Proton Conduction in Stable, Crystalline, and Porous Hydrogen-Bonded Metal-Organic Frameworks

Area of Science:

• Materials Science
• Crystallography
• Supramolecular Chemistry

Background:

• Hydrogen-bonded metal-organic frameworks (HMOFs) combine hydrogen bonds (HBs) and coordination bonds (CBs) for stable structures.
• Designing HMOFs requires strategies to enhance HB interactions and control framework assembly.

Purpose of the Study:

• To develop a novel approach for constructing stable HMOFs using carbonyl-rich ligands.
• To investigate the structure-property relationships of HMOFs with varying metal nodes.

Main Methods:

• Design of carbonyl-rich molecules with extended arms to promote HB interactions.
• Synthesis of 2+2 layer-interpenetrated HMOFs using Co2+, Ni2+, and Zn2+ metal nodes.
• Characterization of framework stability, structure, and proton conductivity.

Main Results:

• Successful synthesis of stable, interpenetrated HMOFs with open channels.
• Demonstrated proton conductivity of ~10^-3 S cm^-1 at 95°C and 98% RH.
• Low activation energies (< 0.2 eV) for proton transport.

Conclusions:

• Carbonyl-rich planar ligands facilitate the direct construction of stable HMOFs.
• The designed HMOFs exhibit excellent proton conductivity, suitable for electrochemical applications.
• This work provides a valuable strategy for the rational design of advanced crystalline materials.