Cationic axial ligands on sulfur substituted silicon(iv) phthalocyanines: improved hydrophilicity and exceptionally red-shifted absorption into the NIR region

Abstract

Herein, we report the exceptionally red-shifted absorption of sulfur-substituted silicon(IV) phthalocyanines upon introduction of cationic axial ligands. The Q band was red-shifted to approximately 900 nm with improved hydrophilicity by the combination of peripheral sulfur substituents and axial ammonium ligands. One such phthalocyanine exhibited remarkable photocytotoxicity upon irradiation with NIR light (∼810 nm) in live cells.