Issue 17, 2005

Synthesis and spectroscopy of an oligophenyl based cruciform with remarkable π–π 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 (2) 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 2 forms an amorphous glass when cooled from the isotropic melt. Subsequent heating reveals a glass transition temperature at 130 °C. X-Ray single crystal structure analysis of 2,2′-bis(4-tert-butylphenyl)-1,1′-biphenyl (4) and 2 shows that both these molecules with a quater-phenyl substructure adopt a folded solid-state structure. Examining the 1H NMR spectra of 2 and 4 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 π–π interaction rather than being imposed by crystal packing. The optical properties of the cruciform terphenyl dimer 2 are discussed relative to the linear analogue 1,4-bis(4-tert-butylterphenyl)benzene (3).

Graphical abstract: Synthesis and spectroscopy of an oligophenyl based cruciform with remarkable π–π assisted folding

Supplementary files

Article information

Article type
Paper
Submitted
08 Jun 2005
Accepted
19 Jul 2005
First published
02 Aug 2005

Org. Biomol. Chem., 2005,3, 3213-3219

Synthesis and spectroscopy of an oligophenyl based cruciform with remarkable π–π assisted folding

B. S. Nehls, F. Galbrecht, A. Bilge, D. J. Brauer, C. W. Lehmann, U. Scherf and T. Farrell, Org. Biomol. Chem., 2005, 3, 3213 DOI: 10.1039/B508125D

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