Synthesis and spectroscopic properties of benzo- and naphthofuryl-3-hydroxychromones

With the focus of designing new fluorescent probes, four new 3-hydroxy-chro mone derivatives bearing benzofuran and naphthofuran groups were synthesize d. They show bathochromic absorption shifts relative to 3-hydroxyflavone wi th the ability of retention to display the excited-state proton transfer. D isruption of the planarity by the methyl group in the furan ring leads to a decrease of both the extinction coefficient and the contribution of long w avelength absorption band, while molecules without a methyl group showed tw o distinct absorption bands. Shifts to longer wavelengths are also observed in fluorescent spectra, and the absence of the methyl group results in a d ramatic increase of fluorescence quantum yield and lifetime. Of the extende d 3-hydroxychromone derivatives, 3-hydroxy-2-naphtho[2,1-b]furan-2-yl-chrom one has shown comparable, and in some cases better, absorption and fluoresc ence properties than the 3-hydroxychromones synthesized so far, which make it a highly promising candidate as molecular probe for analytical chemistry , biophysics, and cellular biology.