Solvent-free synthesis and chiroptical properties of a C–N axially chiral cruciform dimer of benzo[b]phenoxazine

Abstract

A novel C–N axially chiral molecule composed of two tert-butyl-substituted benzo[b]phenoxazine (BPO) was synthesized via solvent-free reactions. The absolute configurations of the enantiomers were determined by X-ray single-crystal analysis. The enantiomers had a sufficiently high racemization barrier to ignore racemization at room temperature (149 ± 20 kJ mol⁻¹), and the solutions exhibited dual circularly polarized emissions stemming from fluorescence and phosphorescence of |g_CPL| = ca. 1 × 10⁻³.