Unsymmetrically substituted A3B-phthalocyanine derivatives bearing annulated 6-membered N-heterocycles, pyridine and pyrazine rings, have been synthesized by ring expansion reaction of subphthalocyanines. The geometrically constrained subphthalocyanines (A3) were reacted with 1,2-phthalonitrile derivatives (B), in presence of 8-diazabicyclo[5.4.0]undec-7-ene (DBU), to form the A3B-phthalocyanine. The reactions were carried out in DMSO/1-chloronaphthalene at 130-140 °C for 15 h. This approach produces selectively A3B-phthalocyanines with high yields (75-90%) and it requires simple purification procedure since there are not byproducts. The spectroscopic properties of the A3B-phthalocyanines were compared with its homologous non-substituted Zn(II)phthalocyanine. In these compounds, annulated 6-membered N-heterocycles are precursors of cationic groups by methylation and therefore they represent interesting agents with potential applications in photodynamic inactivation of microorganisms.
