A series of novel axially chiral compounds based on 3,3'-bidithieno2,3-b:3',2'-dthiophene (BDTT) bearing two aryl groups (referred to as BDTT-DArs) were synthesized and successfully resolved into their enantiomers. Crystal structure analysis confirms that aromatic substitution can significantly alter the dihedral angle of BDTT with multiple intermolecular interactions. The racemization of enantiomers BDTT-DArs showed that their inversion barriers (ΔG) are in a range of 22.2-37.4 kcal/mol. Owing to their high chiral stability, BDTT-DArs exhibit remarkable circularly polarized luminescence (CPL) properties. In particular, BDTT-D9An and BDTT-D1Py achieve their luminescence dissymmetry factors |glum| up to 0.011. In addition, enantiomers BDTT-D1Py exhibited dual emission, circularly polarized fluorescence (CPF) and circularly polarized phosphorescence (CPP). This work provides critical theoretical insights into heterocyclic aromatic ring with axial chirality in novel CPL materials.
Li et al. (Mon,) studied this question.