Cost-effective 17O enrichment of metal–organic frameworks enables the composition and disorder in mixed-metal materials to be determined using NMR spectroscopy.

The great utility and importance of zeolites in fields as diverse as industrial catalysis and medicine has driven considerable interest in the ability to target new framework types with novel properties and applications. The recently introduced and unconventional assembly, disassembly, organization, reassembly (ADOR) method represents one exciting new approach to obtain solids with targeted structures by selectively disassembling preprepared hydrolytically unstable frameworks and then reassembling the resulting products to form materials with new topologies. However, the hydrolytic mechanisms underlying such a powerful synthetic method are not understood in detail, requiring further investigation of the kinetic behavior and the outcome of reactions under differing conditions. In this work, we report the optimized ADOR synthesis, and subsequent solid-state characterization, of 17O- and doubly 17O- and 29Si-enriched UTL-derived zeolites, by synthesis of 29Si-enriched starting Ge-UTL frameworks and incorporation of 17O from 17O-enriched water during hydrolysis. 17O and 29Si NMR experiments are able to demonstrate that the hydrolysis and rearrangement process occurs over a much longer time scale than seen by diffraction. The observation of unexpectedly high levels of 17O in the bulk zeolitic layers, rather than being confined only to the interlayer spacing, reveals a much more extensive hydrolytic rearrangement than previously thought. This work sheds new light on the role played by water in the ADOR process and provides insight into the detailed mechanism of the structural changes involved.

The Assembly-Disassembly-Organisation-Reassembly (ADOR) mechanism is a recent method for preparing inorganic framework materials and, in particular, zeolites. This flexible approach has enabled the synthesis of isoreticular families of zeolites with unprecedented continuous control over porosity, and the design and preparation of materials that would have been difficult -or even impossible -to obtain using traditional hydrothermal techniques. Applying the ADOR process to a parent zeolite with the UTL framework topology, for example, has led to six previously unknown zeolites (named IPC-n with n = 2, 4, 6, 7, 9 and 10). To realize the full potential of the ADOR method, however, a further understanding of the complex mechanism at play is needed. Here, we probe the disassembly, organisation and reassembly steps of the ADOR process through a combination of in situ solid-state nuclear magnetic resonance (NMR) spectroscopy and powder Xray diffraction (PXRD) experiments. We further use the insight gained to explain the formation of the intriguing structure of zeolite IPC-6.The recently-discovered ADOR process 1-4 has proved to be effective for the preparation of new silicate and aluminosilicate zeolites, providing routes to 'unfeasible' synthesis targets with novel structural features 3 and to families of isoreticular solids whose pore size can be precisely controlled over the whole range of zeolite porosity, from small pore all the way up to extra-large pore materials. 1,4 The process comprises four distinct steps. The assembly (A) process involves the preparation of a parent zeolite with suitable chemical and topological properties for

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.