Efficient Near‐Infrared Fluorophores Based on Cyanostyrene Derivatives for Two‐Photon Fluorescence Bioimaging

Organic fluorescent materials with red/near-infrared (NIR) emission are highly promising for use in biotechnology due to their exceptional advantages. However, traditional red/NIR fluorophores often exhibit weak emission at high concentrations or in an aggregated state due to the aggregate-caused quenching effect, which severely limits their applicability in biological imaging. To address this challenge, we developed a series of cyanostyrene derivatives with aggregation-induced emission characteristics, including 2,3-Bis-(4-styryl-phenyl)-but-2-enedinitrile (DPB), 2,3-Bis-{4-[2-(4-methoxy- phenyl)-vinyl]-phenyl}-but-2-enedinitrile (DOB), 2,3-Bis-{4-[2-(4-diphenylamino- phenyl)-vinyl]-phenyl}-but-2-enedinitrile (DTB), and 2,3-Bis-[4-(2-{4-[phenyl- (4-triphenylvinyl-phenyl)-amino]-phenyl}-vinyl)- phenyl]-but-2-enedinitrile (DTTB). Notably, these compounds exhibited intense solid state fluorescence owing to AIE effect, especially DTTB shows NIR emission with high solid state quantum efficiency (712 nm, Φ