A New Aluminum Porphyrin-Based Porous Hyper-Cross-Linked\nPolymer Modified by Imidazolium Salts for Cooperative Conversion of\nCO<sub>2</sub> into Cyclic Carbonates under Mild Conditions

Metalloporphyrin-based\nporous organic polymers that behave as advanced\nbiomimetic nanoreactors have drawn continuous attention for heterogeneous\nCO<sub>2</sub> cycloaddition conversion in the past decades. However,\nthe use of homogeneous onium salts, usually acting as nucleophilic\ncocatalysts, may increase the cost of product purification and cause\nadditional environmental problems. In this contribution, a new aluminum\nporphyrin-based porous hyper-cross-linked polymer modified by imidazolium\nsalts (denoted as <b>Im@Al-HCP</b>) has been successfully constructed\nfor the first time. The two-step process of hyper-cross-linking reaction\ncombined with postsynthetic modification endows the catalyst with\na large surface area (about 213 m<sup>2</sup>·g<sup>–1</sup>), good CO<sub>2</sub> adsorption capacity (up to 1.45 mmol·g<sup>–1</sup>), and highly dispersed cooperative active sites.\nAccordingly, bifunctional <b>Im@Al-HCP</b> exhibits an outstanding\ncatalytic activity, good recyclability, and broad substrate generality\nwithout cocatalysts and solvents under mild conditions. In particular,\na high turnover frequency (TOF) value of up to 5000 h<sup>–1</sup> can be acquired, which far exceeds that of most reported heterogeneous\ncatalysts under identical conditions. In addition, the as-made heterogeneous\ncatalyst can be recycled for at least six times without an obvious\nloss in catalytic activity. This work not only bring some inspirations\nfor the construction of multifunctional catalysts but also provides\ngreat potential for industrial applications of CO<sub>2</sub> cycloadditions.