A self-locking molecule operative with a photoresponsive key

J Am Chem Soc. 2006 Sep 6;128(35):11600-5. doi: 10.1021/ja0632308.

Abstract

Rotary host 1, composed of a ferrocene unit as a rotary module, is conformationally locked internally in apolar solvents such as benzene by a double intramolecular Zn-N coordination between the zinc porphyrin and aniline units, attached to each cyclopentadienyl (Cp) ring. Upon addition of the cis form of 1,2-bispyridylethylene (cis-2) to (+)-1 ([cis-2]/[(+)-1] = 5.0), an enantiomer of 1, the intramolecular Zn-N coordination bonds in (+)-1 are readily cleaved to form an externally locked, cyclodimeric one-to-one complex (+)-1 subset cis-2, accompanying a rotation of the ferrocene module, as visualized by CD spectroscopy. In contrast, use of trans-2, in place of cis-2, under otherwise identical conditions to the above, did not result in releasing the internal double lock of (+)-1. Such a large difference between the isomers of 2 in the affinity toward host 1, along with their capabilities of photochemical interconversion, allowed for the demonstration of a reversible self-locking operation of 1. Namely, the externally locked state of 1, as in the form of 1 supersetcis-2, spontaneously retrieves the internally locked state, after the release of 2 from 1 upon cis-to-trans photochemical isomerization of ligating 2, while the backward photochemical isomerization of 2 in the presence of 1 results in switching of 1 to its externally locked state.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aniline Compounds / chemistry
  • Circular Dichroism
  • Cyclopentanes / chemistry
  • Ferrous Compounds / chemical synthesis*
  • Ferrous Compounds / chemistry*
  • Magnetic Resonance Spectroscopy
  • Metallocenes
  • Metalloporphyrins / chemistry
  • Models, Molecular
  • Photochemistry
  • Pyridines / chemistry
  • Stereoisomerism

Substances

  • Aniline Compounds
  • Cyclopentanes
  • Ferrous Compounds
  • Metallocenes
  • Metalloporphyrins
  • Pyridines
  • zinc hematoporphyrin
  • aniline
  • ferrocene