Effect of AIE Substituents on the Fluorescence of Tetraphenylethene-Containing BODIPY Derivatives

A series of BODIPY derivatives with
tetraphenylethene (TPE) moieties were designed and synthesized. The
effect of positions and numbers of substitution groups on the fluorescence
of the BODIPYs was investigated. Theoretical calculation and single
crystal structures proved that the TPE substitution groups on the
8-position of BODIPY contributed little to the conjugation, but benefited
the aggregated state emission. On the other hand, the substitutions
on the 3- or 5-position of BODIPY through vinyl bridges increased
the conjugation length, and generated big coplanar π-conjugated
structures with poor aggregated state emission. The compound with
bright aggregated state emission has been further fabricated into
biocompatible fluorescent nanoparticles and used as effective fluorescent
contrast agents for intracellular imaging.