Si-Bridged annulated BODIPYs: synthesis, unique structure and photophysical properties

Two novel Si-bridged meso-annulated BODIPY dyes have been prepared through intermolecular C-I silylation and subsequent intramolecular C-H silylation in a one-pot reaction. A marked redshift of the main spectral bands was observed since the efficient sigma*-pi* conjugation results in a notable stabilization of the LUMOs. Si-annulation blocks the non-radiative decay and contributes to higher fluorescence quantum yields. This strategy is very attractive for the construction of highly emissive polycyclic aromatic hydrocarbons.