CHEN Wen-tong, KUANG Han-mao, CHEN Hua-long

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SOLVOTHERMAL PREPARATION AND CRYSTAL STRUCTURE OF A 2,2'-BIIMIDAZOLE COMPOUND

*CHEN Wen-tong1,2, KUANG Han-mao1,2, CHEN Hua-long1,2

(1. Institute of Applied Chemistry, Jinggangshan University, Ji’an, Jiangxi 343009, China; 2. School of Chemistry and Chemical Engineering, Jinggangshan University, Ji’an, Jiangxi 343009, China)

A biimidazole-containing compound, (H3O)(2,2'-biimidazole)Cl (1), has been obtained through solvothermal reactionsand structurally characterized by single-crystal X-ray diffraction. Compound 1 crystallizes in the space group C2/m of the monoclinic system with four formula units in a cell: a = 16.5760(4), b = 11.5546(4), c = 4.6180(1) ?, β = 96.382(2)°, V = 879.00(4) ?3, C6H9ClN4O, Mr= 188.62, Dc= 1.425 g/cm3, S = 1.022, μ(MoKα) = 0.393 mm-1, F(000) = 392, R = 0.0454 and wR = 0.1298. Compound 1 is characteristic of a 2-D supramolecular layer motif. Compound 1 displays an emission in the blue region.

biimidazole; crystal; fluorescence; solvothermal; supramolecular

INTRODUCTION

Supramolecular chemistry has recently obtained more and more interest to prepare novel solid state compounds because supramolecular chemistry makes use of self-assembly to yield novel compoundsby virtue of different kinds of weak intermolecular cooperative interactions, such as aromatic π-π stacking interactions,hydrogen bonding interactions,ion-ion interactions,ion-dipole interactions and dipole-dipole interactions, to interlink building subunits together and a great deal of supramolecular compounds have been synthesized thus far[1-3].2,2'-biimidazole is a useful building subunit in forming supramolecular or extended structures because of its ability to bind to metal centers via the nitrogen atoms[4-5]. Blue fluorescent compounds have gained increasing attention for many years because blue fluorescence is a key color component for full-color electroluminescent displays. My recent work in synthesizing supramolecular compounds are mainly aiming at thepreparation of 2,2'-biimidazole- containing compounds with blue fluorescence. Herein, I report the synthesis, characterization and fluorescence of a biimidazole-containing compound,(H3O)(2,2'-biimidazole)Cl(1), which was prepared through a solvothermal reaction.

1 EXPERIMENTAL

1.1 Preparation of (H3O)(2,2'-biimidazole)Cl(1)

All reactants of A.R. gradewere commercially obtained and used without further purification.IR spectra were obtained with a Perkin-Elmer Spectrum One FT-IR spectrometer using KBr discs. The fluorescent data were collected at room temperature on a computer-controlled Jobin Yvon FluoroMax-3 spectrometer in fluorescence mode. The title compound wassynthesized by mixing HgCl2(0.1 mmol, 272 mg), 2,2' - biimidazole (0.1 mmol, 134 mg), concentrated hydrochloric acid (1 mL) and 10 mL distilled waterin a 23 mL Teflon-lined stainless steel autoclave and heated at 200 oC for 10 days. After being slowly cooled to room temperature at a rate of 6 oC/h, colourless crystals suitable for X-ray analysis were obtained. The yield is 21%. Fourier transform IR (KBr, cm?1): 3358(s), 3156(vs), 2790(w), 1624(m), 1527(s), 1420(m), 1335(w), 1307(m), 1216(w), 1172(m), 1100(vs), 992(m), 936(w), 880(w), 755(vs), 682(m), 619(w), 484(w), and 422(w).

1.2 X-ray structural determination

X-ray diffraction data set was conducted on a Rigaku Mercury CCD X-ray diffractometer with graphite monochromatic Mo-radiation (= 0.71073 ?) using ascan technique. CrystalClear software was used for data reduction and empirical absorption correction[6]. The structure was solved by the direct methods using the Siemens SHELXTLTMVersion 5 package of crystallographic software[7]. The difference Fourier maps based on the atomic positions yield all atoms. The structure was refined using a full-matrix least-squares refinement on2. All atoms were refined anisotropically. The summary of crystallographic data and structure analysis is given in Table 1. The selected bond lengths and bond angles are listed in Table 2. Crystallographic data for the structural analysis have been deposited with the Cambridge Crystallographic Data Centre, CCDC No. CCDC 905165. Copies of this information may be obtained free of charge from the Director, CCDC, 12 Union Road, Cambridge, CBZ 1EZ, UK (Fax: +44-1223-336033; E-mail: deposit@ccdc.cam.ac.uk or www:http://www.ccdc. cam.ac.uk).

Table 1 Summary of Crystallographic Data and Structural Analyses for compound 1

Table 2 Selected Bond Lengths and Bond Angles of compound 1

Symmetry codes: #1, -,.

2 RESULTS AND DISCUSSION

Single-crystal X-ray diffraction analysis reveals that compound 1 features an isolated structure, comprising of one neutral 2,2'-biimidazole molecule, one chloride anion and one protonated lattice water molecule. Compound 1 crystallizes in the space group2/of the monoclinic system with four formula units in a cell. All the crystallographic independent atoms, except for Cl1 and O1W atoms, are in the general positions. An ORTEP diagram of compound 1is shown in Figure1.Between two imidazole rings the dihedral angle is 3.20(1)°. The atoms on the 2,2'-biimidazole rings are -0.027 ? ~ +0.030 ? deviating from their ring planes. The 2,2'-biimidazole molecules and the chloride anions connect to each other via N-H···Cl and C-H···Cl hydrogen-bonding interactions to yield a one-dimensional (1-D) chain-like structure, as shown in Figure 2. The 1-D chains then further interlink together through O-H···Cl and O-H···O hydrogen-bonding interactions, forming a 2-D supramolecular layer(Figure 2). The electrostatic effect and Van der waals force between the 2-D layers solidify the crystal packing of 1 (Figure 3).

Fig. 1 An ORTEP drawing of 1 with 20% thermal ellipsoids. The hydrogen atoms were omitted for clarity.

Fig. 2 The 2-D supramolecular layer of 1 viewed down along c-axis. The dashed lines represent the hydrogen bondings (?): O1W-H1WA···Cl1 3.109(7), O1W-H1WB···O1W(-x, y, -z) 2.826(13), N2-H2A···Cl1 3.119(2), C2-H2B···Cl1(1/2-x, 1/2+y, 1-z) 3.727(3)

Fig. 3 The packing diagram of 1 viewed down along c-axis

The fluorescent spectra of the solid-state sample of 1 were measured under room temperature. As shown in Figure 4, the fluorescent spectra reveal that compound 1 exhibits a broad blue emission band with a maximum wavelength at around 450 nm when it was excited at 345 nm.

Fig. 4 Solid-state fluorescent spectra of 1 at room temperature

In conclusion, a biimidazole-containing compound,(H3O)(2,2'-biimidazole)Cl(1), has been synthesized through a solvothermal reaction and structurally characterized by X-ray single-crystal diffraction.Compound 1 is characteristic of an isolated structure. Fluorescent investigation reveals that compound 1 displays a broad emission in the blue region.

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[2] Gass I A, Batten S R, Forsyth C M, et al. Supramolecular aspects of iron(ii) crown-dipyridyl spin-crossover compounds [J]. Coord. Chem. Rev., 2011 (255): 2058-2067.

[3] Akhbari K, Morsali A. thallium(I) supramolecular compounds: structural and properties consideration [J]. Coord. Chem. Rev., 2010 (254): 1977-2006.

[4] Laurila E, Oresmaa L, Niskanen M, et al. Metal?metal interactions in stacked mononuclear and dinuclear rhodium 2,2′-Biimidazole carbonyl complexes [J]. Crys. Growth & Des., 2010 (10): 3775-3786.

[5] Borel C, Larsson K, Hakansson M, et al. Oxalate- and squarate-Biimidazole supramolecular synthons: hydrogen-Bonded networks based on [Co(H2biimidazole)3]3+[J]. Crys. Growth & Des., 2009 (9): 2821-2827.

[6] Rigaku. CrystalClear Version 1.35[M]. Rigaku: Corporation, 2002.

[7] Siemens, SHELXTLTM Ver. 5 Reference manual, siemens energy & automation Inc[M]. Madison: Wisconsin, 1994.

一種2,2'-聯(lián)咪唑化合物的水熱合成和晶體結構

*陳文通1,2，匡漢茂1,2，陳華龍1,2

(1.井岡山大學應用化學研究所，江西，吉安 343009；2.井岡山大學化學化工學院，江西，吉安 343009)

通過溶劑熱反應法合成了一種2,2'-聯(lián)咪唑化合物(H3O)(2,2'-biimidazole)Cl (1)，并對該化合物進行了X-射線單晶結構分析。標題化合物屬于單斜晶系的C2/m空間群，晶胞參數(shù)如下：= 16.5760(4),= 11.5546(4),= 4.6180(1) ?,= 96.382(2)°,= 879.00(4) ?3, C6H9ClN4O,M= 188.62,D= 1.425 g/cm3,= 1.022,(Mo) = 0.393 mm-1,(000) = 392,= 0.0454和= 0.1298。該化合物具有二維超分子結構。該化合物能夠發(fā)出藍色熒光。

聯(lián)咪唑；晶體；熒光；溶劑熱；超分子

O641

A

10.3969/J.issn.1674-8085.2013.05.006

O641

A

10.3969/j.issn.1674-8085.2013.05.005

2013-05-06

2013-07-07

The science and technology project of Jiangxi Provincial Department of Education (GJJ11535).

1674-8085(2013)05-0019-04

*CHEN Wen-tong (1973-), male, born in Gutian, Fujian province, PhD., associate Prof.,major in structure chemistry(E-mail: wtchen_2000@yahoo.cn);

KUANG Han-mao (1963-), male, born in Ji’an, Jiangxi province, bachelor, associate Prof., major in physical chemistry (E-mail: k1h2m3@126.com);

CHEN Hua-long (1976-), male, born in Ji’an, Jiangxi province, master, associate Prof., major in physical chemistry (E-mail: chenhl88@163.com).