Theoretical investigation of turn off–on mechanism of a new fluorescence probe L

Abstract

In this paper, themechanism of probe L and derivative L-HK inthe detection ofCys was researched. The infrared vibration spectrum, geometric parameters and interaction region indicator (IRI) isosurface prove that the hydrogen bond enhancement in the excited state is beneficial to excited state intramolecular proton transfer (ESIPT). The potential energy curve (PEC) shows L-HK has an ultra-fast ESIPT process, so it emits single fluorescence. In addition, the intramolecular charge transfer (ICT) process was verified by the frontier molecular orbitals (FMOs). Throughcalculating the reorganizationenergy, the quenching mechanism of probe L was explored.