Synthesis and spectral properties of polymethine dyes derived from 5-methyl-11-phenyl-5H-indeno[2,1-b]quinoline

Based on the 5-methyl-11-phenyl-5H-indeno[2,1-b]quinoline nucleus, symmetric and unsymmetric cationoid polymethine dyes as well as merocyanines have been synthesized, and their absorption spectra have been studied. As shown, the absorption maxima are shifted with reference to the analogous oxa-compounds hypsochromically for symmetric or strongly asymmetric (containing the low-electron-donor second end residue) dyes, and bathochromically for slightly asymmetric (containing the high- or medium-electron-donor second end residue) dyes.