Synthesis, isotopic enrichment and solid-state NMR characterization of zeolites derived from the assembly, disassembly, organisation, reassembly process

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 PDFPeer reviewe

Calculation and experimental measurement of paramagnetic NMR parameters of phenolic oximate Cu(II) complexes

This work was supported by the EPSRC through the Collaborative Computational Project on NMR Crystallography (CCP-NC), via EP/M022501/1. SEA would also like to thank the Royal Society and Wolfson Foundation for a merit award. MB would like to thank EaStCHEM and the School of Chemistry for support and access to a computer cluster maintained by Dr. H. Früchtl. ZK gratefully acknowledges a scholarship from the China Scholarship Council. For research data supporting this publication see DOI: http://dx.doi.org/10.17630/9061ace0-88fb-4a55-a1eb-05e020f369fd.We present a strategy for predicting the unusual 1H and 13C shifts in NMR spectra of paramagnetic bisoximato copper(II) complexes using DFT. We demonstrate good agreement with experimental measurements, although 1H-13C correlation spectra show that a combined experimental and theoretical approach remains necessary for full assignment.PostprintPostprintPeer reviewe

A procedure for identifying possible products in the Assembly-Disassembly-Organisation-Reassembly (ADOR) synthesis of zeolites

The authors would like to thank the EPSRC (grants: EP/K025112/1; EP/K005499/1; EP/K503162/1; EP/N509759/1) for funding opportunities. R.E.M., J.C. and M.M. would like to acknowledge OP VVV "Excellent Research Teams", project No. CZ.02.1.01/0.0/0.0/15_003/0000417 - CUCAM. S.E.A. would like to thank the Royal Society and the Wolfson Foundation for a merit award. J.C. acknowledges the Czech Science Foundation (P106/12/G015).High-silica zeolites, some of the most important and widely used catalysts in industry, have potential for application across a wide range of traditional and emerging technologies. The many structural topologies of zeolites have a variety of potential uses, so a strong drive to create new zeolites exists. Here, we present a protocol, the assembly–disassembly–organization–reassembly (ADOR) process, for a relatively new method of preparing these important solids. It allows the synthesis of new high-silica zeolites (Si/Al >1,000), whose synthesis is considered infeasible with traditional (solvothermal) methods, offering new topologies that may find novel applications. We show how to identify the optimal conditions (e.g., duration of reaction, temperature, acidity) for ADOR, which is a complex process with different possible outcomes. Following the protocol will allow researchers to identify the different products that are possible from a reaction without recourse to repetitive and time-consuming trial and error. In developing the protocol, germanium-containing UTL zeolites were subjected to hydrolysis conditions using both water and hydrochloric acid as media, which provides an understanding of the effects of temperature and pH on the disassembly (D) and organization (O) steps of the process that define the potential products. Samples were taken from the ongoing reaction periodically over a minimum of 8 h, and each sample was analyzed using powder X-ray diffraction to yield a time course for the reaction at each set of conditions; selected samples were analyzed using transmission electron microscopy and solid-state NMR spectroscopy.PostprintPeer reviewe

In situ solid-state NMR and XRD studies of the ADOR process and the unusual structure of zeolite IPC-6

R.E.M. and M.N. thank the Royal Society and the E.P.S.R.C. (Grants EP/L014475/1, EP/K025112/1 and EP/K005499/1) for funding work in this area. R.E.M. and J.Č. acknowledge the Czech Science Foundation for the project P106/12/G015 and OP VVV "Excellent Research Teams", project No. CZ.02.1.01/0.0/0.0/15_003/0000417 - CUCAM. S.E.A. would like to thank the ERC (EU FP7 Consolidator Grant 614290 “EXONMR”) and the Royal Society and Wolfson Foundation for a merit award. The UK 850 MHz solid-state NMR Facility used in this research was funded by EPSRC and BBSRC (contract reference PR140003), as well as the University of Warwick including via part funding through Birmingham Science City Advanced Materials Projects 1 and 2 supported by Advantage West Midlands (AWM) and the European Regional Development Fund (ERDF). W.A.S. and D.S.W. acknowledge the Research Council of Norway and NOTUR are acknowledged for providing the computer time at the Norwegian supercomputer facilities (under the project number NN2875k).The assembly–disassembly–organization–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, where 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, organization and reassembly steps of the ADOR process through a combination of in situ solid-state NMR spectroscopy and powder X-ray diffraction experiments. We further use the insight gained to explain the formation of the unusual structure of zeolite IPC-6.PostprintPeer reviewe

17O solid-state NMR spectroscopy of A2B2O7 oxides : quantitative isotopic enrichment and spectral acquisition?

We would like to thank the ERC (EU FP7 Consolidator Grant 614290 “EXONMR”) and EPSRC (EP/L505079/1, EP/M506631/1, EP/L005581/2 and EP/K031511/1). SEA would also like to thank the Royal Society and Wolfson Foundation for a merit award. The UK 850 MHz solid-state NMR Facility used in this research was funded by EPSRC and BBSRC (contract reference PR140003), as well as the University of Warwick including via part funding through Birmingham Science City Advanced Materials Projects 1 and 2 supported by Advantage West Midlands (AWM) and the European Regional Development Fund (ERDF). Collaborative assistance from the 850 MHz Facility Manager (Dinu Iuga, University of Warwick) is acknowledged. The research data (and/or materials) supporting this publication can be accessed at DOI: 10.17630/843cd0a1-4963-45f6-9285-10bf32c84c8d. Accepted 06/02/2018The 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.Publisher PDFPeer reviewe

Synthesis, Isotopic Enrichment, and Solid-State NMR Characterization of Zeolites Derived from the Assembly, Disassembly, Organization, Reassembly Process

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