COLOR AND CONSTITUTION RELATIONSHIPS IN ORGANIC PIGMENTS .5. THE INFLUENCE OF SOLVENTS, THE CENTRAL METAL ATOM AND SUBSTITUENTS ON THE ELECTRONIC-SPECTRA OF PHTHALOCYANINES

Phthalocyanines provide the most important classical organic pigments in the blue and green shade area and some derivatives are of interest as near infrared absorbers. In this paper, the influence of solvents, and the nature of the metal atom and substituents on the solution elec tronic spectra of a wide range of phthalocyanines is discussed. Correl ation with the results of PPP MO calculations is reported where approp riate. From this series of publications, a comprehensive understanding of the relationship between the colour and the molecular structure of phthalocyanines has emerged.