Programming local confinements in crystalline frameworks through reticular chemistry

Area of Science:

• Materials Science
• Chemistry
• Nanotechnology

Background:

• Controlling chemical environments in porous materials is crucial for adsorption and catalysis.
• Achieving precise control over functional sites within stable frameworks remains a challenge.

Purpose of the Study:

• To develop a strategy for programming tunable confinement in porous crystalline materials.
• To create novel metal-organic frameworks (MOFs) for selective chemical applications, specifically CO2 capture.

Main Methods:

• Utilized reticular chemistry to construct triazolate MOFs from specific zinc nodes.
• Employed linker geometry to direct the formation of the ith-d topology, creating inward-pointing functional groups.
• Performed post-synthetic modification (chloride-to-hydroxide exchange) to introduce reactive sites.

Main Results:

• Synthesized two isoreticular MOFs, NU-6000 and NU-6001, with varying pore sizes but identical topology.
• Demonstrated reversible CO2 chemisorption via bicarbonate formation facilitated by Zn-OH groups.
• Observed confinement effects limiting site accessibility in NU-6000, leading to high CO2 capture efficiency at low concentrations (30 ppm) and high site utilization (61.4% at 420 ppm).

Conclusions:

• Reticular chemistry offers a viable route to engineer confined chemical environments within MOFs.
• The developed MOFs exhibit exceptional performance for low-pressure CO2 capture due to programmed confinement.
• This strategy provides a pathway for designing advanced materials for selective gas adsorption and catalysis.