Synthesis and characterisation of N-substituted bis-phenols as precursors for unsymmetrical triarylmethane cations

Bis-(4-hydroxy-3,5-dimethylphenyl)(4-aminophenyl)methane derivatives (1–6) are synthesised and characterised. Inclusion of acetonitrile by bis-(4-hydroxy-3,5-dimethylphenyl)(4-N,N′-dimethylaminophenyl)methane is observed in the crystal structure. Cations generated from these compounds have characteristic visible absorptions. An alternative method for generation of these cations from quinone methide namely 4-[(4′-hydroxy-3′,5′-dimethylphenyl)(4-N,N′-dimethylaminophenyl)methylene]-2,6-dimethylcyclohexa-2,5-dienone under very mild condition is described. The characteristic absorption peaks of the cationic species are used to distinguish different isomeric forms.