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Determination of the Photoisomerization Quantum Yield of a Hydrazone Photoswitch
Published on: February 7, 2022
Photoswitchable dynamic combinatorial libraries: coupling azobenzene photoisomerization with hydrazone exchange
Lindsey A Ingerman1, Marcey L Waters
1Department of Chemistry, CB 3290, University of North Carolina, Chapel Hill, North Carolina 27599, USA.
The Journal of Organic Chemistry
|November 27, 2008
Summary
This study introduces a novel azobenzene monomer enabling dynamic libraries through hydrazone exchange and photoisomerization. Light triggers a conformational change, stabilizing specific receptors for controlled molecular recognition.
Area of Science:
- Supramolecular Chemistry
- Organic Chemistry
- Photochemistry
Background:
- Dynamic combinatorial chemistry (DCC) allows for the creation of molecular libraries that can adapt and evolve.
- Azobenzene derivatives are known for their photoresponsive properties, enabling light-induced structural changes.
- Molecular receptors are crucial for selective binding and recognition events in various chemical and biological systems.
Purpose of the Study:
- To synthesize a novel azobenzene-based monomer capable of undergoing both hydrazone exchange and photoisomerization.
- To construct dynamic combinatorial libraries (DCLs) using this monomer and evaluate their responsiveness to external stimuli.
- To investigate the potential of light-switchable receptors for controlled molecular recognition.
Main Methods:
- Synthesis of a novel azobenzene monomer with dual dynamic functionalities.
- Formation of cyclic and multi-building block libraries via acid-promoted hydrolysis and monomer addition.
- Characterization of library composition under thermal equilibrium and light irradiation.
- Investigation of template-directed stabilization of photoisomerized species.
Main Results:
- The azobenzene monomer successfully formed dynamic combinatorial libraries of cyclic oligomers and multi-building block systems.
- Thermal equilibration favored the trans isomer of azobenzene macrocycles.
- Light-induced isomerization shifted the library members to their cis-azo form.
- A pentaproline template stabilized the cis-azobenzene receptor, slowing thermal relaxation and amplifying its presence due to binding interactions.
Conclusions:
- A novel photoswitchable monomer was developed for creating dynamic combinatorial libraries.
- Light can be used to control the isomeric state and conformational preferences of the library members.
- Template-directed binding can stabilize photoisomerized receptors, offering a method for amplification and control in molecular recognition.
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