Silicon phthalocyanines with tetraphenylethene substituents: Synthesis, photophysical and aggregation-induced emission properties

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This work presents the synthesis and characterization of three silicon phthalocyanine derivatives, SiPc 1, SiPc 2 and SiPc 3, incorporating tetraphenylethylene (TPE) units at peripheral and axial positions, to evaluate their photophysical properties and aggregation-induced emission (AIE) behavior. SiPc 1, axially substituted with TPE, exhibited diminished fluorescence and singlet oxygen generation, but displayed AIE in the near-infrared region (700–900 nm) upon water addition. SiPc 2, with peripheral TPE units, showed enhanced fluorescence and singlet oxygen generation without AIE. SiPc 3, featuring axial and peripheral TPE units, demonstrated reduced fluorescence, singlet oxygen generation, and no AIE. These results highlight the ability to modulate photodynamic activity and AIE properties through strategic TPE substitution on silicon phthalocyanines, suggesting potential applications in image-guided phototherapy.