Deepening insights of AIE plus TICT activated fluorescent sensor mechanism in probe molecule DPA-CI

The DPA-CI molecule is a novel fluorescent sensing probe synthesized with TICT and AIE properties. It can detect phosgene, generating DPA-CI-PS. We investigated their photophysical mechanisms in THF solvent using DFT and TD-DFT methods. Large torsion angles and noticeable charge separation confirmed that the TICT occurs in DPA-CI. Due to the formation of a robust cyclic structure, the TICT is inhibited in DPA-CI-PS. Besides, based on NBO analysis, we demonstrated that DPA-CI-PS exhibits significant AIE characters. This work clearly illuminates the detection mechanism, which offers theoretical insights valuable for developing efficient fluorescent sensing probes.