A musclelike [2](2)rotaxane: synthesis, performance, and molecular dynamics simulations

J Org Chem. 2014 Aug 1;79(15):6996-7004. doi: 10.1021/jo501127h. Epub 2014 Jul 23.

Abstract

A novel bistable symmetric [2](2)rotaxane was prepared by a threading-followed-by-stoppering strategy and characterized with (1)H, (13)C, and 2D ROESY NMR spectroscopy and HR-ESI spectrometry. The symmetric [2](2)rotaxane system consists of an anthracene-based bis(crown ether) as macrocycles, and each of the two dibenzo[24]crown-8 (DB24C8) rings is threaded by the pendant substituents of a symmetrically substituted central rotatable ferrocene subunit that possesses two distinguishable recognition sites for the DB24C8 ring: namely, a dibenzylammonium site and an N-methyltriazolium site. The uniform shuttling motion of the thread relative to the two DB24C8 rings in [2](2)rotaxane can be driven by external acid-base stimuli, which was evidenced by (1)H and 2D ROESY NMR spectroscopy. Furthermore, molecular dynamics simulations of the [2](2)rotaxane were carried out both in protonated (stretched) and in neutral (contracted) forms. The calculated percentage change in molecular length of the [2](2)rotaxane between the two end-capping bis(methoxyl)phenyl groups is about 48% in the two different states (in acetone), which is much larger than the percentage change (∼27%) in human muscle. Moreover, in the two states, the C*-Cp-Cp-C* dihedral angles are computed as -177° in the stretched state and -112° in the contracted state, indicating a correlation between the translational and rotational motions of the [2](2)rotaxane.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Crown Ethers / chemistry*
  • Magnetic Resonance Spectroscopy
  • Molecular Conformation
  • Molecular Dynamics Simulation
  • Molecular Structure
  • Quaternary Ammonium Compounds / chemistry*
  • Rotaxanes / chemical synthesis*
  • Rotaxanes / chemistry*
  • Triazoles / chemistry*

Substances

  • Crown Ethers
  • Quaternary Ammonium Compounds
  • Rotaxanes
  • Triazoles
  • dibenzyldimethylammonium