Synthesis, crystal structures and properties of transition metal coordination polymers based on a rigid triazole dicarboxylic acid

Abstract

Four coordination polymers associated with the rigid organic ligand 3,5-bis(4′-carboxyl-phenyl)-1,2,4-triazole (H₂L) and transition metal salts were prepared by the hydrothermal method and structurally characterized, namely, {[Mn₃L₃(phen)₂]·H₂O}_n (1), {[Zn₄L₂(μ₂-O)₂(H₂O)₅]·3H₂O}_n (2), {[CdL(H₂O)₂]·3H₂O}_n (3), {[CuL(phen)(H₂O)]·H₂O}_n (4), (phen = 1,10-phenanthroline). Compound 1 consists of two types of symmetric trinuclear Mn(II) subunits, which are further bridged by the carboxylate groups of the L²⁻ ligand, resulting in a 2D layer structure. In 2, Zn(II) ions are bridged by μ₂-O and the L²⁻ ligands are arranged in a 4-connected 2D layer topological architecture. Compounds 3 and 4 display a 1D double chain and a zigzag chain structure, respectively. It is noted that the nitrogen atoms of H₂L are simultaneously coordinated to two Zn(II) ions in 2. In addition, the magnetic properties of 1 and the photoluminescence of 2 and 3 were investigated.