Construction of Metal−Organic Frameworks (M = Cd(II), Co(II), Zn(II), and Cu(II)) Based on Semirigid Oxadiazole Bridging Ligands by Solution and Hydrothermal Reactions

Abstract

Two new symmetric and unsymmetrical semirigid organic ligands 2,5-bis(4-(1H-1,2,4-triazol-1-ylmethyl)phenyl)-1,3,4-oxadiazole (L1) and 4-(1H-1,2,4-trizol-1-ylmethyl)benzoic acid (L2) have been prepared. L2 was generated from L1 by a hydrothermal reaction via the hydrolysis of the central oxadiazole ring of L1. The solution and hydrothermal reactions of L1 with various inorganic M(II) (M ) Cd, Co, Zn, and Cu) ions have been investigated. Compounds [Cd(L1) 3) were obtained in solution by a combination of L1 with corresponding metal salts, while compounds Zn(L2) 2 (4), Co(L2) 2 (5), and [Co(L2) 2 ]‚H 2 O (6) were synthesized by a hydrothermal technique with in situ generated unsymmetrical L2 ligand. In addition, compounds 4-6 could also be prepared by direct combination of L2 with corresponding metal salts under the same hydrothermal conditions. All six new coordination polymers were fully characterized by infrared spectroscopy, elemental analysis, single-crystal X-ray diffraction, and thermogravimetric analysis. Compounds 1-3 are isostructural and feature a onedimensional chain motif composed of an M 2 L 2 -macroring as the based building block. Compounds 4 and 5 form a novel chiral and acentric non-interpenetrating two-dimensional network consisting of right-and left-handed helical ML chains, respectively. Compound 6 adopts a unique non-interpenetrating three-dimensional framework, in which the inorganic ‚‚‚Co-O-Co-O‚‚‚ chains are connected to each other through unsymmetric L2 ligands. In the solid state, L1-L2 and their complexes 1-6 are luminescent. The Kurtz powder measurements show that both 4 and 5 are nonlinear optical (NLO) active and have potential applications as NLO-active materials.

A novel heterostranded double-helical coordination polymer with chiral channels emitting blue fluorescence

“…The control of helicity at supramolecular level is a fascinating challenge for chemists [1], because helix is an essence of life [2][3][4] and is also important in advanced materials, such as the double-helical structure for DNA [5,6], right or left-handed quartz [7], which provides an important impetus for the creation of artificial helical structures in supramolecular chemistry and material science with potential applications in the fields of asymmetric catalysis [8], nonlinear optical materials [9] and the aesthetically appealing topologies of helical compounds [10][11][12]. Up to date, many single-, double-, triple-and higher-order stranded helical complexes have been generated by self-assembly processes via the judicious choice of suitable ligand [13][14][15][16][17][18][19].…”

Theoretical investigation on structures, electronic spectra and nonlinear optical properties of gold compounds [X-“Au(PMe3)”2]

“…On the basis of the TDDFT results, a two-level model [24] gives a rational explanation for third-order NLO coefficients, 4 3…”

“…New materials with desirable nonlinear optical (NLO) properties have been the subject of intense interest because these materials may provide efficient means for modifying the nature of an incident light beam, and have potential applications in photonic devices, i.e., for optical data acquisition, storage, transmission and processing [1][2][3][4]. NLO materials under investigation are incredibly diverse, including organic and inorganic molecules, polymers, liquid crystals, inclusion complexes and composites.…”

A novel two-dimensional framework based on unprecedented cadmium(II) chains

“…Although derivatives of the 1,2,4-triazole ligand, especially the amino-substituted (Keij et al, 1984;Shakir et al, 2003), aryl-substituted (Klingele & Brooker, 2003;Wang et al, 2007) and alkyl-substituted (Bradford et al, 2004;Yi et al, 2004) derivatives, have been well studied, very little attention has been paid to carboxylate-substituted 1,2,4-triazole ligands (Ding et al, 2008). Previously, we reported a study of the M II (M = Co and Zn) coordination chemistry of the carboxylatesubstituted 1,2,4-triazole 4-[(1H-1,2,4-triazol-1-yl)methyl]benzoic acid (HL; Zhao et al, 2007). As an extension of this study, we investigated the self-assembly reaction of L À with cadmium chloride under hydrothermal conditions, and the novel supramolecular complex [CdLCl(H 2 O)] n , (I), was isolated.…”