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

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 .