Pyrilocyanines. 36.α-thienyl substituted pyrilo- and thiopyrilocyanines
Symmetrical and nonsymmetrical 2,6- (and 4,6-)-di-α-thienyl substituted α- and γ-pyrilo- and thiopyrilocyanines have been synthesized. The effect of changing the phenyl groups for α-thienyl on the electronic absorption spectral parameters of the dyes obtained is discussed. It was found that such a change leads to a decrease in the effective length and increase in the electron donor ability of the hetero fragments containing these groups. The more intense coloring of the thienyl substituted dyes is due to interaction of the polymethine and quasilocal electronic transitions.