6-Isothiocyanatoquinoline is primarily utilized in biochemical research as a fluorescent labeling agent. It is commonly employed to tag proteins, peptides, and other biomolecules, enabling their detection and analysis in various experimental setups. The compound’s isothiocyanate group reacts efficiently with amino groups, forming stable thiourea linkages, which makes it a valuable tool for conjugation in fluorescence microscopy and immunoassays. Additionally, its quinoline moiety provides strong fluorescence properties, enhancing its utility in tracking and imaging applications. This chemical is also explored in the development of diagnostic probes and sensors due to its ability to bind selectively to specific biological targets.