A New Series of CuII Coordination Polymers Derived from Bis-pyridyl-bis-urea Ligands and Various Dicarboxylates and Their Role in Methanolysis of Epoxide Ring-Opening Catalysis
摘要:
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 Cu-II species that presumably acted as the catalyst.