Syntheses, Structures And Properties Of The Coordination Polymers Constructed By 2-chlorophenyl-imidazole Dicarboxylate

In recent years, coordination polymers have become a research hotspot due to their potential applications in magnetism, adsorption, catalysis, recognition and other fields. A great number of coordination polymers with unique structures and superior performances have been reported. In this article, we introduce o-chlorophenyl, m-chlorophenyl and p-chlorophenyl groups into 2-position substituted imidazole dicarboxylates separately,and twelve polymers with novel structures have been synthesized under hydro(solvo)thermal conditions. This paper contains two parts as follows:1. Twelve polymers have been synthesized by the self-assembly of metal ions and imidazole dicarboxylate ligands, which comprise four 2D polymers of alkalineearth metals [Sr(o-Cl Ph HIDC)(H2O) 2]n(1), [Mg(m-Cl Ph HIDC)(H2O)2]n(2), Sr(m-Cl Ph HIDC)(H2O)]n(3) and [Sr(p-Cl Ph HIDC)(H2O)]n(4); two 3D polymers {[Co3(m-Cl Ph IDC)2(H2O)6]·2H2O}n(5) and {[Co3(p-Cl Ph HIDC)3(H2O)3]·6H2O}n(6); one nickel tetranuclear complex [Ni4(p-Cl Ph HIDC)4(CH3CN)4(H2O)4]·4H2O(7); three lead polymers, 1D {[Pb(o-Cl Ph H2IDC)2]·H2O}n(8), 2D [Pb3(p-Cl Ph IDC)2(H2O)]n(9) and 3D [Pb(p-Cl Ph H2IDC)2]n(10); and two cadmium polymers, 2D [Cd3(p-Cl Ph H2IDC)2(p-Cl Ph HIDC)2(H2O)2]n(11) and 3D {[Cd2(p-Cl Ph HIDC)2(4,4￠-bipy)]·H2O}n(12)(o-Cl Ph H3 IDC = 2-(2-chlorophenyl)-1H-imidazole-4,5-dicarboxylic acid, m-Cl Ph H3 IDC = 2-(3-chlorophenyl)-1H-imidazole-4,5-dicarboxylic acid, p-Cl Ph H3 IDC = 2-(4-chlorophenyl)-1H-imidazole-4,5-dicarboxylic acid). Their molecular structures were obtained by by means of elemental analysis, IR spectra and single-crystal X-ray diffraction. We analyzed the effects of the metal, the substituent position, p H, template agent, temperature, solvent on the structures. They are also characterized by photoluminescence, thermal stability and their purities were verified by X-ray powder diffraction.2. Polymer 12 was explored by small molecule recognition because of its remarkable structural and fluorescent features. Upon immersing the crystalline samples of 12 in solvents, methanol, ether, acetone, THF, acetonitrile, DMF and pyridine, for 10 h, 12 shows selective recognition for pyridine, with a visual color change from pearl to pink, under UV lamp at 254 nm, while other solvents fail to induce an obvious color change. To verify the selective recognition to pyridine, fluorescence spectra, X-ray powder diffraction and solid-state ultraviolet absorption spectra was employed.