Cd(ii) and Zn(ii) coordination polymer-assisted CO2/cyclohexene oxide copolymerization with a double metal cyanide catalyst

Abstract

It is attractive but challenging to develop a cocatalyst for CO₂/cyclohexene oxide (CHO) copolymerization with a double metal cyanide (DMC) catalyst. In this study, we synthesized three coordination polymers (CPs) [Cd(3N3PY)(NDC)]·0.58H₂O (1), [Zn(3N3PY)(IPA)]·3H₂O (2) and [Cd(3N3PY)(NPA)]·2DMF·2H₂O (3) (3N3PY = 4′-(4-(1H-1,2,4-triazol-1-yl)phenyl)-2,2′:6′,2′′-terpyridine, H₂NDC = 2,6-naphthalene dicarboxylic acid, H₂IPA = isophthalic acid, H₂NPA = 2,2′-dinitro-4,4′-biphenyldicarboxylic acid). Crystal structural analyses show that 1–3 are different one-dimensional (1D) chains that further assemble into three-dimensional (3D) supramolecular structures by π–π and hydrogen bonding interactions. CPs 1–3 were applied as cocatalysts to assist DMC for CO₂/CHO copolymerization and the efficient proportion of carbonate P_–OC(O)O– in the product is 59% achieved for 2 at 80 °C in 1 MPa CO₂. The proportion of carbonate F(CO₂) and conversion rate of CHO (C_CHO) are 63% and 93%, respectively. The mechanistic study on structure–activity relationship and chemoselectivity was performed.