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

Abstract

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 (|glum| from 2.1 to 3.7×10−3; BCPL from 11.3 to 27.2).