High-pressure studies of metal organic framework materials

Comparison of the variable temperature X-ray diffraction (form I (298 K), form II (453 K)) and variable pressure powder neutron diffraction patterns. Note the peak intensities for the two different measurements are not comparable, but the peak positions are, as they depend solely on the unit cell dimensions. Reprinted with permission from [93]. Copyright 2009 American Chemical Society. 

15 High-pressure studies of metal organic framework materials 

In this case history, we tell a story that involves the use of two standard structural chemistry techniques, but applied under extreme conditions, to investigate what happens when a highly porous crystalline material is subjected to very high pressures. 

Representation of the porous structure of MOF-5, [Zri40(bdc)3] (bdc = 1,4-benzenedicarboxylate). The Zn40(C02)6 units are represented by tetrahedra, while the large sphere represents the largest availahle pore space in the crystal 

It turns out that compressing MOF materials to very high pressures gives results that are much more significant than just academic curiosity. Similar experiments performed on the zeolitic imidazolate framework known as ZIF-8 [(Zn(meim)2], meim = 2-methylimidazolate again show expansion at modest pressures as the PTM is squeezed into the cavities, but at 1.5 GPa the material undergoes a phase transition 

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