Controlling of Enantiomeric and Phosphorescent Behaviors in Symmetric and Unsymmetric S-Shaped Double Helicenes Containing Thiophene and/or Thiopyran Rings

Symmetric and unsymmetric S-shaped double helicenes S55, S66, and S56 containing thiophene and/or thiopyran rings have been straightforwardly synthesized, and their stereochemical and (chir)optical properties have been systematically investigated. Unlike symmetric double helicene S55 containing a pair of (P,P)-/(M,M)-enantiomers and S66 adopting only a mesomer lacking chirality, unsymmetric double helicene S56 possesses four distinct enantiomers with (P,P)-/(P,M)-/(M,P)-/(M,M)-configurations. Moreover, S55 and S56 display intense phosphorescence with an afterglow lasting 6-7 s.