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Photoinduced pH drops in water.

Matthieu Emond1, Jing Sun, Jean Grégoire

  • 1Ecole Normale Supérieure, Département de Chimie, UMR CNRS-ENS-UPMC Paris 06 8640 Pasteur, 24, rue Lhomond, 75231 Paris Cedex 05, France.

Physical Chemistry Chemical Physics : PCCP
|March 9, 2011
PubMed
Summary

Researchers developed three systems using a 2-hydroxyazobenzene platform to control pH changes in water. These molecular, supramolecular, and polymeric strategies enable reversible proton release upon light exposure.

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Area of Science:

  • Photochemistry
  • Supramolecular Chemistry
  • Polymer Science

Background:

  • 2-hydroxyazobenzene derivatives are known photochromic compounds.
  • Controlling proton release in aqueous solutions is crucial for various chemical and biological applications.
  • Tuning solubility and photophysical properties of photoresponsive molecules is an ongoing challenge.

Purpose of the Study:

  • To evaluate a 2-hydroxyazobenzene platform for photoreleasing protons in aqueous solutions.
  • To investigate molecular, supramolecular, and polymeric strategies for tuning solubility and photophysical properties.
  • To achieve reversible, light-induced pH drops with controllable amplitude and kinetics.

Main Methods:

  • Synthesis and physicochemical analysis of three distinct 2-hydroxyazobenzene systems.
  • Photochemical evaluation of proton release in aqueous media upon UV-Vis irradiation.
  • Kinetic and thermodynamic characterization of the photoinduced pH changes.

Main Results:

  • Successfully synthesized and characterized molecular, supramolecular, and polymeric 2-hydroxyazobenzene systems.
  • Demonstrated reversible photo-generation of pH drops in water across all three strategies.
  • Achieved tunable pH drops up to one unit amplitude on a 10-100 second timescale using 365 nm illumination.

Conclusions:

  • The 2-hydroxyazobenzene platform is effective for light-triggered proton release in water.
  • Molecular, supramolecular, and polymeric approaches offer versatile methods to tune photoresponsive properties.
  • These systems provide a controllable way to modulate pH in aqueous environments using light.