N-heterocyclic carbene(Cu) synergistic photothermal hydrogen release involving double hydrogen transfer catalyzed by porphyrin(Cu)-based conjugated microporous polymers for efficient quinoline hydrogenation

Abstract

Photothermal-driven double hydrogen transfer (DHT) strategies are highly desirable for boosting the hydrogen utilization efficiency of ammonia borane complexes and enabling green hydrogen evolution. In this work, three porphyrin-based CMPs, namely Im-PCMP, NHC(Cu)-PCMP and NHC(Cu)-PCMP(Cu), were synthesized via the Suzuki–Miyaura coupling reaction (N-heterocyclic carbene, NHC). NHC(Cu)-PCMP(Cu) showed outstanding catalytic activity in the photothermal reductive hydrogenation of quinoline and its derivatives with high yields and selectivity. The isotopic labeling and control experiments revealed: (1) outstanding photothermal conversion efficiencies (η = 79%) of NHC(Cu)-PCMP(Cu), attributed to the synergistic effects of metal–carbene and porphyrin metallization via bimetallic regulation strategies; (2) enhanced activation of the N–H⋯H–B bond through NHC(Cu)-mediated cooperative catalysis; and (3) effective DHT reductive hydrogenation of quinoline and its derivatives with t-BuNH₂BH₃ as the hydrogen donor through a heterogeneous photothermal process.