Yellow-green fluorescent crystals of the title compound, C19H18O3, were obtained by the reaction of hy-droxy-aceto-phenone and 4-tert-butyl-benzaldehyde with hydrogen peroxide as oxidant. The plane of the benzene ring is slightly twisted to the mean plane of the 4H-chromene-4-one moiety (r.m.s. deviation = 0.0191 Å) by 10.53 (8)°. In the crystal, mol-ecules are linked by pairs of O-H⋯O hydrogen bonds, forming inversion dimers with an R 2 (2)(10) ring motif. The dimers are linked via C-H⋯π inter-actions, forming sheets parallel to (10-1).
Keywords: crystal structure; flavonol; fluorescent material; hydrogen bonding.