Extended conjugation in di- and tri-arylmethane dyes. Part IV. Electronic absorption spectra of some phenanthrene analogues of Malachite Green

Abstract

Absorption spectra of five phenanthrene analogues of Malachite Green have been determined for solutions in 98% acetic acid. The spectral changes are correlated with steric and electronic factors. For a series of α-aryl derivatives of Michler's Hydrol Blue, the position of the first band is approximately related to the ability of the aryl system to delocalise charge in the derived univalent cation.