Cubic octanuclear Ni(II) clusters in highly porous polypyrazolyl-based materials

Area of Science:

• Materials Science
• Inorganic Chemistry
• Crystallography

Background:

• Coordination polymers are crystalline materials constructed from metal ions and organic ligands.
• Developing materials with high porosity is crucial for applications in gas storage, separation, and catalysis.

Purpose of the Study:

• To synthesize and characterize novel highly porous coordination polymers.
• To investigate the structural properties and porosity of these materials after thermal treatment.

Main Methods:

• Synthesis of coordination polymers using nickel salts and bis-pyrazolyl ligands.
• Single-crystal X-ray diffraction to determine crystal structures.
• Gas sorption analysis to quantify pore volume and surface area.

Main Results:

• Two coordination polymers incorporating rare octanuclear hydroxo-nickel clusters were successfully synthesized.
• Mild thermal treatment resulted in the formation of significant lattice cavities, occupying up to 72% of the total crystal volume.
• The porosity is attributed to the unique cluster structure and the long bis-pyrazolyl spacers.

Conclusions:

• The study demonstrates the successful design of highly porous coordination polymers with unique nickel clusters.
• The materials show potential for applications requiring large internal surface areas and tunable pore sizes.
• Thermal treatment is an effective method for enhancing the porosity of these coordination polymers.