DFT/TD-DFT calculations on the sensing mechanism of a dual response near-infrared fluorescent chemosensor for superoxide anion and hydrogen polysulfides: photoinduced electron transfer

摘要: Previous studies have shown that intracellular O2˙−/H2Sn are related to cytoprotection processes. In order detect these two important species spontaneously, a sensitive chemosensor HCy-FN has been developed. the present study, sensing mechanisms of fluorescent HCy-FN, its oxidation product Cy-FN and elimination Keto-Cy investigated in detail using density functional theory (DFT) time-dependent (TD-DFT) methods. The theoretical study indicates there intramolecular charge transfer (ICT) states Cy-FN, they energetically beneath bright state, which is responsible for photoinduced electron (PET) process resulting fluorescence quenching. Whereas, emits strong because absence PET. calculated vertical excitation energies agree well with experimental values calculation results can deeply explain observed phenomena.