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Control over the spatial distribution of components in metal-organic frameworks has potential to unlock improved performance and new behaviour in separations, sensing and catalysis. We report an unprecedented single-step synthesis of multi-component metal-organic framework (MOF) nanoparticles based on the canonical ZIF-8 (Zn) system and its Cd analogue, which form with a core-shell structure whose internal interface can be systematically tuned. We use scanning transmission electron microscopy, X-ray energy dispersive spectroscopy and a new composition gradient model to fit high-resolution X-ray diffraction data to show how core-shell composition and interface characteristics are intricately controlled by synthesis temperature and reaction composition. Particle formation is investigated by in situ X-ray diffraction, which reveals that the spatial distribution of components evolves with time and is determined by the interplay of phase stability, crystallisation kinetics and diffusion. This work opens up new possibilities for the control and characterisation of functionality, component distribution and interfaces in MOF-based materials.

Deoxyfluorination is a primary method for the formation of C−F bonds. Bespoke reagents are commonly used because of issues associated with the low reactivity of metal fluorides. Reported here is the development of a simple strategy for deoxyfluorination, using first‐row transition‐metal fluorides, and it overcomes these limitations. Using CuF2 as an exemplar, activation of an O‐alkylisourea adduct, formed in situ, allows effective nucleophilic fluoride transfer to a range of primary and secondary alcohols. Spectroscopic investigations have been used to probe the origin of the enhanced reactivity of CuF2. The utility of the process in enabling 18F‐radiolabeling is also presented.

We thank the University of St Andrews for PhD studentships (D.E.S and S.C.), GlaxoSmithKline and the University of Glasgow for financial support. Deoxyfluorination is a primary method for the formation of C–F bonds. Bespoke reagents are commonly used due to issues associated with the low reactivity of metal fluorides. Here, we report the development of a simple strategy for deoxyfluorination using first‐row transition metal fluorides that overcomes these limitations. Using CuF2 as an exemplar, activation of an O ‐alkylisourea adduct formed in situ allows effective nucleophilic fluoride transfer to a range of primary and secondary alcohols. Spectroscopic investigations have been used to probe the origin of the enhanced reactivity of CuF2 . The utility of the process towards enabling 18F‐radiolabeling is also presented. Postprint

Investigation of the conditions required for quantitative isotopic enrichment and the acquisition of quantitative 17O NMR spectra of ceramic oxides., The potential of 17O NMR spectroscopy for the investigation of A2B2O7 ceramic oxides important in the encapsulation of radioactive waste is demonstrated, with post-synthetic enrichment by exchange with 17O2 gas. For Y2Sn2O7, Y2Ti2O7 and La2Sn2O7 pyrochlores, enrichment of the two distinct O species is clearly non quantitative at lower temperatures (∼700 °C and below) and at shorter times, despite these being used in prior work, with preferential enrichment of OA2B2 favoured over that of OA4. At higher temperatures, the 17O NMR spectra suggest that quantitative enrichment has been achieved, but the integrated signal intensities do not reflect the crystallographic 1 : 6 (O1 : O2) ratio until corrected for differences in T1 relaxation rates and, more importantly, the contribution of the satellite transitions. 17O NMR spectra of Y2Zr2O7 and Y2Hf2O7 defect fluorites showed little difference with any variation in enrichment temperature or time, although an increase in the absolute level of enrichment (up to ∼7.5%) was observed at higher temperature. DFT calculations show that the six distinct resonances observed cannot be assigned unambiguously, as each has contributions from more than one of the five possible next nearest neighbour environments. For La2Ti2O7, which adopts a layered perovskite-like structure, little difference in the spectral intensities is observed with enrichment time or temperature, although the highest absolute levels of enrichment (∼13%) were obtained at higher temperature. This work demonstrates that 17O NMR has the potential to be a powerful probe of local structure and disorder in oxides, but that considerable care must be taken both in choosing the conditions for 17O enrichment and the experimental acquisition parameters if the necessary quantitative measurements are to be obtained for more complex systems.

We would like to thank the ERC (EU FP7 Consolidator Grant 614290 “EXONMR”), the Leverhulme Trust (IN-2012-094), and EPSRC (EP/K025112/1, EP/L014475/1, and EP/M506631/1 (for GPMB)). S.E.A. would like to thank the Royal Society and the Wolfson Foundation for a merit award. The research data (and/or materials) supporting this publication can be accessed at DOI: 10.17630/d66d1146-5892-4f14-8e41-dfc075a8cd91. 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. Publisher PDF