New Insight into the Fluorescence Mechanism in a Fluorescent Probe for Detecting Zn2+ and CN− Through Theoretical Calculations

In this work, we investigated the fluorescence mechanism of the probe (E)-3-((4-(diethylamino)-2-hydro xybenzylidene)amino)-2,3-dihydrothiophene-2-carboxamide (DHADC) for both Zn2+ and CN- by using density functional theory (DFT) and time-dependent DFT (TD-DFT) methods. Utilizing the constructed potential energy curves both in the ground and excited states as a function of the distance of N2 center dot center dot center dot H1, the proton transfer process of DHADC has been explored. According to the calculated spectra, another more reasonable structure of DHADC-CN for the product of DHADC responding to CN- has been proposed. All of the simulated absorption and emission spectra in this work are in agreement well with those in the experiment. Furthermore, the excited state decay picture and the fluorescence quenching mechanism of DHADC, as well as the fluorescence mechanism for Zn2+ and CN- have been fully explored. (C) 2021 Elsevier B.V. All rights reserved.