Metal-organic frameworks (MOFs) have been investigated for several years for their potential as catalysts and gas storage materials because many have very large internal surface areas. However, their piezo-functional properties are now coming to the fore with the discovery that applied pressure distorts, but does not break, their internal structure.

Researchers at Texas A&M University and Berkeley Lab, both USA, have demonstrated that an energy-absorbing cushioning effect occurs when the zinc-containing MOF known as ZAG-4 is put under pressure. The team has shown that the flexible alkyl chain in the organic ligands of ZAG-4 allows the structure to deform under a pressure up to almost 10 Pascals without being destroyed.

Springy MOF compounds might one day find applications in highly sensitive pressure sensors, shock-absorbing materials, pressure switches, or smart body armor.

• MOFs Under Pressure: The Reversible Compression of a Single Crystal,
  Kevin J. Gagnon, Christine M. Beavers, Abraham Clearfield,
  J. Am. Chem. Soc. 2013.
  DOI: 10.1021/ja311613p