Hemiindigo: Highly Bistable Photoswitching at the Biooptical Window

Area of Science:

• Organic Chemistry
• Photochemistry
• Materials Science

Background:

• Hemiindigo, a known blue-absorbing chromophore, has been largely overlooked as a photoswitch.
• Existing photoswitches often require UV light or lack thermal stability.

Purpose of the Study:

• To investigate hemiindigo derivatives as visible-light-responsive photoswitches.
• To achieve red-shifted absorption and high photochromic performance in hemiindigo compounds.

Main Methods:

• Synthesized and characterized five substituted hemiindigo derivatives.
• Investigated photoisomerization efficiency using visible light irradiation (470-680 nm).
• Assessed thermal stability and half-lives of the isomeric states.

Main Results:

• Achieved red-shifted absorption spectra for hemiindigo derivatives.
• Demonstrated high isomeric yields: >90% E isomer (blue/green light) and 99% Z isomer (red light).
• Observed exceptional thermal bistability with half-lives up to 83 years at 25 °C.

Conclusions:

• Substituted hemiindigos exhibit excellent photochromic properties in the visible spectrum.
• These compounds are highly stable and distinguishable by the naked eye.
• Developed hemiindigo photoswitches show significant promise for diverse scientific applications.