A new series of Cu^II coordination polymers derived from bis-pyridyl-bis-urea ligands and various dicarboxylates and their role in methanolysis of epoxide ring-opening catalysis

Abstract

A crystal engineering approach has been adopted in synthesizing six new mixed ligand based Cu^II coordination polymers (CPs) derived from two bis-pyridyl-bis-urea ligands, namely, N,N′-bis-(3-pyridyl)ethylene-bis-urea (L1) and N,N′-bis-(3-pyridyl)propylene-bis-urea (L2), and various dicarboxylates. The single crystal structures of the coordination polymers displayed diverse supramolecular architectures such as a one-dimensional (1D) chain, 1D-looped chain, and two-dimensional grid. Although none of them displayed an open-framework structure, which is believed to be conducive for heterogeneous catalysis, almost all of them showed moderate to excellent epoxide ring-opening catalysis. Powder X-ray diffraction indicated structural changes/degradation of the CPs, which might be generating substrate accessible CuII species that presumably acted as the catalyst.