Circularly Polarized Luminescence Liquids Based on Siloxybinaphthyls: Best Binaphthyl Dihedral Angle in the Excited State. (23rd March 2021)

• Record Type: Journal Article
• Authors: Takaishi, Kazuto; Matsumoto, Tomoki; Kawataka, Miyu; Ema, Tadashi
• Is Part Of: Angewandte Chemie. Volume 133:Number 18(2021)
• Page Start: 10056
• Page End: 10060
• Publication Date: 2021-03-23
• Subjects: binaphthyls -- circularly polarized luminescence -- conformation analysis -- fluorescence -- liquids; Chemistry -- Periodicals; 540
• DOI: 10.1002/ange.202101226
• Languages: English
• ISSNs: 0044-8249

Abstract

Abstract: 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; Φ fl, liquid =0.21, | g lum, liquid |=1.6×10 −3 ). The | g lum, 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 ( θ μ, m =77°), which is a key factor in their CPL activity. The best binaphthyl dihedral angle in the excited state is approximately 110°. Abstract : Circularly polarized luminescence (CPL) neat liquids based on siloxybinaphthyls were developed. The position of the substitution has a crucial effect on the CPL activity and liquefaction. In the excited state, the binaphthyls specifically adopt a transoid conformation with a dihedral angle of 121°, which is close to the best binaphthyl dihedral angle for the high CPL activity.