The effects of cyclic terminal groups on the electronic absorption spectra of di- and tri-phenylmethane dyes

Abstract

The spectral shifts of the first absorption bands brought about by cyclic terminal groups in analogues of Michler's Hydrol Blue, Malachite Green, and Crystal Violet are determined mainly by inductive effects. Dye cations containing terminal pyrrolidino substituents are significantly more stable than those possessing piperidino groups as a result of differences in basicity brought about by a change in size of the saturated heterocyclic ring.