A new fast-responding fluorimetric “turn-on” sensor based on benzothiazole-phenanthridine for the sensitive, selective, and reversible detection of Cu2+ in real water samples and its use in bio-imaging

Abstract

This article describes a new chemosensor, 2-(benzo[d]thiazol-2-yl)-6-(7,8,13,14-tetrahydrodibenzo [a, i] phenanthridin-5-yl) phenol (BTPP), which is based on the combination of phenanthridine and benzothiazole groups for the sensitive and selective detection of Cu2+. Following the successful synthesis of BTPP in a single step, the molecular structure of BTPP was verified by 1H NMR, 13C NMR, mass spectrometry, and X-ray single-crystal analysis. These sensors exhibit high optical selectivity for the Cu2+ ion across a broad spectrum of other common metal ions in ACN/H2O (1:1) solution, resulting in an extraordinary fluorescence off-on response with a very low Limit of Detection (LOD) value. When Cu2+ was added to the compound BTPP, it displayed outstanding properties such as bright yellow emission, rapid reaction time (10 s), detection over a wide pH range (pH = 6–12), and reversibility with glutathione(GSH). FT-IR analysis, 1H NMR titration experiments, HRMS, and Job's plot analysis were used to determine the mechanism of BTPP's binding to Cu2+. Inspired by these remarkable sensing characteristics, we successfully used BTPP to detect Cu2+ in paper strip-based detection, ambient water samples, and fluorescent bio-imaging in E. coli bacteria with satisfying results.