title: Preparation, structures and preliminary host-guest studies of fluorinated syn-bis-quinoxaline molecular tweezers.
abstract: A series of polycyclic frameworks with fluorinated syn-facial quinoxaline sidewalls has been prepared as potential molecular tweezers for electron-rich guest compounds. Our synthetic route to the cyclooctadiene-derived scaffolds 16a-d takes advantage of the facile isolation of a novel spirocyclic precursor 9b with the crucial syn-orientation of its two alkene moieties. The crystal structure of 16c displays two features typical of a molecular tweezer: inclusion of a solvent molecule in the molecular cleft and self-association of the self-complementary scaffolds. Furthermore, host-guest NMR studies of compound 16c in solution show chemical exchange between the unbound and bound electron-rich guest, N,N,N',N'-tetramethyl-p-phenylenediamine.
authors.affiliation: Department of Chemistry, The University of North Carolina at Charlotte, 9201 University City Blvd., Charlotte, NC 28223, USA. metzkorn@uncc.edu
authors.forename: Markus
authors.initials: M
authors.lastname: Etzkorn
authors.forename: Jacob C
authors.initials: JC
authors.lastname: Timmerman
authors.forename: Matthew D
authors.initials: MD
authors.lastname: Brooker
authors.forename: Xin
authors.initials: X
authors.lastname: Yu
authors.forename: Michael
authors.initials: M
authors.lastname: Gerken