Flexible Zirconium Metal-Organic Frameworks as Bioinspired Switchable Catalysts

Area of Science:

• Materials Science
• Catalysis
• Supramolecular Chemistry

Background:

• Flexible metal-organic frameworks (MOFs) offer diverse structures and stimuli-responsive pores for host-guest chemistry.
• Developing MOFs with tunable properties is crucial for advanced applications like switchable catalysis.

Purpose of the Study:

• To design and investigate a flexible zirconium-based MOF (Zr-MOF) system, the PCN-700 series, for switchable catalysis.
• To explore the modulation of breathing behavior in PCN-700 through linker modification.
• To demonstrate the on/off switching of catalytic activity in response to structural transformations.

Main Methods:

• Design and synthesis of the PCN-700 series of flexible Zr-MOFs.
• Characterization using successive single-crystal X-ray diffraction to study breathing behaviors.
• Modulation of pore size and flexibility via pre-functionalization and post-synthetic linker installation.
• Catalytic testing in cycloaddition reactions of CO2 with epoxides.
• Computational molecular simulations to understand structure-activity relationships.

Main Results:

• The PCN-700 series exhibits significant breathing behavior, with amplitudes tunable by linker modification.
• Catalytic activity for CO2 cycloaddition with epoxides was successfully switched on and off.
• Reversible structural transformations directly correlate with the observed switchable catalytic performance.
• The MOF's responsive behavior mimics allosteric regulation found in biological enzymes.

Conclusions:

• The PCN-700 series represents a novel flexible Zr-MOF system capable of switchable catalysis.
• Tunable breathing of MOFs is an effective strategy for controlling catalytic activity.
• This work provides a platform for designing responsive catalytic materials inspired by biological systems.