Methane Storage in Paddlewheel-Based Porous Coordination Cages.

Area of Science:

• Materials Science
• Chemistry
• Nanotechnology

Background:

• Gas adsorption in porous materials is crucial for storage and separation.
• Porous coordination cages are underexplored for gas adsorption despite their potential.
• Surface area data is often missing for these molecular systems.

Purpose of the Study:

• To synthesize and characterize novel carbazole-based porous coordination cages.
• To investigate their gas adsorption properties, particularly methane uptake.
• To establish new benchmarks for surface area in coordination cages.

Main Methods:

• Synthesis and characterization of carbazole-based coordination cages.
• Activation protocols to achieve high surface areas.
• Gas adsorption measurements (Brunauer-Emmett-Teller - BET) at high pressure.
• Powder neutron diffraction for pore structure analysis.

Main Results:

• A chromium analog achieved a record BET surface area of 1235 m²/g.
• Optimized synthesis and activation yielded high surface areas for multiple cages.
• The chromium(II) cage showed significant methane (CH₄) adsorption capacities (194 cm³/g and 148 cm³/cm³ at 65 bar).

Conclusions:

• Carbazole-based porous coordination cages are promising for gas storage applications.
• Precise control over synthesis and activation is key to maximizing surface area and adsorption.
• Optimal pore design in these cages leads to high methane uptake.