Molecular Oxygen Activation by Redox-Switchable Anthraquinone-Based Metal-Organic Frameworks

Area of Science:

• Materials Science
• Supramolecular Chemistry
• Electrochemistry

Background:

• Coordination networks offer tunable properties through linker design.
• Redox-active linkers enable dynamic functional materials.
• Anthraquinone derivatives are known for their redox activity.

Purpose of the Study:

• To incorporate a redox-active dipyridyl-substituted anthraquinone (DPAq) into crystalline coordination networks.
• To investigate the stability and redox-switchability of the DPAq linker within the solid-state framework.
• To explore the potential for hydrogen peroxide generation via redox cycling.

Main Methods:

• Synthesis of 2,6-di(pyridin-4-yl)-9,10-anthraquinone (DPAq).
• Formation of crystalline coordination networks utilizing DPAq as a linker.
• Characterization of framework stability and hydrogen bonding interactions.
• Investigation of redox state control and reversibility using thermal treatment and soaking procedures.

Main Results:

• DPAq was successfully incorporated as a redox-active linker in crystalline coordination networks.
• The oxidation state of DPAq could be controlled before and maintained after framework formation.
• Hydrogen bonding was identified as a key stabilization factor for the networks.
• Reversible switching of the anthraquinone-anthrahydroquinone redox pair was achieved in the solid state.
• Oxidation process led to the formation of hydrogen peroxide from molecular oxygen.

Conclusions:

• Stable crystalline coordination networks incorporating redox-active DPAq linkers can be constructed.
• The redox state of the DPAq linker is controllable and switchable even within the solid-state framework.
• These materials demonstrate potential for applications involving redox chemistry and oxygen activation, including hydrogen peroxide generation.