Steric effects in di- and tri-arylmethane dyes. Part XII. Electronic absorption spectra of some derivatives of Michler's Hydrol Blue containing α-trifluoromethyl groups

Abstract

Absorption spectra of some derivatives of Michler's Hydrol Blue containing α-trifluoromethyl groups have been determined for solutions in 98% acetic acid; the dye bases show very little tendency to form the corresponding univalent cations. The parent dye (I; R = CF₃) is electronically symmetrical and a pronounced bathochromic shift of the first band is observed. Unsymmetrical conformations result when further crowding substituents are introduced into the α-trifluoromethyl derivative.