Theoretical investigation of a pyrene-based fluorescent probe for CN−: Recognition-induced TICT suppression and fluorescence turn-on mechanism

Abstract

In this study, the mechanism of a pyrene ring-based fluorescent probe PDA for detecting CN⁻ was investigated in detail. CN⁻ attacks the CC bond in PDA, leading to a nucleophilic addition reaction. The products are proved to exist in molecular form through pKa analysis, and the reaction process is rationalized by the Gibbs free energy profiles. According to FMO and LIIC analyses, the fluorescence quenching of PDA is attributed to TICT mechanism, which is suppressed during the recognition process, hence, the product PDA-CN recovers the fluorescence. These findings provide a theoretical foundation for the design of efficient fluorescence sensors.