Pore-Opening of Zeolitic Imidazolate Framework COK-17 under Nitrogen Pressure: Study Using Inelastic Neutron Scattering

Flexible Zeolitic Imidazolate Frameworks (ZIF) are unique in a sense that their pore aperture can be regulated using the applied gas pressure. Utilizing this phenomenon, a single ZIF can be used selective for different gases depending on the applied gas pressure and gas-type. In order to understand the flexibility of ZIFs at molecular level, different techniques are being utilized. Inelastic neutron scattering has shown that linker rotation under gas pressure causes the pore-aperture opening in methylimidazolate based frameworks. On the other hand, X-ray diffraction based studies have shown that lattice deformation under gas pressure cause the pore-aperture tuning. In this regard, we propose to investigate the flexibility of a recently reported ZIF i.e. COK-17 using INS under N2 gas pressure. The COK-17 has shown very high gas separation selectivity attributed to its pore-aperture tuning under gas pressure.