Photophysical features of naphthols having esters, formyl and acetyl groups and the difluoroboronated complex in solution and the solid state

1-Hydroxy-2-acetonaphthone, compound 1b is known to undergo excited-state intramolecular proton transfer (ESIPT) in the lowest excited singlet state in solution, giving weak fluorescence with a large Stokes-shift. We converted compound 1b to the corresponding difluoroboronated (BF₂) complex 2b, and investigated the photophysical features in solution and the solid state along with those of the related compound 1d. The other compounds 1a, 1c and 1d were unsuccessful in forming the corresponding BF₂ complexes. Blue fluorescence from compounds 1a, 1b and 1d and yellow one from compound 2b in the solid state were recorded. Compounds 1a, 1b and 1d moderately fluoresced with quantum yields of ca. 0.2 in both solution and solid state. Compound 2b showed fluorescence in the solid state with a quantum yield of 0.18 and in solution with a quantum yield of 0.65. The present study introduces potentials of ESIPT molecules, the related compounds and the corresponding difluoroboronated complexes to solid-state fluorophores.