Study on ESIPT process of fluorescence probe BT-ITC for detecting H2S in DMF/H2O mixed solution

Abstract

A probe molecule named BT-ITC with an isothiocyanate group was synthesized and evaluated for its H2S sensing ability based on the excited state intramolecular proton transfer (ESIPT) process J K Kim, S Y Bong, R Park, J Park, D Ok Jang 2022 An ESIPT-based fluorescent turn-on probe with isothiocyanate for detecting hydrogen sulfide in environmental and biological systems, Spectrochimica Acta Part A 278 121333. The BT-ITC molecule has a large Stokes shift, short response time, and low detection limit. The end result of the reaction between the molecules BT-ITC and H2S is the BTC-NH2 molecule. The hydrogen bond of the Enol structure BTC-NH2 molecule in excited-state (S1 state) is strengthened, compared to the ground-state (S0 state). The calculated absorption and fluorescence spectra were in good agreement with the experimental values. The frontier molecule orbitals (FMOs), the potential energy curve (PEC), and scatter plots of reduced density gradient (RDG) were calculated. According to aforementioned, it was discovered that the charges of BTC-NH2 molecule were rearranged via an electron transition brought on by photoexcitation. This changes the acidity and alkaline of the proton donor and acceptor, and thus promotes the ESIPT process.