Highly efficient conversion of CO2 at atmospheric pressure to cyclic carbonates with in situ-generated homogeneous catalysts from a copper-containing coordination polymer

摘要

A copper-containing coordination polymer ((CuL)(n), L = (Z)-2-(5-chlorin-2-hydroxy benzylideneamino) acetic acid, namely BIT-C), was facilely synthesized and structurally analyzed by single-crystal X-ray diffraction. BIT-C has an outstanding catalytic activity for the conversion of atmospheric pressure CO2 and various epoxides to cyclic carbonates. Several quaternary ammonium halides, ionic liquids, and organic bases were illustrated to be effective co-catalysts. Using BIT-C, Bu4NBr, and phenyl glycidyl ether, direct capture and conversion of CO2 from the air was shown to be feasible at the room temperature, with 19% yield of phenoxy propylene carbonate. During reaction, multistage dissociation of BIT-C was detected. The binuclear Cu fragment ((CuL)(2)) was demonstrated to be essential active species in catalysis and unable to be generated from the raw materials of BIT-C but currently only from the multistage dissociation of BIT-C. Kinetic analysis and DFT calculations suggest a reaction mechanism where a copper center activates epoxides and CO2 successively. (C) 2015 Elsevier Inc. All rights reserved.