Synthesis, Structures And Properties Of Methoxyphenyl Andbromophenyl Substituted Imidazole Dicarboxylate-based Coordination Polymers

Choosing organic ligand plays an important role in the self-assembly of coordination polymers. Imidazole-4,5-dicarboxylic acid and 2-position substituted imidazole dicarboxylates show strong coordination abilities, which have received considerable attention. In this paper, twelve MOFs based on 2-(2-bromophenyl)-1H-imidazole-4,5-dicarboxylic acid(o-Br H3 Ph IDC), 2-(3-bromophenyl)-1H-imidazole-4,5-dicarboxylic acid(m-Br H3 Ph IDC) and 2-(3-methoxyphenyl)-1H-imidazole-4,5-dicarboxylic acid(p-H3 MOPh IDC) ligands have been successfully synthesized under hydrothermal/solvthermal conditions and characterized by IR, elemental analyses and single-crystal X-ray diffraction. Moreover, thermogravimetric analysis and luminescent properties of the complexes have also been studied.Polymer [Cd(HMOPh IDC)(2,2’-bipy)]n(1) is a 1D chain with 2,2’-bipy appending in the same side chain. Polymer {[Cd2(H2MOPh IDC)2(4,4’-bipy)]×H2O}n(2) is a 3D structure. Polymer [Zn0.5(p-MOPh H2IDC)·H2O]n(3) is a 2D rhombus grid structure. In polymer [Zn(HMOPh IDC)(4,4’-bipy)]n(4), the adjacent chains are linked by 4,4’-bipy leading to a 2-D grid. 4,4’-bipy in [Cd2(HMOPh IDC)2(4,4’-bipy)(H2O)2]n(11) plays a same role in 4. Polymer {[Cd4(p-MOPh HIDC)4(C2H5OH)2(H2O)2]·4C2H5OH·2H2O}n(5) is a 3D structure bearing 1D channel. Polymer {[Sr2(p-H2 MOPh IDC)2(C8H4O4)(H2O)6]·6H2O}n(6) is also a 2D grid. Polymer [Sr(H2MOPh IDC)2]n(7) is a 3D structure. Polymer [Pb(H2MOPh IDC)2]n(8) is a 3D structure with floriated 1D channel. Polymer [Sr(o-Br Ph HIDC)(H2O)2]n(9) is a 2D structure composed of carboxyl oxygen atoms. Polymer [Ba(o-Br Ph H2IDC)2(H2O)]n(10) is a 3D structure which contains left and right helix chains. Polymer {[Co3(m-Br Ph IDC)2(H2O)7]·H2O}(12) is a 3D structure with dumbbell-like 1D channel. In these polymers, the three imidazole dicarboxylate ligands show strong coordination ability and various coordination modes.Finally, the thermogravimetric analyses and fluorescence measurements of the polymers were investigated. The results indicate polymers 4 and 7 have strong stability, which do not decompose below 300°C. The solid-state fluorescent determinations show that the polymers show luminescence emission except the polymers bearing quenching Co2+ and Pb2+ ions. Especially, 11 indicates sensing properties to pyridine. The sensing mechanism has been proposed.