Azobenzene Photoswitching with Near-Infrared Light Mediated by Molecular Oxygen

Area of Science:

• Photochemistry
• Materials Science
• Photobiology

Background:

• Efficient photoisomerization of azobenzenes using low-energy light is crucial for applications like photobiology.
• Direct isomerization with modified azobenzenes using near-infrared light remains challenging.

Purpose of the Study:

• To develop an efficient method for cis-to-trans isomerization of azobenzenes using near-infrared light.
• To explore the use of molecular iodine as a photocatalyst for this process.

Main Methods:

• Utilizing molecular iodine as a photocatalyst for indirect cis-to-trans isomerization of 4,4'-dimethoxyazobenzene.
• Employing 770 nm near-infrared light as the energy source.
• Investigating the role of molecular oxygen and other photosensitizers like palladium phthalocyanine.

Main Results:

• Achieved robust cis-to-trans isomerization of 4,4'-dimethoxyazobenzene over 1000 cycles under ambient conditions.
• Demonstrated that the catalysis is mediated by molecular oxygen.
• Showed that other singlet-oxygen-generating photosensitizers can also catalyze the isomerization.

Conclusions:

• The developed photocatalytic approach using molecular iodine and near-infrared light is effective for azobenzene isomerization.
• The process is mediated by singlet oxygen, suggesting broader applicability with other photosensitizers.
• Further research is needed to explore catalyst optimization and applicability to other azobenzene derivatives.