Regulating the Combinations of Donor and Acceptor Units via DFT Calculations for Photocatalysts with Efficient Electron–Hole Separation and Transfer Dynamics

Donor-acceptor (D-A)-type conjugated microporous polymers (CMPs) are considered promising photocatalytic materials due to their easily tunable structures and optical properties. However, the rational combination of D and A units to design D-A-type CMPs with efficient electron-hole separation and transfer dynamics remains an ongoing challenge. Herein, we employed Density Functional Theory (DFT) calculations to evaluate 16 potential D-A pair combinations and their respective electron-hole separation and transfer dynamics. These combinations consisted of M-salens (M = Zn, Cu, Co, and Ni) as bromine-containing monomers and four alkyne-based monomers: 2,4,6-tris(4-ethynylphenyl)-1,3,5-triazine (TEPT), 4,4″-diethyl-5'-(4-ethynylphenyl)-1, 1':3',1″-terphenyl (TEPB), tris(4-ethynylphenyl) amine (TEPA), and 3,7-diethyl-10-(4-ethynylphenyl)-10H-phenothiazine (TEPP). Eight D-A pair combinations were obtained via DFT calculation, with their electron-hole separation and transfer dynamics ranking as follows: Zn-salen-TEPA > Zn-salen-TEPP > Zn-salen-TEPT > Cu-salen-TEPP > Cu-salen-TEPA > Cu-salen-TEPT > Ni-salen-TEPT > Co-salen-TEPT. Based on these results, three D-A pairs exhibiting the highest electron-hole separation and transfer dynamics were selected for the synthesis of corresponding CMPs and subsequent photoelectric characterization. Experimental enhancements aligned closely with the DFT predictions. Notably, the photocatalytic aerobic oxidative amidation of diverse aldehydes and amines catalyzed by Zn-salen-TEPA under blue LED irradiation achieved a yield of up to 97%, which surpassed the performance of most reported works. This work offers novel perspectives on the rational design of D-A-type CMPs endowed with highly efficient photocatalytic activity.