Strong H(2) binding and selective gas adsorption within the microporous coordination solid...

Area of Science:

• Materials Science
• Inorganic Chemistry
• Nanotechnology

Background:

• Metal-organic frameworks (MOFs) are crystalline materials with tunable porous structures.
• Previous research has focused on MOFs incorporating heavier metal ions like zinc.
• Exploring MOFs with lighter, more abundant metal ions is crucial for sustainable materials development.

Purpose of the Study:

• To synthesize and characterize a novel porous metal-organic framework (MOF) using magnesium ions.
• To investigate the structural analogy between the new magnesium MOF and a known zinc MOF.
• To evaluate the gas adsorption and separation capabilities of the synthesized magnesium MOF.

Main Methods:

• Solvothermal synthesis of Mg3(NDC)3(DEF)4 (NDC = 2,6-naphthalenedicarboxylate, DEF = N,N-diethylformamide).
• X-ray diffraction to determine the crystal structure.
• Thermogravimetric analysis for desolvation studies.
• Gas adsorption measurements (H2, O2, N2, CO) at cryogenic temperatures (77 and 87 K).

Main Results:

• Successful synthesis of Mg3(NDC)3(DEF)4, the first porous MOF containing Mg2+ ions.
• The framework structure is analogous to Zn3(NDC)3(CH3OH)2.2DMF.H2O, showing Mg2+ can substitute for Zn2+.
• Desolvation yields a microporous solid Mg3(NDC)3 with a BET surface area of 190 m2/g.
• High H2 adsorption enthalpies (7.0-9.5 kJ/mol) and selective adsorption of H2/O2 over N2/CO were observed.

Conclusions:

• A novel Mg-MOF with a structure analogous to Zn-MOFs has been synthesized.
• The desolvated Mg-MOF exhibits significant porosity and selective gas adsorption properties.
• This material shows promise for applications in gas separation technologies.