Pyrilocyanines. 37. Pyrilo-2-cyanines with perfluorophenyl substituents

Article abstract of DOI:10.1007/BF02290884

Symmetrical and nonsymmetrical pyrilo-2-cyanines have been synthesized containing the 6-perfluorophenyl-4-phenylpyrilium residue. As an example of these compounds we have analyzed the effect of changing phenyl groups for perfluorophenyl in terms of the long wavelength electronic absorption spectra for the above types of dyes. It was found that this change leads to a decrease in the effective length and the electron donor ability of hetero residues containing these groups. The former effect gives rise to a hypsochromic shift of the absorption band and the second to a broadening of these bands associated with increased vibrational interactions in the molecules and their solvates. 1998 Plenum Publishing Corporation.