Condensed Heterocycles with a Thiazole Ring. 15. Dyes Based on Thiazolotriazine

Article abstract of DOI:10.1007/BF00633183

Unsymmetrical tri- and pentamethinecyanine dyes with a thiazolo<3,4-b><1,2,4>triazine ring were synthesized.The electron-density distribution on the atoms of the dyes in the ground, first, and second excited states were calculated by a quantum-chemical method.It was established that the first two electron transitions are localized on the same atoms of the dyes and that charge transfer to the triazine fragment of the molecule is realized upon excitation.The degree of participation of the heterocyclic ring in the first electron transition, which is responsible for the color of the dye, decreases with an increase in the length of the polymethine chain.