Substituted xanthylocyanines. III. Dyes containing non-symmetrically substituted xanthylium core

A series of symmetrically and non-symmetrically substituted dyes were prepared from 9-methylxanthylium salts. The absorbance spectra of these compounds contain two bands – intense longwave and less intense shortwave. The nature of electronic transitions in polymethine dyes and dependence of the position and intensity of absorbance bands on the structure of end nucleus are discussed. The electron-donating properties of the synthesized xanthylium cores were studied.