PYRYLOCYANINES. 15. BENZOPYRYLO-2-CYANINES

Article abstract of DOI:10.1007/BF00513425

Symmetrical 4,4'-diphenyl-substituted benzopyrylo-2-monomethylidene, carbo-, and dicarbocyanines and their thio analogs, as well as unsymmetrical carbocyanines that contain, in addition to 4-phenylbenzopyrylium or 4-phenylbenzothiopyrylium rings, 3-ethylbenzothiazolium or 1,3,3-trimethyl-3H-indolium residues, were synthetised.The indicated dyes were more highly colored than their isomers that contain flavylium or thioflavylium residues.On the basis of the deviations calculated from the centres of the absorption bands it was concluded that the benzopyran residues in the dyes of the α series have greater electron donor character than those in the dyes of the γ series.