Engineering Dynamic Proton "Hubs" in Hydrogen-Bonded Frameworks for Superprotonic Conductivity.

Area of Science:

• Materials Science
• Supramolecular Chemistry
• Electrochemistry

Background:

• Mimicking biological proton conduction in synthetic materials is challenging.
• Hydrogen-bonded organic frameworks (HOFs) offer potential for proton transport applications.

Purpose of the Study:

• To engineer dynamic proton "hubs" within HOFs for enhanced proton conduction.
• To investigate the mechanism of synergistic proton transport in these engineered frameworks.

Main Methods:

• Design and synthesis of ammonium-sulfonate HOFs (BPDS_NH4) incorporating supramolecular secondary building units (SSBUs) as proton hubs.
• Proton conductivity measurements under varying temperature and humidity.
• Activation energy analysis and H/D isotope effect studies to elucidate transport mechanisms.

Main Results:

• The synthesized ammonium-sulfonate HOF, BPDS_NH4, achieved a proton conductivity of 0.21 S cm⁻¹ at 90°C and 90% RH.
• Proton hubs facilitate synergistic vehicular transport and Grotthuss hopping.
• Experimental evidence supports the coupled nature of these transport mechanisms.

Conclusions:

• The construction of supramolecular proton hubs is a viable strategy for designing advanced proton-conducting materials.
• This approach offers a blueprint for mimicking synergistic proton conduction found in biological systems.
• The engineered HOFs show promise for applications requiring efficient proton transport.