Synthesis and spectra of tris(4-dimethylaminophenyl)divinylenes

Condensation of 1,1-bis(4-dimethylaminophenyl) ethylene with substituted ke tones in acetic anhydride in the presence of perchloric acid yielded NIR po lymethine dyes. The VIS-NIR spectra of the dyes were measured and interpret ed by the semiempirical AM1 method. The influence of molecular structure va riations as well as of the electron density distribution, on the position o f the peaks at longest wavelength has been studied. The results indicate th at the additional (dimethylamino)phenyl bonded to C-5 atom might lead to la mbda(max), increase. On the other hand, the use of substituents with higher electron donor or acceptor character should not significantly affect the p osition of lambda(max). (C) 1998 Elsevier Science Ltd. All rights reserved.