Circularly Polarized Luminescence of a Stereogenic Curved Paraphenylene Anchoring a Chiral Binaphthyl in Solution and
Kenta Sato1, Masashi Hasegawa1, Yuki Nojima1
1Department of Chemistry, Graduate School of Science, Kitasato University, 1-15-1 Kitasato, Minami-ku, Sagamihara, Kanagawa, 252-0373, Japan.
Abstract:
A curved stereogenic [6]paraphenylene ([6]PP), anchoring a chiral binaphthyl scaffold at 7,7'-positions, was prepared and investigated for its properties as a solid-state circularly polarized luminescence (CPL) dye. X-ray analysis revealed a helically twisted structure of PP units induced by axial chirality of binaphthyl framework. The curved [6]PP exhibits fluorescence in powder and polymethyl methacrylate (PMMA) film as well as solution. A significant increase in quantum yield was observed for a non-fluid PMMA film owing the suppression of the molecular motion. The gCPL values of the dye in solution and as PMMA film were almost the same (4.3-4.4×10-3 ) and lager than that in powder. TD-DFT calculations in the excited state suggest that the exciton can be delocalized into a twisted PP unit to produce a larger magnetic transition dipole moment.
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