Circularly polarised luminescence (CPL) is the spontaneous differential emission of left- or right-circularly polarized light from an excited electronic state in the presence of a chiral field. Although many highly efficient condensed phase CPL systems have been disclosed, the discovery of “bright” solution phase CPL emitters presents an ongoing challenge. Herein we present our investigations into the synthesis of chiral boron-chelated dipyrromethenes (BODIPYs) as solution phase, small organic molecule based, circularly polarised luminophores (CPL-SOMs). We have demonstrated that helically chiral N,N,O,O-boron chelated dipyrromethenes show solution-phase CPL in the red region of the visible spectrum. The parent dipyrromethene being desymmetrised through O-chelation of boron by the 3,5-ortho-phenolic substituents, thus inducing a helical chirality in the fluorophore. The combination of high luminescence dissymmetry factors (|glum| up to 4.7 x10-3) and fluorescence quantum yields (ΦF up to 0.73) gives efficient circularly polarized emission in comparison to other chiral small organic fluorophore systems. Current work aims to maximise |glum| values in the helically chiral BODIPY series through an improved understanding of the link between |glum| and molecular structure.

Synthesis and circularly polarized luminescence of chiral boron-chelated dipyrromethene fluorophores

256th National Meeting (2018)

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