A near-infrared fluorescent probe with thiadiazole unit as key skeleton for ICT and ESIPT mechanism and effective detection of Cu2+.

[Display omitted] • A NIR fluorescent probe was synthesized with fluorescent emission at 695 nm and Stoke's shift as large as 260 nm. • 1,3,4-Thiadiazole is a wonderful unit for ESIPT and ICT process and a good identify group for mental ions. • Probe could identify Cu2+ over other analytes with high sensitivity, fast response within 30 s and low detection limit (0.026 μM). • Probe was suitable to assay the Cu2+ level in wine, fruits and herbs. Fluorescent probe L-I was synthesized to demonstrate that 1,3,4-thiadiazole is an attractive moiety and could be utilized as positive hydrogen bond acceptor for excited state intramolecular proton transfer (ESIPT) processes, guider of electrons movement for intramolecular charge transfer (ICT) process and identify group for mental ions. Furthermore, dicyanoisophorone framework was employed to improve the fluorescence characteristics and near-infrared (NIR) fluorescent emission at 695 nm accompanied by a Stoke's shift as large as 260 nm was obtained. L-I could selectively detect Cu2+ over other analytes taking advantages of high sensitivity, fast response within 30 s and low detection limit (0.026 μM). More important, L-I exhibited good performance for detection of Cu2+ in actual water samples, food products, traditional Chinese medicine and for cell imaging which demonstrates practical significance in the fields of environmental monitor, food safety and biotechnology. [ABSTRACT FROM AUTHOR]