Thiophene-based vinylene-linked donor-acceptor covalent organic frameworks for photocatalytic organic transformations

Donor-acceptor (D-A) type vinylene-linked covalent organic frameworks (COFs) exhibit promising potential as catalysts for photocatalytic organic conversion. However, the correlation between the strength of the D-A system and D-A COFs' photocatalytic performance remains ambiguous. Herein, two thiophene-based vinylene-linked D-A COFs with different D-A effects, namely TTDA-COF and TPDA-COF, were designed and synthesized, and their photocatalytic performance was evaluated. The triazine-containing TTDA-COF exhibited superior photocatalytic activity compared to the pyridine-containing TPDA-COF, achieving conversion rates of 95 % for sulfide and 92 % for phenylboronic acid under optimized conditions. Additionally, TTDA-COF demonstrated excellent substrate adaptability and recyclability. The plausible catalytic mechanisms of two photocatalytic reactions were speculated. Further material characterization and theoretical calculations revealed that the enhancement of D-A effect could significantly amplify charge transfer between the donor and acceptor, thereby facilitating more efficient separation and migration of carriers. This study may provide valuable insights for the development of highly efficient D-A COF photocatalysts.