A New Thiophene‐Appended Fluorescein‐Hydrazone‐Based Chromo‐Fluorogenic Sensor for the Screening of Hg2+ Ions in Real Water Samples

Abstract

AbstractA simple yet efficient, Hg2+ selective sensor, based on a fluroescein‐thiophene conjugate, namely, (Z)‐3′,6′‐dihydroxy‐2‐(((3‐methylthiophen‐2‐yl)methylene)amino)spiro[isoindoline‐1,9′‐xanthen]‐3‐one (FT) has been designed and synthesized. The compound was well characterized by analytical techniques such as HR‐MS, FTIR, UV‐visible absorption, steady‐state fluorescence and time‐resolved spectrophotometric techniques. Comprehensive analysis demonstrated FTas a highly specific and ultra‐sensitive sensor towards Hg2+ ions in presence of several other interfering metal ions in ethanol/H2O (9 : 1, v/v) at pH=7.2 buffered with 10 mM HEPES buffer at room temperature. The complexation of the probe FT with Hg2+ was well confirmed by ESI‐MS and FTIR spectral analysis. The detection limit of the probe FT towards Hg2+ was achieved down to 137 nM. The structure of ligand FT and FT‐Hg2+ complex were well corroborated by theoretical studies as well. In addition, the FT‐Hg2+ complex was found to be reversible in presence of di‐sodium EDTA and hence decipher its recyclability capabilities. The significance of the present probe FT lies in its successful application for the detection and quantification of Hg2+ in real water samples and logic gate fabrication for future incorporation in small organic molecule based efficient molecular devices.