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Vanlommel S, Borgmans S, Chandran CV, Radhakrishnan S, Van Der Voort P, Breynaert E, Van Speybroeck V. Computational Protocol for the Spectral Assignment of NMR Resonances in Covalent Organic Frameworks. J Chem Theory Comput 2024. [PMID: 38650071 DOI: 10.1021/acs.jctc.3c01414] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/25/2024]
Abstract
Solid-state nuclear magnetic resonance spectroscopy is routinely used in the field of covalent organic frameworks to elucidate or confirm the structure of the synthesized samples and to understand dynamic phenomena. Typically this involves the interpretation and simulation of the spectra through the assumption of symmetry elements of the building units, hinging on the correct assignment of each line shape. To avoid misinterpretation resulting from library-based assignment without a theoretical basis incorporating the impact of the framework, this work proposes a first-principles computational protocol for the assignment of experimental spectra, which exploits the symmetry of the underlying building blocks for computational feasibility. In this way, this protocol accommodates the validation of previous experimental assignments and can serve to complement new NMR measurements.
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Affiliation(s)
- Siebe Vanlommel
- Center for Molecular Modeling, Ghent University, Technologiepark 46, 9052 Ghent, Belgium
| | - Sander Borgmans
- Center for Molecular Modeling, Ghent University, Technologiepark 46, 9052 Ghent, Belgium
| | - C Vinod Chandran
- NMRCoRe, NMR/X-Ray Platform for Convergence Research, Celestijnenlaan 200F, Box 2461, B-3001 Leuven, Belgium
| | - Sambhu Radhakrishnan
- NMRCoRe, NMR/X-Ray Platform for Convergence Research, Celestijnenlaan 200F, Box 2461, B-3001 Leuven, Belgium
| | - Pascal Van Der Voort
- Department of Chemistry, Ghent University, Krijgslaan 281 (S3), 9000 Ghent, Belgium
| | - Eric Breynaert
- NMRCoRe, NMR/X-Ray Platform for Convergence Research, Celestijnenlaan 200F, Box 2461, B-3001 Leuven, Belgium
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2
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Morais AF, Radhakrishnan S, Arbiv G, Dom D, Duerinckx K, Chandran CV, Martens JA, Breynaert E. Noncontact In Situ Multidiagnostic NMR/Dielectric Spectroscopy. Anal Chem 2024; 96:5071-5077. [PMID: 38513052 DOI: 10.1021/acs.analchem.3c03007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/23/2024]
Abstract
Introduction of a dielectric material in a nuclear magnetic resonance (NMR) probe head modifies the frequency response of the probe circuit, a phenomenon revealed by detuning of the probe. For NMR spectroscopy, this detuning is corrected for by tuning and matching the probe head prior to the NMR measurement. The magnitude of the probe detuning, "the dielectric shift", provides direct access to the dielectric properties of the sample, enabling NMR spectrometers to simultaneously perform both dielectric and NMR spectroscopy. By measuring sample dielectric permittivity as a function of frequency, dielectric permittivity spectroscopy can be performed using the new methodology. As a proof of concept, this was evaluated on methanol, ethanol, 1-propanol, 1-pentanol, and 1-octanol using a commercial cross-polarization magic angle spinning (CPMAS) NMR probe head. The results accurately match the literature data collected by standard dielectric spectroscopy techniques. Subsequently, the method was also applied to investigate the solvent-surface interactions of water confined in the micropores of an MFI-type, hydrophilic zeolite with a Si/Al ratio of 11.5. In the micropores, water adsorbs to Bro̷nsted acid sites and defect sites, resulting in a drastically decreased dielectric permittivity of the nanoconfined water. Theoretical background for the new methodology is provided using an effective electric circuit model of a CPMAS probe head with a solenoid coil, describing the detuning resulting from the insertion of dielectric samples in the probe head.
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Affiliation(s)
- Alysson F Morais
- Centre for Surface Chemistry and Catalysis - Characterization and Application Team (COK-KAT), Celestijnenlaan 200F Box 2461, 3001 Heverlee, Belgium
- NMR for Convergence Research (NMRCoRe), KU Leuven, Celestijnenlaan 200F Box 2461, 3001 Heverlee, Belgium
| | - Sambhu Radhakrishnan
- Centre for Surface Chemistry and Catalysis - Characterization and Application Team (COK-KAT), Celestijnenlaan 200F Box 2461, 3001 Heverlee, Belgium
- NMR for Convergence Research (NMRCoRe), KU Leuven, Celestijnenlaan 200F Box 2461, 3001 Heverlee, Belgium
| | - Gavriel Arbiv
- Centre for Surface Chemistry and Catalysis - Characterization and Application Team (COK-KAT), Celestijnenlaan 200F Box 2461, 3001 Heverlee, Belgium
- NMR for Convergence Research (NMRCoRe), KU Leuven, Celestijnenlaan 200F Box 2461, 3001 Heverlee, Belgium
- Center for Molecular Water Science (CMWS), Notkestraße 85, 22607 Hamburg, Germany
| | - Dirk Dom
- Centre for Surface Chemistry and Catalysis - Characterization and Application Team (COK-KAT), Celestijnenlaan 200F Box 2461, 3001 Heverlee, Belgium
- NMR for Convergence Research (NMRCoRe), KU Leuven, Celestijnenlaan 200F Box 2461, 3001 Heverlee, Belgium
| | - Karel Duerinckx
- Centre for Surface Chemistry and Catalysis - Characterization and Application Team (COK-KAT), Celestijnenlaan 200F Box 2461, 3001 Heverlee, Belgium
- NMR for Convergence Research (NMRCoRe), KU Leuven, Celestijnenlaan 200F Box 2461, 3001 Heverlee, Belgium
| | - C Vinod Chandran
- Centre for Surface Chemistry and Catalysis - Characterization and Application Team (COK-KAT), Celestijnenlaan 200F Box 2461, 3001 Heverlee, Belgium
- NMR for Convergence Research (NMRCoRe), KU Leuven, Celestijnenlaan 200F Box 2461, 3001 Heverlee, Belgium
| | - Johan A Martens
- Centre for Surface Chemistry and Catalysis - Characterization and Application Team (COK-KAT), Celestijnenlaan 200F Box 2461, 3001 Heverlee, Belgium
- NMR for Convergence Research (NMRCoRe), KU Leuven, Celestijnenlaan 200F Box 2461, 3001 Heverlee, Belgium
| | - Eric Breynaert
- Centre for Surface Chemistry and Catalysis - Characterization and Application Team (COK-KAT), Celestijnenlaan 200F Box 2461, 3001 Heverlee, Belgium
- NMR for Convergence Research (NMRCoRe), KU Leuven, Celestijnenlaan 200F Box 2461, 3001 Heverlee, Belgium
- Center for Molecular Water Science (CMWS), Notkestraße 85, 22607 Hamburg, Germany
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3
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Radhakrishnan S, Smet S, Chandran CV, Sree SP, Duerinckx K, Vanbutsele G, Martens JA, Breynaert E. Prediction of Cu Zeolite NH 3-SCR Activity from Variable Temperature 1H NMR Spectroscopy. Molecules 2023; 28:6456. [PMID: 37764230 PMCID: PMC10537069 DOI: 10.3390/molecules28186456] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2023] [Revised: 08/28/2023] [Accepted: 09/04/2023] [Indexed: 09/29/2023] Open
Abstract
Selective catalytic reduction (SCR) of NOx by ammonia is one of the dominant pollution abatement technologies for near-zero NOx emission diesel engines. A crucial step in the reduction of NOx to N2 with Cu zeolite NH3-SCR catalysts is the generation of a multi-electron donating active site, implying the permanent or transient dimerization of Cu ions. Cu atom mobility has been implicated by computational chemistry as a key factor in this process. This report demonstrates how variable temperature 1H NMR reveals the Cu induced generation of sharp 1H resonances associated with a low concentration of sites on the zeolite. The onset temperature of the appearance of these signals was found to strongly correlate with the NH3-SCR activity and was observed for a range of catalysts covering multiple frameworks (CHA, AEI, AFX, ERI, ERI-CHA, ERI-OFF, *BEA), with different Si/Al ratios and different Cu contents. The results point towards universal applicability of variable temperature NMR to predict the activity of a Cu-zeolite SCR catalyst. The unique relationship of a spectroscopic feature with catalytic behavior for zeolites with different structures and chemical compositions is exceptional in heterogeneous catalysis.
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Affiliation(s)
- Sambhu Radhakrishnan
- Centre for Surface Chemistry and Catalysis—Characterization and Application Team (COK-KAT), KU Leuven, Celestijnenlaan 200F Box 2461, 3001 Heverlee, Belgium
- NMR/X-ray Platform for Convergence Research (NMRCoRe), KU Leuven, Celestijnenlaan 200F Box 2461, 3001 Heverlee, Belgium
| | - Sam Smet
- Centre for Surface Chemistry and Catalysis—Characterization and Application Team (COK-KAT), KU Leuven, Celestijnenlaan 200F Box 2461, 3001 Heverlee, Belgium
| | - C. Vinod Chandran
- Centre for Surface Chemistry and Catalysis—Characterization and Application Team (COK-KAT), KU Leuven, Celestijnenlaan 200F Box 2461, 3001 Heverlee, Belgium
- NMR/X-ray Platform for Convergence Research (NMRCoRe), KU Leuven, Celestijnenlaan 200F Box 2461, 3001 Heverlee, Belgium
| | - Sreeprasanth Pulinthanathu Sree
- Centre for Surface Chemistry and Catalysis—Characterization and Application Team (COK-KAT), KU Leuven, Celestijnenlaan 200F Box 2461, 3001 Heverlee, Belgium
| | - Karel Duerinckx
- Centre for Surface Chemistry and Catalysis—Characterization and Application Team (COK-KAT), KU Leuven, Celestijnenlaan 200F Box 2461, 3001 Heverlee, Belgium
- NMR/X-ray Platform for Convergence Research (NMRCoRe), KU Leuven, Celestijnenlaan 200F Box 2461, 3001 Heverlee, Belgium
| | - Gina Vanbutsele
- Centre for Surface Chemistry and Catalysis—Characterization and Application Team (COK-KAT), KU Leuven, Celestijnenlaan 200F Box 2461, 3001 Heverlee, Belgium
| | - Johan A. Martens
- Centre for Surface Chemistry and Catalysis—Characterization and Application Team (COK-KAT), KU Leuven, Celestijnenlaan 200F Box 2461, 3001 Heverlee, Belgium
- NMR/X-ray Platform for Convergence Research (NMRCoRe), KU Leuven, Celestijnenlaan 200F Box 2461, 3001 Heverlee, Belgium
| | - Eric Breynaert
- Centre for Surface Chemistry and Catalysis—Characterization and Application Team (COK-KAT), KU Leuven, Celestijnenlaan 200F Box 2461, 3001 Heverlee, Belgium
- NMR/X-ray Platform for Convergence Research (NMRCoRe), KU Leuven, Celestijnenlaan 200F Box 2461, 3001 Heverlee, Belgium
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4
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Radhakrishnan S, Lejaegere C, Duerinckx K, Lo WS, Morais AF, Dom D, Chandran CV, Hermans I, Martens JA, Breynaert E. Hydrogen bonding to oxygen in siloxane bonds drives liquid phase adsorption of primary alcohols in high-silica zeolites. Mater Horiz 2023; 10:3702-3711. [PMID: 37401863 PMCID: PMC10463557 DOI: 10.1039/d3mh00888f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/09/2023] [Accepted: 06/27/2023] [Indexed: 07/05/2023]
Abstract
Upon liquid phase adsorption of C1-C5 primary alcohols on high silica MFI zeolites (Si/Al = 11.5-140), the concentration of adsorbed molecules largely exceeds the concentration of traditional adsorption sites: Brønsted acid and defect sites. Combining quantitative in situ1H MAS NMR, qualitative multinuclear NMR and IR spectroscopy, hydrogen bonding of the alcohol function to oxygen atoms of the zeolite siloxane bridges (Si-O-Si) was shown to drive the additional adsorption. This mechanism co-exists with chemi- and physi-sorption on Brønsted acid and defect sites and does not exclude cooperative effects from dispersive interactions.
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Affiliation(s)
- Sambhu Radhakrishnan
- Centre for Surface Chemistry and Catalysis - Characterization and Application Team (COK-KAT), KU Leuven, Celestijnenlaan 200F Box 2461, 3001-Heverlee, Belgium.
- NMRCoRe - NMR/X-Ray platform for Convergence Research, KU Leuven, Celestijnenlaan 200F Box 2461, 3001-Heverlee, Belgium
| | - Charlotte Lejaegere
- Centre for Surface Chemistry and Catalysis - Characterization and Application Team (COK-KAT), KU Leuven, Celestijnenlaan 200F Box 2461, 3001-Heverlee, Belgium.
| | - Karel Duerinckx
- Centre for Surface Chemistry and Catalysis - Characterization and Application Team (COK-KAT), KU Leuven, Celestijnenlaan 200F Box 2461, 3001-Heverlee, Belgium.
- NMRCoRe - NMR/X-Ray platform for Convergence Research, KU Leuven, Celestijnenlaan 200F Box 2461, 3001-Heverlee, Belgium
| | - Wei-Shang Lo
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, Wisconsin 53706, USA
| | - Alysson F Morais
- Centre for Surface Chemistry and Catalysis - Characterization and Application Team (COK-KAT), KU Leuven, Celestijnenlaan 200F Box 2461, 3001-Heverlee, Belgium.
- NMRCoRe - NMR/X-Ray platform for Convergence Research, KU Leuven, Celestijnenlaan 200F Box 2461, 3001-Heverlee, Belgium
| | - Dirk Dom
- Centre for Surface Chemistry and Catalysis - Characterization and Application Team (COK-KAT), KU Leuven, Celestijnenlaan 200F Box 2461, 3001-Heverlee, Belgium.
- NMRCoRe - NMR/X-Ray platform for Convergence Research, KU Leuven, Celestijnenlaan 200F Box 2461, 3001-Heverlee, Belgium
| | - C Vinod Chandran
- Centre for Surface Chemistry and Catalysis - Characterization and Application Team (COK-KAT), KU Leuven, Celestijnenlaan 200F Box 2461, 3001-Heverlee, Belgium.
- NMRCoRe - NMR/X-Ray platform for Convergence Research, KU Leuven, Celestijnenlaan 200F Box 2461, 3001-Heverlee, Belgium
| | - Ive Hermans
- Centre for Surface Chemistry and Catalysis - Characterization and Application Team (COK-KAT), KU Leuven, Celestijnenlaan 200F Box 2461, 3001-Heverlee, Belgium.
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, Wisconsin 53706, USA
- Department of Chemical and Biological Engineering, Wisconsin Energy Institute, University of Wisconsin-Madison, 1552 University Ave, Madison, WI 53726, USA
| | - Johan A Martens
- Centre for Surface Chemistry and Catalysis - Characterization and Application Team (COK-KAT), KU Leuven, Celestijnenlaan 200F Box 2461, 3001-Heverlee, Belgium.
- NMRCoRe - NMR/X-Ray platform for Convergence Research, KU Leuven, Celestijnenlaan 200F Box 2461, 3001-Heverlee, Belgium
| | - Eric Breynaert
- Centre for Surface Chemistry and Catalysis - Characterization and Application Team (COK-KAT), KU Leuven, Celestijnenlaan 200F Box 2461, 3001-Heverlee, Belgium.
- NMRCoRe - NMR/X-Ray platform for Convergence Research, KU Leuven, Celestijnenlaan 200F Box 2461, 3001-Heverlee, Belgium
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5
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Vanderschaeghe H, Houlleberghs M, Verheyden L, Dom D, Chandran CV, Radhakrishnan S, Martens JA, Breynaert E. Absolute Quantification of Residual Solvent in Mesoporous Silica Drug Formulations Using Magic-Angle Spinning NMR Spectroscopy. Anal Chem 2022; 95:1880-1887. [PMID: 36579853 DOI: 10.1021/acs.analchem.2c03646] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Porous silica is used as a drug delivery agent to improve the bioavailability of sparsely soluble compounds. In this approach, the active pharmaceutical ingredient (API) is commonly loaded into the porous silica by incipient wetness impregnation using organic solvents. Subsequent solvent elimination is critical as the residual solvent concentration cannot exceed threshold values set by health and safety regulations (e.g., EMA/CHMP/ICH/82260/2006). For dichloromethane and methanol, for example, residual concentrations must be below 600 and 3000 ppm, respectively. Today, EU and USA Pharmacopoeias recommend tedious procedures for residual solvent quantification, requiring extraction of the solvent and subsequent quantification using capillary gas chromatography with static headspace sampling (sHS-GC). This work presents a new method based on the combination of standard addition and absolute quantification using magic-angle spinning nuclear magnetic resonance spectroscopy (MAS qNMR). The methodology was originally developed for absolute quantification of water in zeolites and has now been validated for quantification of residual solvent in drug formations using mesoporous silica loaded with ibuprofen dissolved in DCM and MeOH as test samples. Interestingly, formulations prepared using as-received or predried mesoporous silica contained 5465 versus 484.9 ppm DCM, respectively. This implies that the initial water content of the silica carrier can impact the residual solvent concentration in drug-loaded materials. This observation could provide new options to minimize the occurrence of these undesired solvents in the final formulation.
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Affiliation(s)
- Hannah Vanderschaeghe
- Center for Surface Chemistry and Catalysis (COK-kat), KU Leuven, Celestijnenlaan 200F, Box 2461, 3001Heverlee, Belgium
| | - Maarten Houlleberghs
- Center for Surface Chemistry and Catalysis (COK-kat), KU Leuven, Celestijnenlaan 200F, Box 2461, 3001Heverlee, Belgium
| | - Loes Verheyden
- Center for Surface Chemistry and Catalysis (COK-kat), KU Leuven, Celestijnenlaan 200F, Box 2461, 3001Heverlee, Belgium
| | - Dirk Dom
- Center for Surface Chemistry and Catalysis (COK-kat), KU Leuven, Celestijnenlaan 200F, Box 2461, 3001Heverlee, Belgium
- NMR/X-ray platform for Convergence Research (NMRCoRe), KU Leuven, Celestijnenlaan 200F, Box 2461, 3001Heverlee, Belgium
| | - C Vinod Chandran
- Center for Surface Chemistry and Catalysis (COK-kat), KU Leuven, Celestijnenlaan 200F, Box 2461, 3001Heverlee, Belgium
- NMR/X-ray platform for Convergence Research (NMRCoRe), KU Leuven, Celestijnenlaan 200F, Box 2461, 3001Heverlee, Belgium
| | - Sambhu Radhakrishnan
- Center for Surface Chemistry and Catalysis (COK-kat), KU Leuven, Celestijnenlaan 200F, Box 2461, 3001Heverlee, Belgium
- NMR/X-ray platform for Convergence Research (NMRCoRe), KU Leuven, Celestijnenlaan 200F, Box 2461, 3001Heverlee, Belgium
| | - Johan A Martens
- Center for Surface Chemistry and Catalysis (COK-kat), KU Leuven, Celestijnenlaan 200F, Box 2461, 3001Heverlee, Belgium
| | - Eric Breynaert
- Center for Surface Chemistry and Catalysis (COK-kat), KU Leuven, Celestijnenlaan 200F, Box 2461, 3001Heverlee, Belgium
- NMR/X-ray platform for Convergence Research (NMRCoRe), KU Leuven, Celestijnenlaan 200F, Box 2461, 3001Heverlee, Belgium
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6
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Park SH, Radhakrishnan S, Choi W, Chandran CV, Kemp KC, Breynaert E, Bell RG, Kirschhock CEA, Hong SB. Hydrogen-Bonded Water-Aminium Assemblies for Synthesis of Zeotypes with Ordered Heteroatoms. J Am Chem Soc 2022; 144:18054-18061. [PMID: 36136766 DOI: 10.1021/jacs.2c07661] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Water plays a central role in the crystallization of a variety of organic, inorganic, biological, and hybrid materials. This is also true for zeolites and zeolite-like materials, an important class of industrial catalysts and adsorbents. Water is always present during their hydrothermal synthesis, either with or without organic species as structure-directing agents. Apart from its role as a solvent or a catalyst, structure direction by water in zeolite synthesis has never been clearly elucidated. Here, we report the crystallization of phosphate-based molecular sieves using rationally designed, hydrogen-bonded water-aminium assemblies, resulting in molecular sieves exhibiting the crystallographic ordering of heteroatoms. We demonstrate that a 1:1 assembly of water and diprotonated N,N-dimethyl-1,2-ethanediamine acts as a structure-directing agent in the synthesis of a silicoaluminophosphate material with phillipsite (PHI) topology, using SMARTER crystallography, which combines single-crystal X-ray diffraction and nuclear magnetic resonance spectroscopy, as well as ab initio molecular dynamics simulations. The molecular arrangement of the hydrogen-bonded assembly matches well with the shape and size of subunits in the PHI structure, and their charge distributions result in the strict ordering of framework tetrahedral atoms. This concept of structure direction by water-containing supramolecular assemblies should be applicable to the synthesis of many classes of porous materials.
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Affiliation(s)
- Sung Hwan Park
- Center for Ordered Nanoporous Materials Synthesis, Division of Environmental Science and Engineering, POSTECH, Pohang 37673, Korea
| | - Sambhu Radhakrishnan
- Center for Surface Chemistry and Catalysis, Characterization and Application Team (COK-kat), KU Leuven, Celestijnenlaan 200 F - box 2461, 3001 Heverlee, Belgium.,NMR/X-ray platform for Convergence Research (NMRCoRe), KU Leuven, Celestijnenlaan 200 F - box 2461, 3001 Heverlee, Belgium
| | - Wanuk Choi
- Center for Ordered Nanoporous Materials Synthesis, Division of Environmental Science and Engineering, POSTECH, Pohang 37673, Korea
| | - C Vinod Chandran
- Center for Surface Chemistry and Catalysis, Characterization and Application Team (COK-kat), KU Leuven, Celestijnenlaan 200 F - box 2461, 3001 Heverlee, Belgium.,NMR/X-ray platform for Convergence Research (NMRCoRe), KU Leuven, Celestijnenlaan 200 F - box 2461, 3001 Heverlee, Belgium
| | - Kingsley Christian Kemp
- Center for Ordered Nanoporous Materials Synthesis, Division of Environmental Science and Engineering, POSTECH, Pohang 37673, Korea
| | - Eric Breynaert
- Center for Surface Chemistry and Catalysis, Characterization and Application Team (COK-kat), KU Leuven, Celestijnenlaan 200 F - box 2461, 3001 Heverlee, Belgium.,NMR/X-ray platform for Convergence Research (NMRCoRe), KU Leuven, Celestijnenlaan 200 F - box 2461, 3001 Heverlee, Belgium
| | - Robert G Bell
- Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ, U.K
| | - Christine E A Kirschhock
- Center for Surface Chemistry and Catalysis, Characterization and Application Team (COK-kat), KU Leuven, Celestijnenlaan 200 F - box 2461, 3001 Heverlee, Belgium
| | - Suk Bong Hong
- Center for Ordered Nanoporous Materials Synthesis, Division of Environmental Science and Engineering, POSTECH, Pohang 37673, Korea
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Houlleberghs M, Verheyden L, Voorspoels F, Chandran CV, Duerinckx K, Radhakrishnan S, Martens JA, Breynaert E. Magneto‐Hydrodynamic
Mixing: a New Technique for Preparing Carbomer Hydrogels. AIChE J 2022. [DOI: 10.1002/aic.17911] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Maarten Houlleberghs
- Center for Surface Chemistry and Catalysis ‐ Characterization and Application Team (COK‐kat) KU Leuven Heverlee Belgium
| | - Loes Verheyden
- Center for Surface Chemistry and Catalysis ‐ Characterization and Application Team (COK‐kat) KU Leuven Heverlee Belgium
| | | | - C. Vinod Chandran
- Center for Surface Chemistry and Catalysis ‐ Characterization and Application Team (COK‐kat) KU Leuven Heverlee Belgium
- NMR‐Xray platform for Convergence Research (NMRCoRe) KU Leuven Heverlee Belgium
| | - Karel Duerinckx
- Center for Surface Chemistry and Catalysis ‐ Characterization and Application Team (COK‐kat) KU Leuven Heverlee Belgium
- NMR‐Xray platform for Convergence Research (NMRCoRe) KU Leuven Heverlee Belgium
| | - Sambhu Radhakrishnan
- Center for Surface Chemistry and Catalysis ‐ Characterization and Application Team (COK‐kat) KU Leuven Heverlee Belgium
- NMR‐Xray platform for Convergence Research (NMRCoRe) KU Leuven Heverlee Belgium
| | - Johan A. Martens
- Center for Surface Chemistry and Catalysis ‐ Characterization and Application Team (COK‐kat) KU Leuven Heverlee Belgium
- NMR‐Xray platform for Convergence Research (NMRCoRe) KU Leuven Heverlee Belgium
| | - Eric Breynaert
- Center for Surface Chemistry and Catalysis ‐ Characterization and Application Team (COK‐kat) KU Leuven Heverlee Belgium
- NMR‐Xray platform for Convergence Research (NMRCoRe) KU Leuven Heverlee Belgium
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8
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De Man WL, Chandran CV, Wouters AGB, Radhakrishnan S, Martens JA, Breynaert E, Delcour JA. Hydration of Wheat Flour Water-Unextractable Cell Wall Material Enables Structural Analysis of Its Arabinoxylan by High-Resolution Solid-State 13C MAS NMR Spectroscopy. J Agric Food Chem 2022; 70:10604-10610. [PMID: 35977412 DOI: 10.1021/acs.jafc.2c04087] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
To enable its structural characterization by nuclear magnetic resonance (NMR) spectroscopy, the native structure of cereal water-unextractable arabinoxylan (WU-AX) is typically disrupted by alkali or enzymatic treatments. Here, WU-AX in the wheat flour unextractable cell wall material (UCWM) containing 40.9% ± 1.5 arabinoxylan with an arabinose-to-xylose ratio of 0.62 ± 0.04 was characterized by high-resolution solid-state NMR without disrupting its native structure. Hydration of the UCWM (1.7 mg H2O/mg UCWM) in combination with specific optimizations in the NMR methodology enabled analysis by solid-state 13C NMR with magic angle spinning and 1H high-power decoupling (13C HPDEC MAS NMR) which provided sufficiently high resolution to allow for carbon atom assignments. Spectral resonances of C-1 from arabinose and xylose residues of WU-AX were here assigned to the solid state. The proportions of un-, mono-, and di-substituted xyloses were 59.2, 19.5, and 21.2%, respectively. 13C HPDEC MAS NMR showed the presence of solid-state fractions with different mobilities in the UCWM. This study presents the first solid-state NMR spectrum of wheat WU-AX with sufficient resolution to enable assignment without prior WU-AX solubilization.
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Affiliation(s)
- Wannes L De Man
- Laboratory of Food Chemistry and Biochemistry (LFCB) and Leuven Food Science and Nutrition Research Centre (LFoRCe), KU Leuven, Kasteelpark Arenberg 23, B-3001Heverlee, Belgium
| | - C Vinod Chandran
- Centre for Surface Chemistry and Catalysis (COK-KAT), KU Leuven, Celestijnenlaan 200F─box 2461, B-3001Heverlee, Belgium
- X-ray/NMR Platform for Convergence Research (NMRCoRe), KU Leuven, Celestijnenlaan 200F─box 2461, B-3001Heverlee, Belgium
| | - Arno G B Wouters
- Laboratory of Food Chemistry and Biochemistry (LFCB) and Leuven Food Science and Nutrition Research Centre (LFoRCe), KU Leuven, Kasteelpark Arenberg 23, B-3001Heverlee, Belgium
| | - Sambhu Radhakrishnan
- Centre for Surface Chemistry and Catalysis (COK-KAT), KU Leuven, Celestijnenlaan 200F─box 2461, B-3001Heverlee, Belgium
- X-ray/NMR Platform for Convergence Research (NMRCoRe), KU Leuven, Celestijnenlaan 200F─box 2461, B-3001Heverlee, Belgium
| | - Johan A Martens
- Centre for Surface Chemistry and Catalysis (COK-KAT), KU Leuven, Celestijnenlaan 200F─box 2461, B-3001Heverlee, Belgium
- X-ray/NMR Platform for Convergence Research (NMRCoRe), KU Leuven, Celestijnenlaan 200F─box 2461, B-3001Heverlee, Belgium
| | - Eric Breynaert
- Centre for Surface Chemistry and Catalysis (COK-KAT), KU Leuven, Celestijnenlaan 200F─box 2461, B-3001Heverlee, Belgium
- X-ray/NMR Platform for Convergence Research (NMRCoRe), KU Leuven, Celestijnenlaan 200F─box 2461, B-3001Heverlee, Belgium
| | - Jan A Delcour
- Laboratory of Food Chemistry and Biochemistry (LFCB) and Leuven Food Science and Nutrition Research Centre (LFoRCe), KU Leuven, Kasteelpark Arenberg 23, B-3001Heverlee, Belgium
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9
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Vanlommel S, Hoffman AE, Smet S, Radhakrishnan S, Asselman K, Chandran CV, Breynaert E, Kirschhock CE, Martens JA, Van Speybroeck V. How Water and Ion Mobility Affect the NMR Fingerprints of the Hydrated JBW Zeolite: a Combined Computational‐Experimental Investigation. Chemistry 2022; 28:e202202621. [PMID: 36005885 PMCID: PMC10092413 DOI: 10.1002/chem.202202621] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2022] [Indexed: 11/08/2022]
Abstract
An important aspect within zeolite synthesis is to make fully tunable framework materials with controlled aluminium distribution. A major challenge in characterising these zeolites at operating conditions is the presence of water. In this work, we investigate the effect of hydration on the 27 Al NMR parameters of the ultracrystalline K,Na-compensated aluminosilicate JBW zeolite using experimental and computational techniques. The JBW framework, with Si/Al ratio of 1, is an ideal benchmark system as a stepping stone towards more complicated zeolites. The presence and mobility of water and extraframework species directly affect NMR fingerprints. Excellent agreement between theoretical and experimental spectra is obtained provided dynamic methods are employed with hydrated structural models. This work shows how NMR is instrumental in characterising aluminium distributions in zeolites at operating conditions.
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Affiliation(s)
- Siebe Vanlommel
- Ghent University: Universiteit Gent Center for Molecular Modeling BELGIUM
| | | | - Sam Smet
- KU Leuven: Katholieke Universiteit Leuven Center for Surface Chemistry and Catalysis BELGIUM
| | - Sambhu Radhakrishnan
- KU Leuven: Katholieke Universiteit Leuven Center for Surface Chemistry and Catalysi BELGIUM
| | - Karel Asselman
- KU Leuven: Katholieke Universiteit Leuven Center for Surface Chemistry and Catalysis BELGIUM
| | - C. Vinod Chandran
- KU Leuven: Katholieke Universiteit Leuven Center for Surface Chemistry and Catalysis BELGIUM
| | - Eric Breynaert
- KU Leuven: Katholieke Universiteit Leuven Center for Surface Chemistry and Catalysis BELGIUM
| | | | - Johan A. Martens
- KU Leuven: Katholieke Universiteit Leuven Center for Surface Chemistry and Catalysis BELGIUM
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10
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Pellens N, Doppelhammer N, Radhakrishnan S, Asselman K, Chandran CV, Vandenabeele D, Jakoby B, Martens JA, Taulelle F, Reichel EK, Breynaert E, Kirschhock CEA. Nucleation of Porous Crystals from Ion-Paired Prenucleation Clusters. Chem Mater 2022; 34:7139-7149. [PMID: 36032557 PMCID: PMC9404542 DOI: 10.1021/acs.chemmater.2c00418] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Current nucleation models propose manifold options for the formation of crystalline materials. Exploring and distinguishing between different crystallization pathways on the molecular level however remain a challenge, especially for complex porous materials. These usually consist of large unit cells with an ordered framework and pore components and often nucleate in complex, multiphasic synthesis media, restricting in-depth characterization. This work shows how aluminosilicate speciation during crystallization can be documented in detail in monophasic hydrated silicate ionic liquids (HSILs). The observations reveal that zeolites can form via supramolecular organization of ion-paired prenucleation clusters, consisting of aluminosilicate anions, ion-paired to alkali cations, and imply that zeolite crystallization from HSILs can be described within the spectrum of modern nucleation theory.
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Affiliation(s)
- Nick Pellens
- Center
for Surface Chemistry and Catalysis—Characterisation and Application
Team (COK-KAT), KU Leuven, Celestijnenlaan 200F, 3001 Leuven, Belgium
| | - Nikolaus Doppelhammer
- Center
for Surface Chemistry and Catalysis—Characterisation and Application
Team (COK-KAT), KU Leuven, Celestijnenlaan 200F, 3001 Leuven, Belgium
- Institute
for Microelectronics and Microsystems JKU Linz, 4040 Linz, Austria
| | - Sambhu Radhakrishnan
- Center
for Surface Chemistry and Catalysis—Characterisation and Application
Team (COK-KAT), KU Leuven, Celestijnenlaan 200F, 3001 Leuven, Belgium
- NMR-Xray
Platform for Convergence Research (NMRCoRe), KU Leuven, 3001 Leuven, Belgium
| | - Karel Asselman
- Center
for Surface Chemistry and Catalysis—Characterisation and Application
Team (COK-KAT), KU Leuven, Celestijnenlaan 200F, 3001 Leuven, Belgium
| | - C. Vinod Chandran
- Center
for Surface Chemistry and Catalysis—Characterisation and Application
Team (COK-KAT), KU Leuven, Celestijnenlaan 200F, 3001 Leuven, Belgium
- NMR-Xray
Platform for Convergence Research (NMRCoRe), KU Leuven, 3001 Leuven, Belgium
| | - Dries Vandenabeele
- Center
for Surface Chemistry and Catalysis—Characterisation and Application
Team (COK-KAT), KU Leuven, Celestijnenlaan 200F, 3001 Leuven, Belgium
| | - Bernhard Jakoby
- Institute
for Microelectronics and Microsystems JKU Linz, 4040 Linz, Austria
| | - Johan A. Martens
- Center
for Surface Chemistry and Catalysis—Characterisation and Application
Team (COK-KAT), KU Leuven, Celestijnenlaan 200F, 3001 Leuven, Belgium
- NMR-Xray
Platform for Convergence Research (NMRCoRe), KU Leuven, 3001 Leuven, Belgium
| | - Francis Taulelle
- Center
for Surface Chemistry and Catalysis—Characterisation and Application
Team (COK-KAT), KU Leuven, Celestijnenlaan 200F, 3001 Leuven, Belgium
- NMR-Xray
Platform for Convergence Research (NMRCoRe), KU Leuven, 3001 Leuven, Belgium
| | - Erwin K. Reichel
- Institute
for Microelectronics and Microsystems JKU Linz, 4040 Linz, Austria
| | - Eric Breynaert
- Center
for Surface Chemistry and Catalysis—Characterisation and Application
Team (COK-KAT), KU Leuven, Celestijnenlaan 200F, 3001 Leuven, Belgium
- NMR-Xray
Platform for Convergence Research (NMRCoRe), KU Leuven, 3001 Leuven, Belgium
| | - Christine E. A. Kirschhock
- Center
for Surface Chemistry and Catalysis—Characterisation and Application
Team (COK-KAT), KU Leuven, Celestijnenlaan 200F, 3001 Leuven, Belgium
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11
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Asselman K, Radhakrishnan S, Pellens N, Chandran CV, Houlleberghs M, Xu Y, Martens JA, Sree SP, Kirschhock CE, Breynaert E. HSIL-Based Synthesis of Ultracrystalline K,Na-JBW, a Zeolite Exhibiting Exceptional Framework Ordering and Flexibility. Chem Mater 2022; 34:7159-7166. [PMID: 36032550 PMCID: PMC9404536 DOI: 10.1021/acs.chemmater.2c01059] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
A reproducible synthesis strategy for ultracrystalline K,Na-aluminosilicate JBW zeolite is reported. The synthesis uses a Na-based hydrated silicate ionic liquid (HSIL) as a silicon source and gibbsite as the aluminum source. 27Al and 23Na NMR spectra exhibit crystalline second-order quadrupole patterns in the hydrated as well as dehydrated states and distinct resonances for different T-sites demonstrating an exceptional degree of order of the elements of the JBW framework, observed for the first time in a zeolite. Detailed structural analysis via NMR crystallography, combining powder X-ray diffraction and solid-state NMR of all elements (27Al, 29Si, 23Na, 39K, and 1H), reveals remarkable de- and rehydration behavior of the JBW framework, transforming from its as-made hydrated structure via a modified anhydrous state into a different rehydrated symmetry while showing astonishing flexibility for a semicondensed aluminosilicate. Its crystallinity, exceptional degree of ordering of the T atoms and sodium cations, and the fully documented structure qualify this defect-free K,Na-aluminosilicate JBW zeolite as a suitable model system for developing NMR modeling methods.
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Affiliation(s)
- Karel Asselman
- Center
for Surface Chemistry and Catalysis − Characterisation and
Application Team (COK-KAT), KU Leuven, Celestijnenlaan 200F, 3000 Leuven, Belgium
| | - Sambhu Radhakrishnan
- Center
for Surface Chemistry and Catalysis − Characterisation and
Application Team (COK-KAT), KU Leuven, Celestijnenlaan 200F, 3000 Leuven, Belgium
- NMR/X-ray
Platform for Convergence Research (NMRCoRe), KU Leuven, Celestijnenlaan
200F, 3000 Leuven, Belgium
| | - Nick Pellens
- Center
for Surface Chemistry and Catalysis − Characterisation and
Application Team (COK-KAT), KU Leuven, Celestijnenlaan 200F, 3000 Leuven, Belgium
| | - C. Vinod Chandran
- Center
for Surface Chemistry and Catalysis − Characterisation and
Application Team (COK-KAT), KU Leuven, Celestijnenlaan 200F, 3000 Leuven, Belgium
- NMR/X-ray
Platform for Convergence Research (NMRCoRe), KU Leuven, Celestijnenlaan
200F, 3000 Leuven, Belgium
| | - Maarten Houlleberghs
- Center
for Surface Chemistry and Catalysis − Characterisation and
Application Team (COK-KAT), KU Leuven, Celestijnenlaan 200F, 3000 Leuven, Belgium
| | - Yijue Xu
- National
High Magnetic Field Laboratory, 1860 East Paul Dirac Drive, Tallahassee, Florida 32310, United States
| | - Johan A. Martens
- Center
for Surface Chemistry and Catalysis − Characterisation and
Application Team (COK-KAT), KU Leuven, Celestijnenlaan 200F, 3000 Leuven, Belgium
| | - Sreeprasanth Pulinthanathu Sree
- Center
for Surface Chemistry and Catalysis − Characterisation and
Application Team (COK-KAT), KU Leuven, Celestijnenlaan 200F, 3000 Leuven, Belgium
| | - Christine E.A. Kirschhock
- Center
for Surface Chemistry and Catalysis − Characterisation and
Application Team (COK-KAT), KU Leuven, Celestijnenlaan 200F, 3000 Leuven, Belgium
| | - Eric Breynaert
- Center
for Surface Chemistry and Catalysis − Characterisation and
Application Team (COK-KAT), KU Leuven, Celestijnenlaan 200F, 3000 Leuven, Belgium
- NMR/X-ray
Platform for Convergence Research (NMRCoRe), KU Leuven, Celestijnenlaan
200F, 3000 Leuven, Belgium
- National
High Magnetic Field Laboratory, 1860 East Paul Dirac Drive, Tallahassee, Florida 32310, United States
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12
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Hoffmann A, De Prins M, Sree SP, Vanbutsele G, Smet S, Chandran CV, Radhakrishnan S, Breynaert E, Martens JA. Selective catalytic reduction of NO x with ammonia (NH 3-SCR) over copper loaded LEV type zeolites synthesized with different templates. Phys Chem Chem Phys 2022; 24:15428-15438. [PMID: 35708199 DOI: 10.1039/d2cp01512a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
LEV type zeolites were synthesized with four different structure-directing agents and converted to copper loaded NH3-SCR catalysts. The synthesis recipe was found to impact the respective Al population in the two topologically different framework sites in double and single 6-rings, resolvable by 27Al MAS NMR spectroscopy. Hydrothermal stability was found to be related to the silanol concentration, Si/Al ratio, particle size, crystal morphology, crystal defects, external surface area, and microporosity. Catalytic activity in NH3-SCR was dependent on preferential Al siting in the double 6-rings. Levinite synthesized using adamantylamine showed the strongest preference for Al atoms sitting in double 6-ring sites, and showed the highest catalytic turnover frequency. Unfortunately, because of the large crystal size, copper loading of this sample was limited to 0.6 wt% while other samples could be loaded with copper up to 3.3 wt%. An optimum combination of hydrothermal stability and catalytic activity was obtained with N,N'-bis-dimethylpentanediyldiammonium dibromide as structure-directing agent.
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Affiliation(s)
- Andreas Hoffmann
- Center for Surface Chemistry and Catalysis: Characterization and Application Team, KU Leuven, Celestijnenlaan 200F, Box 2461, 3001 Heverlee, Leuven, Belgium.
| | - Michiel De Prins
- Center for Surface Chemistry and Catalysis: Characterization and Application Team, KU Leuven, Celestijnenlaan 200F, Box 2461, 3001 Heverlee, Leuven, Belgium.
| | - Sreeprasanth Pulinthanathu Sree
- Center for Surface Chemistry and Catalysis: Characterization and Application Team, KU Leuven, Celestijnenlaan 200F, Box 2461, 3001 Heverlee, Leuven, Belgium.
| | - Gina Vanbutsele
- Center for Surface Chemistry and Catalysis: Characterization and Application Team, KU Leuven, Celestijnenlaan 200F, Box 2461, 3001 Heverlee, Leuven, Belgium.
| | - Sam Smet
- Center for Surface Chemistry and Catalysis: Characterization and Application Team, KU Leuven, Celestijnenlaan 200F, Box 2461, 3001 Heverlee, Leuven, Belgium.
| | - C Vinod Chandran
- Center for Surface Chemistry and Catalysis: Characterization and Application Team, KU Leuven, Celestijnenlaan 200F, Box 2461, 3001 Heverlee, Leuven, Belgium.
| | - Sambhu Radhakrishnan
- Center for Surface Chemistry and Catalysis: Characterization and Application Team, KU Leuven, Celestijnenlaan 200F, Box 2461, 3001 Heverlee, Leuven, Belgium.
| | - Eric Breynaert
- Center for Surface Chemistry and Catalysis: Characterization and Application Team, KU Leuven, Celestijnenlaan 200F, Box 2461, 3001 Heverlee, Leuven, Belgium.
| | - Johan A Martens
- Center for Surface Chemistry and Catalysis: Characterization and Application Team, KU Leuven, Celestijnenlaan 200F, Box 2461, 3001 Heverlee, Leuven, Belgium.
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13
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Houlleberghs M, Verheyden L, Voorspoels F, Chandran CV, Duerinckx K, Radhakrishnan S, Martens JA, Breynaert E. Dispersing carbomers, mixing technology matters! RSC Adv 2022; 12:7830-7834. [PMID: 35424734 PMCID: PMC8982170 DOI: 10.1039/d2ra00176d] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2022] [Accepted: 02/25/2022] [Indexed: 11/21/2022] Open
Abstract
Mixing dry carbomer powder with water using magneto-hydrodynamic mixing yielded carbomer dispersions with higher viscosity and increased storage modulus as compared to conventional high shear mixing. 1H NMR spectroscopy demonstrated this to be induced by a different water distribution, accompanied by lower ionization and higher degradation of the polymer in case of high shear mixing. This investigation reveals 1H MAS NMR to provide suitable sensitivity and resolution to detect structural changes induced in organic polymers during their hydration. Magnetohydrodynamic mixing yields carbomer dispersions with higher viscosity and higher storage modulus as compared to high shear mixing. 1H NMR reveals molecular level differences in water distribution, polymer degradation and charge stabilization.![]()
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Affiliation(s)
- Maarten Houlleberghs
- Characterization and Application Team (COK-kat), KU Leuven 3001 Heverlee Belgium
| | - Loes Verheyden
- Characterization and Application Team (COK-kat), KU Leuven 3001 Heverlee Belgium
| | - Filip Voorspoels
- Master of Bioscience Engineering: Catalytic Technology KU Leuven Belgium
| | - C Vinod Chandran
- Characterization and Application Team (COK-kat), KU Leuven 3001 Heverlee Belgium .,NMR-Xray platform for Convergence Research (NMRCoRe), KU Leuven 3001 Heverlee Belgium
| | - Karel Duerinckx
- Characterization and Application Team (COK-kat), KU Leuven 3001 Heverlee Belgium .,NMR-Xray platform for Convergence Research (NMRCoRe), KU Leuven 3001 Heverlee Belgium
| | - Sambhu Radhakrishnan
- Characterization and Application Team (COK-kat), KU Leuven 3001 Heverlee Belgium .,NMR-Xray platform for Convergence Research (NMRCoRe), KU Leuven 3001 Heverlee Belgium
| | - Johan A Martens
- Characterization and Application Team (COK-kat), KU Leuven 3001 Heverlee Belgium .,NMR-Xray platform for Convergence Research (NMRCoRe), KU Leuven 3001 Heverlee Belgium
| | - Eric Breynaert
- Characterization and Application Team (COK-kat), KU Leuven 3001 Heverlee Belgium .,NMR-Xray platform for Convergence Research (NMRCoRe), KU Leuven 3001 Heverlee Belgium
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14
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Radhakrishnan S, Lauwers K, Chandran CV, Trébosc J, Pulinthanathu Sree S, Martens JA, Taulelle F, Kirschhock CEA, Breynaert E. NMR Crystallography Reveals Carbonate Induced Al-Ordering in ZnAl Layered Double Hydroxide. Chemistry 2021; 27:15944-15953. [PMID: 34624150 DOI: 10.1002/chem.202101275] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2021] [Indexed: 11/08/2022]
Abstract
Layered double hydroxides (LDHs) serve a score of applications in catalysis, drug delivery, and environmental remediation. Smarter crystallography, combining X-ray diffraction and NMR spectroscopy revealed how interplay between carbonate and pH determines the LDH structure and Al ordering in ZnAl LDH. Carbonate intercalated ZnAl LDHs were synthesized at different pH (pH 8.5, pH 10.0, pH 12.5) with a Zn/Al ratio of 2, without subsequent hydrothermal treatment to avoid extensive recrystallisation. In ideal configuration, all Al cations should be part of the LDH and be coordinated with 6 Zn atoms, but NMR revealed two different Al local environments were present in all samples in a ratio dependent on synthesis pH. NMR-crystallography, integrating NMR spectroscopy and X-ray diffraction, succeeded to identify them as Al residing in the highly ordered crystalline phase, next to Al in disordered material. With increasing synthesis pH, crystallinity increased, and the side phase fraction decreased. Using 1 H-13 C, 13 C-27 Al HETCOR NMR in combination with 27 Al MQMAS, 27 Al-DQ-SQ measurements and Rietveld refinement on high-resolution PXRD data, the extreme anion exchange selectivity of these LDHs for CO3 2- over HCO3 - was linked to strict Al and CO3 2- ordering in the crystalline LDH. Even upon equilibration of the LDH in pure NaHCO3 solutions, only CO3 2- was adsorbed by the LDH. This reveals the structure directing role of bivalent cations such as CO3 2- during crystallization of [M2+ 4 M3+ 2 (OH)2 ]2+ [A2- ]1 ⋅yH2 O LDH phases.
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Affiliation(s)
- Sambhu Radhakrishnan
- NMRCoRe, KU Leuven, Celestijnenlaan 200F Box, 2461, 3001, Belgium.,Centre for Surface Chemistry and Catalysis, Characterization and Application Team (COK-KAT), KU Leuven, Celestijnenlaan 200F Box, 2461, 3001, Belgium
| | - Karl Lauwers
- Centre for Surface Chemistry and Catalysis, Characterization and Application Team (COK-KAT), KU Leuven, Celestijnenlaan 200F Box, 2461, 3001, Belgium
| | - C Vinod Chandran
- NMRCoRe, KU Leuven, Celestijnenlaan 200F Box, 2461, 3001, Belgium.,Centre for Surface Chemistry and Catalysis, Characterization and Application Team (COK-KAT), KU Leuven, Celestijnenlaan 200F Box, 2461, 3001, Belgium
| | - Julien Trébosc
- Univ. Lille, CNRS, INRAE, Centrale Lille, Univ. Artois, FR 2638 - IMEC - Institut Michel-Eugène Chevreul, 59000, Lille, France
| | - Sreeprasanth Pulinthanathu Sree
- Centre for Surface Chemistry and Catalysis, Characterization and Application Team (COK-KAT), KU Leuven, Celestijnenlaan 200F Box, 2461, 3001, Belgium
| | - Johan A Martens
- Centre for Surface Chemistry and Catalysis, Characterization and Application Team (COK-KAT), KU Leuven, Celestijnenlaan 200F Box, 2461, 3001, Belgium
| | - Francis Taulelle
- Centre for Surface Chemistry and Catalysis, Characterization and Application Team (COK-KAT), KU Leuven, Celestijnenlaan 200F Box, 2461, 3001, Belgium
| | - Christine E A Kirschhock
- Centre for Surface Chemistry and Catalysis, Characterization and Application Team (COK-KAT), KU Leuven, Celestijnenlaan 200F Box, 2461, 3001, Belgium
| | - Eric Breynaert
- NMRCoRe, KU Leuven, Celestijnenlaan 200F Box, 2461, 3001, Belgium.,Centre for Surface Chemistry and Catalysis, Characterization and Application Team (COK-KAT), KU Leuven, Celestijnenlaan 200F Box, 2461, 3001, Belgium
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15
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Asselman K, Pellens N, Radhakrishnan S, Chandran CV, Martens JA, Taulelle F, Verstraelen T, Hellström M, Breynaert E, Kirschhock CEA. Super-ions of sodium cations with hydrated hydroxide anions: inorganic structure-directing agents in zeolite synthesis. Mater Horiz 2021; 8:2576-2583. [PMID: 34870303 DOI: 10.1039/d1mh00733e] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
In inorganic zeolite formation, a direct correspondence between liquid state species in the synthesis and the supramolecular decoration of the pores in the as-made final zeolite has never been reported. In this paper, a direct link between the sodium speciation in the synthesis mixture and the pore structure and content of the final zeolite is demonstrated in the example of hydroxysodalite. Super-ions with 4 sodium cations bound by mono- and bihydrated hydroxide are identified as structure-directing agents for the formation of this zeolite. This documentation of inorganic solution species acting as a templating agent in zeolite formation opens new horizons for zeolite synthesis by design.
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Affiliation(s)
- Karel Asselman
- COK-Kat, KU Leuven, Celestijnenlaan 200F, 3001 Heverlee, Belgium.
| | - Nick Pellens
- COK-Kat, KU Leuven, Celestijnenlaan 200F, 3001 Heverlee, Belgium.
| | - Sambhu Radhakrishnan
- COK-Kat, KU Leuven, Celestijnenlaan 200F, 3001 Heverlee, Belgium.
- NMRCoRe, KU Leuven, Celestijnenlaan 200F, 3001 Heverlee, Belgium
| | - C Vinod Chandran
- COK-Kat, KU Leuven, Celestijnenlaan 200F, 3001 Heverlee, Belgium.
- NMRCoRe, KU Leuven, Celestijnenlaan 200F, 3001 Heverlee, Belgium
| | - Johan A Martens
- COK-Kat, KU Leuven, Celestijnenlaan 200F, 3001 Heverlee, Belgium.
- NMRCoRe, KU Leuven, Celestijnenlaan 200F, 3001 Heverlee, Belgium
| | - Francis Taulelle
- COK-Kat, KU Leuven, Celestijnenlaan 200F, 3001 Heverlee, Belgium.
- NMRCoRe, KU Leuven, Celestijnenlaan 200F, 3001 Heverlee, Belgium
| | - Toon Verstraelen
- Center for Molecular Modelling (CMM), Ghent University, Technologiepark 903, B-9052 Ghent, Belgium
| | - Matti Hellström
- Software for Chemistry and Materials B.V., 1081HV Amsterdam, The Netherlands
| | - Eric Breynaert
- COK-Kat, KU Leuven, Celestijnenlaan 200F, 3001 Heverlee, Belgium.
- NMRCoRe, KU Leuven, Celestijnenlaan 200F, 3001 Heverlee, Belgium
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16
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Geerts L, Geerts-Claes H, Skorikov A, Vermeersch J, Vanbutsele G, Galvita V, Constales D, Chandran CV, Radhakrishnan S, Seo JW, Breynaert E, Bals S, Sree SP, Martens JA. Spherical core-shell alumina support particles for model platinum catalysts. Nanoscale 2021; 13:4221-4232. [PMID: 33586739 DOI: 10.1039/d0nr08456e] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
γ- and δ-alumina are popular catalyst support materials. Using a hydrothermal synthesis method starting from aluminum nitrate and urea in diluted solution, spherical core-shell particles with a uniform particle size of about 1 μm were synthesized. Upon calcination at 1000 °C, the particles adopted a core-shell structure with a γ-alumina core and δ-alumina shell as evidenced by 2D and 3D electron microscopy and 27Al magic angle spinning nuclear magnetic resonance spectroscopy. The spherical alumina particles were loaded with Pt nanoparticles with an average size below 1 nm using the strong electrostatic adsorption method. Electron microscopy and energy dispersive X-ray spectroscopy revealed a homogeneous platinum dispersion over the alumina surface. These platinum loaded alumina spheres were used as a model catalyst for bifunctional catalysis. Physical mixtures of Pt/alumina spheres and spherical zeolite particles are equivalent to catalysts with platinum deposited on the zeolite itself facilitating the investigation of the catalyst components individually. The spherical alumina particles are very convenient supports for obtaining a homogeneous distribution of highly dispersed platinum nanoparticles. Obtaining such a small Pt particle size is challenging on other support materials such as zeolites. The here reported and well-characterized Pt/alumina spheres can be combined with any zeolite and used as a bifunctional model catalyst. This is an interesting strategy for the examination of the acid catalytic function without the interference of the supported platinum metal on the investigated acid material.
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Affiliation(s)
- Lisa Geerts
- KU Leuven, Center for Surface Chemistry and Catalysis, Celestijnenlaan 200F, 3001 Leuven, Belgium.
| | - Hannelore Geerts-Claes
- KU Leuven, Center for Surface Chemistry and Catalysis, Celestijnenlaan 200F, 3001 Leuven, Belgium.
| | - Alexander Skorikov
- University of Antwerp, Electron Microscopy for Materials Science, Groenenborgerlaan 171, 2020 Antwerpen, Belgium
| | - Julie Vermeersch
- KU Leuven, Center for Surface Chemistry and Catalysis, Celestijnenlaan 200F, 3001 Leuven, Belgium.
| | - Gina Vanbutsele
- KU Leuven, Center for Surface Chemistry and Catalysis, Celestijnenlaan 200F, 3001 Leuven, Belgium.
| | - Vladimir Galvita
- Ghent University, Laboratory for Chemical Technology, Technologiepark 125, 9052, Zwijnaarde, Belgium
| | - Denis Constales
- Ghent University, Department of Electronics and information systems, Krijgslaan 281 S8, 9000, Ghent, Belgium
| | - C Vinod Chandran
- KU Leuven, Center for Surface Chemistry and Catalysis, Celestijnenlaan 200F, 3001 Leuven, Belgium.
| | - Sambhu Radhakrishnan
- KU Leuven, Center for Surface Chemistry and Catalysis, Celestijnenlaan 200F, 3001 Leuven, Belgium.
| | - Jin Won Seo
- KU Leuven, Department of Materials Engineering, Kasteelpark Arenberg 44, bus 2450, 3001 Leuven, Belgium
| | - Eric Breynaert
- KU Leuven, Center for Surface Chemistry and Catalysis, Celestijnenlaan 200F, 3001 Leuven, Belgium.
| | - Sara Bals
- University of Antwerp, Electron Microscopy for Materials Science, Groenenborgerlaan 171, 2020 Antwerpen, Belgium
| | | | - Johan A Martens
- KU Leuven, Center for Surface Chemistry and Catalysis, Celestijnenlaan 200F, 3001 Leuven, Belgium.
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17
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Krishnaraj C, Sekhar Jena H, Bourda L, Laemont A, Pachfule P, Roeser J, Chandran CV, Borgmans S, Rogge SMJ, Leus K, Stevens CV, Martens JA, Van Speybroeck V, Breynaert E, Thomas A, Van Der Voort P. Strongly Reducing (Diarylamino)benzene-Based Covalent Organic Framework for Metal-Free Visible Light Photocatalytic H 2O 2 Generation. J Am Chem Soc 2020; 142:20107-20116. [PMID: 33185433 PMCID: PMC7705891 DOI: 10.1021/jacs.0c09684] [Citation(s) in RCA: 108] [Impact Index Per Article: 27.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
![]()
Photocatalytic
reduction of molecular oxygen is a promising route
toward sustainable production of hydrogen peroxide (H2O2). This challenging process requires photoactive semiconductors
enabling solar energy driven generation and separation of electrons
and holes with high charge transfer kinetics. Covalent organic frameworks
(COFs) are an emerging class of photoactive semiconductors, tunable
at a molecular level for high charge carrier generation and transfer.
Herein, we report two newly designed two-dimensional COFs based on
a (diarylamino)benzene linker that form a Kagome (kgm) lattice and show strong visible light absorption. Their high crystallinity
and large surface areas (up to 1165 m2·g–1) allow efficient charge transfer and diffusion. The diarylamine
(donor) unit promotes strong reduction properties, enabling these
COFs to efficiently reduce oxygen to form H2O2. Overall, the use of a metal-free, recyclable photocatalytic system
allows efficient photocatalytic solar transformations.
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Affiliation(s)
- Chidharth Krishnaraj
- COMOC - Center for Ordered Materials, Organometallics and Catalysis, Department of Chemistry, Ghent University, Krijgslaan 281-S3, 9000 Ghent, Belgium.,Department of Chemistry/Functional Materials, Technische Universität Berlin, Hardenbergstraße 40, 10623 Berlin, Germany
| | - Himanshu Sekhar Jena
- COMOC - Center for Ordered Materials, Organometallics and Catalysis, Department of Chemistry, Ghent University, Krijgslaan 281-S3, 9000 Ghent, Belgium
| | - Laurens Bourda
- COMOC - Center for Ordered Materials, Organometallics and Catalysis, Department of Chemistry, Ghent University, Krijgslaan 281-S3, 9000 Ghent, Belgium.,XStruct - Bio-Inorganic Chemistry, Department of Chemistry, Ghent University, Krijgslaan 281-S3, 9000 Ghent, Belgium
| | - Andreas Laemont
- COMOC - Center for Ordered Materials, Organometallics and Catalysis, Department of Chemistry, Ghent University, Krijgslaan 281-S3, 9000 Ghent, Belgium
| | - Pradip Pachfule
- Department of Chemistry/Functional Materials, Technische Universität Berlin, Hardenbergstraße 40, 10623 Berlin, Germany
| | - Jérôme Roeser
- Department of Chemistry/Functional Materials, Technische Universität Berlin, Hardenbergstraße 40, 10623 Berlin, Germany
| | - C Vinod Chandran
- NMRCoRe, Celestijnenlaan 200F, Box 2461, 3001 Leuven, Belgium.,Center for Surface Chemistry and Catalysis - Characterisation and Application Team (COK-kat), Department of Microbial and Molecular Systems (M2S), KU Leuven, Celestijnenlaan 200F, Box 2461, 3001 Leuven, Belgium
| | - Sander Borgmans
- Center for Molecular Modeling (CMM), Ghent University, Technologiepark 46, B-9052 Zwijnaarde, Belgium
| | - Sven M J Rogge
- Center for Molecular Modeling (CMM), Ghent University, Technologiepark 46, B-9052 Zwijnaarde, Belgium
| | - Karen Leus
- COMOC - Center for Ordered Materials, Organometallics and Catalysis, Department of Chemistry, Ghent University, Krijgslaan 281-S3, 9000 Ghent, Belgium
| | - Christian V Stevens
- Synthesis, Bioresources and Bioorganic Chemistry Research Group (SynBioC), Department of Green Chemistry and Technology, Ghent University, Coupure Links 653, 9000 Ghent, Belgium
| | - Johan A Martens
- NMRCoRe, Celestijnenlaan 200F, Box 2461, 3001 Leuven, Belgium.,Center for Surface Chemistry and Catalysis - Characterisation and Application Team (COK-kat), Department of Microbial and Molecular Systems (M2S), KU Leuven, Celestijnenlaan 200F, Box 2461, 3001 Leuven, Belgium
| | - Veronique Van Speybroeck
- Center for Molecular Modeling (CMM), Ghent University, Technologiepark 46, B-9052 Zwijnaarde, Belgium
| | - Eric Breynaert
- NMRCoRe, Celestijnenlaan 200F, Box 2461, 3001 Leuven, Belgium.,Center for Surface Chemistry and Catalysis - Characterisation and Application Team (COK-kat), Department of Microbial and Molecular Systems (M2S), KU Leuven, Celestijnenlaan 200F, Box 2461, 3001 Leuven, Belgium
| | - Arne Thomas
- Department of Chemistry/Functional Materials, Technische Universität Berlin, Hardenbergstraße 40, 10623 Berlin, Germany
| | - Pascal Van Der Voort
- COMOC - Center for Ordered Materials, Organometallics and Catalysis, Department of Chemistry, Ghent University, Krijgslaan 281-S3, 9000 Ghent, Belgium
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18
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Radhakrishnan S, Colaux H, Chandran CV, Dom D, Verheyden L, Taulelle F, Martens J, Breynaert E. Trace Level Detection and Quantification of Crystalline Silica in an Amorphous Silica Matrix with Natural Abundance 29Si NMR. Anal Chem 2020; 92:13004-13009. [PMID: 32830954 DOI: 10.1021/acs.analchem.0c01756] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A protocol for the detection of trace amounts of quartz in amorphous silica gels by NMR spectroscopy was developed and tested on commercially available samples. Using natural abundance 29Si MAS NMR spectroscopy with CPMG acquisition and standard addition of crystalline quartz, quantitative detection of quartz concentrations down to 0.1% wt. was achieved. CPMG permitted to suppress the amorphous silica-derived signal, benefitting from the extremely long T2 relaxation time of quartz in 29Si and hence dramatically increasing the sensitivity. Dedicated post-processing exploiting the known CPMG spikelet frequencies allowed to probe the near-absence of quartz in commercial, 100% silica samples, enabling assessment of conformity of unknown samples to EU legislation (REACH).
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Affiliation(s)
- Sambhu Radhakrishnan
- NMRCoRe, Celestijnenlaan 200F, box 2461, 3001 Leuven, Belgium.,Center for Surface Chemistry and Catalysis - Characterisation and Application Team (COK-kat), Department of Microbial and Molecular Systems (M2S), KU Leuven, Celestijnenlaan 200F, box 2461, 3001 Leuven, Belgium
| | - Henri Colaux
- Center for Surface Chemistry and Catalysis - Characterisation and Application Team (COK-kat), Department of Microbial and Molecular Systems (M2S), KU Leuven, Celestijnenlaan 200F, box 2461, 3001 Leuven, Belgium
| | - C Vinod Chandran
- NMRCoRe, Celestijnenlaan 200F, box 2461, 3001 Leuven, Belgium.,Center for Surface Chemistry and Catalysis - Characterisation and Application Team (COK-kat), Department of Microbial and Molecular Systems (M2S), KU Leuven, Celestijnenlaan 200F, box 2461, 3001 Leuven, Belgium
| | - Dirk Dom
- NMRCoRe, Celestijnenlaan 200F, box 2461, 3001 Leuven, Belgium.,Center for Surface Chemistry and Catalysis - Characterisation and Application Team (COK-kat), Department of Microbial and Molecular Systems (M2S), KU Leuven, Celestijnenlaan 200F, box 2461, 3001 Leuven, Belgium
| | - Loes Verheyden
- Center for Surface Chemistry and Catalysis - Characterisation and Application Team (COK-kat), Department of Microbial and Molecular Systems (M2S), KU Leuven, Celestijnenlaan 200F, box 2461, 3001 Leuven, Belgium
| | - Francis Taulelle
- NMRCoRe, Celestijnenlaan 200F, box 2461, 3001 Leuven, Belgium.,Center for Surface Chemistry and Catalysis - Characterisation and Application Team (COK-kat), Department of Microbial and Molecular Systems (M2S), KU Leuven, Celestijnenlaan 200F, box 2461, 3001 Leuven, Belgium
| | - Johan Martens
- NMRCoRe, Celestijnenlaan 200F, box 2461, 3001 Leuven, Belgium.,Center for Surface Chemistry and Catalysis - Characterisation and Application Team (COK-kat), Department of Microbial and Molecular Systems (M2S), KU Leuven, Celestijnenlaan 200F, box 2461, 3001 Leuven, Belgium
| | - Eric Breynaert
- NMRCoRe, Celestijnenlaan 200F, box 2461, 3001 Leuven, Belgium.,Center for Surface Chemistry and Catalysis - Characterisation and Application Team (COK-kat), Department of Microbial and Molecular Systems (M2S), KU Leuven, Celestijnenlaan 200F, box 2461, 3001 Leuven, Belgium
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19
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Ostyn NR, Steele JA, De Prins M, Sree SP, Chandran CV, Wangermez W, Vanbutsele G, Seo JW, Roeffaers MBJ, Breynaert E, Martens JA. Low-temperature activation of carbon black by selective photocatalytic oxidation. Nanoscale Adv 2019; 1:2873-2880. [PMID: 36133590 PMCID: PMC9416906 DOI: 10.1039/c9na00188c] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/27/2019] [Accepted: 05/21/2019] [Indexed: 06/15/2023]
Abstract
Carbon black is chemically modified by selective photocatalytic oxidation, removing amorphous carbon and functionalizing the graphitic fraction to produce porous, graphitized carbon black, commonly used as an adsorbent in chromatography. In contrast to pyrolytic treatments, this photocatalytic modification proceeds under mild reaction conditions using oxygen, nitric oxide, water vapor and a titanium dioxide photocatalyst at 150 °C. The photo-oxidation can be performed both with the photocatalyst in close proximity (contact mode) or physically separated from the carbon. Structural analysis of remotely photo-oxidized carbon black reveals increased hydrophilic properties as compared to pyrolysis at 700 °C in a N2 atmosphere. Carbon black photo-oxidation selectively mineralizes sp3-hybridized carbon, leading to enhanced graphitization. This results in an overall improved structural ordering by enriching carbon black with sp2-hybridized graphitic carbon showing decreased interplanar distance, accompanied by a twofold increase in the specific surface area. In addition, the photo-oxidized material is activated by the presence of oxygen functionalities on the graphitic carbon fraction, further enhancing the adsorptive properties.
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Affiliation(s)
- Niels R Ostyn
- Centre for Surface Chemistry and Catalysis, KU Leuven Celestijnenlaan 200F, box 2461 3001 Heverlee Belgium +32 16 32 16 37
| | - Julian A Steele
- Centre for Surface Chemistry and Catalysis, KU Leuven Celestijnenlaan 200F, box 2461 3001 Heverlee Belgium +32 16 32 16 37
| | - Michiel De Prins
- Centre for Surface Chemistry and Catalysis, KU Leuven Celestijnenlaan 200F, box 2461 3001 Heverlee Belgium +32 16 32 16 37
| | | | - C Vinod Chandran
- Centre for Surface Chemistry and Catalysis, KU Leuven Celestijnenlaan 200F, box 2461 3001 Heverlee Belgium +32 16 32 16 37
| | - Wauter Wangermez
- Centre for Surface Chemistry and Catalysis, KU Leuven Celestijnenlaan 200F, box 2461 3001 Heverlee Belgium +32 16 32 16 37
| | - Gina Vanbutsele
- Centre for Surface Chemistry and Catalysis, KU Leuven Celestijnenlaan 200F, box 2461 3001 Heverlee Belgium +32 16 32 16 37
| | - Jin Won Seo
- Department of Materials Engineering, KU Leuven Kasteelpark Arenberg 44 3001 Heverlee Belgium
| | - Maarten B J Roeffaers
- Centre for Surface Chemistry and Catalysis, KU Leuven Celestijnenlaan 200F, box 2461 3001 Heverlee Belgium +32 16 32 16 37
| | - Eric Breynaert
- Centre for Surface Chemistry and Catalysis, KU Leuven Celestijnenlaan 200F, box 2461 3001 Heverlee Belgium +32 16 32 16 37
| | - Johan A Martens
- Centre for Surface Chemistry and Catalysis, KU Leuven Celestijnenlaan 200F, box 2461 3001 Heverlee Belgium +32 16 32 16 37
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20
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Chandran CV, Kirschhock CEA, Radhakrishnan S, Taulelle F, Martens JA, Breynaert E. Alumina: discriminative analysis using 3D correlation of solid-state NMR parameters. Chem Soc Rev 2019; 48:134-156. [PMID: 30444247 DOI: 10.1039/c8cs00321a] [Citation(s) in RCA: 57] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Synthetic transition aluminas (χ, κ, θ, γ, δ, η, ρ) exhibit unique adsorptive and catalytic properties leading to numerous practical applications. Generated by thermal transformation of aluminium (oxy)hydroxides, structural differences between them arise from the variability of aluminium coordination numbers and degree of dehydroxylation. Unequivocal identification of these phases using X-ray diffraction has proven to be very difficult. Quadrupolar interactions of 27Al nuclei, highly sensitive to each site symmetry, render advanced 27Al solid-state NMR a unique spectroscopic tool to fingerprint and identify the different phases. In this paper, 27Al NMR spectroscopic data on alumina reported in literature are collected in a comprehensive library. Based on this dataset, a new 3D correlative method of NMR parameters is presented, enabling fingerprinting and identification of such phases. Providing a gold standard from crystalline samples, this approach demonstrates that any sort of crystalline, ill crystallized or amorphous, mixed periodic or aperiodically ordered transition alumina can now be assessed beyond the current limitations of characterisation. Adopting the presented approach as a standard characterisation of alumina samples will readily reveal NMR parameter-structure-property relations suitable to develop new or improved applications of alumina. Methodological guidance is provided to assist consistent implementation of this characterisation throughout the fields involved.
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Affiliation(s)
- C Vinod Chandran
- Center for Surface Chemistry and Catalysis, Celestijnenlaan 200 F - box 2461, KU Leuven, 3001 Heverlee, Belgium.
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21
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Vallaey B, Radhakrishnan S, Heylen S, Chandran CV, Taulelle F, Breynaert E, Martens JA. Reversible room temperature ammonia gas absorption in pore water of microporous silica-alumina for sensing applications. Phys Chem Chem Phys 2018; 20:13528-13536. [PMID: 29726873 DOI: 10.1039/c8cp01586d] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Microporous silica and silica-alumina powders exhibit a reversible uptake and release of ammonia gas from water vapor containing gas mixtures at ambient temperature, with capacities of 0.9 and 2.0 mmol g-1 in the presence of 100 ppm and 1000 ppm NH3, respectively. The ammonia trapping mechanism was revealed using a combination of direct excitation 1H MAS, 1H-1H EXSY and 1H DQ-SQ NMR spectroscopy, indicating that the major part of the captured ammonia is blended in the hydrogen bonded water network in the pores of the adsorbent. A small fraction is irreversibly bound as result of protonation and chemisorption. While common ammonia adsorbents need thermal regeneration, microporous silica-alumina can be regenerated by sweeping with dry gas at ambient temperature, desorbing the physisorbed fraction together with occluded water. As carbon dioxide does not interfere with the ammonia absorption process, this reversible absorption process of ammonia gas at ambient temperature is particularly attractive for sensor applications.
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Affiliation(s)
- Brecht Vallaey
- KU Leuven, Centre for Surface Chemistry and Catalysis, Celestijnenlaan 200F, Leuven B-3001, Belgium.
| | - Sambhu Radhakrishnan
- KU Leuven, Centre for Surface Chemistry and Catalysis, Celestijnenlaan 200F, Leuven B-3001, Belgium.
| | - Steven Heylen
- KU Leuven, Centre for Surface Chemistry and Catalysis, Celestijnenlaan 200F, Leuven B-3001, Belgium.
| | - C Vinod Chandran
- KU Leuven, Centre for Surface Chemistry and Catalysis, Celestijnenlaan 200F, Leuven B-3001, Belgium.
| | - Francis Taulelle
- KU Leuven, Centre for Surface Chemistry and Catalysis, Celestijnenlaan 200F, Leuven B-3001, Belgium.
| | - Eric Breynaert
- KU Leuven, Centre for Surface Chemistry and Catalysis, Celestijnenlaan 200F, Leuven B-3001, Belgium.
| | - Johan A Martens
- KU Leuven, Centre for Surface Chemistry and Catalysis, Celestijnenlaan 200F, Leuven B-3001, Belgium.
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22
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Uhlendorf J, Ruprecht B, Witt E, Chandran CV, Dörrer L, Hüger E, Strauß F, Heitjans P, Schmidt H. Slow Lithium Transport in Metal Oxides on the Nanoscale. Z PHYS CHEM 2017. [DOI: 10.1515/zpch-2016-0939] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Abstract
This article reports on Li self-diffusion in lithium containing metal oxide compounds. Case studies on LiNbO3, Li3NbO4, LiTaO3, LiAlO2, and LiGaO2 are presented. The focus is on slow diffusion processes on the nanometer scale investigated by macroscopic tracer methods (secondary ion mass spectrometry, neutron reflectometry) and microscopic methods (nuclear magnetic resonance spectroscopy, conductivity spectroscopy) in comparison. Special focus is on the influence of structural disorder on diffusion.
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Affiliation(s)
- Johanna Uhlendorf
- Technische Universität Clausthal , Institut für Metallurgie, AG Mikrokinetik , Clausthal-Zellerfeld , Germany
| | - Benjamin Ruprecht
- Institut für Physikalische Chemie und Elektrochemie , Leibniz Universität Hannover , Hannover , Germany
| | - Elena Witt
- Institut für Physikalische Chemie und Elektrochemie , Leibniz Universität Hannover , Hannover , Germany
| | - C. Vinod Chandran
- Institut für Physikalische Chemie und Elektrochemie , Leibniz Universität Hannover , Hannover , Germany
| | - Lars Dörrer
- Technische Universität Clausthal , Institut für Metallurgie, AG Mikrokinetik , Clausthal-Zellerfeld , Germany
| | - Erwin Hüger
- Technische Universität Clausthal , Institut für Metallurgie, AG Mikrokinetik , Clausthal-Zellerfeld , Germany
| | - Florian Strauß
- Technische Universität Clausthal , Institut für Metallurgie, AG Mikrokinetik , Clausthal-Zellerfeld , Germany
- Institut für Physikalische Chemie und Elektrochemie , Leibniz Universität Hannover , Hannover , Germany
- CZM – Clausthaler Zentrum für Materialtechnik , Clausthal-Zellerfeld , Germany
| | - Paul Heitjans
- Institut für Physikalische Chemie und Elektrochemie , Leibniz Universität Hannover , Hannover , Germany
- ZFM – Zentrum für Festkörperchemie und Neue Materialien , Hannover , Germany
| | - Harald Schmidt
- Technische Universität Clausthal , Institut für Metallurgie, AG Mikrokinetik , Clausthal-Zellerfeld , Germany
- CZM – Clausthaler Zentrum für Materialtechnik , Clausthal-Zellerfeld , Germany
- ZFM – Zentrum für Festkörperchemie und Neue Materialien , Hannover , Germany
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23
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Skripov AV, Volgmann K, Chandran CV, Skoryunov RV, Babanova OA, Soloninin AV, Orimo SI, Heitjans P. NMR Studies of Lithium Diffusion in Li3(NH2)2I Over Wide Range of Li+ Jump Rates. Z PHYS CHEM 2017. [DOI: 10.1515/zpch-2016-0925] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Abstract
We have studied the Li diffusion in the complex hydride Li3(NH2)2I which appears to exhibit fast Li ion conduction. To get a detailed insight into the Li motion, we have applied 7Li nuclear magnetic resonance spectroscopy methods, such as spin-lattice relaxation in the laboratory and rotating frames of reference, as well as spin-alignment echo. This combined approach allows us to probe Li jump rates over the wide dynamic range (~102–109 s−1). The spin-lattice relaxation data in the range 210–410 K can be interpreted in terms of a thermally-activated Li jump process with a certain distribution of activation energies. However, the low-temperature spin-alignment echo decays at T≤200 K suggest the presence of another Li jump process with the very low effective activation energy.
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Affiliation(s)
- Alexander V. Skripov
- Institute of Metal Physics, Ural Branch of the Russian Academy of Sciences , S. Kovalevskoi 18 , Ekaterinburg 620990 , Russia
| | - Kai Volgmann
- Institut für Physikalische Chemie und Elektrochemie, Leibniz Universität Hannover , Callinstr. 3-3a , Hannover 30167 , Germany
| | - C. Vinod Chandran
- Institut für Physikalische Chemie und Elektrochemie, Leibniz Universität Hannover , Callinstr. 3-3a , Hannover 30167 , Germany
| | - Roman V. Skoryunov
- Institute of Metal Physics, Ural Branch of the Russian Academy of Sciences , S. Kovalevskoi 18 , Ekaterinburg 620990 , Russia
| | - Olga A. Babanova
- Institute of Metal Physics, Ural Branch of the Russian Academy of Sciences , S. Kovalevskoi 18 , Ekaterinburg 620990 , Russia
| | - Alexei V. Soloninin
- Institute of Metal Physics, Ural Branch of the Russian Academy of Sciences , S. Kovalevskoi 18 , Ekaterinburg 620990 , Russia
| | - Shin-ichi Orimo
- Institute for Materials Research , Tohoku University , Sendai 980-8577 , Japan
- WPI-Advanced Institute for Materials Research , Tohoku University , Sendai 980-8577 , Japan
| | - Paul Heitjans
- Institut für Physikalische Chemie und Elektrochemie, Leibniz Universität Hannover , Callinstr. 3-3a , Hannover 30167 , Germany
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24
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Tsai CL, Roddatis V, Chandran CV, Ma Q, Uhlenbruck S, Bram M, Heitjans P, Guillon O. Li7La3Zr2O12 Interface Modification for Li Dendrite Prevention. ACS Appl Mater Interfaces 2016; 8:10617-26. [PMID: 27029789 DOI: 10.1021/acsami.6b00831] [Citation(s) in RCA: 189] [Impact Index Per Article: 23.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Al-contaminated Ta-substituted Li7La3Zr2O12 (LLZ:Ta), synthesized via solid-state reaction, and Al-free Ta-substituted Li7La3Zr2O12, fabricated by hot-press sintering (HP-LLZ:Ta), have relative densities of 92.7% and 99.0%, respectively. Impedance spectra show the total conductivity of LLZ:Ta to be 0.71 mS cm(-1) at 30 °C and that of HP-LLZ:Ta to be 1.18 mS cm(-1). The lower total conductivity for LLZ:Ta than HP-LLZ:Ta was attributed to the higher grain boundary resistance and lower relative density of LLZ:Ta, as confirmed by their microstructures. Constant direct current measurements of HP-LLZ:Ta with a current density of 0.5 mA cm(-2) suggest that the short circuit formation was neither due to the low relative density of the samples nor the reduction of Li-Al glassy phase at grain boundaries. TEM, EELS, and MAS NMR were used to prove that the short circuit was from Li dendrite formation inside HP-LLZ:Ta, which took place along the grain boundaries. The Li dendrite formation was found to be mostly due to the inhomogeneous contact between LLZ solid electrolyte and Li electrodes. By flatting the surface of the LLZ:Ta pellets and using thin layers of Au buffer to improve the contact between LLZ:Ta and Li electrodes, the interface resistance could be dramatically reduced, which results in short-circuit-free cells when running a current density of 0.5 mA cm(-2) through the pellets. Temperature-dependent stepped current density galvanostatic cyclings were also carried out to determine the critical current densities for the short circuit formation. The short circuit that still occurred at higher current density is due to the inhomogeneous dissolution and deposition of metallic Li at the interfaces of Li electrodes and LLZ solid electrolyte when cycling the cell at large current densities.
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Affiliation(s)
- Chih-Long Tsai
- Institute of Energy and Climate Research, Materials Synthesis and Processing (IEK-1), Forschungszentrum Jülich GmbH , 52425 Jülich, Germany
- Jülich Aachen Research Alliance: JARA-Energy
| | - Vladimir Roddatis
- Institute of Materials Physics, University of Göttingen , Friedrich-Hund-Platz 1, 37077 Göttingen, Germany
| | - C Vinod Chandran
- Institute of Physical Chemistry and Electrochemistry, Leibniz University Hannover , Callinstrasse 3-3a, 30167 Hannover, Germany
| | - Qianli Ma
- Institute of Energy and Climate Research, Materials Synthesis and Processing (IEK-1), Forschungszentrum Jülich GmbH , 52425 Jülich, Germany
- Jülich Aachen Research Alliance: JARA-Energy
| | - Sven Uhlenbruck
- Institute of Energy and Climate Research, Materials Synthesis and Processing (IEK-1), Forschungszentrum Jülich GmbH , 52425 Jülich, Germany
- Jülich Aachen Research Alliance: JARA-Energy
| | - Martin Bram
- Institute of Energy and Climate Research, Materials Synthesis and Processing (IEK-1), Forschungszentrum Jülich GmbH , 52425 Jülich, Germany
- Jülich Aachen Research Alliance: JARA-Energy
| | - Paul Heitjans
- Institute of Physical Chemistry and Electrochemistry, Leibniz University Hannover , Callinstrasse 3-3a, 30167 Hannover, Germany
| | - Olivier Guillon
- Institute of Energy and Climate Research, Materials Synthesis and Processing (IEK-1), Forschungszentrum Jülich GmbH , 52425 Jülich, Germany
- Jülich Aachen Research Alliance: JARA-Energy
- Institute of Mineral Engineering, Rheinisch-Westfälische Technische Hochschule (RWTH) Aachen University, Mauerstrasse 5, 52064 Aachen, Germany
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25
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Abstract
Abstract
In this work nuclear magnetic resonance (NMR) and impedance
spectroscopy (IS) studies on Li ion dynamics in
microcrystalline γ-LiAlO2 are presented. The sample
was prepared by solid state synthesis between Li2CO3 and
Al2O3 in air, followed by a quenching procedure. The
presence of phase-pure γ-LiAlO2 was confirmed by
X-ray powder diffraction including Rietveld refinement. Further
structural characterization was done with 6Li, 7Li
and 27Al NMR. Several NMR techniques such as spin-lattice
relaxation measurements, motional narrowing experiments, as well as
spin-alignment echo were employed for the investigation of Li
ion diffusion. The measurements were carried out at high temperatures
(up to 970 K) in order to access the regime of Li
ion motion being very slow. The dc conductivities measured by IS in
the temperature range from 680 K to 870 K were
converted to diffusion coefficients being compatible with those
obtained by NMR.
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Affiliation(s)
- Elena Witt
- Institut für Physikalische Chemie und Elektrochemie, and ZFM – Center for Solid State Chemistry and New Materials, Leibniz Universität Hannover, Callinstr. 3–3a, 30167 Hannover, Germany
| | - Suliman Nakhal
- Institut für Chemie, Technische Universität Berlin, Straße des 17. Juni 135, 10623 Berlin, Germany
| | - C. Vinod Chandran
- Institut für Physikalische Chemie und Elektrochemie, and ZFM – Center for Solid State Chemistry and New Materials, Leibniz Universität Hannover, Callinstr. 3–3a, 30167 Hannover, Germany
| | - Martin Lerch
- Institut für Chemie, Technische Universität Berlin, Straße des 17. Juni 135, 10623 Berlin, Germany
| | - Paul Heitjans
- Institut für Physikalische Chemie und Elektrochemie, and ZFM – Center for Solid State Chemistry and New Materials, Leibniz Universität Hannover, Callinstr. 3–3a, 30167 Hannover, Germany
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Fu L, Tang K, Oh H, Manickam K, Bräuniger T, Chandran CV, Menzel A, Hirscher M, Samuelis D, Maier J. "Job-Sharing" Storage of Hydrogen in Ru/Li₂O Nanocomposites. Nano Lett 2015; 15:4170-5. [PMID: 25915434 DOI: 10.1021/acs.nanolett.5b01320] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
A "job-sharing" hydrogen storage mechanism is proposed and experimentally investigated in Ru/Li2O nanocomposites in which H(+) is accommodated on the Li2O side, while H(-) or e(-) is stored on the side of Ru. Thermal desorption-mass spectroscopy results show that after loading with D2, Ru/Li2O exhibits an extra desorption peak, which is in contrast to Ru nanoparticles or ball-milled Li2O alone, indicating a synergistic hydrogen storage effect due to the presence of both phases. By varying the ratio of the two phases, it is shown that the effect increases monotonically with the area of the heterojunctions, indicating interface related hydrogen storage. X-ray diffraction, Fourier transform infrared spectroscopy, and nuclear magnetic resonance results show that a weak LiO···D bond is formed after loading in Ru/Li2O nanocomposites with D2. The storage-pressure curve seems to favor H(+)/H(-) over H(+)/e(-) mechanism.
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Affiliation(s)
- Lijun Fu
- †Max Planck Institute for Solid State Research, Heisenbergstrasse 1, Stuttgart, Germany
| | - Kun Tang
- †Max Planck Institute for Solid State Research, Heisenbergstrasse 1, Stuttgart, Germany
| | - Hyunchul Oh
- ‡Max Planck Institute for Intelligent Systems, Heisenbergstrasse 3, Stuttgart, Germany
| | - Kandavel Manickam
- ‡Max Planck Institute for Intelligent Systems, Heisenbergstrasse 3, Stuttgart, Germany
| | - Thomas Bräuniger
- †Max Planck Institute for Solid State Research, Heisenbergstrasse 1, Stuttgart, Germany
| | - C Vinod Chandran
- †Max Planck Institute for Solid State Research, Heisenbergstrasse 1, Stuttgart, Germany
| | - Alexander Menzel
- §Institute of Physical Chemistry, University of Innsbruck, Innrain 80-82, Innsbruck, Austria
| | - Michael Hirscher
- ‡Max Planck Institute for Intelligent Systems, Heisenbergstrasse 3, Stuttgart, Germany
| | - Dominik Samuelis
- †Max Planck Institute for Solid State Research, Heisenbergstrasse 1, Stuttgart, Germany
| | - Joachim Maier
- †Max Planck Institute for Solid State Research, Heisenbergstrasse 1, Stuttgart, Germany
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Chandran CV, Hempel G, Bräuniger T. 19F-decoupling of half-integer spin quadrupolar nuclei in solid-state NMR: application of frequency-swept decoupling methods. Solid State Nucl Magn Reson 2011; 40:84-87. [PMID: 21856132 DOI: 10.1016/j.ssnmr.2011.07.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2011] [Revised: 07/28/2011] [Accepted: 07/29/2011] [Indexed: 05/31/2023]
Abstract
In solid-state NMR studies of minerals and ion conductors, quadrupolar nuclei like (7)Li, (23)Na or (133)Cs are frequently situated in close proximity to fluorine, so that application of (19)F decoupling is beneficial for spectral resolution. Here, we compare the decoupling efficiency of various multi-pulse decoupling sequences by acquiring (19)F-decoupled (23)Na-NMR spectra of cryolite (Na(3)AlF(6)). Whereas the MAS spectrum is only marginally affected by application of (19)F decoupling, the 3Q-filtered (23)Na signal is very sensitive to it, as the de-phasing caused by the dipolar interaction between sodium and fluorine is three-fold magnified. Experimentally, we find that at moderate MAS speeds, the decoupling efficiencies of the frequency-swept decoupling schemes SW(f)-TPPM and SW(f)-SPINAL are significantly better than the conventional TPPM and SPINAL sequences. The frequency-swept sequences are therefore the methods of choice for efficient decoupling of quadrupolar nuclei with half-integer spin from fluorine.
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Affiliation(s)
- C Vinod Chandran
- Max-Planck-Institute of Solid-State Research, Stuttgart, Germany
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Paul S, Vinod Chandran C, Bräuniger T, Madhu PK. Sweep direction and efficiency of the swept-frequency two pulse phase modulated scheme for heteronuclear dipolar-decoupling in solid-state NMR. J Magn Reson 2011; 209:261-268. [PMID: 21345704 DOI: 10.1016/j.jmr.2011.01.019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2010] [Revised: 01/14/2011] [Accepted: 01/19/2011] [Indexed: 05/30/2023]
Abstract
We present here a bimodal Floquet theoretical and experimental investigation of the direction of sweep in the swept-frequency two pulse phase modulated (SW(f)-TPPM) scheme used for heteronuclear dipolar decoupling in solid-state NMR. The efficiency of the decoupling turns out to be independent of the sweep direction.
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Affiliation(s)
- Subhradip Paul
- Department of Chemical Sciences, Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Mumbai, India
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Chandran CV, Madhu PK, Wormald P, Bräuniger T. Frequency-swept pulse sequences for 19F heteronuclear spin decoupling in solid-state NMR. J Magn Reson 2010; 206:255-263. [PMID: 20729111 DOI: 10.1016/j.jmr.2010.07.018] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/09/2010] [Revised: 07/19/2010] [Accepted: 07/26/2010] [Indexed: 05/29/2023]
Abstract
Heteronuclear spin decoupling pulse sequences in solid-state NMR have mostly been designed and applied for irradiating 1H as the abundant nucleus. Here, a systematic comparison of different methods for decoupling 19F in rigid organic solids is presented, with a special emphasis on the recently introduced frequency-swept sequences. An extensive series of NMR experiments at different MAS frequencies was conducted on fluorinated model compounds, in combination with large sets of numerical simulations. From both experiments and simulations it can be concluded that the frequency-swept sequences SWf-TPPM and SWf-SPINAL deliver better and more robust spin decoupling than the original sequences SPINAL and TPPM. Whereas the existence of a large chemical shift anisotropy and isotropic shift dispersion for 19F does compromise the decoupling efficiency, the relative performance hierarchy of the sequences remains unaffected. Therefore, in the context of rigid organic solids under moderate MAS frequencies, the performance trends observed for 19F decoupling are very similar to those observed for 1H decoupling.
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Affiliation(s)
- C Vinod Chandran
- Max-Planck-Institute of Solid-State Research, Heisenbergstr. 1, 70569 Stuttgart, Germany
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Chandran CV, Cuny J, Gautier R, Le Pollès L, Pickard CJ, Bräuniger T. Improving sensitivity and resolution of MQMAS spectra: a 45Sc-NMR case study of scandium sulphate pentahydrate. J Magn Reson 2010; 203:226-235. [PMID: 20089429 DOI: 10.1016/j.jmr.2009.12.021] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2009] [Revised: 12/18/2009] [Accepted: 12/24/2009] [Indexed: 05/28/2023]
Abstract
To efficiently obtain multiple-quantum magic-angle spinning (MQMAS) spectra of the nuclide 45Sc (I=7/2), we have combined several previously suggested techniques to enhance the signal-to-noise ratio and to improve spectral resolution for the test sample, scandium sulphate pentahydrate (ScSPH). Whereas the 45Sc-3QMAS spectrum of ScSPH does not offer sufficient resolution to clearly distinguish between the 3 scandium sites present in the crystal structure, these sites are well-resolved in the 5QMAS spectrum. The loss of sensitivity incurred by using MQMAS with 5Q coherence order is partly compensated for by using fast-amplitude modulated (FAM) sequences to improve the efficiency of both 5Q coherence excitation and conversion. Also, heteronuclear decoupling is employed to minimise dephasing of the 45Sc signal during the 5Q evolution period due to dipolar couplings with the water protons in the ScSPH sample. Application of multi-pulse decoupling schemes such as TPPM and SPINAL results in improved sensitivity and resolution in the F(1) (isotropic) dimension of the 5QMAS spectrum, the best results being achieved with the recently suggested SW(f)-TPPM sequence. By numerical fitting of the 45Sc-NMR spectra of ScSPH from 3QMAS, 5QMAS and single-quantum MAS at magnetic fields B(0)=9.4 T and 17.6 T, the isotropic chemical shift delta(iso), the quadrupolar coupling constant chi, and the asymmetry parameter eta were obtained. Averaging over all experiments, the NMR parameters determined for the 3 scandium sites, designated (a), (b) and (c) are: delta(iso)(a)=-15.5+/-0.5 ppm, chi(a)=5.60+/-0.10 MHz, eta(a)=0.06+/-0.05; delta(iso)(b)=-12.9+/-0.5 ppm, chi(b)=4.50+/-0.10 MHz, eta(b)=1.00+/-0.00; and delta(iso)(c)=-4.7+/-0.2 ppm, chi(c)=4.55+/-0.05 MHz, eta(c)=0.50+/-0.02. The NMR scandium species were assigned to the independent crystallographic sites by evaluating their experimental response to proton decoupling, and by density functional theory (DFT) calculations using the PAW and GIPAW approaches, in the following way: Sc(1) to (c), Sc(2) to (a), and Sc(3) to (b). The need to compute NMR parameters using an energy-optimised crystal structure is once again demonstrated.
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Affiliation(s)
- C Vinod Chandran
- Max-Planck-Institute of Solid-State Research, Heisenbergstr. 1, D-70569 Stuttgart, Germany
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Chandran CV, Bräuniger T. Efficient heteronuclear dipolar decoupling in solid-state NMR using frequency-swept SPINAL sequences. J Magn Reson 2009; 200:226-232. [PMID: 19631567 DOI: 10.1016/j.jmr.2009.07.006] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/25/2009] [Revised: 07/01/2009] [Accepted: 07/04/2009] [Indexed: 05/28/2023]
Abstract
Aiming to improve heteronuclear spin decoupling efficiency in NMR spectroscopy of solids and liquid crystals, we have modified the original Small Phase Incremental ALteration (SPINAL) sequence by incorporating a frequency sweep into it. For the resulting sequence, termed SW(f)-SPINAL, the decoupling performance of a large number of sweep variants was explored by both numerical simulations and NMR experiments. It is found that introducing a frequency sweep generally increases both the 'on-resonance' decoupling performance and the robustness towards parameter offsets compared to the original SPINAL sequence. This validates the concept of extending the range of efficient decoupling by introducing frequency sweeps, which was recently suggested in the context of the frequency-swept SW(f)-TPPM method. The sequence found to be best performing among the SW(f)-SPINAL variants consists of fully swept 16 pulse pairs and is designated SW(f)(lin)(32)-SPINAL-32. Its good decoupling performance for rigid spin systems is confirmed by numerical simulations and also experimentally, by evaluating the CH(2) resonance of a powder sample of l-tyrosine under MAS. For moderate MAS frequencies, the new sequence matches the decoupling achieved with SW(f)-TPPM, and outperforms all other tested sequences, including TPPM and SPINAL-64. SW(f)(lin)(32)-SPINAL-32 also shows excellent decoupling characteristics for liquid crystalline systems, as exemplified by experiments on the 5CB liquid crystal.
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Affiliation(s)
- C Vinod Chandran
- Max-Planck-Institute of Solid-State Research, Stuttgart, Germany
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Vinod Chandran C, Madhu PK, Kurur ND, Bräuniger T. Swept-frequency two-pulse phase modulation (SWf-TPPM) sequences with linear sweep profile for heteronuclear decoupling in solid-state NMR. Magn Reson Chem 2008; 46:943-947. [PMID: 18666219 DOI: 10.1002/mrc.2285] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Recently, a pulse scheme for heteronuclear spin decoupling in solid-state NMR, called swept-frequency two-pulse phase modulation (SW(f)-TPPM), was introduced which outperforms the standard TPPM and small phase incremental alteration (SPINAL) schemes. It has also been shown that the frequency-sweep profile can be varied to achieve optimal efficiency for crystalline and liquid-crystalline samples, respectively. Here we present a detailed comparison of the proton decoupling performance for SW(f)-TPPM sequences with tangential sweep profiles (SW(f) (tan)-TPPM) and linear sweep profiles (SW(f) (lin)-TPPM). Using the (13)CH(2) resonance of crystalline tyrosine as a model system, it is shown that linear profiles have a decoupling performance which is at least as good and in some instances slightly better than that obtained from tangential sweep profiles. While tangential sweep profiles require a tangent cut-off angle as an additional parameter, the lack of that parameter makes linear sweep profiles easier to implement and optimise.
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Affiliation(s)
- C Vinod Chandran
- Institute of Physics, University of Halle, Friedemann-Bach-Platz 6, 06108 Halle, Germany
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Sabarinathan V, Vinod Chandran C, Ramasamy S, Ganapathy S. 119Sn magic angle spinning NMR of nanocrystalline SnO2. J Nanosci Nanotechnol 2008; 8:321-328. [PMID: 18468077] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Nanocrystalline SnO2 samples of different grain sizes, prepared by inert gas condensation technique (IGCT) and chemical precipitation method and conforming to the tetragonal phase, have been studied by variable speed (3-10 kHz) 119Sn MAS NMR at 11.74 Tesla field. 119Sn solid-state NMR results show that the IGCT prepared samples have good crystallinity and phase purity compared to the samples prepared by the chemical method. The determination of 119Sn chemical shielding parameters (delta iso, delta delta and eta) from slow MAS spectra shows that the 119Sn isotropic chemical shift (delta iso) is strongly influenced at smaller grain sizes, attributable to the change in the O2- local symmetry for the surface 119Sn ions at smaller grain sizes. The observed line widths in MAS spectra are significantly larger than the life-time broadening due to spin-lattice (T1) and spin-spin (T2) relaxation. The 119Sn MAS NMR spectra are thus inhomogeneously broadened by a distribution of isotropic chemical shifts, the line broadening increasing with decrease in grain size.
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Affiliation(s)
- V Sabarinathan
- Department of Nuclear Physics, University of Madras, Guindy Campus, Chennai 600025, India
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