title: Synthesis and spectroscopy of an oligophenyl based cruciform with remarkable pi-pi assisted folding.
abstract: A facile route has been developed for the preparation of a new family of oligophenyls based on a 2,5,2',5'-tetra-aryl substituted biphenyl structural motif. The cruciform terphenyl dimer 2,5,2',5'-tetra(4-tert-butylphenyl)-1,1'-biphenyl () has been prepared in a two step protocol as a representative of this interesting class of materials. The thermal behaviour of the cruciform was analysed by DSC and shows that forms an amorphous glass when cooled from the isotropic melt. Subsequent heating reveals a glass transition temperature at 130 degrees C. X-Ray single crystal structure analysis of 2,2'-bis(4-tert-butylphenyl)-1,1'-biphenyl () and shows that both these molecules with a quater-phenyl substructure adopt a folded solid-state structure. Examining the (1)H NMR spectra of and reveals that the interactions that induce this folding in the solid-state are sufficiently strong to bias foldamer formation also in solution. Consequently, it is reasonable to assume that the folded conformation within the lattice is due to intramolecular pi-pi interaction rather than being imposed by crystal packing. The optical properties of the cruciform terphenyl dimer are discussed relative to the linear analogue 1,4-bis(4-tert-butylterphenyl)benzene ().
authors.affiliation: Bergische Universität Wuppertal, Institut für Polymertechnologie, Makromolekulare Chemie, Gauss-Strasse 20, D-42097 Wuppertal, Germany.
authors.forename: Benjamin S
authors.initials: BS
authors.lastname: Nehls
authors.forename: Frank
authors.initials: F
authors.lastname: Galbrecht
authors.forename: Askin
authors.initials: A
authors.lastname: Bilge
authors.forename: David J
authors.initials: DJ
authors.lastname: Brauer
authors.forename: Christian W
authors.initials: CW
authors.lastname: Lehmann
authors.forename: Ullrich
authors.initials: U
authors.lastname: Scherf
authors.forename: Tony
authors.initials: T
authors.lastname: Farrell
mesh_terms: D001713:Biphenyl Compounds / Q000138:chemical synthesis / Q000737:chemistry; D018360:Crystallography, X-Ray; D019281:Dimerization; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008958:Models, Molecular; D015394:Molecular Structure
chemical_list: C506712:2,5,2',5'-tetra(4-tert-butylphenyl)-1,1'-biphenyl; D001713:Biphenyl Compounds