Synthesis, crystal structure and luminescent properties of three new zinc/cadmium coordination polymers containing cyanoacetate and 1,2-di(4-pyridyl)ethylene

Abstract

Three mixed-ligand coordination polymers based on cyanoacetate (cna) and 1,2-di(4-pyridyl)ethylene (dpe), namely [M(cna)2(dpe)]n (M=ZnII (1), (2), and CdII (3)) were synthesised and structurally characterized. Compound 1 exhibits a 1D zigzag polymeric chain, while compounds 2 and 3 are isostructural exhibiting 1D-ladder chain structures built from double-μ2-dpe connecting between [M2(μ1,3-cna)2(cna)2] secondary building units. The adjacent polymeric chains of 1–3 are linked by various intermolecular weak hydrogen bonds and N⋯π and/or C–H⋯π interactions through cyanoacetate and dpe ligands, stabilizing overall 3D supramolecular networks. Furthermore, the divergence of structural motifs between 1 and isostructures 2 and 3 strongly influences on their solid-state photoluminescent properties at room temperature. Compound 1 exhibits intense photoluminescence, whereas this is quenched in compounds 2 and 3.