Phenothiazine-derived fluorescent chemosensor: A versatile platform enabling swift cyanide ion detection and its multifaceted utility in paper strips, environmental water, food samples and living cells

Abstract

A phenothiazine-linked pyridine acetonitrile with a cyanoethylene bond PZ-PY has been synthesized by Knoevenagel condensation reaction and characterized by spectroscopic and analytical techniques. The structure of PZ-PY was confirmed through single-crystal X-ray diffraction studies; revealing its monoclinic crystal system with a P21/c space group. The absorption maximum and emission spectrum of the PZ-PY receptor were observed at 431 and 608 nm respectively. Cyanide anion is one of the most prevalent chemicals in the environment, its toxic nature poses a constant threat to human daily life. The PZ-PY receptor’s recognition of cyanide ions is associated with remarkable photophysical properties. The binding stoichiometry of PZ-PY-CN- was confirmed by Job’s plot, B-H studies, 1H NMR titration, TD-DFT, and ESI-mass spectroscopy. The relatively low limit of detection was determined to be 8.79 × 10 -8 M in a linear range between 0 and 120 µL. PZ-PY receptor exhibits an aggregation-caused quenching (ACQ) nature with the increase in water fraction; it is stable between pH 2 to 11. Moreover, the practical applicability of PZ-PY was investigated through the test strip, solid-state, bioimaging (A547 cell line), detection of cyanide in diverse water samples (tap water, distilled water, and lake water), and food samples (sprouted potatoes, bitter almonds, and cassava).