Abstract

The preparation and the solvatochromic behavior of two dyes, obtained by condensation of N,N?-dimethylbarbituric acid with dimethylaminobenzaldehyde and with 4,4?-bis(N,N-dimethylamino)benzophenone (Michler's ketone) are described. The latter dye is rather sensitive to the polarity of the medium, and in particular, to the hydrogen-bond-donor ability of protic solvents. The solvatochromism of both compounds is discussed in terms of the ?* and ET(30) solvent polarity scales and their differences in behavior interpreted with the aid of semiempirical calculations. © 2001 Elsevier Science B.V.