopt

251

distorted pentagonal bipyramid geometries with three N and two O atoms from two

252

trans-chelating imidazoledicarboxylates and one pyridyl of three individual (HL)2−

253

ligands in the equatorial plane and two O atoms from water molecules at the apical

254

sites (the bond lengths of Cd−N and Cd−O ranging from 2.334(5) to 2.453(5) Å). The

255

Cd2 is in a sharply distorted octahedron with two N and two O atoms from two

256

trans-chelating imidazoledicarboxylates of two (HL)2− ligands in the equatorial plane

257

and two O atoms from one water molecule and one bridging carboxylate of another

258

(HL)2− ligand at the apical sites (the bond lengths of Cd−N and Cd−O ranging from

259

2.283(4) to 2.360(7) Å). Cd4 is five-coordinated by two N and three O atoms from

260

two trans-chelating imidazoledicarboxylates of two (HL)2− ligands and a water

261

molecule and thereby form a distorted trigonal bipyramid geometry with the three

262

coordinated O atoms in the equatorial plane and the two N atoms at the apical sites

263

(the bond lengths of Cd−N and Cd−O ranging from 2.184(10) to 2.278(5) Å). Notably,

264

the bond lengths of Cd−N and Cd−O in 2 comparatively shorten with the decrease of 9



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265

coordination number of CdII ions from 7 to 5, but fall in the normal ranges.27‒31 As for

266

the four crystallographically independent (HL)2− ligands, two of them adopt

267

µ3-kN,O:kN′,O′:kN′′ coordination mode observed in 1 to connect Cd1, Cd3 (Cd3E)

268

and Cd4 (Cd4C), one adopts µ3-kN,O:kN′,O′:kO′′ coordination mode to bridge Cd1,

269

Cd2 and Cd2D, and the other adopts µ-kN,O:kN′,O′ coordination mode to chelate Cd2

270

and Cd3 (Figure 3). In 2 the four crystallographically independent (HL)2− ligands vary

271

the dihedral angles between their imidazole and pyridyl groups from 21.1(3) to

272

32.7(3)°, matching coordination requirement in different conformers.

273

As shown in Figure 4a, the Cd1 and Cd2 in adjacent [Cd4(HL)4] subunits are

274

bis-chelated by the ligands (HL)2− in the µ3-kN,O:kN′,O′:kO′′ coordination mode. As a

275

result those subunits are bridged into b axially extended left- and right-handed helixes

276

with the 21 helical pitches being 8.2845(1) Å. The adjacent left- and right-handed

277

helixes are further linked together along c axis through the ligands (HL)2− in the

278

µ3-kN,O:kN′,O′:kN′′ coordination mode bis-chelating with the Cd1 and Cd4 of

279

adjacent helixes, which results in a meso-layer (Figure 4b). Notably, the ligands

280

(HL)2− which bridge left- and right-handed helixes into meso-layers further use their

281

Npyridyl to ligate Cd3 nodes in adjacent layers, and finally form a complicated 3D

282

framework (Figure 5a). In 2 three-fourths of CdII centers and (HL)2− ligands act as

283

3-connected nodes while the other one-fourth of them just acts as connections. The

284

molar ratio of those nodes is 2:2:1:1, and thus the resulting structure can be simplified

285

as a rare 3-connected network with a Schläfli symbol of (5·6·12)2 (5·122)2 (62·12)

286

(5·62) (Figure 5b).

287

[Cd(HL)(phen)]n (3). Compound 3 crystallizes in monoclinic P21/c space group,

288

and its asymmetrical unit contains one CdII, one (HL)2−, and one phen. The CdII center

289

in 3 is located in a N4O2 coordination octahedron cis-chelated by two

290

imidazoledicarboxylates of two (HL)2− ligands and one phen molecule (Figure 6). The

291

bond lengths of Cd−N and Cd−O range from 2.213(3) to 2.438(3) Å while the cis-

292

and trans-bond angles range from 69.6(1)−159.8(1)°, indicating a sharp distortion of

293

the coordination geometry from an ideal octahedron. In 3, the dihedral angle between

294

the imidazole and pyridyl groups of (HL)2− ligand is 37.3(2)°, being very similar to 10


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295

that in 1. Notably, the introduction of the planar chelating ligand phen not only edges

296

out the coordination of the smaller solvent molecules, but limits the dimension of the

297

resulting polymer and the coordination number of (HL)2− ligands as well. Due to the

298

stronger chelation and steric hindrance of auxiliary phen ligands, (HL)2− ligands in 3

299

only use their imidazoledicarboxylates to bis-chelate CdII centers, and thereby form a

300

c axially extended zigzag polymeric chain (Figure 6). Their pyridyls do not participate

301

in the further coordination with CdII. In the chain structure, every chelating phen leans

302

to one (HL)2− ligand so that doubly intrachain π···π interactions occur between the two

303

ligands (Figure S10; the centroid-to-centroid distance between the pyridyl ring

304

N5C18C19C20C21C22 of phen and the imidazole ring N1AC2AC3AN2AC21C5A of (HL)2−

305

being 3.798(2) Å; the centroid-to-centroid distance between the pyridyl ring

306

N4C11C12C13C14C17 of phen and the pyridyl ring C6AC7AC8AC9AN3AC10A of (HL)2−

307

being 3.548(3) Å; A = x, 1/2 − y, − 1/2 + z). The neighboring polymeric chains

308

connect each other through interchain Br···Ocarboxyl interactions (3.041(3) Å),25,26

309

resulting in a 2D supramolecular framework (Figure S11).

310

[Cd2(HL)2(bpy)]n (4). Compound 4 crystallizes in orthorhombic Pccn space group,

311

and its asymmetrical unit contains one CdII, one (HL)2−, and one half bpy molecule.

312

As showed in Figure 7, the CdII center is in a sharply distorted N4O2 octahedron

313

ligated by two N and two O atoms from two cis-chelating imidazoledicarboxylates of

314

two (HL)2− ligands and two other N atoms from the pyridyls of another (HL)2− ligand

315

and one bpy molecule, respectively. The dihedral angle between the two chelating

316

rings is 69.3(3)°, which is smaller than that observed in 1. The bond distances and

317

bond angles are comparable with those values found in the octahedral CdII of 1.

318

Ligands (HL)2− in 4 also adopt µ3-kN,O:kN′,O′:kN′′ coordination mode, and link

319

CdII centers into a meso-layer with the (4,82)-topology as observed in 1 (Figure 2).

320

The dihedral angle between the imidazole and pyridyl groups of ligand (HL)2− is

321

38.1(3)°, being very similar to those found in 1 and 3. In 4, those a axially extended

322

left-

323

imidazoledicarboxylates with CdII centers have a shorter 21 helical pitch of 7.8467(4)

324

Å. Along c axis, adjacent hetero-chiral helixes further tie together through the further

and

right-handed

helixes

formed

by

the

bis-N,O-chelation

11


of

the


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

325

coordination of the pyridyls of (HL)2− ligands with CdII nodes to form the meso-layers.

326

Uniquely, the rigid rod-like ancillary ligands bpy further bridge CdII centers from

327

adjacent homo-chiral helixes in different meso-layers, and then form a 3D

328

coordination polymer (Figure 8). In a sense, the formation of 4 can be regarded as the

329

in-situ replacement of the terminal ligands DMF in 1 by the bridges bpy.

330

Topologically, the 3D structure of 4 can be simplified as a (3,4)-connected network

331

with the Schläfli symbol of (4·82)(4·82·103) where (HL)2− ligands and CdII centers act

332

as 3- and 4-connected nodes, respectively (Figure 8b).

333

{[Cd3(HL)3(pbim)2]·H2O}n (5). Compound 5 crystallizes in triclinic P-1 space

334

group, and its asymmetrical unit consists of three CdII, three (HL)2−, two pbim, and

335

two lattice H2O. As shown in Figure 9, the three crystallographically independent CdII

336

all adopt six-coordinated distorted octahedral geometries. The Cd1 and Cd3 in N3O3

337

octahedra are coordinated by two N and two O atoms from two cis-chelating

338

imidazoledicarboxylates of two (HL)2− ligands, one O from the carboxylate of another

339

(HL)2− ligand, and one N atom from a pbim molecule. The Cd2 as the interval of Cd1

340

and Cd3 is in a N4O2 octahedron ligated by two N and two O atoms from two

341

cis-chelating imidazoledicarboxylates of two (HL)2− ligands and another two N atoms

342

from two pbim molecules. Every CdII center in 5 is cis-chelated by two (HL)2− ligands

343

like that found in 1, but the dihedral angles between two chelating rings ranging from

344

63.8(3) to 69.5(3)° is smaller than that of 79.9(2)° in 1 and close to that in 3. The

345

Cd−N and Cd−O distances cover a normal range of 2.251(7)−2.485(6) Å. The three

346

crystallographically independent (HL)2− ligands in 5 adopt two kinds of coordination

347

modes: one adopting µ-kN,O:kN′,O′ coordination mode just like that observed in 3

348

and the other two adopting µ3-kN,O:kN′,O′:kO′ coordination mode. As observed in 3,

349

the pyridyls of all (HL)2− ligands in 5 do not participate in the further coordination

350

with CdII. For the three crystallographically independent (HL)2− ligands, the dihedral

351

angles between their imidazole and pyridyl groups are 30.8(5), 44.8(5), and 41.1(5)°,

352

respectively. The two crystallographically independent pbim ligands bridge Cd1 and

353

Cd2 or Cd2 and Cd3, respectively, and the dihedral angles between their two

354

imidazole rings are 41.9(6) and 33.9(6)°, respectively. 12


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355

Complex 5 features a 2D network consisting of polymeric macrocycle chains

356

(Figure 10a). As shown in Figure 10b, there are two kinds of similar trinuclear rings:

357

one formed by a (HL)2− ligand in µ3-kN,O:kN′,O′:kO′ coordination mode connecting

358

Cd1, Cd1B and Cd2 and a pbim bridging Cd1 and Cd2, and the other formed by

359

another (HL)2− ligand in µ3-kN,O:kN′,O′:kO′ coordination mode connecting Cd2, Cd3

360

and Cd3C and another pbim bridging Cd2 and Cd3C. Through sharing with the Cd2

361

nodes and the µ-Ocarboxylic-bridging binuclear [(µ-O)2(Cd3)2] or [(µ-O)2(Cd1)2] units,

362

those trinuclear rings are linked into the macrocyclic chain structure. The ligands

363

(HL)2− in the µ-kN,O:kN′,O′ coordination mode bis-chelate with Cd1 and Cd3 atoms

364

of adjacent chains to form the 2D network. Topologically, two-thirds (HL)2− ligands

365

act as 3-connected nodes while the other one-third (HL)2− ligands and all pbim ligands

366

just act as connectors, and all CdII centers can be regarded as 4-connected nodes. In

367

this way, the structure of 5 can be rationalized as a (3,4)-connected net. The molar

368

ratio of those three kinds of nodes is 2:2:1. Thus, the framework of 5 is symbolized as

369

a very novel (3·4·8)2(3·4·5·82·9)2(32·82·92) network (Figure 11). The crystal packing

370

analysis show that those 2D frameworks interdigitate together along b axis through

371

interlayered π···π interactions between pbim molecules of adjacent layers (Figure S12,

372

the centroid-to-centroid distance between the imidazole and phenylene rings of pbim

373

ligands being 3.649(6) Å).

374

Photoluminescence Properties. The solid-state luminescent properties of

375

cadmium(II) polymers 1–5 were investigated at room temperature (the phase purity

376

was confirmed by powder X-ray diffraction as shown in Figures S1−5). Compounds

377

1–5 all exhibited one emission band centered at 421, 448, 449, 444 and 400 nm upon

378

excitation at 366, 365, 383, 362 and 345 nm, respectively (Figure 12). In combination

379

with the emission spectra of free ligands H3L, phen, bpy and pbim (Figures S13−14),

380

the emission bands of 1–5 that slightly blue- or red-shift from the 425 nm emission of

381

free ligand H3L can be mainly attributed to the intraligand π–π* transitions of (HL)2−

382

ligands, which can be compared with those emissions reported for cadmium(II)

383

complexes with other N-donor ligands.16‒19,27‒31 The differences in the excitation and

384

emission energies for 1–5 is dependent on metal–ligand perturbations, and thereby on 13



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

385

the coordination geometries of CdII in every compound. Additionally, the relatively

386

broad emission bands for 3–5 indicate some contribution from the intraligand π–π*

387

transitions of the auxiliary ligands phen, bpy and pbim. On the whole, complexes 1–5

388

exhibit stronger emission intensities compared to the emission peak of free ligand H3L.

389

The intensity increase of the luminescence for these complexes may be attributed to

390

the chelation of (HL)2− with CdII centers, which increases the rigidity of (HL)2− and

391

reduces the nonradiative relaxation process (CHEF effect).16,17,31,41,42 As shown in

392

Figure 12, however, the emissions for (HL)2‒-bridged 2D polymer 1 and 3D polymer

393

2, especially for 1, are more stronger than those for 1–3D polymers 3–5 built from the

394

mixed ligands (main ligand (HL)2‒ and auxiliary ligands phen, bpy and pbim). The

395

obvious difference in the emission intensities for 1–5 could be further explained based

396

on their structures. For the 1–3D polymers 3–5, the mismatching emission spectra of

397

main ligand (HL)2‒ and auxiliary ligands phen, bpy and pbim not only broaden the

398

emission bands of 3–5 but also flatten the distribution of the emission intensities. In

399

another word, the excitation light with certain light flux is synchronously absorbed by

400

the main and auxiliary ligands in the resulting complexes, but the emission spectra of

401

the main and auxiliary ligands are not matching as overlaid each other, and thereby

402

broaden the emission bands and reduce the emission intensities in the end. As for the

403

emission intensity of (HL)2‒-bridged 3D polymer 2 being greatly weakened in

404

comparison with that of (HL)2‒-bridged 2D polymer 1, it may be contributed to that

405

the coordinated water in 2 more easily consumes energy through thermal vibration

406

than the coordinated DMF in 1 does.17

407 408

CONCLUSION

409

Five 1–3D cadmium(II) polymers with architectural diversities and interesting

410

topologies have been successfully synthesized through traditional evaporation method

411

or hydro/solvothermal methods using H3L ligand or H3L ligand incorporating with

412

auxiliary ligands phen, bpy and pbim, respectively. In those complexes, doubly

413

deprotonated H3L ligands and CdII atoms display versatile coordination modes. 14


Page 14 of 30

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414

Complex 1 is a 2D helical structure with (4·82) topology built up from 3-connected

415

(HL)2‒ and CdII nodes. Complex 2 containing (HL)2‒-bridged tetranuclear CdII

416

subunits is a 3D helical structure where both (HL)2‒ and CdII adopt three coordination

417

modes to form a rare 3-connected network with (5·8·12)2(5·12·16)2(5·82)(82·12)

418

topology. As substituted the smaller terminal ligands DMF or water with larger

419

terminal ligands phen, (HL)2‒ ligands only use their imidazoledicarboxylates to

420

bis-chelate CdII centers into a zigzag chain structure of 3. Complex 4 is a

421

(3,4)-connected 3D network with (4·82)(4·82·103) topology built up from the

422

(HL)2‒-bridged (4,82) meso-layer observed in 1 being further linked by rod-like bpy

423

bridges replacing terminal ligands DMF. Complex 5 is a (3,4)-connected 2D novel

424

network with (3·4·8)2(3·4·5·82·9)2(32·82·92) topology, consisting of (HL)2‒- and

425

pbim-bridged macrocycle chains. As expected that the strongly bis-chelating

426

coordination mode µ-kN,O:kN′,O′ of the imidazoledicarboxylate of (HL)2‒ absolutely

427

dominates the assemblies with CdII in those complexes. Intriguingly, the additional

428

ligands, such as smaller terminal ligands water and DMF, larger planar terminal

429

ligand phen, and as well as rod-like and V-shaped bridges bpy and pbim, exert

430

obvious influence upon the coordination modes of ligands (HL)2‒ and the resulting

431

architectures. Clearly, larger terminal and bridging ligands phen and pbim could limit

432

the coordination of the pyridyl of (HL)2‒ through steric hindrance. Moreover, the

433

photoluminescence properties of these compounds are significantly influenced by the

434

additional ligands, and clearly indicate that the matching emission spectra of main and

435

auxiliary ligands play a key role in the rational design and synthesis for new

436

photoluminescent MOF materials incorporating with two or more functional organic

437

ligands.

438 439

ASSOCIATED CONTENT

440

Supporting Information

441

Additional structural figures for the related compounds, the TGA curves and PXRD

442

patterns, the table for selected bond length and angles, as well as X-ray 15



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Page 16 of 30

443

crystallographic files in CIF format for compounds 1−5 are available in supporting

444

material section. This material is available free of charge via the Internet at

445

http://pubs.acs.org.

446

Accession Codes

447

CCDC 1520279‒1520283 contain the supplementary crystallographic data for this

448

paper.

449

www.ccdc.cam.ac.uk/data_request/cif, or by emailing [email protected],

450

or by contacting The Cambridge Crystallographic Data Centre, 12 Union Road,

451

Cambridge CB2 1EZ, UK; fax: +44 1223 336033.

These

data

can

be

obtained

free

of

charge

via

452 453

AUTHOR INFORMATION

454

Corresponding Author

455

*E-mail: [email protected]. Telephone: +86 0371 67783126.

456 457

ACKNOWLEDGEMENTS

458

We gratefully acknowledge financial support from the National Natural Science

459

Foundation of China (21271157), and the Foundation and Research in Cutting-Edge

460

Technologies in the Project of Henan Province (122300410092).

461 462 463 464 465 466 467 468 469 470 471 16


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472

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473

(1) Gamage, N. D.-H.; McDonald, K. A.; Matzger, A. J. Angew. Chem., Int. Ed. 2016, 55,

474

12099−12103.

475

(2) Noh, T. H.; Jung, O. S. Acc. Chem. Res. 2016, 49, 1835−1843.

476

(3) Maza, W. A.; Padilla, R.; Morris, A. J. J. Am. Chem. Soc. 2015, 137, 8161−8168.

477

(4) Rosi, N. L.; Eckert, J.; Eddaoudi, M.; Vodak, D. T.; Kim, J.; O’ Keeffe, M.; Yaghi, O. M.

478

Science 2003, 300, 1127−1129.

479

(5) He, H.; Song, Y.; Sun, F.; Zhao, N.; Zhu, G. Cryst. Growth Des. 2015, 15, 2033−2038.

480

(6) Manna, P.; Das, S. K. Cryst. Growth Des. 2015, 15, 1407−1421.

481

(7) Zheng, J.; Wu, M.; Jiang, F.; Su, W.; Hong, M. Chem. Sci. 2015, 6, 3466−3470.

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(8) Li, S.-M.; Zheng, X.-J.; Yuan, D.-Q.; Ablet, A.; Jin, L.-P. Inorg. Chem. 2012, 51,

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(9) Zou, R.-Q.; Sakurai, H.; Xu, Q. Angew. Chem. Int. Ed. 2006, 45, 2542–2546.

485

(10) Maji, T. K.; Mostafa, G.; Chang, H.-C.; Kitagawa, S. Chem. Commun. 2005, 2436–2438.

486

(11) Liu, Y.; Kravtsov, V. C.; Larsen, R.; Eddaoudi, M. Chem. Commun. 2006, 1488–1490.

487

(12) Wang, Y.-L.; Yuan, D.-Q.; Bi, W.-H.; Li, X.; Li, X.-J.; Li, F.; Cao, R. Cryst. Growth Des.

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2005, 5, 1849−1855. (13) Sun, Y.-Q.; Zhang, J.; Chen, Y.-M.; Yang, G.-Y. Angew. Chem. Int. Ed. 2005, 44, 5814–5817.

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(14) Fang, R.-Q.; Zhang, X.-M. Inorg. Chem. 2006, 45, 4801−4810.

492

(15) Lu, W.-G.; Su, C.-Y.; Lu, T.-B.; Jiang, L.; Chen, J.-M. J. Am. Chem. Soc. 2006, 128, 34–35.

493

(16) Li, X.; Wu, B.; Niu, C.; Niu, Y.; Zhang, H. Cryst. Growth Des. 2009, 9, 3423−3431.

494

(17) Li, X.; Wu, B.; Wang, Y.; Zhang, Y.; Niu, C.; Niu, Y.; Hou, W. Inorg. Chem. 2010, 49,

495

2600–2613.

496

(18) Wang, S.; Zhang, L.; Li, G.; Huo, Q.; Liu, Y. CrystEngComm 2008, 10, 1662−1666.

497

(19) Gu, Z.-G.; Liu, Y.-T.; Hong, X.-J.; Zhan, Q.-G.; Zheng, Z.-P.; Zheng, S.-R.; Li, W.-S.; Hu,

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S.-J.; Cai, Y.-P. Cryst. Growth Des. 2012, 12, 2178–2186. (20) Tan, Y.-H.; Wu, J.-S.; Yang, C.-S.; Liu, Q.-R.; Tang, Y.-Z.; Ye, B.-H. Polyhedron 2013, 57, 24–29. (21) Zhang, F.; Li, Z.; Ge, T.; Yao, H.; Li, G.; Lu, H.; Zhu, Y. Inorg. Chem. 2010, 49, 17



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3776–3788. (22) Gao, Y.-C.; Liu, Q.-H.; Zhang, F.-W.; Li, G.; Wang, W.-Y.; Lu, H.-J. Polyhedron 2011, 30, 1–8. (23) Ma, T.; Zhang, J.; Jing, X.; Feng, Q.; Zheng, B.; Yan, Y.; Huo, Q.; Liu, Y. Inorg. Chem. Commun. 2012, 20, 201−204.

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(24) Jing, X.; Zhou, X.; Zhao, T.; Huo, Q.; Liu, Y. Cryst. Growth Des. 2012, 12, 4225−4229.

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(25) Li, B.; Zang, S.-Q.; Wang, L.-Y.; Mak, T. C. W. Coord. Chem. Rev. 2016, 308, 1–21.

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510

(27) Zhang, J.-W.; Hu, M.-C.; Li, S.-N.; Li, S.-N.; Jiang, Y.-C.; Zhai, Q.-G. Cryst. Growth Des.

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523

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524

(35) Shi, Z.-Q.; Li, Y.-Z.; Guo, Z.-J.; Zheng, H.-G. Cryst. Growth Des. 2013, 13, 3078–3086.

525

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(38) Sheldrick, G. M. SADABS, Version 2.05; University of Göttingen: Göttingen, Germany.

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533

(42) Ablet, A.; Li, S.-M.; Cao, W.; Zheng, X.-J.; Jin, L.-P. Polyhedron 2014, 83, 122–129.

534 535 536

Table 1. Crystal data and structure refinement for 1−5.

537 Compounds

1

2

3

4

5

Formula

C13H11BrCdN4O5

C40H28Br4Cd4N12O22

C22H12BrCdN5O4

C30H16Br2Cd2N8O8

C56H37Br3Cd3N17O13

Temp (K)

293(2)

293(2)

293(2)

293(2)

293(2)

Formula weight

495.57

1797.98

602.68

1001.13

1732.96

Crystal system

Monoclinic

Monoclinic

Monoclinic

Orthorhombic

Triclinic

Space group

C2/c

P21/c

P21/c

Pccn

P-1

a (Å)

28.565(6)

16.4142(2)

8.8871(4)

7.8467(4)

11.1165(10)

b (Å)

8.7606(5)

8.28450(10)

18.6012(7)

24.5543(9)

15.7681(14)

c (Å)

16.250(8)

37.0955(5)

13.0166(3)

16.3121(8)

19.8435(19)

α/°

90

90

90

90

110.171(8)

β/°

124.45(5)

90.4080(10)

99.837(3)

90

101.702(8)

γ/°

90

90

90

90

97.305(7)

V (Å3)

3353.1(17)

5044.25(11)

2120.15(13)

3142.9(3)

3122.7(5)

Z, ρcalcd (g/cm3)

8, 1.963

4, 2.368

4, 1.888

4, 2.116

2, 1.843

GOF

1.062

1.066

1.033

1.123

1.033

R1, wR2

0.0408

0.0506

0.0342

0.0475

0.0531

(I > 2 σ(I))

0.1092

0.1329

0.0622

0.1005

0.1531

1.287

1.838

0.526

0.843

1.056

-0.673

-1.321

-0.701

-1.114

-1.097

Largest

diff.

peak and hole

538 539 19



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

540

Captions for the Scheme and Figures

541

Scheme 1. Schematic representation of main ligand H3L and auxiliary organic ligands phen, bpy

542

and pbim as well as all the coordination modes of the deprotonated ligand H3L found.

543

Figure 1. ORTEP view of coordination environment of CdII atom in 1 with thermal ellipsoid at

544

50% probability level (H atoms were omitted for clarity). Symmetry code: (A) 1/2 − x, 1/2 − y, 1 −

545

z; (B) x, − y, − 1/2 + z.

546

Figure 2. (a) View of helical-constructed meso-layer in 1. (b) Schematic representation of the 2D

547

3-connected (4·82) topology (cyan and black balls represent CdII and (HL)2‒ nodes, respectively;

548

light-gray lines represent the connections of CdII nodes with the pyridyl groups of (HL)2‒ nodes).

549

Figure 3. ORTEP view of coordination environments of CdII and coordination modes of (HL)2−

550

ligands in 2 with thermal ellipsoid at 30% probability level (H atoms and Br atoms were omitted

551

for clarity). Symmetry code: (A) 1 − x, − 1/2 + y, 3/2 − z; (B) 1 + x, y, z; (C) 1 − x, − y, 1 – z; (D) 1

552

− x, 1/2 + y, 3/2 − z; (E) 1 − x, y, z.

553

Figure 4. (a) View of right- and left-handed helical chains built from [Cd4(HL)4] subunits. (b)

554

Helical-constructed meso-layer in 2 (H atoms, coordination water as well as the

555

5-bromo-3-pyridiyl groups of the ligands (HL)2‒ which link the meso layer into a 3D framework

556

were omitted for clarity). Symmetry code: (A) 1 − x, − 1/2 + y, 3/2 − z; (C) 1 − x, − y, 1 − z; (D) 1

557

− x, 1/2 + y, 3/2 − z; (H) x, 1/2 − y, − 1/2 + z; (I) x, − 1/2 − y, − 1/2 + z.

558

Figure 5. (a) View of 3D polymeric framework in 2. (b) Schematic representation of the 3D

559

3-connected (5·6·12)2(5·122)2(62·12)(5·62) topology (cyan and brassy balls represent CdII and

560

(HL)2‒ nodes, respectively).

561

Figure 6. ORTEP view of coordination environment of CdII and 1D zigzag polymeric chain

562

structure in 3 with thermal ellipsoid at 50% probability level (H atoms were omitted for clarity).

563

Symmetry code: (A) x, 1/2 − y, − 1/2 + z; (B) x, 1/2 − y, 1/2 + z.

564

Figure 7. ORTEP view of coordination environment of CdII in 4 with thermal ellipsoid at 30%

565

probability level (H atoms were omitted for clarity). Symmetry code: (A) − 1/2 + x, 1 − y, 3/2 − z;

566

(B) 1/2 − x, y, 1/2 + z.

567


568

(3,4)-connected (4·82)(4·82·103) topology showing (HL)2‒-bridged (4,82) meso-layer observed in 1

569

and bpy-bridged homo-helixes (cyan and black balls represent CdII and (HL)2‒ nodes, respectively; 20


Page 20 of 30

Page 21 of 30

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


570

light-gray lines represent the connections of CdII nodes with the pyridyl groups of (HL)2‒ nodes;

571

gold lines represent the connections of bpy).

572

Figure 9. ORTEP view of coordination environments of CdII in 5 with thermal ellipsoid at 15%

573

probability level (H atoms were omitted for clarity). Symmetry code: (A) 1 − x, − y, 1 – z; (B) − x,

574

− y, 1 – z; (C) 1 − x, − y, – z.

575

Figure 10. (a) View of 2D polymeric framework in 5, and (b) polymeric macrocycle chains

576

containing trinuclear rings. Symmetry code: (A) 1 − x, − y, 1 – z; (B) − x, − y, 1 – z; (C) 1 − x, − y,

577

– z; (D) 1 − x, y, z.

578

Figure 11. Schematic representation of the 2D (3,4)-connected (3·4·8)2(3·4·5·82·9)2(32·82·92)

579

topology of 5 (cyan and brassy balls represent CdII and (HL)2‒ nodes, respectively).

580

Figure 12. Luminescent behaviors of compounds 1−5 in the solid state at room temperature.

581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 21



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

600 601

Scheme 1. Schematic representation of the main ligand H3L and auxiliary organic ligands phen,

602

bpy and pbim as well as the coordination modes of the deprotonated ligand H3L.

603

604 605 606

607 608 609

Figure 1. ORTEP view of coordination environment of CdII atom in 1 with thermal ellipsoid at

610

50% probability level (hydrogen atoms were omitted for clarity). Symmetry code: (A) 1/2 − x, 1/2

611

− y, 1 − z; (B) x, − y, − 1/2 + z.

612 22


Page 22 of 30

Page 23 of 30

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


613

a

614 615

b

616 617

Figure 2. (a) View of helical-constructed meso-layer in 1. (b) Schematic representation of the 2D

618

3-connected (4·82) topology (cyan and black balls represent CdII and (HL)2‒ nodes, respectively;

619

light-gray lines represent the connections of CdII nodes with the pyridyl groups of (HL)2‒ nodes).

620 621

Figure 3. ORTEP view of coordination environments of CdII and coordination modes of (HL)2−

622

ligands in 2 with thermal ellipsoid at 30% probability level (H atoms and Br atoms were omitted

623

for clarity). Symmetry code: (A) 1 − x, − 1/2 + y, 3/2 − z; (B) 1 + x, y, z; (C) 1 − x, − y, 1 – z; (D) 1

624

− x, 1/2 + y, 3/2 − z; (E) 1 − x, y, z.

625 23



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

626 627

a

628 629

b

630 631

Figure 4. (a) View of right- and left-handed helical chains built from [Cd4(HL)4] subunits. (b)

632

Helical-constructed meso-layer in 2 (hydrogen atoms, coordination water as well as the

633

5-bromo-3-pyridiyl groups of the ligands (HL)2‒ which link the meso layer into a 3D framework

634

were omitted for clarity). Symmetry code: (A) 1 − x, − 1/2 + y, 3/2 − z; (C) 1 − x, − y, 1 − z; (D) 1

635

− x, 1/2 + y, 3/2 − z; (H) x, 1/2 − y, − 1/2 + z; (I) x, − 1/2 − y, − 1/2 + z.

636 637 24


Page 24 of 30

Page 25 of 30

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


638 639

a

640 641 642 643

b

644 645 646 647


648

3-connected (5·6·12)2(5·122)2(62·12)(5·62) topology (cyan and brassy balls represent CdII and

649

(HL)2‒ nodes, respectively).

650 651 25



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

652 653

654 655 656 657

Figure 6. ORTEP view of coordination environment of CdII and 1D zigzag polymeric chain

658

structure in 3 with thermal ellipsoid at 50% probability level (hydrogen atoms were omitted for

659

clarity). Symmetry code: (A) x, 1/2 − y, − 1/2 + z; (B) x, 1/2 − y, 1/2 + z.

660

661 662 663

Figure 7. ORTEP view of coordination environment of CdII in 4 with thermal ellipsoid at 30%

664

probability level (hydrogen atoms were omitted for clarity). Symmetry code: (A) − 1/2 + x, 1 − y,

665

3/2 − z; (B) 1/2 − x, y, 1/2 + z.

666 26


Page 26 of 30

Page 27 of 30

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


667 668

a

669 670

b

671 672 673


674

(3,4)-connected (4·82)(4·82·103) topology showing (HL)2‒-bridged (4,82) meso-layer observed in 1

675

and bpy-bridged homo-helixes (cyan and black balls represent CdII and (HL)2‒ nodes, respectively;

676

light-gray lines represent the connections of CdII nodes with the pyridyl groups of (HL)2‒ nodes;

677

gold lines represent the connections of bpy).

678 27



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

679

680 681

Figure 9. ORTEP view of coordination environments of CdII in 5 with thermal ellipsoid at 15%

682

probability level (H atoms were omitted for clarity). Symmetry code: (A) 1 − x, − y, 1 – z; (B) − x,

683

− y, 1 – z; (C) 1 − x, − y, – z.

684 685

Figure 10. (a) View of 2D polymeric framework in 5, and (b) polymeric macrocycle chains

686

containing trinuclear rings. Symmetry code: (A) 1 − x, − y, 1 – z; (B) − x, − y, 1 – z; (C) 1 − x, − y,

687

– z; (D) 1 − x, y, z. 28


Page 28 of 30

Page 29 of 30

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


688

689 690

Figure 11. Schematic representation of the 2D (3,4)-connected (3·4·8)2(3·4·5·82·9)2(32·82·92)

691

topology of 5 (cyan and brassy balls represent CdII and (HL)2‒ nodes, respectively).

692 693

694 695

Figure 12. Luminescent behaviors of compounds 1−5 in the solid state at room temperature.

696 697 698 699 29



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 30 of 30

700

For Table of Contents Use Only

701 702 703

Synthesis, Structural Diversity and Properties of Cd–MOFs Based on

704

2-(5-Bromo-pyridin-3-yl)-1H-imidazole-4,5-dicarboxylate and

705

N-Heterocyclic Ancillary Ligands

706 707

Ruiying Wang,†,‡ Lina Liu,† Lulu Lv,† Xing Wang,† Rui Chen,† and Benlai Wu*,†

708 709

Five 1‒3D cadmium(II) coordination polymers with architectural diversities and

710

interesting

711

2-(5-bromo-pyridin-3-yl)-1H-imidazole-4,5-dicarboxylic

712

versatile coordination modes, has been synthesized and structurally determined.

713

Intriguingly, the additional ligands exert obvious influence not only upon the

714

coordination modes of the main ligand but also upon the architectures and

715

photoluminescence properties of the resulting complexes.

topologies,

in

which

the

doubly acid

716

717 718

30


and

deprotonated CdII

display

Synthesis, Structural Diversity, and Properties of Cd MetalâOrganic

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