Coordination polymers with bis(2-benzimidazole) ligand as bridging ligand: From 1D chain to 3D microporous structure

Abstract

Three coordination polymers, i.e. [Co(HL)(HBDC)] n ( 1 ), [Co(HL)(BDC) 0.5 ] n ( 2 ) and {[Zn 2 (H 2 L)(BTC) 2 ](H 4 L)(H 2 O) 2 } n ( 3 ) (L = 2, 2′-(ethanediyl)bis(1H-benzimidazole), H 2 BDC = 1, 4-benzenedicarboxylic acid, H 3 BTC = 1, 3, 5-benzene tricarboxylic acid), have been synthesized under hydrothermal conditions based on bis(2-benzimidazole) and two multi-dentate carboxylate ligands, with different metal ions such as Zn II and Co II . The structures of these coordination polymers have been determined by X-ray single‐crystal diffraction. The diverse coordination modes of the H 2 L ligand and the varying geometries of multi-dentate carboxylate ligands play an important role in the construction of coordination polymers. Various assembly patterns have been observed, including one-dimensional (1D) chain ( 1 ), two-dimensional (2D) 3-connected network structure with honeycomb topology ( 2 ), and three-dimensional (3D) 3,4-connected porous structure with (6 3 )(6 5 ,8) topology ( 3 ). Thermal analyses of the three polymers have been performed and discussed. Furthermore, strong room temperature photoluminescence of compound 3 was observed. Three new metal–organic frameworks based on the bis(2-benzimidazole), [Co(HL)(HBDC)] n ( 1 ), [Co(HL)(BDC) 0.5 ] n ( 2 ) and {[Zn 2 (H 2 L)(BTC) 2 ](H 4 L)(H 2 O) 2 } n ( 3 ), have been successfully synthesized under hydrothermal conditions and characterized by X-ray single-crystal diffractions. In addition, strong photoluminescence at room temperature of compound 3 was observed at room temperature. ► Compound 1 shows a 1D chain architecture with L ligand hanging outside the chain structure. ► Compound 2 exhibits a 2D extra-large 32-membered ring network with honeycomb topology. ► Compound 3 exhibits a 3D 3, 4-connected porous structure with (6 3 )(6 5 ,8) topology.