Accessible Microwave Synthetized Conjugated Poly(Azomethine-Pyridine) Network and Its Metal Complexes for CO2 Conversion

A conjugated crosslinked polyazornethine containing pyridine units (PAM-Py) was prepared from two commercial monomers, 2,6-diaminopyridirie and isophthaldehyde, under microwave heating in only 30 min. Taking advantage of its thermal and chemical stability, porosity (S-BET of 192 m(2)/g), insolubility, and ability to coordinate metals through the pyridine or imine N atoms, ruthenium-, aluminum-, iron-, and cobalt-poly(azomethine-pyridine) complexes (PAM-PyM) were prepared. The resulting metal polymers were evaluated as heterogeneous catalysts for the cycloaddition of CO2 to epoxides yielding selectively the corresponding cyclic carbonates. All heterogeneous catalysts showed an extraordinary effectiveness with very high yields of epoxide conversion (up to 98%), turnover numbers up to 7425, and were reused at least five times without loss in catalytic activity. (C) 2018 Wiley Periodicals, Inc.