Synthesis and Structural Diversification of Circularly Polarised Luminescence Active, Helically Chiral, "Confused" N,N,O,C-BODIPYs

Helically chiral boron-chelated dipyrromethene (BODIPY) dyes are known to exhibit solution phase circularly polarized luminescence (CPL), but examples are limited to a few synthetically accessible molecular architectures. We report a B-N chelation, SNAr, Suzuki cross-coupling, B-O chelation cascade reaction for the synthesis of understudied helically chiral, N,N,O,C-boron chelated, "confused" BODIPYs, from readily accessible 3,5-dibromo-BODIPY starting materials. Using this approach we have prepared a series of helically chiral "confused" BODIPYs with variation of the 3,5-subsitutents. Following resolution by chiral HPLC, absolute stereochemistry was assigned through comparison of the experimental and calculated ECD spectra, and solution phase chiroptical properties including CPL were determined (vertical bar g(lum)vertical bar from 2.1 to 3.7x10(-3); B-CPL from 11.3 to 27.2).