Circularly polarised luminescence from helically chiral “confused” N,N,O,C-Boron-Chelated Dipyrromethenes (BODIPYs).

Abstract

Chiral organic fluorophores have significant promise in the development of efficient emitters of circularly polarized light. Herein we describe a helically chiral boron dipyrromethene (BODIPY) with a hitherto unreported N,N,O,C-boron-chelation motif, synthesised by means of a one-pot boron metathesis, nucleophilic aromatic substitution (SNAr), Suzuki coupling, boron chelation, cascade reaction. Resolution of the racemic BODIPY (by preparative HPLC on a chiral stationary phase) allowed examination of the chiroptical properties of the resulting enantiomers (λmax(abs)=593 nm, λmax(em)=622 nm, ϵ=30 000 m−1 cm−1, φF=0.49, |glum|=3.7×10−3 (hexane)). This is the first example of circularly polarised emission from a non-C2-symmetric helically chiral N,N,O,C-BODIPY and as such provides a valuable benchmark for future developments in this compound series.