Water Resistant Metal-Organic Frameworks


The construction of nanoporous metal-organic frameworks (MOF) by copolymerization of organic molecules with metal ions has received widespread attention in recent years. These materials are thermally robust and, in many cases, have high porosity. However, recent experiments have shown that some MOFs are not stable when exposed to >4% water, limiting their usefulness.

Coordination bonding overcomes this limitation, requires mild conditions to create frameworks, and brings myriad choices of building blocks. Trifluoromethoxy group, which has been proved on most water repellent polymers and coating materials, reduces the water damage on MOF structures. A water resistant MOF, namely, ZnMOF3 is obtained through both solvothermal synthesis and microwave assisted solvothermal synthesis. It has a comparable vapor adsorbtion capacity with the commonly used MOFs, but does not adsorb moisture at 70 C.

In addition, exposing ZnMOF3 to boiling water vapor for one week does not result in any dramatic X-ray powder pattern change. ZnMOF3 is a potential adsorbent in many industrial applications such as air adsorption.