Amidino Pentadienylium Salts − A New Cyanine Dye Type

Abstract

The reactivity of carboxonium salts permits substitution of one or both of the reactive terminal ethoxy groups by amidino moieties. In this way, new cyanine dyes with extended conjugation paths are obtained. These have been studied by UV/vis spectrophotometry. Furthermore, the X‐ray structure of 1b has been determined and compared with that predicted by molecular mechanical calculations.