Sr2+ and Cd2+ coordination polymers: the effect of the different coordinating behaviour of a newly designed tricarboxylic acid

Abstract

This article presents the investigation of the coordination behavior of a newly synthesized tricarboxylate ligand, obtained by joining imidazole dicarboxylic acid and 4-carboxybenzyl moieties [cbimdaH₃, 1-(4-carboxybenzyl)-1H-imidazole-4,5-dicarboxylic acid]. Two novel coordination polymers were obtained through solvothermal reactions under similar conditions namely [Sr(cbimdaH)(H₂O)]_n (1) and [Cd₂(cbimdaH)₂(H₂O)₆]_n·(DMF)_3n(H₂O)_3n (2), with the ligand behaving as a dianionic tricarboxylate linker. The single crystal X-ray structures show that while 1 forms a 3D coordination polymer, 2 forms a 1D polymer which is further assembled in three dimensions through supramolecular interactions (H-bonding). Complex 1 consists of Sr²⁺ ions in a distorted dodecahedral coordination geometry, while 2 consists of Cd²⁺ ions in distorted pentagonal bipyramidal geometries. A topology study reveals that 1 has a new topology based on the 5,6-coordinated 3D net architecture. The luminescence properties of the complexes in the solid state and their thermal stabilities were studied.