A Reversible Photoacid Functioning in PBS Buffer under Visible Light.

Area of Science:

• Photochemistry
• Supramolecular Chemistry
• Chemical Biology

Background:

• Proton transfer is fundamental to many biological processes.
• Controlling proton concentration (pH) dynamically is challenging in physiological conditions.
• Photoresponsive molecules offer external control over chemical reactions.

Purpose of the Study:

• To design and characterize a photoacid capable of reversible proton release under visible light.
• To evaluate its performance in a biologically relevant buffer (PBS, pH 7.4).
• To explore its potential applications in biomedical fields.

Main Methods:

• Design based on indazole's dual acid-base property and tautomerization.
• Photoreaction studies using visible light irradiation.
• Quantum yield determination.
• pH measurements in aqueous solutions.

Main Results:

• A metastable-state photoacid was successfully synthesized.
• Reversible proton release was achieved in PBS buffer (pH 7.4) under visible light.
• High quantum yield (0.73) and efficiency at moderate light intensity (10^2 μmol·m⁻²·s⁻¹).
• Demonstrated a reversible pH change of 1.7 units in a 0.1 mM aqueous solution.

Conclusions:

• The developed photoacid offers efficient and reversible proton control under visible light.
• Its properties are suitable for physiological conditions, enabling applications in controlling proton-transfer processes.
• This photoacid represents a promising tool for biomedical applications requiring precise pH modulation.