A new 1,3,4-thiadiazole-based ESIPT probe for detection of Hcy/Cys and GSH by two-channel fluorescent procedure and its potential applications

In practical application, we proved that substituted 1,3,4-thiadiazole showed the property of excited state intramolecular proton transfer (ESIPT). A “turn-on” fluorescent probe L-C with 1,3,4-thiadiazole moiety as fluorophore and 7-nitro-1,2,3-benzoxazole unit as recognition site was designed and synthesized. Based on the difference reactivity of biothiols with probe, L-C was used to simultaneously detect and distinguish Hcy/Cys and GSH by different response times and adjusting two different fluorescence signals (blue–green). Under dual excitation wavelengths of 330 nm and 470 nm, L-C had good selectivity, high sensitivity and low detection limit. This probe also provided a good performance for real-time monitoring of biothiols in vegetable and fruit matrices. The luminescence mechanism was clarified by NMR titration, HRMS and density functional theory calculations. This work afforded a feasible and promising strategy for constructing ESIPT fluorescent materials.