Effects of two benzenedicarboxylic acids on the construction of CdII coordination polymers incorporating a flexible N-donor ligand.

Abstract

Compared with the monomorphic type of ligand, combining mixed ligands in one coordination polymer offers greater tunability of the structural framework. Employment of N-heterocyclic ligands and aromatic polycarboxylates is an effective approach for the construction of metal-organic frameworks (MOFs). Two new coordination polymers incorporating both 2-[(1H-imidazol-1-yl)methyl]-1H-benzimidazole (imb) and benzenedicarboxylic acid isomers, namely, catena-poly[[[di-μ-chlorido-bis[(2-carboxybenzoato-κ2O1,O1')cadmium(II)]]-bis{μ-2-[(1H-imidazol-1-yl)methyl]-1H-benzimidazole-κ2N:N'}] dihydrate], {[Cd(C8H5O4)Cl(C11H10N4)]·H2O}n, (I), and poly[[aqua(μ2-benzene-1,3-dicarboxylato-κ3O1,O1':O3){μ2-2-[(1H-imidazol-1-yl)methyl]-1H-benzimidazole-κ2N:N'}cadmium(II)] dihydrate], {[Cd(C8H4O4)(C11H10N4)(H2O)]·2H2O}n, (II), have been prepared and structurally characterized by single-crystal X-ray diffraction. In polymer (I), imb ligands bridge CdII ions, forming a one-dimensional chain, and 2-carboxybenzoate anions coordinate to the CdII ions in a terminal fashion. Polymer (II) exhibits a two-dimensional network structure in which imb ligands and the benzene-1,3-dicarboxylate anions join CdII ions co-operatively. This indicates that changing of the aromatic dicarboxylic acids can result in polymers with different compositions and architectures. Moreover, their IR spectra, PXRD (powder X-ray diffraction) patterns, thermogravimetric analyses and fluorescence properties were also investigated.