Building N-Heterocyclic Carbene into Triazine-Linked Polymer for Multiple CO 2 Utilization.

The development of new CO ₂ detection technologies and CO ₂ "capture-conversion" materials is of great significance due to the growing environmental crisis. Here, multifunctional triazine-linked polymers with built-in N-heterocyclic carbene (NHC) sites (designated as NHC-triazine@polymer) are presented for simultaneous CO ₂ detection, capture, activation, and catalytic conversion. NHC-triazine@polymer were readily obtained through polymerization of cyanophenyl-substituted NHC. The obtained film-like polymers exhibited interesting CO ₂ -triggered fluorescence "turn-on" response and CO ₂ -sensitive reversible color change. Both NHC and triazine sites could act as efficient binding sites for CO ₂ , and the CO ₂ uptake of NHC and triazine reached 1.52 and 1.36 mmol g ^-1 , respectively. Notably, after being captured by NHC, CO ₂ was activated into a zwitterionic adduct NHC-CO ₂ that could be easily transformed into cyclic carbonate in the presence of epoxides. Moreover, NHC-triazine@polymer were stable and active catalysts for the conversion of low-concentration CO ₂ in a gas mixture (7 vol %) into cyclic carbonates as well as for hydrosilylation of CO ₂ to formamides.
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