Microporous materials, containing pores and channels of similar dimensions to small molecules have a range of applications in catalysis, gas storage and separation and in drug delivery. Their complex structure,...

Aluminosilicate zeolites are traditionally used in high-temperature applications at low water vapour pressures where the zeolite framework is generally considered to be stable and static. Increasingly, zeolites are being considered for applications under milder aqueous conditions. However, it has not yet been established how neutral liquid water at mild conditions affects the stability of the zeolite framework. Here, we show that covalent bonds in the zeolite chabazite (CHA) are labile when in contact with neutral liquid water, which leads to partial but fully reversible hydrolysis without framework degradation. We present ab initio calculations that predict novel, energetically viable reaction mechanisms by which Al-O and Si-O bonds rapidly and reversibly break at 300 K. By means of solid-state NMR, we confirm this prediction, demonstrating that isotopic substitution of 17O in the zeolitic framework occurs at room temperature in less than one hour of contact with enriched water.

Mixed-metal (Al,Ga)-MIL-53 materials were synthesised and enriched in ¹⁷O. An NMR crystallographic approach reveals the cation distribution on the atomic level, and the effect of this on the breathing behaviour of the framework.