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CO2 triggering and controlling orthogonally multiresponsive photochromic systems
Tamim A Darwish1, Richard A Evans, Michael James
1Australian Nuclear Science and Technology Organisation, Locked Bag 2001, Kirrawee DC, New South Wales 2232, Australia. tamim.darwish@ansto.gov.au
Journal of the American Chemical Society
|August 5, 2010
Summary
A new method uses carbon dioxide (CO(2)) to reversibly control spiropyran photochromism. Adding or removing CO(2) with an amidine sensitizer switches the photochromic effect on and off, enabling new applications.
Area of Science:
- Organic Chemistry
- Materials Science
- Photochemistry
Background:
- Spiropyrans are photochromic compounds whose color changes upon light exposure.
- Controlling photochromism reversibly is crucial for advanced material applications.
- Existing methods for controlling spiropyran photochromism can be limited.
Purpose of the Study:
- To develop a novel, generic method for reversible control of spiropyran photochromism.
- To investigate the role of carbon dioxide (CO(2)) and amidine sensitizers in modulating photochromic behavior.
- To enable CO(2)-responsive applications for spiropyran-based materials.
Main Methods:
- Utilizing spiropyrans in alcohol solutions with an amidine (DBU) as a CO(2) sensitizer.
- Applying and removing carbon dioxide (CO(2)) to solutions to switch photochromism.
- Employing inert gas bubbling to remove CO(2) and deactivate the photochromic effect.
- Testing the effect of CO(2)/DBU on other photochromic dye classes (spirooxazines, chromenes).
Main Results:
- Spiropyrans exhibit reversible photochromism controlled by the presence or absence of CO(2) when an amidine sensitizer is used.
- The photochromic effect is activated by CO(2) addition and deactivated by CO(2) removal.
- This CO(2)/DBU stimulus specifically affects spiropyrans, not spirooxazines or chromenes.
- Orthogonal activation of spiropyran and spirooxazine mixtures yielded four distinct color states.
Conclusions:
- A new, generic method for reversible CO(2)-controlled photochromism of spiropyrans has been established.
- This CO(2)/DBU system offers a facile way to activate and deactivate photochromic properties.
- The selectivity of this method allows for orthogonal control in mixed dye systems, expanding application possibilities.
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