Synthesis and evaluation of organic pigments. 4. New monoarylide and diarylide pigments

Several naphthalocyanines, including soluble asymmetrical derivatives, were prepared by conventional condensation methods or by ring-expansion of the corresponding subnaphthalocyanine. the latter method offers two major advantages, over the mixed condensation method, viz., convenient purification and relatively high yield. electronic absorption spectral data indicate that the majority of the new colorants have Q-bands above 750 nm. the substituent effect at peripheral sites was small with respect to the position of the Q-bands, but the nature of the central metal atoms significantly affected the Q-bands. In addition, asymmetrical tri-t-butyl naphthalocyaninatozinc shows interesting spectral properties in solvents without heteroatoms, due to the formation of plane-to-plane and head-to-tail aggregated dimers simultaneously, which can be prevented in solvents such as ether, alcohol and amines.