The effects of N-alkyl and heterocycloalkyl substituents on the light absorption properties of a range of novel dyes based on the 1-naphthyl analogue of Crystal Violet, Victoria Blue, have been investigated. Interaction between the N-terminal group and the peri-hydrogen atom on the naphthyl residue can result in deconjugation of the former, whereupon the dyes exhibit Malachite Green character. Such steric influences are correlated with 1 H NMR data.