Functionalization and solubilization of polycyclic aromatic compounds by sulfoniumization

Abstract

Despite their unique physical properties and diverse applications in materials science, poor solubility of polycyclic aromatic hydrocarbons (PAHs) limits further fine-tuning and investigation of these systems. Herein, we report a sulfoniumization strategy to solubilize and functionalize a diverse range of PAHs in a one-step protocol using a triethylene glycol ether-substituted diaryl sulfoxide. While mono-sulfoniumization is generally observed, modification of the reaction conditions to favor bis-sulfoniumization is shown. The downstream applicability of the resulting PAH sulfonium salts is validated through a series of post-functionalization reactions that include C–C and C–heteroatom bond formation, while their application in annulative π-extension (APEX) is showcased by the synthesis of tetra-tert-butylquaterrylene from perylene. The red-shifted absorption and fluorescence, along with high water solubility of the PAH sulfonium salts, enable their application in bio-imaging, where they demonstrate selective mitochondrial staining without cytotoxicity.