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González-Camuñas N, Cantín Á, Dawson DM, Lozinska MM, Martínez-Triguero J, Mattock J, Cox PA, Ashbrook SE, Wright PA, Rey F. Synthesis of the large pore aluminophosphate STA-1 and its application as a catalyst for the Beckmann rearrangement of cyclohexanone oxime. JOURNAL OF MATERIALS CHEMISTRY. A 2024; 12:15398-15411. [PMID: 38933527 PMCID: PMC11197783 DOI: 10.1039/d4ta01132e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/19/2024] [Accepted: 05/04/2024] [Indexed: 06/28/2024]
Abstract
The preparation of stable large pore aluminophosphate (AlPO) zeotypes offers materials for applications in adsorption and catalysis. Here we report the synthesis of the pure AlPO with the SAO topology type (AlPO STA-1) using N,N'-diethylbicyclo[2.2.2]oct-7-ene-2,3:5,6-dipyrrolidine (DEBOP) as the organic structure directing agent in the presence of fluoride. The AlPO STA-1 can be rendered microporous (pore volume 0.36 cm3 g-1) via calcination and the calcined form remains stable in the presence of moisture. The structure of the dehydrated form has been established by Rietveld refinement (tetragonal P4̄n2, a = 13.74317(10) Å, c = 21.8131(5) Å, V = 4119.94(16) Å3). Multinuclear 27Al and 31P MAS NMR, together with 2D COSY and CASTEP NMR calculations, enables resolution and assignment of the signals from all crystallographically distinct Al and P framework sites. Structural elucidation of the as-prepared aluminophosphate-fluoride is more challenging, because of the presence of partially protonated OSDA molecules in the 3D-connected channel system and in particular because the fluoride ions coordinate with positional disorder to some of the Al atoms to give 5-fold as well as tetrahedrally-coordinated framework Al species. These are postulated to occupy Al-F-Al bridging sites, where they are responsible for distortion of the framework [P4̄n2, a = 13.3148(9) Å, c = 22.0655(20) Å, V = 3911.9(7) Å3]. Calcination and removal of fluoride ions and OSDAs allows the framework to expand to its relaxed configuration. The SAO topology type aluminophosphate can also be synthesised with small amounts of Si and Ge in the framework, and these SAPO and GeAPO STA-1 materials are also stable to template removal. IR spectroscopy with CO as a probe at 123 K indicates all have weak-to-mild acidity, increasing in the order AlPO < GeAPO < SAPO. These STA-1 materials have been investigated for their activity in the Beckmann rearrangement of cyclohexanone oxime to ε-caprolactam at 598 K: while all are active, the AlPO form is favoured due to its high selectivity and slow deactivation, both of which are a consequence of its very weak acid strength, which is nevertheless sufficient to catalyse the reaction.
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Affiliation(s)
- Nuria González-Camuñas
- Instituto de Tecnología Química (ITQ), Universitat Politècnica de València (UPV) - Consejo Superior de Investigaciones Científicas (CSIC) 46022 Valencia Spain
- Instituto de Tecnología Cerámica, Universidad Jaume I Campus Universitario Riu Sec, Avda. Vicente Sos Baynat s/n 12006 Castellón Spain
| | - Ángel Cantín
- Instituto de Tecnología Química (ITQ), Universitat Politècnica de València (UPV) - Consejo Superior de Investigaciones Científicas (CSIC) 46022 Valencia Spain
| | - Daniel M Dawson
- EaStCHEM School of Chemistry, University of St Andrews Purdie Building, St Andrews KY16 9ST UK
| | - Magdalena M Lozinska
- EaStCHEM School of Chemistry, University of St Andrews Purdie Building, St Andrews KY16 9ST UK
| | - Joaquín Martínez-Triguero
- Instituto de Tecnología Química (ITQ), Universitat Politècnica de València (UPV) - Consejo Superior de Investigaciones Científicas (CSIC) 46022 Valencia Spain
| | - James Mattock
- School of Pharmacy and Biomedical Sciences, University of Portsmouth Portsmouth PO1 2DT UK
| | - Paul A Cox
- School of Pharmacy and Biomedical Sciences, University of Portsmouth Portsmouth PO1 2DT UK
| | - Sharon E Ashbrook
- EaStCHEM School of Chemistry, University of St Andrews Purdie Building, St Andrews KY16 9ST UK
| | - Paul A Wright
- EaStCHEM School of Chemistry, University of St Andrews Purdie Building, St Andrews KY16 9ST UK
| | - Fernando Rey
- Instituto de Tecnología Química (ITQ), Universitat Politècnica de València (UPV) - Consejo Superior de Investigaciones Científicas (CSIC) 46022 Valencia Spain
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Ashbrook SE, Dawson DM, Gan Z, Hooper JE, Hung I, Macfarlane LE, McKay D, McLeod LK, Walton RI. Application of NMR Crystallography to Highly Disordered Templated Materials: Extensive Local Structural Disorder in the Gallophosphate GaPO-34A. Inorg Chem 2020; 59:11616-11626. [PMID: 32799506 DOI: 10.1021/acs.inorgchem.0c01450] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
We present an NMR crystallographic investigation of two as-made forms of the recently characterized gallophosphate GaPO-34A, which has an unusual framework composition with a Ga:P ratio of 7:6 and contains both hydroxide and fluoride anions and either 1-methylimidazolium or pyridinium as the structure-directing agent. We combine previously reported X-ray crystallographic data with solid-state NMR spectroscopy and periodic density functional theory (DFT) calculations to show that the structure contains at least three distinct types of disorder (occupational, compositional, and dynamic). The occupational disorder arises from the presence of six anion sites per unit cell, but a total occupancy of five of these, leading to full occupancy of four sites and partial occupancy of the fifth and sixth (which are related by symmetry). The mixture of OH and F present leads to compositional disorder on the occupied anion sites, although the occupancy of some sites by F is calculated to be energetically unfavorable and signals relating to F on these sites are not observed by NMR spectroscopy, confirming that the compositional disorder is not random. Finally, a combination of high-field 71Ga NMR spectroscopy and variable-temperature 13C and 31P NMR experiments shows that the structure directing agents are dynamic on the microsecond time scale, which can be supported by averaging the 31P chemical shifts calculated with the SDA in different orientations. This demonstrates the value of an NMR crystallographic approach, particularly in the case of highly disordered crystalline materials, where the growth of large single crystals for conventional structure determination may not be possible owing to the extent of disorder present.
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Affiliation(s)
- Sharon E Ashbrook
- School of Chemistry, EaStCHEM and Centre of Magnetic Resonance, University of St Andrews, North Haugh, St Andrews, Fife KY16 9ST, United Kingdom
| | - Daniel M Dawson
- School of Chemistry, EaStCHEM and Centre of Magnetic Resonance, University of St Andrews, North Haugh, St Andrews, Fife KY16 9ST, United Kingdom
| | - Zhehong Gan
- Center of Interdisciplinary Magnetic Resonance, National High Magnetic Field Laboratory, 1800 East Paul Dirac Drive, Tallahassee, Florida 32310, United States
| | - Joseph E Hooper
- School of Chemistry, EaStCHEM and Centre of Magnetic Resonance, University of St Andrews, North Haugh, St Andrews, Fife KY16 9ST, United Kingdom
| | - Ivan Hung
- Center of Interdisciplinary Magnetic Resonance, National High Magnetic Field Laboratory, 1800 East Paul Dirac Drive, Tallahassee, Florida 32310, United States
| | - Laurie E Macfarlane
- School of Chemistry, EaStCHEM and Centre of Magnetic Resonance, University of St Andrews, North Haugh, St Andrews, Fife KY16 9ST, United Kingdom
| | - David McKay
- School of Chemistry, EaStCHEM and Centre of Magnetic Resonance, University of St Andrews, North Haugh, St Andrews, Fife KY16 9ST, United Kingdom
| | - Lucy K McLeod
- Department of Chemistry, University of Warwick, Coventry CV4 7AL, United Kingdom
| | - Richard I Walton
- Department of Chemistry, University of Warwick, Coventry CV4 7AL, United Kingdom
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Dawson DM, Moran RF, Sneddon S, Ashbrook SE. Is the 31 P chemical shift anisotropy of aluminophosphates a useful parameter for NMR crystallography? MAGNETIC RESONANCE IN CHEMISTRY : MRC 2019; 57:176-190. [PMID: 30105879 DOI: 10.1002/mrc.4788] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2018] [Revised: 08/01/2018] [Accepted: 08/06/2018] [Indexed: 05/12/2023]
Abstract
The 31 P chemical shift anisotropy (CSA) offers a potential source of new information to help determine the structures of aluminophosphate (AlPO) framework materials. We investigate how to measure the CSAs, which are small (span of ~20-30 ppm) for AlPOs, demonstrating the need for CSA-amplification experiments (often in conjunction with 27 Al and/or 1 H decoupling) at high magnetic field (20.0 T) to obtain accurate values. We show that the most shielded component of the chemical shift tensor, δ33 , is related to the length of the shortest P─O bond, whereas the more deshielded components, δ11 and δ22 can be related more readily to the mean P─O bond lengths and P─O─Al angles. Using the case of Mg-doped STA-2 as an example, the CSA is shown to be much larger for P(OAl)4-n (OMg)n environments, primarily owing to a much shorter P─O(Mg) bond affecting δ33 , however, because the mean P─O bond lengths and P─O─T (T = Al, Mg) bond angles do not change significantly between P(OAl)4 and P(OAl)4-n (OMg)n sites, the isotropic chemical shifts for these species are similar, leading to overlapped spectral lines. When the CSA information is included, spectral assignment becomes unambiguous, therefore, although the specialist conditions required might preclude the routine measurement of 31 P CSAs in AlPOs, in some cases (particularly doped materials), the experiments can still provide valuable additional information for spectral assignment.
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Affiliation(s)
- Daniel M Dawson
- School of Chemistry, EaStCHEM and Centre of Magnetic Resonance, University of St Andrews, St Andrews, UK
| | - Robert F Moran
- School of Chemistry, EaStCHEM and Centre of Magnetic Resonance, University of St Andrews, St Andrews, UK
| | - Scott Sneddon
- School of Chemistry, EaStCHEM and Centre of Magnetic Resonance, University of St Andrews, St Andrews, UK
| | - Sharon E Ashbrook
- School of Chemistry, EaStCHEM and Centre of Magnetic Resonance, University of St Andrews, St Andrews, UK
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Unuabonah EI, Nöske R, Weber J, Günter C, Taubert A. New micro/mesoporous nanocomposite material from low-cost sources for the efficient removal of aromatic and pathogenic pollutants from water. BEILSTEIN JOURNAL OF NANOTECHNOLOGY 2019; 10:119-131. [PMID: 30680284 PMCID: PMC6334806 DOI: 10.3762/bjnano.10.11] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/13/2018] [Accepted: 12/19/2018] [Indexed: 06/09/2023]
Abstract
A new micro/mesoporous hybrid clay nanocomposite prepared from kaolinite clay, Carica papaya seeds, and ZnCl2 via calcination in an inert atmosphere is presented. Regardless of the synthesis temperature, the specific surface area of the nanocomposite material is between ≈150 and 300 m2/g. The material contains both micro- and mesopores in roughly equal amounts. X-ray diffraction, infrared spectroscopy, and solid-state nuclear magnetic resonance spectroscopy suggest the formation of several new bonds in the materials upon reaction of the precursors, thus confirming the formation of a new hybrid material. Thermogravimetric analysis/differential thermal analysis and elemental analysis confirm the presence of carbonaceous matter. The new composite is stable up to 900 °C and is an efficient adsorbent for the removal of a water micropollutant, 4-nitrophenol, and a pathogen, E. coli, from an aqueous medium, suggesting applications in water remediation are feasible.
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Affiliation(s)
- Emmanuel I Unuabonah
- Environmental and Chemical Processes Research Laboratory, Centre for Chemical and Biochemical Research, Redeemer’s University, PMB 230, Ede, Osun State, Nigeria
- Department of Chemical Sciences, Redeemer’s University, PMB 230, Ede, Osun State, Nigeria
- Institute of Chemistry, University of Potsdam, 14476 Potsdam, Germany
- State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, 116023, China
| | - Robert Nöske
- Institute of Chemistry, University of Potsdam, 14476 Potsdam, Germany
| | - Jens Weber
- Department of Chemistry, Hochschule Zittau/Görlitz (University of Applied Science), Theodor-Körner-Allee 16, 02763 Zittau, Germany
| | - Christina Günter
- Department of Earth and Environmental Science, University of Potsdam, 14476 Potsdam, Germany
| | - Andreas Taubert
- Institute of Chemistry, University of Potsdam, 14476 Potsdam, Germany
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Ashbrook SE, Griffin JM, Johnston KE. Recent Advances in Solid-State Nuclear Magnetic Resonance Spectroscopy. ANNUAL REVIEW OF ANALYTICAL CHEMISTRY (PALO ALTO, CALIF.) 2018; 11:485-508. [PMID: 29324182 DOI: 10.1146/annurev-anchem-061417-125852] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
The sensitivity of nuclear magnetic resonance (NMR) spectroscopy to the local atomic-scale environment offers great potential for the characterization of a diverse range of solid materials. Despite offering more information than its solution-state counterpart, solid-state NMR has not yet achieved a similar level of recognition, owing to the anisotropic interactions that broaden the spectral lines and hinder the extraction of structural information. Here, we describe the methods available to improve the resolution of solid-state NMR spectra and the continuing research in this area. We also highlight areas of exciting new and future development, including recent interest in combining experiment with theoretical calculations, the rise of a range of polarization transfer techniques that provide significant sensitivity enhancements, and the progress of in situ measurements. We demonstrate the detailed information available when studying dynamic and disordered solids and discuss the future applications of solid-state NMR spectroscopy across the chemical sciences.
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Affiliation(s)
- Sharon E Ashbrook
- School of Chemistry, EaStCHEM and Centre of Magnetic Resonance, University of St. Andrews, St. Andrews KY16 9ST, United Kingdom;
| | - John M Griffin
- Department of Chemistry and Materials Science Institute, Lancaster University, Lancaster LA1 4YB, United Kingdom
| | - Karen E Johnston
- Department of Chemistry, Durham University, South Road, Durham DH1 3LE, United Kingdom
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Chatterjee S, Bhanja P, Paul L, Ali M, Bhaumik A. MnAPO-5 as an efficient heterogeneous catalyst for selective liquid phase partial oxidation reactions. Dalton Trans 2018; 47:791-798. [PMID: 29244052 DOI: 10.1039/c7dt03897f] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Heterogeneous catalysts play a key role in addressing the economic and environmental issues of the chemical industry due to their several advantages, like ease of product separation, work-up and high recycling efficiency. Herein, we report the synthesis of a robust manganese(iv)-containing aluminophosphate material (MnAPO-5), with an AFI framework topology. This material has been characterized thoroughly by powder XRD, XPS, UHR TEM, FE SEM, 31P CP MAS NMR, atomic absorption spectroscopy, UV-visible spectroscopy and TGA. The Mn-containing microporous material has been employed as a heterogeneous catalyst for the oxidation of styrene and the synthesis of adipic acid from cyclohexanone in the presence of tert-butyl hydroperoxide (TBHP) as the oxidant in air and it displayed very high recycling efficiency.
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Affiliation(s)
- Sauvik Chatterjee
- Department of Materials Science, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700 032, India.
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7
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Broom LK, Clarkson GJ, Guillou N, Hooper JE, Dawson DM, Tang CC, Ashbrook SE, Walton RI. A gel aging effect in the synthesis of open-framework gallium phosphates: structure solution and solid-state NMR of a large-pore, open-framework material. Dalton Trans 2017; 46:16895-16904. [PMID: 29171855 PMCID: PMC5789431 DOI: 10.1039/c7dt03709k] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2017] [Accepted: 11/15/2017] [Indexed: 11/21/2022]
Abstract
The templated zeolite-analogue GaPO-34 (CHA structure type) crystallises from a gel precursor Ga2O3 : 2H3PO4 : 1HF : 1.7SDA : 70H2O (where SDA = structure directing agent), treated hydrothermally for 24 hours at 170 °C using either pyridine or 1-methylimizadole as SDA and one of either poorly crystalline ε-Ga2O3 or γ-Ga2O3 as gallium precursor. If the same gels are stirred for periods shorter than 2 hours but treated under identical hydrothermal conditions, then a second phase crystallises, free of GaPO-34. If β-Ga2O3 is used as a reagent only the second phase is found to crystallise, irrespective of gel aging time. The competing phase, which we denote GaPO-34A, has been structurally characterised using synchrotron powder X-ray diffraction for the pyridine material, GaPO-34A(pyr), and using single-crystal X-ray diffraction for the 1-methylimiazole material, GaPO-34A(mim). The structure of GaPO-34A(pyr), P1[combining macron], a = 10.22682(6) Å, b = 12.09585(7) Å, c = 13.86713(8) Å, α = 104.6531(4)°, β = 100.8111(6)°, γ = 102.5228(6)°, contains 7 unique gallium sites and 6 phosphorus sites, with empirical formula [Ga7P6O24(OH)2F3(H2O)2]·2(C5NH6). GaPO-34A(mim) is isostructural but is modelled as a half volume unit cell, P1[combining macron], a = 5.0991(2) Å, b = 12.0631(6) Å, c = 13.8405(9) Å, α = 104.626(5)°, β = 100.346(5)°, γ = 101.936(4)°, with a gallium and a bridging fluoride partially occupied and two partially occupied SDA sites. Solid-state 31P and 71Ga NMR spectroscopy confirms the structural complexity of GaPO-34A with signals resulting from overlapping lineshapes from multiple Ga and P sites, while 1H and 13C solid-state NMR spectra confirm the presence of the protonated SDA and provide evidence for disorder in the SDA. The protonated SDA is located in 14-ring one-dimensional channels with hydrogen bonding deduced from the SDA nitrogens to framework oxygen distances. Upon thermal treatment to investigate SDA removal, structure collapse occurs, which may be due the large number of bridging hydroxides and fluorides in the as-made material, and the unequal amounts of gallium and phosphorus present.
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Affiliation(s)
- Lucy K Broom
- Department of Chemistry, University of Warwick, Coventry, CV4 7AL, UK.
| | - Guy J Clarkson
- Department of Chemistry, University of Warwick, Coventry, CV4 7AL, UK.
| | - Nathalie Guillou
- Institut Lavoisier Versailles, UMR CNRS 8180, Université de Versailles St-Quentin-en-Yvelines, Université Paris-Saclay, 78035 Versailles, France
| | - Joseph E Hooper
- School of Chemistry, EaStCHEM and Centre of Magnetic Resonance, University of St Andrews, North Haugh, St Andrews, KY16 9ST, UK
| | - Daniel M Dawson
- School of Chemistry, EaStCHEM and Centre of Magnetic Resonance, University of St Andrews, North Haugh, St Andrews, KY16 9ST, UK
| | - Chiu C Tang
- Diamond Light Source, Diamond House, Harwell Science and Innovation Campus, Fermi Ave, Didcot OX11 0DE, UK
| | - Sharon E Ashbrook
- School of Chemistry, EaStCHEM and Centre of Magnetic Resonance, University of St Andrews, North Haugh, St Andrews, KY16 9ST, UK
| | - Richard I Walton
- Department of Chemistry, University of Warwick, Coventry, CV4 7AL, UK.
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Moran RF, Dawson DM, Ashbrook SE. Exploiting NMR spectroscopy for the study of disorder in solids. INT REV PHYS CHEM 2017. [DOI: 10.1080/0144235x.2017.1256604] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Affiliation(s)
- Robert F. Moran
- School of Chemistry, EaStCHEM and St Andrews Centre of Magnetic Resonance, University of St Andrews, North Haugh, St Andrews KY16 9ST, UK
| | - Daniel M. Dawson
- School of Chemistry, EaStCHEM and St Andrews Centre of Magnetic Resonance, University of St Andrews, North Haugh, St Andrews KY16 9ST, UK
| | - Sharon E. Ashbrook
- School of Chemistry, EaStCHEM and St Andrews Centre of Magnetic Resonance, University of St Andrews, North Haugh, St Andrews KY16 9ST, UK
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Haouas M, Taulelle F, Martineau C. Recent advances in application of (27)Al NMR spectroscopy to materials science. PROGRESS IN NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY 2016; 94-95:11-36. [PMID: 27247283 DOI: 10.1016/j.pnmrs.2016.01.003] [Citation(s) in RCA: 113] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/28/2015] [Revised: 01/28/2016] [Accepted: 01/28/2016] [Indexed: 06/05/2023]
Abstract
Valuable information about the local environment of the aluminum nucleus can be obtained through (27)Al Nuclear Magnetic Resonance (NMR) parameters like the isotropic chemical shift, scalar and quadrupolar coupling constants, and relaxation rate. With nearly 250 scientific articles per year dealing with (27)Al NMR spectroscopy, this analytical tool has become popular because of the recent progress that has made the acquisition and interpretation of the NMR data much easier. The application of (27)Al NMR techniques to various classes of compounds, either in solution or solid-state, has been shown to be extremely informative concerning local structure and chemistry of aluminum in its various environments. The development of experimental methodologies combined with theoretical approaches and modeling has contributed to major advances in spectroscopic characterization especially in materials sciences where long-range periodicity and classical local NMR probes are lacking. In this review we will present an overview of results obtained by (27)Al NMR as well as the most relevant methodological developments over the last 25years, concerning particularly on progress in the application of liquid- and solid-state (27)Al NMR to the study of aluminum-based materials such as aluminum polyoxoanions, zeolites, aluminophosphates, and metal-organic-frameworks.
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Affiliation(s)
- Mohamed Haouas
- Institut Lavoisier de Versailles (UMR CNRS 8180), Tectospin Group, Université de Versailles Saint Quentin en Yvelines, 78035 Versailles, France.
| | - Francis Taulelle
- Institut Lavoisier de Versailles (UMR CNRS 8180), Tectospin Group, Université de Versailles Saint Quentin en Yvelines, 78035 Versailles, France
| | - Charlotte Martineau
- Institut Lavoisier de Versailles (UMR CNRS 8180), Tectospin Group, Université de Versailles Saint Quentin en Yvelines, 78035 Versailles, France
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Ashbrook SE, McKay D. Combining solid-state NMR spectroscopy with first-principles calculations - a guide to NMR crystallography. Chem Commun (Camb) 2016; 52:7186-204. [PMID: 27117884 DOI: 10.1039/c6cc02542k] [Citation(s) in RCA: 151] [Impact Index Per Article: 18.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Recent advances in the application of first-principles calculations of NMR parameters to periodic systems have resulted in widespread interest in their use to support experimental measurement. Such calculations often play an important role in the emerging field of "NMR crystallography", where NMR spectroscopy is combined with techniques such as diffraction, to aid structure determination. Here, we discuss the current state-of-the-art for combining experiment and calculation in NMR spectroscopy, considering the basic theory behind the computational approaches and their practical application. We consider the issues associated with geometry optimisation and how the effects of temperature may be included in the calculation. The automated prediction of structural candidates and the treatment of disordered and dynamic solids are discussed. Finally, we consider the areas where further development is needed in this field and its potential future impact.
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Affiliation(s)
- Sharon E Ashbrook
- School of Chemistry, EaStCHEM and Centre of Magnetic Resonance, University of St Andrews, St Andrews, KY16 9ST, UK.
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Moran RF, McKay D, Pickard CJ, Berry AJ, Griffin JM, Ashbrook SE. Hunting for hydrogen: random structure searching and prediction of NMR parameters of hydrous wadsleyite. Phys Chem Chem Phys 2016; 18:10173-81. [PMID: 27020937 PMCID: PMC4840454 DOI: 10.1039/c6cp01529h] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2016] [Accepted: 03/15/2016] [Indexed: 11/21/2022]
Abstract
The structural chemistry of materials containing low levels of nonstoichiometric hydrogen is difficult to determine, and producing structural models is challenging where hydrogen has no fixed crystallographic site. Here we demonstrate a computational approach employing ab initio random structure searching (AIRSS) to generate a series of candidate structures for hydrous wadsleyite (β-Mg2SiO4 with 1.6 wt% H2O), a high-pressure mineral proposed as a repository for water in the Earth's transition zone. Aligning with previous experimental work, we solely consider models with Mg3 (over Mg1, Mg2 or Si) vacancies. We adapt the AIRSS method by starting with anhydrous wadsleyite, removing a single Mg(2+) and randomly placing two H(+) in a unit cell model, generating 819 candidate structures. 103 geometries were then subjected to more accurate optimisation under periodic DFT. Using this approach, we find the most favourable hydration mechanism involves protonation of two O1 sites around the Mg3 vacancy. The formation of silanol groups on O3 or O4 sites (with loss of stable O1-H hydroxyls) coincides with an increase in total enthalpy. Importantly, the approach we employ allows observables such as NMR parameters to be computed for each structure. We consider hydrous wadsleyite (∼1.6 wt%) to be dominated by protonated O1 sites, with O3/O4-H silanol groups present as defects, a model that maps well onto experimental studies at higher levels of hydration (J. M. Griffin et al., Chem. Sci., 2013, 4, 1523). The AIRSS approach adopted herein provides the crucial link between atomic-scale structure and experimental studies.
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Affiliation(s)
- Robert F. Moran
- School of Chemistry , EaStCHEM and Centre of Magnetic Resonance , University of St Andrews , St Andrews KY16 9ST , UK .
| | - David McKay
- School of Chemistry , EaStCHEM and Centre of Magnetic Resonance , University of St Andrews , St Andrews KY16 9ST , UK .
| | - Chris J. Pickard
- Department of Materials Science & Metallurgy , University of Cambridge , 27 Charles Babbage Road , Cambridge CB3 0FS , UK
| | - Andrew J. Berry
- Research School of Earth Sciences , Australian National University , Canberra , ACT 2601 , Australia
| | - John M. Griffin
- Department of Chemistry , Lancaster University , Lancaster LA1 4YB , UK
| | - Sharon E. Ashbrook
- School of Chemistry , EaStCHEM and Centre of Magnetic Resonance , University of St Andrews , St Andrews KY16 9ST , UK .
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Ashbrook SE, Dawson DM, Seymour VR. Recent developments in solid-state NMR spectroscopy of crystalline microporous materials. Phys Chem Chem Phys 2015; 16:8223-42. [PMID: 24675798 DOI: 10.1039/c4cp00578c] [Citation(s) in RCA: 65] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Microporous materials, having pores and channels on the same size scale as small to medium molecules, have found many important applications in current technologies, including catalysis, gas separation and drug storage and delivery. Many of their properties and functions are related to their detailed local structure, such as the type and distribution of active sites within the pores, and the specific structures of these active sites. Solid-state NMR spectroscopy has a strong track record of providing the requisite detailed atomic-level insight into the structures of microporous materials, in addition to being able to probe dynamic processes occurring on timescales spanning many orders of magnitude (i.e., from s to ps). In this Perspective, we provide a brief review of some of the basic experimental approaches used in solid-state NMR spectroscopy of microporous materials, and then discuss some more recent advances in this field, particularly those applied to the study of crystalline materials such as zeolites and metal-organic frameworks. These advances include improved software for aiding spectral interpretation, the development of the NMR-crystallography approach to structure determination, new routes for the synthesis of isotopically-labelled materials, methods for the characterisation of host-guest interactions, and methodologies suitable for observing NMR spectra of paramagnetic microporous materials. Finally, we discuss possible future directions, which we believe will have the greatest impact on the field over the coming years.
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Affiliation(s)
- Sharon E Ashbrook
- School of Chemistry, EaStCHEM and St Andrews Centre for Magnetic Resonance, St Andrews KY16 9ST, UK.
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Seymour VR, Eschenroeder ECV, Wright PA, Ashbrook SE. An NMR crystallographic approach to monitoring cation substitution in the aluminophosphate STA-2. SOLID STATE NUCLEAR MAGNETIC RESONANCE 2015; 65:64-74. [PMID: 25465483 DOI: 10.1016/j.ssnmr.2014.10.007] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2014] [Revised: 10/18/2014] [Accepted: 10/23/2014] [Indexed: 06/04/2023]
Abstract
The substitution of the divalent cations Mg(2+) and Zn(2+) into the aluminophosphate (AlPO) framework of STA-2 has been studied using an "NMR crystallographic" approach, combining multinuclear solid-state NMR spectroscopy, X-ray diffraction and first-principles calculations. Although the AlPO framework itself is inherently neutral, the positive charge of the organocation template in an as-made material is usually balanced either by the coordination to the framework of anions from the synthesis solution, such as OH(-) or F(-), and/or by the substitution of aliovalent cations. However, the exact position and distribution of the substituted cations can be difficult to determine, but can have a significant impact upon the catalytic properties a material exhibits once calcined. For as-made Mg substituted STA-2, the positive charge of the organocation template is balanced by the substitution of Mg(2+) for Al(3+) and, where required, by hydroxide anions coordinated to the framework [27] Al MAS NMR spectra show that Al is present in both tetrahedral and five-fold coordination, with the latter dependent on the amount of substituted cations, and confirms the bridging nature of the hydroxyl groups, while high-resolution MQMAS spectra are able to show that Mg appears to preferentially substitute on the Al1 site. This conclusion is also supported by first-principles calculations. The calculations also show that (31)P chemical shifts depend not only on the topologically-distinct site in the SAT framework, but also on the number of next-nearest-neighbour Mg species, and the exact nature of the coordinated hydroxyls (whether the P atom forms part of a six-membered ring, P(OAl)2OH, where OH bridges between two Al atoms). The calculations demonstrate a strong correlation between the (31)P isotropic chemical shift and the average 〈P-O-M〉 bond angle. In contrast, for Zn substituted STA-2, both X-ray diffraction and NMR spectroscopy show less preference for substitution onto Al1 or Al2, with both appearing to be present, although that into Al1 appears slightly more favoured.
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Affiliation(s)
- Valerie R Seymour
- School of Chemistry, EaStCHEM and Centre of Magnetic Resonance, University of St Andrews, North Haugh, St Andrews KY16 9ST, UK
| | - Eike C V Eschenroeder
- School of Chemistry, EaStCHEM and Centre of Magnetic Resonance, University of St Andrews, North Haugh, St Andrews KY16 9ST, UK
| | - Paul A Wright
- School of Chemistry, EaStCHEM and Centre of Magnetic Resonance, University of St Andrews, North Haugh, St Andrews KY16 9ST, UK
| | - Sharon E Ashbrook
- School of Chemistry, EaStCHEM and Centre of Magnetic Resonance, University of St Andrews, North Haugh, St Andrews KY16 9ST, UK.
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Burgess KMN, Bryce DL. On the crystal structure of the vaterite polymorph of CaCO3: a calcium-43 solid-state NMR and computational assessment. SOLID STATE NUCLEAR MAGNETIC RESONANCE 2015; 65:75-83. [PMID: 25306191 DOI: 10.1016/j.ssnmr.2014.08.003] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/14/2014] [Accepted: 08/29/2014] [Indexed: 06/04/2023]
Abstract
The vaterite polymorph of CaCO3 has puzzled crystallographers for decades in part due to difficulties in obtaining single crystals. The multiple proposed structures for the vaterite polymorph of CaCO3 are assessed using a combined (43)Ca solid-state nuclear magnetic resonance (SSNMR) spectroscopic and computational approach. A combination of improved experimental and computational methods, along with a calibrated chemical shift scale and (43)Ca nuclear quadrupole moment, allow for improved insights relative to our earlier work (Bryce et al., J. Am. Chem. Soc. 2008, 130, 9282). Here, we synthesize a (43)Ca isotopically-enriched sample of vaterite and perform high-resolution quadrupolar SSNMR experiments including magic-angle spinning (MAS), double-rotation (DOR), and multiple-quantum (MQ) MAS experiments at magnetic field strengths of 9.4 and 21.1T. We identify one crystallographically unique Ca(2+) site in vaterite with a slight distribution in both chemical shifts and quadrupolar parameters. Both the experimental (43)Ca electric field gradient tensor and the isotropic chemical shift for vaterite are compared to those calculated with the gauge-including projector-augmented-wave (GIPAW) DFT method in an attempt to identify the model that best represents the crystal structure of vaterite. Simulations of (43)Ca DOR and MAS NMR spectra based on the NMR parameters computed for a total of 18 structural models for vaterite allow us to distinguish between these models. Among these 18, the P3221 and C2 structures provide simulated spectra and diffractograms in best agreement with all experimental data.
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Affiliation(s)
- Kevin M N Burgess
- Department of Chemistry and Centre for Catalysis Research and Innovation, University of Ottawa, 10 Marie Curie Private, Ottawa, Ontario, Canada K1N 6N5
| | - David L Bryce
- Department of Chemistry and Centre for Catalysis Research and Innovation, University of Ottawa, 10 Marie Curie Private, Ottawa, Ontario, Canada K1N 6N5.
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Ashbrook SE, Sneddon S. New methods and applications in solid-state NMR spectroscopy of quadrupolar nuclei. J Am Chem Soc 2014; 136:15440-56. [PMID: 25296129 DOI: 10.1021/ja504734p] [Citation(s) in RCA: 87] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Solid-state nuclear magnetic resonance (NMR) spectroscopy has long been established as offering unique atomic-scale and element-specific insight into the structure, disorder, and dynamics of materials. NMR spectra of quadrupolar nuclei (I > (1)/2) are often perceived as being challenging to acquire and to interpret because of the presence of anisotropic broadening arising from the interaction of the electric field gradient and the nuclear electric quadrupole moment, which broadens the spectral lines, often over several megahertz. Despite the vast amount of information contained in the spectral line shapes, the problems with sensitivity and resolution have, until very recently, limited the application of NMR spectroscopy of quadrupolar nuclei in the solid state. In this Perspective, we provide a brief overview of the quadrupolar interaction, describe some of the basic experimental approaches used for acquiring high-resolution NMR spectra, and discuss the information that these spectra can provide. We then describe some interesting recent examples to showcase some of the more exciting and challenging new applications of NMR spectra of quadrupolar nuclei in the fields of energy materials, microporous materials, Earth sciences, and biomaterials. Finally, we consider the possible directions that this highly informative technique may take in the future.
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Affiliation(s)
- Sharon E Ashbrook
- School of Chemistry, EaStCHEM, and Centre of Magnetic Resonance, University of St Andrews , St Andrews KY16 9ST, United Kingdom
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Garino C, Borfecchia E, Gobetto R, van Bokhoven JA, Lamberti C. Determination of the electronic and structural configuration of coordination compounds by synchrotron-radiation techniques. Coord Chem Rev 2014. [DOI: 10.1016/j.ccr.2014.03.027] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
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Martineau C. NMR crystallography: Applications to inorganic materials. SOLID STATE NUCLEAR MAGNETIC RESONANCE 2014; 63-64:1-12. [PMID: 25112798 DOI: 10.1016/j.ssnmr.2014.07.001] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/05/2014] [Revised: 07/03/2014] [Accepted: 07/08/2014] [Indexed: 05/15/2023]
Abstract
Current developments of NMR crystallography as well as some recent applications to diamagnetic inorganic solids are presented. First, we illustrate how solid-state NMR data can be used in combination with diffraction data for the determination of the periodic part of the crystal structures, from the space group selection, to the structure determination over the refinement and validation processes. As ss-NMR, contrary to diffraction (powder and single-crystal), is not restricted to periodic boundary conditions, ss-NMR data can be used to further complete the structural description of materials, including studies of local order/disorder, etc. This illustrated through examples, which are shown and discussed in the second part of this review.
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Affiliation(s)
- Charlotte Martineau
- Tectospin, Institut Lavoisier de Versailles, UMR CNRS 8180, Université de Versailles St-Quentin en Yvelines, 45, avenue des Etats-Unis, 78035 Versailles cedex, France.
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Li Y, Yu J. New stories of zeolite structures: their descriptions, determinations, predictions, and evaluations. Chem Rev 2014; 114:7268-316. [PMID: 24844459 DOI: 10.1021/cr500010r] [Citation(s) in RCA: 269] [Impact Index Per Article: 26.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Affiliation(s)
- Yi Li
- State Key Laboratory of Inorganic Synthesis and Preparative Chemistry, College of Chemistry, Jilin University , Qianjin Street 2699, Changchun 130012, China
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Sneddon S, Dawson DM, Pickard CJ, Ashbrook SE. Calculating NMR parameters in aluminophosphates: evaluation of dispersion correction schemes. Phys Chem Chem Phys 2014; 16:2660-73. [DOI: 10.1039/c3cp54123a] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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