Structure modulation from unstable to stable MOFs by regulating secondary N-donor ligands

Area of Science:

• Materials Science
• Inorganic Chemistry
• Supramolecular Chemistry

Background:

• Metal-organic frameworks (MOFs) are crystalline porous materials with diverse applications.
• Tuning MOF structures through ligand design is crucial for optimizing their properties.
• The development of novel MOFs for gas separation and luminescence is an active research area.

Purpose of the Study:

• To synthesize and characterize new Zn(ii)/Cd(ii)-based MOFs using a semi-rigid ligand (H2tmdb) and various bis-imidazole ligands.
• To investigate the structural stability of the synthesized MOFs.
• To explore the gas adsorption and luminescence properties of the resulting MOFs.

Main Methods:

• Solvothermal synthesis was employed to create four new MOFs: YZ-7, YZ-8, YZ-9, and YZ-10.
• Structural characterization was performed on the synthesized MOFs.
• Gas adsorption isotherms (CO2, CH4, N2, H2) were measured at different temperatures and pressures.
• Luminescence properties were studied for selected MOFs at room temperature.

Main Results:

• Four new Zn(ii)/Cd(ii)-based MOFs were successfully synthesized.
• MOF stability was modulated by altering auxiliary ligand flexibility, with YZ-10 showing enhanced stability.
• YZ-10 demonstrated excellent selective CO2 uptake over CH4 (selectivity 133.2) and N2 (selectivity 19.9) at 298 K and 1 atm.
• YZ-10 also exhibited notable H2 selective uptake over N2 at 77 K.
• Luminescence properties were observed in YZ-8, YZ-9, and YZ-10.

Conclusions:

• The study successfully synthesized and characterized novel Zn(ii)/Cd(ii)-based MOFs.
• Ligand design plays a critical role in controlling MOF stability and gas adsorption performance.
• YZ-10 shows significant potential for selective gas separation (CO2/CH4, CO2/N2, H2/N2) and possesses luminescent characteristics.