Basic-Functionalized Ionic Porous Organic Polymers: Triple Roles in One for Highly Efficient and Recyclable Carboxylative Cyclization of CO2 under Mild Conditions

The transformation of carbon dioxide (CO2) into high-value chemicals is a significant step towards achieving the goal of "carbon neutrality". α-methylene cyclic carbonate, as an intermediate for the synthesis of many important organic compounds, is widely employed in industrial productions. In this work, a series of ionic porous organic polymers (IPOPs) with different basic-functionalized anions were successfully synthesized and adjusted to have certain BET surface areas and high contents of ion sites by post-modification. These basic-functionalized IPOPs could exhibit excellent catalytic performance for carboxylative cyclization of CO2 at 30 °C and 1 bar in presence of silver salts, eliminating the use of the extra organic bases. In the whole catalytic reaction, the basic-functionalized anions could play triple roles: enriching CO2 for further transformation, activating the hydroxyl groups of substrates to improve the catalytic performance, while coordinating with Ag atom to stabilize and regenerate catalyst. Notably, the catalytic system of DCX-4-Tet/Ag2O exhibited excellent recyclability, and the yield of α-alkylidene cyclic carbonate was well maintained at 99 % after 5 cycles. To the best of our knowledge, the catalytic system was the first example of basic-functionalized IPOPs that played multiple roles for highly efficient CO2 cyclization under mild conditions without any extra organic bases.

Cu(I)-Glutathione Assembly Supported on ZIF-8 as Robust and Efficient Catalyst for Mild CO2 Conversions

The Cu-glutathione (GSH) redox system, essential in biology, is designed here as a supramacromolecular assembly in which the tetrahedral 18e Cu(I) center loses a thiol ligand upon adsorption onto ZIF-8, as shown by EXAFS and DFT calculation, to generate a very robust 16e planar trigonal single-atom Cu(I) catalyst. Synergy between Cu(I) and ZIF-8, revealed by catalytic experiments and DFT calculation, affords CO2 conversion into high-value-added chemicals with a wide scope of substrates by reaction with terminal alkynes or propargyl amines in excellent yields under mild conditions and reuse at least 10 times without significant decrease in catalytic efficiency.

In Situ Anchoring of Small-Sized Silver Nanoparticles on Porphyrinic Triazine-Based Frameworks for the Conversion of CO2 into α-Alkylidene Cyclic Carbonates with Outstanding Catalytic Activities under Ambient Conditions

The preparation of catalytic hybrid materials by introducing highly dispersed metallic nanoparticles into porous organic polymers (POPs) may be an ideal and promising strategy for integrated CO2 capture and conversion. In terms of the carboxylative cyclization of propargyl alcohols with CO2, the anchoring of silver nanoparticles (AgNPs) on functional POPs to fabricate efficient heterogeneous catalysts is considered to be quite intriguing but remains challenging. In the contribution, well-dispersed AgNPs were successfully anchored onto the porphyrinic triazine-based frameworks by a simple "liquid impregnation and in situ reduction" strategy. The presence of N-rich dual active sites, porphyrin and triazine, which acted as the electron donor and acceptor, respectively, offered a huge opportunity for the nucleation and growth of metal nanoparticles. Significantly, the as-prepared catalyst Ag/TPP-CTF shows excellent catalytic activity (up to 99%) toward the carboxylative cyclization of propargyl alcohols with CO2 at room temperature, achieving record-breaking activities (TOF up to 615 h-1 at 1 bar and 3077 h-1 at 10 bar). Moreover, the catalyst can be easily recovered and reused at least 10 times with retention of high catalytic activity. The possible mechanism involves small-sized AgNP-mediated alkyne activation, which may promote highly efficient and green conversion of CO2. This work paves the way for immobilizing metal nanoparticles onto functional POPs by surface structure changes for enhanced CO2 catalysis.