Ball-Milling-Induced Amorphization of Zeolitic Imidazolate Frameworks (ZIFs) for the Irreversible Trapping of Iodine
T D Bennett, P J Saines, D A Keen, J-C Tan, and A K Cheeham
Chem Eur J 19, 7049-7055 (2013)
The I2-sorption and -retention properties of several existing zeolitic imidazolate frameworks (ZIF-4, -8, -69) and a novel framework, ZIF-mnIm ([Zn(mnIm)2]; mnIm=4-methyl-5-nitroimidazolate), have been characterised using microanalysis, thermogravimetric analysis and X-ray diffraction. The topologically identical ZIF-8 ([Zn(mIm)2]; mIm=2-methylimidazolate) and ZIF-mnIm display similar sorption abilities, though strikingly different guest-retention behaviour upon heating. We discover that this guest retention is greatly enhanced upon facile amorphisation by ball milling, particularly in the case of ZIF-mnIm, for which I2 loss is retarded by as much as 200 °C. It is anticipated that this general approach should be applicable to the wide range of available metal–organic framework-type materials for the permanent storage of harmful guest species.