A series of axially chiral 1,1′-binaphthyls with trialkylsiloxy (OSiR3) groups were synthesized. Among them, 1 a–c possessing OSiR3 groups at the 7,7′-positions and methyl groups at the 2,2′-positions were liquids at room temperature, and the neat liquids showed circularly polarized luminescence (CPL) (R=Bu; Φfl,liquid=0.21, |glum,liquid|=1.6×10−3). The |glum,liquid| value is the highest of pure liquids. These compounds remained liquid over a broad range of temperatures, down to −50 °C. Time-dependent DFT calculations indicated that in the excited state, the binaphthyls adopt a transoid conformation with a small angle between the electric and magnetic transition dipole moments (θμ,m=77°), which is a key factor in their CPL activity. The best binaphthyl dihedral angle in the excited state is approximately 110°.
- circularly polarized luminescence
- conformation analysis
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