Axial functionalization of subphthalocyanines and subphthalocyanine fused dimers for photodynamic therapy

Abstract

Subphthalocyanines (SubPcs) are peculiar porphyrinoid compounds, exhibiting an intense absorption in the visible region and a particular cone-shaped structure that gives rise to their characteristic reduced aggregation tendency, which makes them suitable photosensitizers for photodynamic therapy (PDT) applications. On the other hand, subphthalocyanine fused dimers (SubPc[Formula: see text] are best known for their [Formula: see text]-extended surface and strong absorption in the near IR region, while keeping a low aggregation tendency. However, they remain unexplored photosensitizers in this field. Herein, the synthesis and study of properties of several axially aryloxy substituted SubPcs and SubPc fused dimers are reported. The axial aryloxy groups additionally bear polar substituents that help increase the solubility of this family of intrinsically hydrophobic compounds in polar solvents. All synthesized SubPcs and SubPc2 showed a good ability to generate singlet oxygen (1O[Formula: see text] in experiments carried out in THF. Although [Formula: see text] values obtained with SubPc fused dimers were lower than those of the corresponding SubPcs bearing the same substituent, the results are encouraging considering their absorption maximum is centered in the therapeutic window.