Facile Fabrication of Pyrazine-linked Metallophthalocyanine-based Porous Organic Polymers (PyMPc-POPs) and their Reduced Graphene Oxide (rGO) Hybrids for Light-Driven CO 2 Cycloaddition

Abstract

Porous organic polymers (POPs) are promising for gas storage and catalysis owing to their robust stability and structural tunability. Incorporating metallophthalocyanines (MPcs) as building units can further enhance POP functionality, introducing conjugated π-systems and metal active sites. This is particularly attractive for photo-driven CO2 cycloaddition, a sustainable route to convert CO2 and epoxides into cyclic carbonates. However, conventional MPc-based POPs often suffer from limited functional diversity and structural rigidity. Their synthesis typically relies on harsh solvothermal/ionothermal conditions, which risk degrading the MPc structure and entail high energy costs. To address these challenges, we report a function-oriented design coupled with a mild synthetic strategy. Using 4-dimethylaminopyridine (DMAP) as a dual-purpose reagent (reaction medium and catalyst), we efficiently constructed pyrazine-linked MPc-POPs (PyCoPc-POPs) by the polymerization of 2,3,5,6-pyrazinetetracarbonitrile (TCNP) in the presence of Co atoms. The pyrazine linker not only enhances framework polarity and CO2 uptake but also provides Lewis basic sites that synergize with CoPc metal centers for catalysis. Furthermore, to improve charge separation and transport—critical for photocatalysis—we integrated reduced graphene oxide (rGO) via an in-situ compositing approach, ensuring intimate contact between the components. The resulting PyCoPc@rGO hybrid exhibited outstanding performance in the photo-driven CO2 cycloaddition, achieving 97.5% epichlorohydrin (ECH) conversion and exceeding 99% carbonate selectivity under mild conditions. This work demonstrates the versatility of our mild synthetic method and offers a new design paradigm for high-performance photocatalytic materials.