A biomass-derived conjugated polymer with imine N and furan O sites for photocatalytic CO2 cycloaddition

The development of efficient, sustainable photocatalytic systems for CO 2 utilization remains critical for green chemical processes. In this work, a biomass-derived conjugated polymer (FDS) was synthesized via Schiff-base condensation of renewable 2,5-diformylfuran and 1,5-naphthalenediamine and employed as a metal-free heterogeneous photocatalyst for the cycloaddition of CO 2 with epoxides. Under visible-light irradiation, FDS enabled the solvent-free conversion of epichlorohydrin and CO 2 at room temperature and atmospheric pressure, affording 4-(chloromethyl)-1,3-dioxolan-2-one in 97% yield within 3 h. The catalyst delivers yields above 90% for a series of epoxide substrates with prolonged reaction time of 6 h, maintains high catalytic performance after 10 consecutive recycling runs, and exhibits considerable activity under natural sunlight irradiation. Mechanistic studies supported by DFT calculations revealed that the imine-linked framework facilitates photoinduced charge separation and epoxide polarization, while CO 2 is cooperatively activated at the imine N and furan O sites. This work presents a sustainable approach for metal-free photocatalytic CO 2 valorization, providing a promising strategy for green chemical manufacturing.