Homochiral Coordination Polymers Based on Aminoacid

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Homochiral Coordination Polymers Based on Aminoacid-Functionalized Isophthalic Acid: Synthesis, Structure determination, and Optical Properties Xing Wang, Keqing Zhang, Lulu Lv, Rui Chen, Wenbo Wang, and Benlai Wu Cryst. Growth Des., Just Accepted Manuscript • DOI: 10.1021/acs.cgd.7b01689 • Publication Date (Web): 29 Jan 2018 Downloaded from http://pubs.acs.org on February 4, 2018

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Crystal Growth & Design

1

Homochiral

2

Aminoacid-Functionalized Isophthalic Acid: Synthesis, Structure

3

determination, and Optical Properties

4

Coordination

Polymers

Based

on

Xing Wang,† Keqing Zhang,‡ Lulu Lv,† Rui Chen,† Wenbo Wang,† 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

ABSTRACT: Three interesting homochiral metal−organic frameworks (HMOFs),

12

namely,

13

{[Pb2(HL)2]·CH3OH·2.5H2O}n (3), have been hydro/solvothermally synthesized

14

through

15

(S)-5-(((1-carboxyethyl)amino)methyl)isophthalic acid (H3L) with corresponding

16

metal sources. Crystallographic analysis indicates that the triply deprotonated H3L

17

ligands can adopt anionic (L)3− and zwitterionic (HL)2− forms, various coordination

18

modes, and versatile hydrogen-bonding connections to construct interesting HMOFs

19

with unique architectures. Complexes 1 and 2 are 2D coordination polymers, but their

20

structural motifs are very different. In 1, anionic (L)3− ligands bridge tetrametallic

21

Zn-clusters to form a 2D layer with (3,6)-connected kgd net. In 2, zwitterionic (HL)2−

22

ligands link CdII ions to generate two types of independent wave-like layers of 63

23

topology, and the two independent layers are further connected to form the unique

24

double-layered homochiral framework through interlayered hydrogen-bonding

25

interactions. The 2D frameworks of 1 and 2 are further extended into their 3D

26

supramolecular structures through complicated interlayered hydrogen-bonding

27

interactions. Coordination polymer 3 is a 3D interpenetrating porous helicate of

28

(62·12)(6·122) topology. Very interestingly, the metal−organic frameworks of 2 and 3

29

possess two positive charge centers respectively from metal ions and zwitterionic

[Zn8(L)4(OH)4(H2O)2]n

the

reaction

(1),

{[Cd2(HL)2(H2O)4]·6H2O}n

of

the

designed

1

ACS Paragon Plus Environment

chiral

(2),

and

ligand

Crystal Growth & Design 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 2 of 29

30

(HL)2− liand, and thus are intriguing HMOFs incorporating Brönsted acid with Lewis

31

acid for potential applications. Furthermore, the thermal stabilities, and solid-state

32

optical properties including CD spectra, and nonlinear optical and luminescent

33

properties of these complexes were also carried out. More importantly, it was found

34

that the coordination mode, hydrogen-bonding site, and charge of H3L ligand can be

35

adjusted through the protonation of its amino group, which perhaps provides a

36

pathway to design and develop novel HMOFs materials based on this type of

37

aminoacid-functionalized polycarboxylate chiral ligands.

38 39

Keywords: Triangular chiral ligand, Structure diversity, Homochiral metal−organic

40

framework, Optical properties, Topology

41 42 43

INTRODUCTION

44

In recent years, investigations upon homochiral metal−organic frameworks (HMOFs)

45

have been motivated by their unique structures and diverse topologies as well as

46

intriguing potential applications in asymmetric catalysis, chiral separations, nonlinear

47

optics, and so on.1−12 To obtain HMOFs, the basic and effective strategy is the use of

48

the selected enantiopure organic ligands to assemble with metal centers, which will

49

result in the chirality of ligands passing to the whole frameworks. In this context,

50

many attempts have been made to design and synthesize a variety of enantiopure

51

organic bridges through incorporating chiral functional groups into organic ligands,

52

and based on this to further fabricate HMOFs.13 −22

53

Very recently, polypyridyl- and polycarboxyl-functionalized chiral linkers have

54

been explored for the construction of HMOFs by our and other groups.23−33 In

55

particular, the modification of an aromatic polycarboxylate ligand attaching a flexible

56

chiral source have been provided a promising approach to design and prepare diverse

57

HMOFs with potential applications.13−15,

58

attached a (S)-2-aminopropanoic acid to 5-methylisophthalic acid according to

59

Scheme

1,

and

synthesized

a

21

Pursuing our work in this area, we

new

chiral

2


triangular

ligand

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60

(S)-5-(((1-carboxyethyl)amino)methyl)isophthalic acid (H3L). The H3L ligand not

61

only possesses all the advantages (namely, the chiral source giving a chance of the

62

formation of HMOFs, rigid isophthalate unit being efficient to construct interesting

63

structures, and the multiple coordination modes of three carboxyl moieties providing

64

great superiority in the fabrication of fascinating coordination polymers with high

65

dimensionalities) suggested by the reported chiral isophthalate-type triangular

66

ligands,13−15 but also features own unique merits originating from its amino group. In

67

the fabrication of HMOFs, H3L ligand can exist in the forms of anionic (L)3− and

68

zwitterionic (HL)2− which depends on whether its amino group is protonated after the

69

three carboxyl groups being completely deprotonated. In the anionic (L)3− form, the N

70

and O atoms of the amino acid group always chelate a metal ion, and the coordination

71

of the N further results in the formation of an additional chiral nitrogen center. In the

72

zwitterionic (HL)2− form, it will give rise to two types of positive charge centers

73

(namely, ammonium ion and metal ion) in the resulting HMOFs, and the

74

incorporation of Brönsted acid and Lewis acid in the polymeric skeleton of the same

75

HMOF is particularly interesting for its further applications.33−36 Moreover, the amino

76

group in H3L ligand adds hydrogen-bonding sites to trap guests and/or extend the

77

structure into a higher-dimensional architecture as well. Remarkably, the coordination

78

mode, hydrogen-bonding site, existence form, and charge of the H3L ligand can be

79

controlled by the protonation of its amino group, which provides a great opportunity

80

to flexibly adjust the architectures and properties of the generated HMOFs.

81

In this work, ZnII, CdII, and PbII ions have been selected as metal centers to prepare

82

H3L-based HMOFs because these ions are excellent candidates for the construction of

83

MOFs owing to their flexible coordination environments and the interesting optical

84

properties of their complexes.37−42 Herein, three interesting HMOFs, namely,

85

[Zn8(L)4(OH)4(H2O)2]n

86

{[Pb2(HL)2]·CH3OH·2.5H2O}n (3), have been hydro/solvothermally prepared. In this

87

contribution, we report their synthesis, crystal structures, thermal stabilities, and

88

optical properties including CD spectra, and nonlinear optical and luminescent

89

properties.

(1),

{[Cd2(HL)2(H2O)4]·6H2O}n

3


(2),

and


Page 4 of 29

90 91

EXPERIMENTAL SECTION

92

Materials and General Procedures. All chemicals were of analytical grade and

93

obtained from commercial sources without further purification. Compounds

94

L-α-alanine methyl ester hydrochloride and 5-bromomethyl-isophthalic acid dimethyl

95

ester were prepared according to literature procedures.15, 23 1H and

96

were recorded with a Bruker DPX-300 spectrometer operating at 300 MHz and 75

97

MHz, respectively. Elemental analyses were performed with a Carlo-Erba 1106

98

elemental analyzer. IR spectra (KBr pellets) were recorded on a Nicolet NEXUS 470

99

FT-IR spectrophotometer from 400 to 4000 cm−1. Thermal analysis curves were

100

scanned from 30 to 800 °C under air on a STA 409 PC thermal analyzer. Solid-state

101

fluorescent spectra were determined at room temperature on a Hitachi F-4500

102

fluorophotometer with a xenon arc lamp as light source. Powder X-ray diffraction

103

(PXRD) patterns of the samples were recorded by a RIGAKU-DMAX2500 X-ray

104

diffractometer with Cu Kα radiation. Specific rotation was measured with a

105

Perkin–Elmer 341 with a wavelength of 589 nm in DMSO solution at a temperature

106

of 20 °C. Solid-state circular dichroism (CD) spectra (KBr pellets) were recorded at

107

room temperature on a MOS-450 spectrometer.

13

C NMR spectra

108

Synthesis of (S)-5-(((1-carboxyethyl)amino)methyl)isophthalic acid (H3L). A

109

mixture of L-α-alanine methyl ester hydrochloride (4.19 g, 30.00 mmol), anhydrous

110

K2CO3 (4.53 g, 40.00 mmol) and dry DMF (40 mL) was stirred at room temperature

111

for 1 h, and then a solution of 5-bromomethyl-isophthalic acid dimethyl ester (2.87 g,

112

10.00 mmol) and dry DMF (20 mL) was added dropwise. The resulting mixture was

113

heated to 50 °C and kept at that temperature with continuous stirring for 32 h. All the

114

above processes took place under nitrogen. The mixture was cooled to room

115

temperature and filtered to remove any solids. A pale yellow oil was obtained after

116

removal of the solvent in vacuo. The pale yellow oil was redissolved in

117

dichloromethane and washed with distilled water several times. After evaporation of

118

the solvent, the pure pale yellow oil was obtained. A mixture of the resulting pale 4


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119

yellow oil, methanol (15 mL), and an aqueous solution of NaOH (25 mL, 5%) was

120

heated at 60 °C with stirring for 12 h. As the pH value of the reaction solution was

121

adjusted to 5, a white precipitate appeared. After having been filtered, washed with

122

distilled water, and dried in air, the white powder H3L was obtained. Yield: 1.52 g,

123

57% (based on 5-bromomethylisophthalic acid dimethyl ester). Anal. Calcd for

124

C12H12NO6 (%): C, 53.93; H, 4.90; N, 5.24. Found: C, 54.12; H, 4.87; N, 5.26. IR

125

(KBr, cm−1): 3380 (m), 3076 (w), 1720 (s), 1616 (s), 1462 (m), 1401 (m), 1362 (m),

126

1224 (s), 1089 (m), 906 (w), 760 (w), 677 (m), 525 (w). 1H NMR (300 MHz, DMSO),

127

δ (ppm): 1.36 (d, 3 H), 3.45 (m, 1 H), 4.14 (m, 2H), 8.27 (d, 2H), 8.44 (m, 1H). 13C

128

NMR (75 MHz, DMSO), δ (ppm): 16.60, 48.99, 56.72, 130.18, 132.59, 134.71,

129

136.05, 167.14, 172.56. [α]20D = +13.6 (c = 0.01 molL−1, DMSO).

130

Synthesis of [Zn8(L)4(OH)4(H2O)2] n (1). A mixture of Zn(OH)2 (0.0099 g, 0.10

131

mmol), H3L (0.0134 g, 0.05 mmol), and deionized H2O (6 mL) was sealed in a 25 mL

132

Teflon-lined stainless autoclave and heated at 110 °C for 120 h. After the mixture was

133

cooled to room temperature at a rate of 5 °Ch−1, colorless block crystals were obtained,

134

washed with distilled water, and dried in air, resulting in 53% yield (based on Zn).

135

Anal. Calcd for C48H48N4O30Zn8 (%): C, 34.24; H, 2.87; N, 3.33. Found: C, 34.17; H,

136

2.88; N, 3.38. IR (KBr, cm−1): 3497 (m), 3362 (m), 3255 (w), 3089 (w), 1614 (s),

137

1578 (s), 1411 (m), 1342 (s), 1305 (m), 1142 (m), 775 (s), 720 (s), 658 (w), 449 (w).

138

Synthesis of {[Cd2(HL)2(H2O)4]·6H2O}n (2). A mixture of CdCO3 (0.0086 g, 0.05

139

mmol), H3L (0.0134 g, 0.05 mmol), methanol (8 mL), and deionized H2O (8 mL) was

140

sealed in a 25 mL Teflon-lined stainless autoclave and heated at 150 °C for 144 h.

141

After the mixture was cooled to room temperature at a rate of 5 °Ch−1, colorless block

142

crystals were obtained, washed with distilled water, and dried in air, resulting in 46%

143

yield (based on Cd). Anal. Calcd for C24H42Cd2N2O22 (%): C, 30.82; H, 4.53; N, 2.99.

144

Found: C, 30.69; H, 4.50; N, 3.03. IR (KBr, cm−1): 3388 (br, s), 3071 (w), 1616 (s),

145

1557 (s), 1451 (s), 1379 (vs), 1240 (m), 1106 (w), 778 (m), 735 (m), 620 (w).

146

Synthesis of {[Pb2(HL)2]·CH3OH·2.5H2O}n (3). A mixture of Pb(NO3)2 (0.0086 g,

147

0.05 mmol), H3L (0.0134 g, 0.05 mmol), methanol (8 mL), and deionized H2O (8 mL)

148

was sealed in a 25 mL Teflon-lined stainless autoclave and heated at 90 °C for 72 h. 5



Page 6 of 29

149

After the mixture was cooled to room temperature at a rate of 5 °Ch−1, colorless block

150

crystals were obtained, washed with distilled water, and dried in air, resulting in 41%

151

yield (based on Pb). Anal. Calcd for C25H31N2O15.5Pb2 (%): C, 29.38; H, 3.06; N, 2.74.

152

Found: C, 29.49; H, 3.09; N, 2.69. IR (KBr, cm−1): 3415 (br, s), 3059 (w), 1602 (s),

153

1544 (s), 1448 (s), 1362 (vs), 1238 (w), 1091 (w), 774 (m), 725 (s), 697 (w), 551 (w).

154

X-ray Structure Determination. On an Oxford diffractometer equipped with a

155

CCD detector, single-crystal X-ray data were collected at 293(2) K using

156

graphite-monochromated Mo Kα radiation (λ = 0.71073 Å) and Cu Kα radiation (λ =

157

1.5418 Å) for 1–2 and 3, respectively. Absorption corrections were applied by using

158

the multiscan program SADABS.43 The structures were solved by direct methods and

159

refined on F2 full-matrix least-squares using the SHELXTL program package.44 All of

160

the non-hydrogen atoms were refined with anisotropic displacement parameters

161

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

162

while the H atoms attached to O and N were located from different Fourier maps and

163

treated as idealized contributions. The crystal data were summarized in Table 1, and

164

the selected bond distances and angles as well as hydrogen-bonding parameters were

165

given in Tables S1–2.

166 167

RESULTS AND DISCUSSION

168

Synthesis and General Characterization of H3L Ligand and Coordination H3 L

ligand

was

synthesized

by

reaction

of

Polymers

170

5-bromomethyl-isophthalic acid dimethyl ester with L-α-alanine methyl ester

171

hydrochloride (Scheme 1), which is similar to our procedure for the synthesis of

172

terpyridyl amino acid ligand.23 The chemical formula of H3L has been confirmed by

173

satisfactory elemental analysis. As for its chirality, it has been proved by the specific

174

rotation and the Cotton effects in its solid-state CD spectrum (Figure S1).

175

The

1–3.

The

169

syntheses of coordination polymers 1–3 were carried

out under

176

hydro/solvothermal conditions. The selected metal sources [Zn(OH)2, CdCO3 and

177

Pb(NO3)2] and reaction conditions such as solvents, metal/ligand ratio, temperature, 6


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178

and reaction time were optimized to attain the formation of crystalline products.

179

The chemical formulas of 1–3 have been confirmed by satisfactory elemental

180

analysis and single-crystal X-ray diffraction. The phase purities of the as-synthesized

181

crystalline products 1–3 were determined by powder X-ray diffraction (PXRD)

182

measurements. The simulated patterns generated from the single-crystal X-ray

183

diffraction data of 1–3 are in good agreement with observed ones, indicating the phase

184

purity of those polycrystalline samples (Figures S2–4). The thermal stabilities of these

185

complexes were investigated under air by the TGA technique (Figure S5). The

186

dehydration process of 1 occurred from 170 to 255 °C with the first weight loss of

187

2.25%, corresponding to the loss of two coordination water molecules (calcd 2.14%).

188

On further heating, the framework of 1 began to collapse above 363 °C. For 2, the

189

weight loss of six lattice water molecules began from 60 to 128 °C with the weight

190

loss of 10.88% (calcd 11.56%). With a plateau region at 128–298 °C, then consecutive

191

decomposition occurred at 298–684 °C, suggesting total destruction of the framework.

192

For 3, a gradual weight loss between 30 and 140 °C is attributed to the release of both

193

the lattice methanol and water molecules (observed 8.36%, calcd 7.54%). On further

194

heating, the framework of 3 began to collapse above 270 °C. The TGA results

195

disclose that these coordination polymers are quite stable. In particular, the anhydrous

196

framework of 1 has excellent thermotolerance up to 363 °C.

197

Structural Analysis and Discussion. [Zn8(L)4(OH)4·(H2O)2] n(1). A single-crystal

198

X-ray diffraction study reveals that that compound 1 crystallizes in the chiral space

199

group P1 with a Flack parameter of 0.047(4). Though the check result using PLATON

200

suggests that there is a possibly higher pseudosymmetry P−1 in the structural model,

201

this can be due to the pseudotranslation symmetry of heavy Zn atoms.45 Its chirality

202

was further confirmed by the solid-state CD spectrum (vide infra). The asymmetric

203

unit of 1 consists of four deprotonated (L)3− ligands, eight independent ZnII ions, four

204

µ3-OH groups, and two coordinated water molecules. The coordination modes of (L)3−

205

ligands are shown in Figure 1a, and each (L)3− ligand is a κ8-linker and connects

206

seven ZnII ions. Every (L)3− ligand in 1 has two chiral centers: the permanent chiral

207

carbon atom of S-configuration and the labile chiral nitrogen atom in the aminoacid 7



208

group of S- or R-configuration owing to its participation in chelating coordination

209

(Figure 1a). Since half nitrogen atoms are of R-configuration whereas the other half

210

are of S-configuration, and in a sense, the chirality of 1 originates in the permanent

211

chiral carbon atoms.

212

The coordination geometries of eight independent ZnII ions in 1 are shown in

213

Figure 1b. Zn1 and Zn8 are coordinated to four bridging carboxylates, one bridging

214

µ3-OH and one water molecule, respectively, forming distorted O6 coordination

215

octahedra. Zn2, Zn3, Zn6 and Zn7 are coordinated to three bridging carboxylates, one

216

amino group and two bridging µ3-OH, respectively, forming distorted NO5

217

coordination octahedra. Zn4 and Zn5 are coordinated to four bridging carboxylates

218

and one bridging µ3–OH, respectively, forming distorted O5 trigonal bipyramid

219

coordination geometries. Notably, there are two similar tetranuclear units

220

[Zn4(µ3-OH)2]6+ (one tetranuclear unit [Zn4(µ3-OH)2]6+ including Zn1–Zn4, and the

221

other including Zn5–Zn8) formed through two independent µ3-OH bridging four

222

independent ZnII ions in the asymmetric unit where the two tetranuclear units are

223

further doubly-bridged by two µ-Ocarboxylate atoms from two different (L)3− ligands. All

224

four edges of every [Zn4(µ3-OH)2]6+ cluster are bridged by (L)3− ligands’ carboxylates

225

in the µ-kO:kO' and µ-O coordination modes. Compared with that four ZnII ions form

226

a tetranuclear unit [Zn4(µ3-OH)2]6+ in an inerratic parallelogram type in the same

227

plane,13, 46 the four ZnII ions in our tetranuclear units [Zn4(µ3-OH)2]6+ slightly deviate

228

from an ideal parallelogram, being reflected by the about 0.1 Å difference between

229

two opposite sides. As shown in Figure 2a, each tetranuclear unit is linked by six (L)3−

230

ligands to produce an interesting 2D framework containing –(Zn−O)n− chain

231

sub-structure formed by µ-Ocarboxylate atoms of (L)3− ligands doubly-bridging those

232

tetranuclear [Zn4(µ3-OH)2]6+ units (Figure 2b). From the viewpoint of structural

233

topology, the (L)3− ligands and the tetranuclear units can be viewed as 3- and

234

6-connected nodes, respectively. Thus, the whole framework of 1 can be described as

235

a (3,6)-connected kgd net with point (Schläfli) symbol of (43)2(46·66·83) (Figure 3).

236

Moreover, the 2D frameworks are further extended into a 3D homochiral

237

supramolecular structure through complicated interlayered hydrogen-bonding 8


Page 8 of 29

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238

interactions originating from Namino, Ohydroxyl and Owater donors to uncoordinated

239

Ocarboxylate acceptors (Figure S6 and Table S2).

240

{[Cd2(HL)2(H2O)4]·6H2O}n (2). Compound 2 also crystallizes in the chiral space

241

group P1 with a Flack parameter of 0.04(2). Its asymmetric structural unit consists of

242

two CdII, two (HL)2− ligands, four coordination water molecules, and six lattice water

243

molecules. The three carboxyls of each H3L ligand in 2 were completely deprotonated,

244

and meanwhile its amino group was protonated. Consequently, the H3L ligand in 2

245

exists in a zwitterionic form of (HL)2−. The two independent (HL)2− ligands act as κ4-

246

and κ5-linkers to connect three symmetry-related Cd1 and three symmetry-related Cd2,

247

respectively (Figure 4a). Due to its protonation, the nitrogen atom in the amino acid

248

group of (HL)2− ligand does not take part in coordination and not generate chirality.

249

Cadmium(II) ions in 2 adopt two coordination geometries (Figure 4b). Cd1 is

250

six-coordinated, and located in a distorted coordination octahedron ligated by four O

251

atoms from one chelating carboxylate and two monodentate carboxylates of three

252

symmetry-related different (HL)2− ligands and two O atoms from water molecules.

253

Cd2 is seven-coordinated, and located in a O7 coordination geometry ligated by five O

254

atoms from two chelating carboxylates and one monodentate carboxylate of three

255

symmetry-related different (HL)2− ligands and two O atoms from water molecules.

256

The outstanding structural feature of 2 is the presence of two types of unsupported

257

wave-like polymeric layers (Figure 5): One is termed as Cd1-layer being generated by

258

the coordination of the symmetry-related κ4-linkers (HL)2− and six-coordinate metal

259

nodes Cd1; The other is termed as Cd2-layer being created by the coordination of the

260

symmetry-related κ5-linkers (HL)2− and seven-coordinate metal nodes Cd2. Of course,

261

Cd1-layer and Cd2-layer have the same chirality originating in the chirality of

262

enantiopure H3L ligands. Topologically, both Cd1-layer and Cd2-layer can be

263

simplified as a 3-connected 2D architecture with the point symbol of 63, in which all

264

CdII centers and (HL)2− ligands act as 3-connected nodes. As presented in Figure 6,

265

one Cd1-layer and one Cd2-layer are further connected to form an unique

266

double-layered

267

hydrogen-bonding interactions occurring between the coordination water molecules

homochiral

framework

through

interlayered

9


regular

O···O


268

and the carboxylates of (HL)2− ligands (Table S2). Interestingly, all the methyls of

269

aminoacid groups in (HL)2− ligands array up and down the double-layered framework,

270

and through the interdigitation of the methyls, those double-layered frameworks pile

271

up along a axis (Figure 6). Between those double-layered frameworks, every

272

protonated amino group of (HL)2− ligand forms two N···O hydrogen-bonds to bind

273

guests H2O and (H2O)5 clusters (Figure S7, Table S2), and thus it extends the

274

double-layered framework into a 3D supramolecular network (Figure S8). Notably,

275

the protonation of amino group in (HL)2− ligand not only balances charge and gives

276

two types of positive charge centers (ammonium and CdII cations) in HMOF 2, but

277

endows additional hydrogen-bonding sites to trap guests and extends the structure into

278

a higher-dimensional architecture as well.

279

{[Pb2(HL)2]·CH3OH·2.5H2O}n (3). Compound 3 crystallizes in the chiral space

280

group P41212 with a Flack parameter of −0.02(1). The asymmetric structural unit of 3

281

contains two PbII, two (HL)2− ligands, one lattice methanol molecule, and two and a

282

half lattice water molecules. As found in 2, each H3L ligand in 3 exists in the

283

zwitterionic (HL)2− form owing to the protonation of its amino group, and acts as a

284

κ4-linker to connect with three PbII ions. The three carboxylates of one independent

285

(HL)2− ligand, namely, [(HL)including N1]2− ligand, one in a chelating coordination mode

286

and the other two in monodentate coordination modes, bind Pb1, Pb2, and Pb1C,

287

respectively. The three carboxylates of the other independent (HL)2− ligand, namely

288

[(HL)including N2]2− ligand, adopting the same coordination modes as the former, bind

289

Pb2, Pb1D, and Pb2B, respectively (Figure 7a). Both Pb1 and Pb2 are ligated by one

290

chelating and two monodentate carboxylates from three different (HL)2− ligands,

291

respectively (Figure 7b). As a result, they form hemidirected four-coordinate

292

geometries with a stereochemically active lone pair, being similar to that of

293

four-coordinate PbII in literature.40 As shown in Figure 8a, every (HL)2− ligand uses its

294

chelating carboxylate and the monodentate carboxylate belonging to the aminoacid

295

group to bridge two independent PbII ions, and in this way it forms right-handed 41

296

helixes along c axis with large pitches of 57.3888(7) Å. Every helix further links with

297

four adjacent homochiral helixes through the coordination of the other monodentate 10


Page 10 of 29

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298

carboxylate of every (HL)2− ligand in the chain (Figure S9). Consequently, it creates a

299

novel 3D porous helical HMOF whose chirality stems from the enantiopure H3L

300

ligands and the derived right-handed helixes (Figure 8b). In the construction of the

301

present HMOF, both PbII centers and (HL)2− ligands act as 3-connected nodes. In view

302

of the topology, however, symmetry-related [(HL)including

303

symmetry-related [(HL)including

304

symmetry-related Pb2 ions have the different correlation of network topology node.

305

The minimum closed loops around the nodes involving in symmetry-related

306

[(HL)including N1]2− ligands and symmetry-related Pb2 ions are (62·12) whereas those

307

around the nodes involving in symmetry-related [(HL)including

308

symmetry-related Pb1 ions are (6·122). Thus, the whole 3D framework can be

309

described as an interesting 3-connected net with point symbol of (62·12)(6·122)

310

[Figure 9]. Notably, the 3D porous helical HMOF have three types of channels: the

311

huge rectangular channel with the opening size ca. 5.09 Å × 28.14 Å and the circular

312

channel with the opening size ca. 8.42 Å along directions [1 0 0] and [0 1 0], and the

313

square channel with the opening size ca. 5.56 Å × 5.56 Å along direction [0 0 1]

314

(considering the atomic van der Waals radii, and see Figure 8b and Figures S10−13).

315

However, two identical frameworks interpenetrate each other to stabilize the whole

316

structure, which effectively reduces the volumes of the channels along directions [1 0

317

0] and [0 1 0] and almost blocks all the pores along direction [0 0 1] (Figure S14).

318

The percent effective free volume is of 18.2% (a total potential solvent volume of

319

1109.6 Å3 out of every unit cell volume of 6104.5 Å3) calculated with PLATON.

320

Additionally, the protonated amino group of every (HL)2− ligand in 3 forms two

321

N···O hydrogen-bonds: one occurring between the two identical frameworks and

322

originating from N−H to uncoordinated Ocarboxylate; the other originating from N−H to

323

Oguest (guest = (H2O)3 cluster and methanol molecule), which binds a (H2O)3 cluster or

324

a methanol molecule in the crystals (Table S2, Figure S15).

2− N2]

2− N1]

ligands and

ligands as well as symmetry-related Pb1 and

2− N2]

ligands and

325

Based on the above structural descriptions of the coordination polymers 1–3, it is

326

found that the triply deprotonated H3L ligands can adopt anionic (L)3− and

327

zwitterionic

(HL)2−

forms,

various

coordination 11


modes,

and

versatile


328

hydrogen-bonding connections to construct interesting HMOFs with unique

329

architectures. Complexes 1 and 2 are 2D coordination polymers, but their structural

330

motifs are very different. In 1, anionic (L)3− ligands bridge tetrametallic Zn-clusters to

331

form the 2D layer with (3,6)-connected kgd net. In 2, zwitterionic (HL)2− ligands link

332

CdII ions to generate two types of independent wave-like layers of 63 topology, and

333

the two independent layers are further connected to form the unique double-layered

334

homochiral framework through the interlayered hydrogen-bonding interactions.

335

Perhaps, the labile coordination geometries of ZnII in 1 and CdII in 2 have somewhat

336

contribution on their novel structures. Furthermore, the 2D frameworks of 1 and 2 are

337

further extended into their 3D supramolecular structures through the complicated

338

interlayered hydrogen-bonding interactions related to the amino groups of (L)3− and

339

(HL)2−. Coordination polymer 3 are the 3D interpenetrating porous helical structure of

340

(62·12)(6·122) topology, which is built up from zwitterionic (HL)2− ligands linking

341

with PbII ions. Very interestingly, the HMOFs 2 and 3 incorporate additional positive

342

charge centers ammoniums into their metal−organic frameworks due to the

343

protonation of the amino group in (HL)2− ligand, and thus results in the formation of

344

the intriguing HMOFs with Brönsted acid and Lewis acid. Clearly, the introduction of

345

amino acid group into the rigid isophthalate unit has great influences on the

346

coordination mode, hydrogen-bonding site, and existence form of the resulting H3L

347

ligands, and finally on structures of the HMOFs for their different structures.

348

Photoluminescence properties. Coordination polymer materials, especially those

349

constructed from d10 metal centers or PbII ions and ligands with chromophoric

350

conjugated structures, often tend to interesting fluorescence properties, and thus have

351

potential applications in luminescent materials.37−42 Therefore, in this work, the

352

solid-state photoluminescence properties of 1–3 as well as the free H3L ligand at room

353

temperature were investigated. As shown in Figure 10, upon excitation at 310 nm,

354

compounds 1−3 and the free H3L ligand all displayed one emission band centered at

355

376, 391, 479, and 387 nm, respectively. Compared to the weak emission of the free

356

H3L ligand, the emissions of 1 and 2 undergo a slight blue- or red-shift, and their

357

emission intensities are obviously enhanced. Based on the similar emission shapes to 12


Page 12 of 29

Page 13 of 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


358

that of the free H3L ligand, as well as the slight wavelength shifts, the emissions of 1

359

and 2 can be mainly attributed to metal-perturbed intraligand emissions as observed in

360

the other complexes of d10 metals.13, 37, 38 The obviously enhanced emission intensities

361

for 1 and 2 may be attributed to ligand chelation at the metal center, which effectively

362

increases the rigidity of the ligands and reduces the energy loss due to radiationless

363

decay. As for the emission of s2-metal PbII complex 3, its wavelength is red shifted by

364

72 nm as compared to the emission of the free H3L ligand. The nature of red-shifted

365

emission band may be tentatively ascribed to the contribution of ligand-to-metal

366

charge transfer (LMCT) similar to those observed in PbII complexes.39

367

Complexes 1−3, especially 1, exhibit stronger solid-state emissions, higher

368

thermostability and insolubility in common solvents, and perhaps have potential

369

applications in optoelectronic devices.

370

Circular Dichroism (CD) and Second-Harmonic Generation (SHG) Efficiency.

371

The homochiral crystal structures of 1−3 prompt us to examine their CD and SHG

372

properties. First, we measured the UV/vis diffuse reflection spectra of 1−3 and the

373

free H3L ligand in the range of 200−800 nm, and the results indicate that they all are

374

characterized by multiple intense absorptions between 200 and 400 nm, ascribed to

375

π→π* transitions associated with the aromatic rings of the ligand (Figure S16). To

376

confirm their chiroptical activities, solid-state CD spectra of 1−3 were measured with

377

KBr pellets (Figure 11). The CD spectrum of 1 exhibits positive Cotton effects

378

centered at 205, 231 and 249 nm, and negative Cotton effects centered at 223, 238 and

379

260 nm. The CD spectrum of 2 exhibits positive Cotton effects centered at 207 and

380

243 nm, and negative Cotton effects centered at 233 and 258 nm. The CD spectrum of

381

3 exhibits positive Cotton effects centered at 201, 220 and 291 nm, and negative

382

Cotton effects centered at 210 and 254 nm. As expected, the inherent chirality of H3L

383

ligands was transmitted to the resulting HMOFs.

384

The second-order nonlinear optical (NLO) properties of 1−3 have been carried out

385

by the Kurtz−Perry method at room temperature. Preliminary experimental results

386

disclose that 1 and 3 are SHG-active with efficiencies approximately 0.75 and 0.20

387

times that of KDP, respectively, suggesting potential application as NLO-active 13



388

Page 14 of 29

materials. As for 2, the SHG signal is very weak.

389 390

CONCLUSION

391

In summary, three interesting HMOFs 1−3 have been successfully synthesized

392

through

the

use

of

our

designed

chiral

ligand

393

(S)-5-(((1-carboxyethyl)amino)methyl)isophthalic acid (H3L). They all crystallize in

394

the chiral space groups, whose phase purities, chirality are further confirmed by

395

PXRD and CD studies, respectively. Further structural analyses reveal that complexes

396

1 and 2 are 2D layered metal−organic networks with different architectures and

397

topologies, and then generated 3D supramolecular structures through the complicated

398

interlayered hydrogen-bonding interactions related to the amino groups of H3L

399

ligands. Complex 3 is a 3D interpenetrating porous metal−organic helicate with

400

interesting (62·12)(6·122) topology. Very interesting, the metal−organic frameworks of

401

2 and 3 possess two positive charge centers respectively from metal ions and

402

zwitterionic (HL)2− ligand, and such is intriguing HMOFs incorporating Brönsted acid

403

with Lewis acid for potential applications. The TGA results confirm that the

404

metal−organic frameworks of compounds 1−3 are quite stable. Moreover, 1 and 3 are

405

SHG-active with efficiencies approximately 0.75 and 0.20 times as much as that of

406

KDP, respectively. More importantly, it is found that the coordination mode,

407

hydrogen-bonding site, and charge of H3L ligand can be adjusted through the

408

protonation of its amino group, which provides a potential pathway to design and

409

develop HMOFs materials based on this type of aminoacid-functionalized

410

polycarboxylate chiral ligands.

411 412

ASSOCIATED CONTENT

413

Supporting Information

414

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

415

patterns, selected bond lengths and angles, and X-ray crystallographic files in CIF

416

format for compounds 1−3 are available in supporting material section. This material 14


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417

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

418

Accession Codes

419

CCDC 1587883‒1587885 contain the supplementary crystallographic data for this

420

paper.

421

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

422

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

423

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

These

data

can

be

obtained

free

of

charge

via

424 425

AUTHOR INFORMATION

426

Corresponding Author

427

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

428

ORCID

429

Benlai Wu: 0000-0003-1354-3365

430

Notes

431

The authors declare no competing financial interest.

432 433

ACKNOWLEDGEMENTS

434

We gratefully acknowledge financial support from the National Natural Science

435

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

436

Technologies in the Project of Henan Province (122300410092). The authors thank Dr.

437

Chengmin Ji for the measurements of the second-order nonlinear optical properties.

438 439

REFERENCES

440

(1) Ma, L.; Abney, C.; Lin, W. Chem. Soc. Rev. 2009, 38, 1248–1256.

441

(2) Yoon, M.; Srirambalaji, R.; Kim, K. Chem. Rev. 2012, 112, 1196–1231.

442

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(4) Liu, Y.; Xuan, W.; Cui, Y. Adv. Mater. 2010, 22, 4112–4135.

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446

(6) Gu, Z.-G.; Fu, W.-Q.; Liu M.; Zhang, J. Chem. Commun. 2017, 53, 1470–1473.

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449

Chem. Mater. 2017, 29, 2321−2332.

450

(9) Zhang, S.-Y.; Wojtas, L.; Zaworotko, M. J. J. Am. Chem. Soc. 2015, 137, 12045−12049.

451

(10) Asnaghi, D.; Corso, R.; Larpent, P.; Bassanetti, I.; Jouaiti, A.; Kyritsakas, N.; Comotti, A.;

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(16) Wu, C.; Lin, W. Angew. Chem. Int. Ed. 2007, 46, 1075−1078.

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(17) Zhuo, C.; Wen, Y.; Hu, S.; Sheng, T.; Fu, R.; Xue, Z.; Zhang, H.; Li, H.; Yuan, J.; Chen, X.;

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Wu, X. Inorg. Chem. 2017, 56, 6275−6280. (18) Song, B.-Q.; Chen, D.-Q.; Ji, Z.; Tang, J; Wang, X.-L.; Zang, H.-Y.; Su, Z.-M. Chem. Commun. 2017, 53, 1892−1895. (19) Zou, C.; Li, Q.; Cheng, F.; Wang, H.; Duan, J.; Jin, W. CrystEngComm, 2017, 19, 2718–2722. (20) Han, X.; Xia, Q.; Huang, J.; Liu, Y.; Tan, C.; Cui, Y. J. Am. Chem. Soc. 2017, 139, 8693–8697. (21) Gedrich, K.; Heitbaum, M.; Notzon, A.; Senkovska, I.; Frçhlich, R.; Getzschmann, J.; Mueller, U.; Glorius, F.; Kaskel S. Chem. Eur. J. 2011, 17, 2099–2106. (22) Mart-Gastaldo, C.; Warren, J. E.; Briggs, M. E.; Armstrong, J. A.; Thomas, K. M.; Rosseinsky, M. J. Chem. Eur. J. 2015, 21, 16027–16034. 16


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482

(26) Xuan, W.; Zhang, M.; Liu, Y.; Chen, Z.; Cui, Y. J. Am. Chem. Soc. 2012, 134, 6904–6907.

483

(27) Chen, S.; Liu, M.; Gu, Z.-G.; Fu, W.-Q.; Zhang, J. ACS Appl. Mater. Interfaces 2016, 8,

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27332−27338. (28) Gu, Z.-G.; Grosjean, S.; Bräse, S.; Wöll, C.; Heinke L. Chem. Commun. 2015, 51, 8998−29001. (29) Nicasio, A. I.; Montilla, F.; Álvarez, E.; Colodrero, R. P.; Galindo, A. Dalton Trans. 2017, 46, 471–482. (30) Kutzscher, C.; Janssen-Müller, D.; Notzon, A.; Stoeck, U.; Bon, V.; Senkovska, I.; Kaskel, S.; Glorius, F. CrystEngComm 2017, 19, 2494–2499.

491

(31) Cai, K.; Zhao, N.; Zhang, N.; Sun, F.-X.; Zhao, Q.; Zhu, G.-S. Nanomaterials 2017, 7, 88.

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(32) Liu, J.; Wang, F.; Zhang, J. Cryst. Growth Des. 2017, 17, 5393−5397.

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(33) Liu, y.; Xi, X.; Ye, C.; Gong, T.; Yang, Z.; Cui, Y. Angew. Chem. Int. Ed. 2014, 53,

494

13821–13825.

495

(34) Xia, Z. Q.; He, C.; Wang, X. G.; Duan, C. Y. Nat. Commun. 2017, 8, 361.

496

(35) Horike, S.; Dincǎ, M.; Tamaki, K.; Long, J. R. J. Am. Chem. Soc. 2008, 130, 5854–5855.

497

(36) Hwang, Y. K.; Hong, D.-Y.; Chang, J.-S.; Jhung, S. H.; Seo, Y.-K.; Kim, J.; Vimont, A.;

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Daturi, M.; Serre, C.; Férey, G. Angew. Chem. Int. Ed. 2008, 47, 4144–4148. (37) Seco, J. M.; Pérez-Yáñez, S.; Briones, D.; García, J. Á.; Cepeda, J.; Rodríguez-Diéguez, A. Cryst. Growth Des. 2017, 17, 3893−3906. (38) Wang, R.; Liu, L.; Lv, L.; Wang, X.; Chen, R.; Wu, B. Cryst. Growth Des. 2017, 17, 3616−3624.

503

(39) Gong, Y.; Jiang, P.-G.; Wang, Y.-X.; Wu T.; Lin, J.-H. Dalton Trans. 2013, 42, 7196–7203.

504

(40) Najaﬁ, E.; Amini, M. M.; Mohajerani, E.; Janghouri, M.; Razavi, H.; Khavasi, H. Inorg.

505

Chim. Acta 2013, 399, 119–125. 17



506 507 508 509

(41) Zhao, M.; Tan, J.; Su, J.; Zhang, J.; Zhang, S.; Wu, J.; Tian, Y. Dyes and Pigments 2016, 130, 216–225. (42) Ma, M.-L.; Qin, J.-H.; Ji, C.; Xu, H.; Wang, R.; Li, B.-J.; Zang, S.-Q.; Hou, H.-W.; Batten, S. R. J. Mater. Chem. C 2014, 2, 1085–1093.

510

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

511

(44) Sheldrick, G. M. Acta Cryst. C 2015, 71, 3–8.

512

(45) Spek, A. L. J. Appl. Crystallogr. 2003, 36, 7–8.

513

(46) Wu, B.-L.; Wang, R.-Y.; Zhang, H.-Y.; Hou, H.-W. Inorg. Chim. Acta 2011, 375, 2–10.

514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 18


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536 537

Table 1. Crystal Data and Structure Refinement for 1−3 compounds

1

2

3

formula

C48H48N4O30Zn8

C24H42Cd2N2O22

C25H31N2O15.5Pb2

temp (K)

293(2)

293(2)

293(2)

formula weight

1683.86

935.39

1021.90

crystal system

triclinic

triclinic

tetragonal

space group

P1

P1

P41212

a (Å)

11.2487(4)

8.8978(5)

10.3136(1)

b (Å)

11.4465(4)

9.8274(6)

10.3136(1)

c (Å)

11.5726(4)

10.3201(6)

57.3888(7)

α/°

71.762(1)

69.655(6)

90

β/°

69.371(1)

86.579(5)

90

γ/°

85.317(1)

85.922(5)

90

V (Å3)

1323.79(8)

843.39(9)

6104.47(14)

Z, ρcalcd (g/cm3)

1, 2.112

1, 1.842

8, 2.224

GOF

1.026

1.042

1.124

flack parameter

0.047(4)

0.04(2)

-0.02(1)

R1, wR2 (I > 2 σ(I))

0.0192, 0.0514

0.0304, 0.0585

0.0445, 0.1100

largest diff. peak and hole

0.417, -0.506

0.687, -0.489

2.180, -0.914

538 539

Captions for the Scheme and Figures

540

Scheme 1. Schematic Representation of the Synthesis Strategy for Chiral Triangular Ligand H3L.

541

Figure 1. (a) Different coordination modes of anionic (L)3− ligands in 1, showing two chiral

542

centers in every (L)3− ligand (the permanent chiral carbon atoms C10, C22, C34 and C46 being of

543

S-configuration, and the labile chiral nitrogen atoms N1 and N4 being of R-configuration while 19



544

the N2 and N3 being of S-configuration). (b) Coordination geometries of eight independent ZnII

545

ions in 1, showing two similar tetranuclear units in the asymmetric unit of 1. Symmetry code: (A)

546

− 1 + x, −1 + y, z; (B) x, y, 1 + z; (C) x, y, −1 + z; (D) 1 + x, 1 + y, −1 + z; (E) − 1 + x, −1 + y, 1 + z;

547

(F) 1 + x, 1 + y, z.

548

Figure 2. (a) View of 2D framework in 1, and (b) –(Zn−O)n− chain sub-structure formed by

549

µ-Ocarboxylate atoms of (L)3− ligands doubly-bridging tetranuclear [Zn4(µ3-OH)2]6+ units. Symmetry

550

code: (A) − 1 + x, −1 + y, z; (B) x, y, 1 + z; (C) x, y, −1 + z; (D) 1 + x, 1 + y, −1 + z; (F) 1 + x, 1 + y,

551

z.

552

Figure 3. Schematic representation of 2D (3,6)-connected kgd topology of 1 (cyan and gray balls

553

represent tetranuclear [Zn4(µ3-OH)2]6+ and (L)3− nodes, respectively).

554

Figure 4. (a) Different coordination modes of zwitterionic (HL)2− ligands in 2, showing the

555

permanent chiral carbon atoms C10 and C22 of S-configuration, and the protonated nitrogen

556

atoms N1 and N2. (b) Different coordination geometries of two independent CdII ions in 2.

557

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

558

Figure 5. View of two types of unsupported wave-like homochiral polymeric layers with 63

559

topology in 2: Cd1-layer generated by the coordination of the symmetry-related κ4-linkers (HL)2−

560

and six-coordinate metal nodes Cd1, and Cd2-layer created by the coordination of the

561

symmetry-related κ5-linkers (HL)2− and seven-coordinate metal nodes Cd2. Symmetry code: (A) x,

562

−1 + y, z; (B) x, −1 + y, 1 + z; (C) x, 1 + y, z; (D) x, 1 + y, −1 + z.

563

Figure 6. View of the unique double-layered homochiral framework in 2 formed by

564

hydrogen-bonding connection between Cd1-layer and Cd2-layer, showing the interdigitation of

565

the methyls between double-layered frameworks.

566


567


568

atoms N1 and N2. (b) Coordination geometries of two independent PbII ions in 3. Symmetry code:

569

(A) 3/2 − y, −1/2 + x, 1/4 + z; (B) −1 + x, y, z; (C) 1 + x, y, z; (D) 1/2 + y, 3/2 – x, −1/4 + z.

570

Figure 8. (a) View of right-handed 41 helix, and (b) novel 3D porous helical HMOF of 3, showing

571

the huge rectangular channels and the circular channels along direction [1 0 0].

572

Figure 9. Schematic representation of 3D 3-connected (62·12)(6·122) topology of 3. The

573

minimum closed loops around the nodes involving in symmetry-related [(HL)including N1]2− ligands 20


Page 20 of 29

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574

(green balls) and symmetry-related Pb2 ions (gray balls) are (62·12) whereas those around the

575

nodes involving in symmetry-related [(HL)including N2]2− ligands (blue balls) and symmetry-related

576

Pb1 ions (brick-red balls) are (6·122).

577

Figure 10. Fluorescent behaviors of compounds 1−3 and free H3L ligand in the solid state at room

578

temperature.

579

Figure 11. Solid-state CD spectra of compounds 1−3.

580 581 582 583 584 585 586 587 588 589

Scheme 1. Schematic Representation of the Synthesis Strategy for Chiral Triangular Ligand

590

H3L.

591 592 593 594 595 596 597 598 21



599 600

(a)

601 602 603 604

(b)

605 606

Figure 1. (a) Different coordination modes of anionic (L)3− ligands in 1, showing two chiral

607

centers in every (L)3− ligand (the permanent chiral carbon atoms C10, C22, C34 and C46 being of

608

S-configuration, and the labile chiral nitrogen atoms N1 and N4 being of R-configuration while

609

the N2 and N3 being of S-configuration). (b) Coordination geometries of eight independent ZnII

610

ions in 1, showing two similar tetranuclear units in the asymmetric unit of 1. Symmetry code: (A)

611

− 1 + x, −1 + y, z; (B) x, y, 1 + z; (C) x, y, −1 + z; (D) 1 + x, 1 + y, −1 + z; (E) − 1 + x, −1 + y, 1 + z;

612

(F) 1 + x, 1 + y, z.

613 614 22


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615 616

(a)

617 618 619

(b)

620 621 622

Figure 2. (a) View of 2D framework in 1, and (b) –(Zn−O)n− chain sub-structure formed by

623

µ-Ocarboxylate atoms of (L)3− ligands doubly-bridging tetranuclear [Zn4(µ3-OH)2]6+ units. Symmetry

624

code: (A) − 1 + x, −1 + y, z; (B) x, y, 1 + z; (C) x, y, −1 + z; (D) 1 + x, 1 + y, −1 + z; (F) 1 + x, 1 + y,

625

z.

626

627 628 629 630

Figure 3. Schematic representation of 2D (3,6)-connected kgd topology of 1 (cyan and gray balls

631

represent tetranuclear [Zn4(µ3-OH)2]6+ and (L)3− nodes, respectively).

632 23



633

(a)

634 635 636

(b)

637 638 639


640


641

atoms N1 and N2. (b) Different coordination geometries of two independent CdII ions in 2.

642

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

643 644 24


Page 24 of 29

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645

646 647 648

Figure 5. View of two types of unsupported wave-like homochiral polymeric layers with 63

649

topology in 2: Cd1-layer generated by the coordination of the symmetry-related κ4-linkers (HL)2−

650

and six-coordinate metal nodes Cd1, and Cd2-layer created by the coordination of the

651

symmetry-related κ5-linkers (HL)2− and seven-coordinate metal nodes Cd2. Symmetry code: (A) x,

652

−1 + y, z; (B) x, −1 + y, 1 + z; (C) x, 1 + y, z; (D) x, 1 + y, −1 + z.

653

654 655

Figure 6. View of the unique double-layered homochiral framework in 2 formed by

656

hydrogen-bonding connection between Cd1-layer and Cd2-layer, showing the interdigitation of

657

the methyls between double-layered frameworks.

658 25



659 660 661

(a)

662 663 664 665

(b)

666 667 668


669


670

atoms N1 and N2. (b) Coordination geometries of two independent PbII ions in 3. Symmetry code:

671

(A) 3/2 − y, −1/2 + x, 1/4 + z; (B) −1 + x, y, z; (C) 1 + x, y, z; (D) 1/2 + y, 3/2 – x, −1/4 + z.

672 26


Page 26 of 29

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673

(a)

674 675

(b)

676 677

Figure 8. (a) View of right-handed 41 helix, and (b) novel 3D porous helical HMOF of 3, showing

678

the huge rectangular channels and the circular channels along direction [1 0 0].

679 680

Figure 9. Schematic representation of 3D 3-connected (62·12)(6·122) topology of 3. The

681

minimum closed loops around the nodes involving in symmetry-related [(HL)including N1]2− ligands

682

(green balls) and symmetry-related Pb2 ions (gray balls) are (62·12) whereas those around the

683

nodes involving in symmetry-related [(HL)including N2]2− ligands (blue balls) and symmetry-related

684

Pb1 ions (brick-red balls) are (6·122). 27



685

686 687 688

Figure 10. Fluorescent behaviors of compounds 1−3 and free H3L ligand in the solid state at room

689

temperature.

690

691 692 693

Figure 11. Solid-state CD spectra of compounds 1−3.

694 28


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695

For Table of Contents Use Only

696 697 698

Homochiral

699

Aminoacid-Functionalized Isophthalic Acid: Synthesis, Structure

700

determination, and Optical Properties

701

Coordination

Polymers

Based

on

Xing Wang, Keqing Zhang, Lulu Lv, Rui Chen, Wenbo Wang, and Benlai Wu

702 703

704 705

Three 2−3D homochiral metal−organic frameworks with unique architectures and

706

interesting topologies were synthesized and characterized by elemental analysis, TGA,

707

spectroscopic methods and X-ray diffraction analysis. More importantly, the

708

coordination mode, hydrogen-bonding site, existence form, and charge of the

709

aminoacid-functionalized polycarboxylate chiral ligand can be controlled by the

710

protonation of its amino group, which results in the structural diversity.

711

29


Homochiral Coordination Polymers Based on Aminoacid

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