A series of lanthanide–organic polymers incorporating ethyl-4,5-imidazole-dicarboxylato and formate coligand: structures, luminescent and magnetic properties

Abstract

Four new lanthanide–organic coordination polymers incorporating both nitrogen heterocyclic dicarboxylate and formate coligands, namely, {[Ln₃(Heimda)₄(μ₂-HCOO)·4H₂O]·2H₂O}_n, (Ln = Sm (1), Dy (2), Ho (3), Er (4), H₃eimda = 1H-2-ethyl-4,5-imidazole-dicarboxylic acid) have been fabricated successfully and characterized systematically. The polymers 1–4 are isomorphous and isostructural, and are built from two dimensional (2-D) double decker networks based on the Ln₄Heimda₄ tetranuclear basic carboxylate as a secondary building unit (SBU). The extensive hydrogen bonds stabilize the crystal structure, forming a 3-D supramolecular tectonics. The luminescence emission spectra of the polymers vary depending on which lanthanide(III) ion is present. Variable-temperature magnetic susceptibility measurements show that the same end-to-end bridging fashion of formate results in the different magnetic properties occurring between adjacent lanthanide(III) centers.