Multiple hindered rotators in a gyroscope-inspired tribenzylamine hemicryptophane

J Org Chem. 2011 Mar 4;76(5):1418-24. doi: 10.1021/jo102480s. Epub 2011 Jan 27.

Abstract

A gyroscope-inspired tribenzylamine hemicryptophane provides a vehicle for exploring the structure and properties of multiple p-phenylene rotators within one molecule. The hemicryptophane was synthesized in three steps in good overall yield using mild conditions. Three rotator-forming linkers were cyclized to form a rigid cyclotriveratrylene (CTV) stator framework, which was then closed with an amine. The gyroscope-like molecule was characterized by (1)H NMR and (13)C NMR spectroscopy, and the structure was solved by X-ray crystallography. The rigidity of the two-component CTV-trismethylamine stator was investigated by (1)H variable-temperature (VT) NMR experiments and molecular dynamics simulations. These techniques identified gyration of the three p-phenylene rotators on the millisecond time scale at -93 °C, with more dynamic but still hindered motion at room temperature (27 °C). The activation energy for the p-phenylene rotation was determined to be ~10 kcal mol(-1). Due to the propeller arrangement of the p-phenylenes, their rotation is hindered but not strongly correlated. The compact size, simple synthetic route, and molecular motions of this gyroscope-inspired tribenzylamine hemicryptophane make it an attractive starting point for controlling the direction and coupling of rotators within molecular systems.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Benzylamines / chemical synthesis*
  • Benzylamines / chemistry
  • Crystallography, X-Ray
  • Models, Molecular
  • Molecular Dynamics Simulation
  • Molecular Structure
  • Polycyclic Compounds / chemical synthesis*
  • Polycyclic Compounds / chemistry
  • Stereoisomerism

Substances

  • Benzylamines
  • Polycyclic Compounds
  • cryptophane
  • tribenzylamine