A new 3-hydroxychromone derivative, 2-(6-diethylaminobenzo [b] furan-2-yl)-3-
hydroxychromone, has been synthesized by a concise route. Possessing dual emission
common for 3-hydroxyflavones, it exhibits strong red shifts of both absorption and
fluorescence spectra, which makes it the longest wavelength fluorescent dye among all
known chromones. It also demonstrates a significant increase in fluorescence quantum yield
in aprotic solvents and shift in solvent-polarity-dependent switch between normal and …