Benzo[f]indazoles: A new class of glow dyes for the generation of versatile fluorophores

The surge of photonics as key enabling technology for lighting has driven the search of new chart of modern applied fluorophores. In this line, we recently found that a set of compounds previously synthesized by us and pertaining to the family of benzo[ f ]indazoles, were able to absorb light and convert it into glow blue fluorescence. Prompted by these findings, we came interested in exploring their viability as versatile fluorophores for bioimaging. To this aim, in this work we present a comprehensive study of the electronic, structural, electrochemical and photophysical properties of this new library of dyes in solution and solid-state under mild and hard irradiation regimes. We intend to understand the molecular structure-photophysics relationship and estimate the strengths and weaknesses of these dyes as potential fluorescent probes for bioimaging or other kind of light-driven applications. One of the main outcome of this study is that the photonic performance of the herein reported benzo[ f ]indazole-based dyes surpasses coumarines, considering as benchmark in the same spectral window, yielding brighter and long lasting emission even under intense and prolonged illumination. • Novel family of low-cost fluorophores with easy synthetic access. • Bright and long-lasting blue-emitting dyes, even in solid-state. • Chemically versatile molecular scaffold for tunable photonics. • Improved brightness and photostability with regard to coumarines.