Synthesis and photophysical properties of D-A type ring-fluorinated benzofuran-3(2H)-one dyes through a novel 1,2-rearangement of a perfluorophenyl group

Dual-state emissive dyes, fluorescent in both solution and solid forms, are widely applied. This paper details the unprecedented synthesis of ring-fluorinated benzo-3-furanones via a 1,2-rearrangement of a perfluorophenyl group and subsequent aromatic nucleophilic substitution. These derivatives were selectively functionalized at the 6-position using carbazole or phenothiazine in good yields. The carbazole-containing derivative showed significant fluorescent solvatochromism in solution. Notably, its solid-state fluorescence quantum yield was markedly higher compared to that in solution, confirming its aggregation-induced emission enhancement (AIEE) properties. This work introduces a new class of AIEE-active fluorescent dyes with promising potential as organic dual-state emission materials.