Rational synthesis of 1,3,4-thiadiazole based ESIPT-fluorescent probe for detection of Cu and HS in herbs, wine and fruits.

Here, 1,3,4-thiadiazole unit was employed as novel excited state intramolecular proton transfer (ESIPT) structure to prepare favorable fluorescent probe. High selectivity and rapid response to Cu was obtained and the settling reaction was also used to recover ESIPT characteristics of probe to achieve sequential detection of HS. Remarkable color change of solution from colorless to bright yellow and fluorescence emission from green to dark realized the visual detection of Cu by naked eyes and transition of probe into portable fluorescent test strips. As expected, L-E could be utilized to quantitatively sense Cu and HS in different actual water and food samples including herbs, wine and fruits. The limits of detection for Cu and HS were as low as 34.5 nM and 38.6 nM. Also, probe L-E achieved real-time, portable, on-site quantitative detection of Cu via a colorimeter and a smartphone platform with limit of detection to 90.3 nM.