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Updated: May 27, 2026

Determination of the Photoisomerization Quantum Yield of a Hydrazone Photoswitch
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Published on: February 7, 2022

Azobenzene photoswitching without ultraviolet light.

Andrew A Beharry1, Oleg Sadovski, G Andrew Woolley

  • 1Department of Chemistry, University of Toronto , 80 St. George Street, Toronto, ON, Canada M5S 3H6.

Journal of the American Chemical Society
|November 16, 2011
PubMed
Summary

This study introduces novel amidoazobenzene photoswitches that utilize green and blue light for bidirectional isomerization, avoiding harmful UV radiation. These photoswitches offer stable performance in biological applications.

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Area of Science:

  • Organic Chemistry
  • Photochemistry
  • Materials Science

Background:

  • Azobenzene photoswitches commonly rely on UV light for photoisomerization.
  • UV light poses risks in biological applications, potentially causing cellular apoptosis.
  • A need exists for photoswitches operable with visible light for biological compatibility.

Purpose of the Study:

  • To develop azobenzene photoswitches that can be activated by visible light.
  • To enable UV-free bidirectional photoswitching for enhanced biological applications.

Main Methods:

  • Synthesized amidoazobenzene derivatives with methoxy group substitutions at ortho positions.
  • Investigated the photophysical properties, including absorption spectra and photoisomerization efficiency.
  • Assessed the thermal stability and switching kinetics of the synthesized compounds.

Main Results:

  • Methoxy group substitution induced a ~35 nm red shift in the trans isomer's n-π* band.
  • Trans-to-cis photoisomerization was achieved using green light (530-560 nm).
  • The cis isomer demonstrated high thermal stability (half-life ~2.4 days) in aqueous solution.
  • Bidirectional photoswitching was accomplished using green light for trans-to-cis and blue light (460 nm) for cis-to-trans isomerization.

Conclusions:

  • Developed novel amidoazobenzene photoswitches operable with visible light, eliminating the need for UV radiation.
  • These photoswitches exhibit thermally stable states and bidirectional switching capabilities.
  • The findings pave the way for safer and more versatile applications of photoswitches in biological systems.