title: Chiral molecular glass: synthesis and characterization of enantiomerically pure thiophene-based [7]helicene.
abstract: Synthesis of thiophene-based [7]helicenes, which are functionalized for both design of organic chiral glasses with strong chiroptical properties and for further homologation to higher [n]helicenes, is reported. The key synthetic transformations are kinetic resolution of the intermediate diketone and the annelation step forming the center benzene ring by means of an intramolecular McMurry reaction. Based upon X-ray crystallographic determinations of the absolute configurations for (+)-enantiomers of the diketone and the [7]helicene, stereochemical correlation between the (R) axial chirality of the diketone and the (M) helical chirality of the [7]helicene is established. One such enantiopure trimethylsilyl-substituted [7]helicene possesses enchanced chiroptical properties and forms a chiral molecular glass.
authors.affiliation: Department of Chemistry, University of Nebraska, Lincoln, NE 68588-0304, USA.
authors.forename: Makoto
authors.initials: M
authors.lastname: Miyasaka
authors.forename: Andrzej
authors.initials: A
authors.lastname: Rajca
authors.forename: Maren
authors.initials: M
authors.lastname: Pink
authors.forename: Suchada
authors.initials: S
authors.lastname: Rajca