A Temporarily Pore-Openable Porous Coordination Polymer for Guest Adsorption/Desorption

Area of Science:

• Materials Science
• Supramolecular Chemistry
• Crystallography

Background:

• Flexible porous coordination polymers (PCPs) are advanced materials with potential in separation, sensing, and actuation.
• Typically, PCPs undergo significant structural changes upon guest molecule interaction.
• Understanding PCP flexibility is crucial for optimizing their performance.

Purpose of the Study:

• To investigate the structural flexibility and guest interaction of a novel one-dimensional PCP.
• To explore the adsorption/desorption properties of the PCP with ethyl acetate and carbon dioxide.
• To characterize a unique temporary pore-opening mechanism in flexible PCPs.

Main Methods:

• Single-crystal X-ray diffraction was used to analyze the crystal structures.
• The study involved desolvated, ethyl acetate-loaded, and CO2-loaded forms of the PCP.
• Gas adsorption/desorption isotherms were measured to understand guest interactions.

Main Results:

• A rare one-dimensional PCP, [Cu2(bza)4(2-apyr)] (1), was synthesized and characterized.
• The PCP exhibits temporary pore opening, a unique flexibility mechanism.
• Isolated pores in (1) prevent guest penetration, while loaded structures block guest release.
• Reversible adsorption/desorption of ethyl acetate and CO2 was observed due to temporary pore opening.
• CO2 adsorption/desorption isotherms showed a Type I behavior, differing from typical flexible PCPs.

Conclusions:

• The discovered PCP demonstrates a novel, temporary pore-opening flexibility.
• This unique mechanism facilitates reversible guest molecule uptake and release.
• The findings provide new perspectives for designing flexible PCPs with tailored properties.