Acid Vapor Responsive Coumarin Coupled Imidazole as Colorimetric and Fluorometric Co ²⁺ Sensor, DFT, and Zebrafish Bioimaging Studies

This work describes a novel Co 2+ ion sensor 3‐(2‐(2‐(4‐nitrophenyl)‐4,5‐diphenyl‐1 H ‐imidazol‐1‐yl)thiazol‐4‐yl)‐2 H ‐chromen‐2‐one ( NBIC ) comprising imidazole and a coumarin‐thiazole moiety. When Co 2+ is present, NBIC shows a notable quenching of fluorescence at 450 nm as a result of complex formation. The limit of detection was found to be 7 μM under optimal conditions. It was discovered that the sensor was quite selective for Co 2+ ions despite many competing ions. The chemosensor NBIC also exhibited colorimetric and fluorometric sensing ability with a visible colorimetric response to trifluoroacetic acid (TFA). The Job's plot validates the 1:1 binding stoichiometry between Co 2+ and NBIC . Further, the study was also validated with zebrafish bioimaging studies.