Synthesis and solution studies on azaphthalocyanines with quaternary aminoethyl substituents

A pyrazinedinitrile derivative carrying dimethylaminoethylsulphanyl groups at positions 5 and 6 was synthesised from 2-dimethylaminoethanethiol hydrochloride and 2,3-dicarbonitrile-5,6-dichloropyrazine. The dicarbonitrile gave magnesium azaphthalocyanine (MgAzaPc) when reacted with magnesium propoxide in propanol. The conversion of the MgAzaPc to a metal-free derivative was achieved by treatment with trifluoroacetic acid. Incorporation of transition metal ions into the inner core of azaphthalocyanine was accomplished by treatment of the metal-free derivative with metal acetates, i.e. Zn(OAc)₂, Co(OAc)₂. These azaphthalocyanines were converted into water-soluble quaternised products by reaction with methyl iodide. Aggregation phenomena were followed for magnesium azaphthalocyanine with quaternisable dimethylamino substituents within a specific range of pH. The compounds were characterised by Fourier transform-infrared, proton nuclear magnetic resonance, mass and ultraviolet-visible spectral data.