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 <b>S55</b>, <b>S66</b>, and <b>S56</b> 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 <b>S55</b> containing a pair of (<i>P</i>,<i>P</i>)-/(<i>M</i>,<i>M</i>)-enantiomers and <b>S66</b> adopting only a mesomer lacking chirality, unsymmetric double helicene <b>S56</b> possesses four distinct enantiomers with (<i>P</i>,<i>P</i>)-/(<i>P</i>,<i>M</i>)-/(<i>M</i>,<i>P</i>)-/(<i>M</i>,<i>M</i>)-configurations. Moreover, <b>S55</b> and <b>S56</b> display intense phosphorescence with an afterglow lasting 6-7 s.