Vinyl-linked covalent organic frameworks (v-COFs) exhibit outstanding photophysical properties and hold significant potential for photocatalytic applications. To elucidate the intrinsic excitation mechanism of this class of COF materials, we employed first-principles calculations to investigate the monolayer v-COF-NO1. Quantum chemical calculations reveal that monolayer v-COF-NO1 possesses a stable molecular structure, characterized by a hexagonal ring with a pore size of 25.10 Å. Among the first 100 excited states, seven excitations exhibit oscillator strengths 0.05. The majority of excited states are characterized by electrons and holes primarily localized at the edges of the hexagonal rings, with holes displaying more pronounced aggregation than electrons. In addition, the simulated ultraviolet–visible spectrum shows a maximum absorption peak at 398.6 nm with an intensity of ∼6.06 × 105 L mol−1 cm−1. Finally, the calculated electronic circular dichroism spectrum reveals that the negative Cotton effect of v-COF-NO1 primarily originates from the S0 → S13 and S0 → S14 excitations.
Yang et al. (Sun,) studied this question.