Acid Vapor Responsive Coumarin Coupled Imidazole as Colorimetric and Fluorometric Co²⁺ Sensor, DFT, and Zebrafish...

This work describes a novel Co²⁺ ion sensor 3-(2-(2-(4-nitrophenyl)-4,5-diphenyl-1H-imidazol-1-yl)thiazol-4-yl)-2H-chromen-2-one (NBIC) comprising imidazole and a coumarin-thiazole moiety. When Co²⁺ 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 Co²⁺ 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 Co²⁺ and NBIC. Further, the study was also validated with zebrafish bioimaging studies.