Circularly Polarized Luminescence of a Stereogenic Curved Paraphenylene Anchoring a Chiral Binaphthyl in Solution and Solid State

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 g(CPL) values of the dye in solution and as PMMA film were almost the same (4.3-4.4x10(-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.

Automated summary

A new curved stereogenic [6]paraphenylene was synthesized and investigated for its properties as a CPL dye in solid-state and solution. The dye showed fluorescence in various forms and TD-DFT calculations suggested potential exciton delocalization for enhanced magnetic transition dipole moment.