An artificial molecular switch that mimics the visual pigment and completes its photocycle in picoseconds

Proc Natl Acad Sci U S A. 2008 Nov 18;105(46):17642-7. doi: 10.1073/pnas.0802376105. Epub 2008 Nov 11.

Abstract

Single molecules that act as light-energy transducers (e.g., converting the energy of a photon into atomic-level mechanical motion) are examples of minimal molecular devices. Here, we focus on a molecular switch designed by merging a conformationally locked diarylidene skeleton with a retinal-like Schiff base and capable of mimicking, in solution, different aspects of the transduction of the visual pigment Rhodopsin. Complementary ab initio multiconfigurational quantum chemistry-based computations and time-resolved spectroscopy are used to follow the light-induced isomerization of the switch in methanol. The results show that, similar to rhodopsin, the isomerization occurs on a 0.3-ps time scale and is followed by <10-ps cooling and solvation. The entire (2-photon-powered) switch cycle was traced by following the evolution of its infrared spectrum. These measurements indicate that a full cycle can be completed within 20 ps.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Isomerism
  • Molecular Mimicry*
  • Photochemistry
  • Retinal Pigments / chemistry*
  • Spectrophotometry, Ultraviolet
  • Spectroscopy, Fourier Transform Infrared
  • Time Factors

Substances

  • Retinal Pigments