Unique Properties of 1,5-Naphthyridin-2(1H)-one Derivatives as Environment-Polarity-Sensitive Fluorescent Dyes

摘要

1,5-Naphthyridin-2(1H)-one is structural component of the fluorescent natural products amarastelline A and nigakinone. Herein, we synthesized several 1,5-naphthyridin-2(1H)-one derivatives and evaluated their fluorescence properties to examine their potential application as fluorescent probes. Among them, compounds that contain a 3-hydroxyl group have unique solvent-dependent fluorescence properties, that is, they exhibit stronger fluorescence in polar and protic solvents. The further installation of an 8-phenyl group resulted in a shifted fluorescence in different solvents. Our results indicate that the 1,5- naphthyridin-2(1H)-one scaffold would be a valuable and useful fluorophore that displays intense fluorescence relative to known bicyclic fluorophores such as hydroxyquinoline. Our findings suggest that the 1,5-naphthyridin-2(1H)-one scaffold would be practical as an environment-polarity-dependent fluorophore, that is, for the development of sensors to detect structural changes in proteins and biomolecular interactions.