Carbazole-containing porphyrazines and phthalocyanines: synthesis, optical properties and application

Abstract

The scope of this review is focused on the advances made in the field of porphyrazines and phthalocyanines decorated by carbazole moieties. Three ways of linkage between carbazole and the porphyrazine or phthalocyanine macrocycle are covered: σ-linkages between the phthalocyanine periphery and the carbazole unit, fusion of carbazole to the porphyrazine core, and substitution of the axial position of the phthalocyanine. Synthetic routes begin with the preparation of the initial nitriles and include approaches to the formation of the carbazole ring. These approaches include S_NAr substitution, Suzuki cross-coupling reaction, Cadogan reductive cyclization, etc. The presence of modification sites in the carbazole unit leads to the possibility of introducing additional functional groups. For example, this allows the corresponding substituted porphyrazine to be easily quaternized and made water-soluble. This has a dramatic effect on the photophysical and photochemical properties of porphyrazines and phthalocyanines. Applications of carbazole-containing tetrapyrrole compounds are discussed, ranging from photodynamic therapy to dye-sensitized solar cells.