Construction of Alkali‐metal‐based Imidazolecarboxylate Coordination Polymers as Efficient Catalysts for Solvent‐free Ring‐opening polymerization of ϵ‐Caprolactone

Abstract

A series of new alkali-metal-based coordination polymers, [Li(H 2 IMDC)(H 2 O)] n (1), [Na 2 (H 2 IMDC) 2 (H 3 IMDC) 2 (H 2 O) 4 ] n (2), and [K(H 2 IMDC)(H 2 O)] n(3), have been constructed under solvothermal conditions by using imidazole-4,5-dicarboxylic acid (H 3 IMDC) as ligand. The structure of the complexes has been determined by single-crystal X-ray diffraction and further characterized by elemental analyses, IR spectra, powder X-ray diffraction and thermogravimetric analyses. The single crystal Xray structural studies showed that their structural dimension-alities varying from 1-D zigzag chain, 2-D 4 4 -sql network to 3-D 4,6-connected coordination framework are strongly governed by the ionic radii and coordination geometries of the metal cations. For the first time, the alkali-metal-based coordination polymers were demonstrated to be effective catalysts for the solvent-free ring-opening polymerization (ROP) of ɛ-caprolactone. The catalytic activity of complexes 1-3 depends on the metal cations, increasing in the order