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Updated: May 10, 2026
09:46
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Large, Tunable, and Reversible pH Changes by Merocyanine Photoacids
Laura Wimberger1, Shyamal K K Prasad1, Martin D Peeks1
1School of Chemistry, UNSW Sydney, Sydney, New South Wales 2052, Australia.
Journal of the American Chemical Society
|November 30, 2021
Summary
New merocyanine photoswitches enable light-controlled pH changes. These molecular switches allow precise, remote regulation of pH-dependent processes, offering tunable recovery times for advanced applications.
Area of Science:
- Photochemistry
- Supramolecular Chemistry
- Chemical Biology
Background:
- Precise control over pH is crucial for many biological and chemical processes.
- Existing methods for pH modulation often lack non-invasive or remote control capabilities.
- Molecular photoswitches offer a potential solution for light-triggered environmental changes.
Purpose of the Study:
- To develop novel merocyanine photoswitches for light-induced pH modulation.
- To investigate the parameters governing pH changes induced by these photoswitches.
- To establish predictive models for photoswitch-driven pH alterations.
Main Methods:
- Synthesis and characterization of new merocyanine photoswitches.
- Irradiation experiments using 450 nm light to induce pH changes.
- Ultrafast transient absorption spectroscopy to study reaction dynamics.
- Development of mathematical models based on experimental parameters.
Main Results:
- Achieved reversible bulk pH changes up to 3.2 units (pH 6.5 to 3.3).
- Demonstrated tunable and predictable thermal recovery timescales.
- Identified key parameters influencing pH modulation: solubility, acidity, equilibrium, and light effects.
- Determined quantum yields and lifetimes of transient merocyanine isomers (30-550 ns).
Conclusions:
- Merocyanine photoswitches can effectively control bulk pH with light.
- The developed models accurately predict pH changes based on experimentally determined parameters.
- Quantum yields are not limiting factors for the observed pH switching efficiency.
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