Structuration of Water in Microporous CAU-10-H under Gigapascal Pressure

Area of Science:

• Materials Science
• Chemistry
• Crystallography

Background:

• Metal-organic frameworks (MOFs) are increasingly explored as water adsorbents.
• Aluminum isophthalate (CAU-10-H) offers high stability, making it suitable for sorption-based heat exchange.
• Understanding MOF behavior under mechanical stress is crucial for material design.

Purpose of the Study:

• To investigate pressure-induced structural changes in CAU-10-H.
• To quantify water uptake and release in CAU-10-H under gigapascal pressures.
• To elucidate the interplay between water molecules and the MOF structure under pressure.

Main Methods:

• High-pressure X-ray diffraction studies on CAU-10-H immersed in water.
• Analysis of structural phase transitions and unit cell volume changes up to 4.08 GPa.
• Quantification of water content within the MOF structure at different pressure points.

Main Results:

• CAU-10-H undergoes four distinct phase transitions between ambient pressure and 4.08 GPa.
• Water content increases significantly with pressure, accompanied by reversible structural changes and gate-opening/closing mechanisms.
• The material fully recovers its initial crystallinity and water content upon pressure release.

Conclusions:

• CAU-10-H exhibits remarkable pressure-modulated water adsorption and desorption capabilities.
• The observed reversible structural transformations highlight the potential for using pressure as a stimulus for MOF-based applications.
• Findings provide a foundation for designing novel MOFs with tunable properties for water management and chemical modifications.