Novel phenothiazine-based fast-responsive colori/fluorimetric sensor for highly sensitive, selective and reversible detection of Cu2+ in real water samples and its application as an efficient solid-state sensor

Abstract A novel highly sensitive and selective phenothiazine-based sensor PN has been successfully synthesized. The sensor PN showed specific recognition towards Cu2+ through dual “naked-eye” colorimetric and “turn-off” fluorescence responses in DMSO/H2O (1:3, V/V) solution with ultrafast response and good reversibility. The detection limit was determined to be as low as 0.179 µM, which was much lower than drinking water permission concentration by the United States Environmental Protection Agency (～20 µM) and the World Health Organization (～30 µM). The 1:1 binding mechanism of PN with Cu2+ was proposed and well confirmed by fluorescence titration, Job’s plot, 1H NMR, HRMS, FTIR analysis and DFT studies. Moreover, the sensor PN was successfully applied to sensitively detect the Cu2+ ions in real water samples with good accuracy and high precision. Furthermore, sensor PN could serve as a cost-effective solid-state sensor for immediate, convenient and “naked-eye” colorimetric detection of Cu2+ in environmental samples.