A Water-Soluble Diarylethene Base for Light-Controlled pH Modulation in Biological Systems

Area of Science:

• Supramolecular Chemistry
• Photochemistry
• Materials Science

Background:

• Molecular photoswitches are crucial for light-controlled applications but often suffer from poor water solubility, limiting their use in biological systems.
• Existing photoswitches struggle to generate significant and sustained pH shifts in aqueous environments.

Purpose of the Study:

• To synthesize and characterize a highly water-soluble photoswitchable diarylethene with dual pH-modulating capabilities.
• To demonstrate reversible pH control in aqueous solutions for bioinspired applications.

Main Methods:

• Synthesis and photophysical characterization of a novel N-heterocyclic imine (NHI)-diarylethene photoswitch.
• Experimental determination of pKa values and development of a model for pH modulation.
• Application of the photoswitch to control the assembly of a pH-responsive protein.

Main Results:

• The NHI-diarylethene exhibits dual photoacidic (pH 6-11) and photobasic (pH 3-6) behavior, a first for photoswitches.
• Achieved a reversible pH change of over 1.7 pH units using alternating UV and visible light.
• Successfully controlled the assembly of a cationic reflectin protein in aqueous solution.

Conclusions:

• This water-soluble photoswitch offers unprecedented dual functionality and operation in the basic pH regime.
• It provides precise, sustained, and reversible pH control in aqueous environments, vital for bioinspired dynamic systems.
• The photoswitch holds promise for biophotonic applications and mimicking biological functions.