Controlling Optical Properties and Function of BODIPY by Using Asymmetric Substitution Effects

Asymmetrically substituted BODIPY analogues of the dye PM567 have been synthesised from 2‐acylpyrroles and pyrroles that bear indene, fluorene or difluorene units. The type of linkage between the fluorene and the BODIPY core plays an important role in the photophysics of the BODIPY chromophore. Indeed, an aliphatic bridge gives rise to an energy‐transfer process between the chromophores, whereas a vinyl spacer allows an electronic interaction between them, leading to a large red shift of the spectral bands. The laser action of the new dyes has been analysed under transversal pumping at 10 Hz repetition rate, in both liquid phase and incorporated into solid polymeric matrices. Lasing efficiencies of up to 40 % were reached with high photostabilities with the laser output remaining at the initial level after 1×105 pump pulses in the same position of the sample. The laser action of the new dyes outperforms the laser behaviour of commercial dyes that emit in the same spectral region. The replacement of fluorene by indene quenches the fluorescence and laser emission, but allows the development of an iron cation fluorescent sensor. It's all under control: A strategy to modulate the photophysical and optical properties of BODIPYs by using asymmetric substitution effects has been developed. New asymmetric BODIPY–indene and BODIPY–fluorene dyes have been synthesized (see figure) by a simple protocol.