Syntheses, structures, fluorescence sensing and magnetic properties of two coordination polymers based on 5-(benzimidazol-2-yl) isophthalic acid ligand

Abstract Two coordination complexes, constructed by 5-(benzimidazol-2-yl) isophthalic acid ligand, namely, [Eu(HL) 2 (NO 3 )] n ( 1 ) and [Tb(HL) 2 (NO 3 )] n ( 2 ) (H 2 L = 5-(benzimidazol-2-yl) isophthalic acid), were obtained under the same reaction conditions and characterized. Complexes 1 and 2 were isostructral, the Ln 3+ cations were linked by the carboxylate groups of L ligand to form 1-D coordination chain. And these chains were connected with four adjacent ones through hydrogen bonds to form a three-dimensional supramolecular network structure. The fluorescence properties of complexes 1 and 2 have been studied. The emission bands are located at violent region 418 nm. The fluorescence intensity is apparently affected by different solvents and metal ions. Among which, the nitrobenzene and Cu 2+ can quench the fluorescence emission efficiently; however, the addition of Cd 2+ enhances the fluorescence intensity. The variable temperature susceptibility of complexes 1 and 2 were also studied.