Fluorescence enhancement of coumarin–quinoline by transition metal ions: Detection of paramagnetic Ni2+ and Co2+

A readily available coumarin–quinoline was employed as a novel fluorescent probe for paramagnetic Co2+ and Ni2+ ions, which are well-known fluorescence quenchers. NMR and IR indicated that the enhanced fluorescence response was attributable to coordination of the paramagnetic Ni2+ or Co2+ ions with the coumarin–quinoline compound. Given the difficulty of designing enhanced fluorescent probes for paramagnetic Co2+ and Ni2+ ions, the coumarin–quinoline compound may inspire the further development of more sophisticated sensing constructs for the fluorescence detection of these transition metal ions.