Novel phenylalanine derivative-based turn-off fluorescent chemosensor for selective Cu2+ detection in physiological pH

Abstract

A novel and unnatural amino acid-based phenylalanine derivative bearing dansyl and benzoxazole moieties (DPB) as a side chain has fine-tuned fluorometric/colorimetric chemosensor was synthesized and characterized through various spectroscopic techniques. It was verified with 16 other competing alkali, alkali-earth, and transition metal ions but it was selectively quenched the Cu2+ ion in aqueous organic media with physiological pH (DMSO/H2O, 1:1, v/v, pH 7.4). The binding interaction was proved as 1:1 by Job’s plot method and the LOD value was found as 3.0 μM which is a much lower value than WHO and EPA guideline value. A naked eye color change was observed with Cu2+ ion, it induces a light yellow to light brown color with a large Red Shift value (307–539 nm) in emission spectra. The utilization of this sensor for water analysis also performing well with a high-level recovery rate of up to 99.92%. The encouraging photophysical results revealed that this probe DPB will act very well by selectively and sensibly as a “turn of” chemosensor towards Cu2+ ion.