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

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,O^1′)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,O^1′: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 Cd^II ions, forming a one‐dimensional chain, and 2‐carboxybenzoate anions coordinate to the Cd^II 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 Cd^II 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.