Rational synthesis of 1,3,4-thiadiazole based ESIPT-fluorescent probe for detection of Cu2+ and H2S in herbs, wine and fruits

Abstract

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 Cu²⁺ was obtained and the settling reaction was also used to recover ESIPT characteristics of probe to achieve sequential detection of H₂S. Remarkable color change of solution from colorless to bright yellow and fluorescence emission from green to dark realized the visual detection of Cu²⁺ by naked eyes and transition of probe into portable fluorescent test strips. As expected, L-E could be utilized to quantitatively sense Cu²⁺ and H₂S in different actual water and food samples including herbs, wine and fruits. The limits of detection for Cu²⁺ and H₂S were as low as 34.5 nM and 38.6 nM. Also, probe L-E achieved real-time, portable, on-site quantitative detection of Cu²⁺ via a colorimeter and a smartphone platform with limit of detection to 90.3 nM.

Keywords: 1,3,4-Thiadiazole; Cu(2+) and H(2)S recognition; ESIPT; Fluorescence probe; Food samples.