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Jackowski K, Wilczek M. Measurements of Nuclear Magnetic Shielding in Molecules. Molecules 2024; 29:2617. [PMID: 38893492 PMCID: PMC11173999 DOI: 10.3390/molecules29112617] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2024] [Revised: 05/24/2024] [Accepted: 05/30/2024] [Indexed: 06/21/2024] Open
Abstract
The origin of nuclear magnetic shielding in diamagnetic molecules is discussed, pointing out various contributions to the shielding from electrons and the effects of intra- and intermolecular interactions. In NMR practice, chemical shifts are determined first as the measure of shielding in observed samples. The descriptions of shielding and chemical shifts are not fully consistent. Gas phase studies permit the withdrawal of intermolecular contributions from shielding and obtaining the magnetic shielding data in isolated molecules. The shielding determination in molecules is possible using at least three methods delivering the reference shielding standards for selected nuclei. The known shielding of one magnetic nucleus can be transferred to other nuclei if the appropriate nuclear magnetic moments are available with satisfactory accuracy. It is possible to determine the nuclear magnetic dipole moments using the most advanced ab initio shielding calculations jointly with the NMR frequencies measurements for small-sized isolated molecules. Helium-3 gas is postulated as all the molecules' primary and universal reference standard of shielding. It can be easily applied using common deuterium lock solvents as the secondary reference standards. The measurements of absolute shielding are available for everyone with the use of standard NMR spectrometers.
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Affiliation(s)
- Karol Jackowski
- Laboratory of NMR Spectroscopy, Faculty of Chemistry, University of Warsaw, Pasteura 1, 02-093 Warsaw, Poland;
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2
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Kleine Büning JB, Grimme S, Bursch M. Machine learning-based correction for spin-orbit coupling effects in NMR chemical shift calculations. Phys Chem Chem Phys 2024; 26:4870-4884. [PMID: 38230684 DOI: 10.1039/d3cp05556f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2024]
Abstract
As one of the most powerful analytical methods for molecular and solid-state structure elucidation, NMR spectroscopy is an integral part of chemical laboratories associated with a great research interest in its computational simulation. Particularly when heavy atoms are present, a relativistic treatment is essential in the calculations as these influence also the nearby light atoms. In this work, we present a Δ-machine learning method that approximates the contribution to 13C and 1H NMR chemical shifts that stems from spin-orbit (SO) coupling effects. It is built on computed reference data at the spin-orbit zeroth-order regular approximation (ZORA) DFT level for a set of 6388 structures with 38 740 13C and 64 436 1H NMR chemical shifts. The scope of the methods covers the 17 most important heavy p-block elements that exhibit heavy atom on the light atom (HALA) effects to covalently bound carbon or hydrogen atoms. Evaluated on the test data set, the approach is able to recover roughly 85% of the SO contribution for 13C and 70% for 1H from a scalar-relativistic PBE0/ZORA-def2-TZVP calculation at virtually no extra computational costs. Moreover, the method is transferable to other baseline DFT methods even without retraining the model and performs well for realistic organotin and -lead compounds. Finally, we show that using a combination of the new approach with our previous Δ-ML method for correlation contributions to NMR chemical shifts, the mean absolute NMR shift deviations from non-relativistic DFT calculations to experimental values can be halved.
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Affiliation(s)
- Julius B Kleine Büning
- Mulliken Center for Theoretical Chemistry, Clausius Institute for Physical and Theoretical Chemistry, University of Bonn, Beringstr. 4, 53115 Bonn, Germany.
| | - Stefan Grimme
- Mulliken Center for Theoretical Chemistry, Clausius Institute for Physical and Theoretical Chemistry, University of Bonn, Beringstr. 4, 53115 Bonn, Germany.
| | - Markus Bursch
- Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470 Mülheim an der Ruhr, Germany.
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Wilson DJD. Extreme NMR shielding in fluoro-nitrogen cations. Phys Chem Chem Phys 2023; 25:25420-25434. [PMID: 37706351 DOI: 10.1039/d3cp03399f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/15/2023]
Abstract
The structure and NMR shielding of a set of N-F containing cations is reported to near-quantitative accuracy from extensive ab initio calculations. Currently, the shortest experimentally confirmed N-F bond is 1.2461(10) Å in NNF+, however CCSD(T)-F12b/cc-pVQZ-F12 optimised geometries suggest that even shorter N-F bonds are possible for both monocations (1.236 Å, HNF+) and dications (1.098 Å, NF2+). NMR shielding constants have been calculated in a composite manner with individual components from coupled-cluster expansions up to CCSDTQP and basis sets up to aug-cc-pCV8Z, together with vibrational and relativistic corrections. 15N and 19F NMR chemical shifts correlate well with available experimental data. Extreme 19F chemical shifts are predicted for HNF+ (1628.9 ppm) and NH2F2+ (1298.0 ppm), which are by far the largest 19F chemical shifts ever reported and well outside the known range of +865 ppm (F2O2) to -448 ppm (ClF). The 15N chemical shift of -1283.07 ppm in HNF+ is similarly extreme, being well outside the known range of 15N chemical shifts of -730 to 260 ppm (CH3NO2 reference). This work highlights the application of state-of-the-art theoretical techniques, and provides accurate NMR properties of both isolated and yet unknown N-F cations, which can serve to guide and supplement NMR experimentation.
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Affiliation(s)
- David J D Wilson
- Department of Chemistry, La Trobe Institute for Molecular Science, La Trobe University, Melbourne, Victoria 3086, Australia.
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Rusakov YY, Rusakova IL. New efficient pecS- n ( n = 1, 2) basis sets for quantum chemical calculations of 31P NMR chemical shifts. Phys Chem Chem Phys 2023. [PMID: 37409722 DOI: 10.1039/d3cp02664g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/07/2023]
Abstract
The basis sets that are used in the quantum chemical calculations of 31P NMR chemical shifts have always been one of the most important factors of accuracy. Regardless of what high-quality approach is employed, using basis sets of insufficient flexibility in the important angular regions may give poor results and lead to misassignments of the signals in the 31P NMR spectra. In this work, it was found that the existing nonrelativistic basis sets for phosphorus atom of double- and triple-ζ quality, specialized for the 31P NMR chemical shifts calculations, are essentially undersaturated in the d-angular space that occurred to play a significant role in the overall accuracy of these calculations. This problem has been thoroughly investigated, and new pecS-n (n = 1, 2) basis sets for phosphorus chemical shifts calculations were proposed. The exponents and contraction coefficients for the pecS-n basis sets were generated with the property-energy consistent method that has been introduced in our earlier paper, and has been proven useful in the creation of efficient property-oriented basis sets. New basis sets were optimized using the GIAO-DFT method with the B97-2 functional. Extensive benchmark calculations showed that the pecS-1 and pecS-2 basis sets provide very good accuracy, characterized by the corrected mean absolute percentage errors against the experiment of about 7.03 and 4.42 ppm, respectively. In particular, the accuracy of 31P NMR chemical shifts calculations achieved with the pecS-2 basis set is one of the most favorable accuracies for today. We believe that our new pecS-n (n = 1, 2) basis sets for phosphorus atom will prove useful in modern large-scale quantum chemical calculations of 31P NMR chemical shifts.
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Affiliation(s)
- Yuriy Yu Rusakov
- A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences, Favorsky St. 1, 664033 Irkutsk, Russian Federation.
| | - Irina L Rusakova
- A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences, Favorsky St. 1, 664033 Irkutsk, Russian Federation.
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Rzepiela K, Kaminský J, Buczek A, Broda MA, Kupka T. Electron Correlation or Basis Set Quality: How to Obtain Converged and Accurate NMR Shieldings for the Third-Row Elements? MOLECULES (BASEL, SWITZERLAND) 2022; 27:molecules27238230. [PMID: 36500321 PMCID: PMC9737175 DOI: 10.3390/molecules27238230] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/02/2022] [Revised: 11/17/2022] [Accepted: 11/22/2022] [Indexed: 11/29/2022]
Abstract
The quality of theoretical NMR shieldings calculated at the quantum-chemical level depends on various theoretical aspects, of which the basis set type and size are among the most important factors. Nevertheless, not much information is available on the basis set effect on theoretical shieldings of the NMR-active nuclei of the third row. Here, we report on the importance of proper basis set selection to obtain accurate and reliable NMR shielding parameters for nuclei from the third row of the periodic table. All calculations were performed on a set of eleven compounds containing the elements Na, Mg, Al, Si, P, S, or Cl. NMR shielding tensors were calculated using the SCF-HF, DFT-B3LYP, and CCSD(T) methods, combined with the Dunning valence aug-cc-pVXZ, core-valence aug-cc-pCVXZ, Jensen polarized-convergent aug-pcSseg-n and Karlsruhe x2c-Def2 basis set families. We also estimated the complete basis set limit (CBS) values of the NMR parameters. Widely scattered nuclear shieldings were observed for the Dunning polarized-valence basis set, which provides irregular convergence. We show that the use of Dunning core-valence or Jensen basis sets effectively reduces the scatter of theoretical NMR results and leads to their exponential-like convergence to CBS. We also assessed the effect of vibrational, temperature, and relativistic corrections on the predicted shieldings. For systems with single bonds, all corrections are relatively small, amounting to less than 4% of the CCSD(T)/CBS value. Vibrational and temperature corrections were less reliable for H3PO and HSiCH due to the high anharmonicity of the molecules. An abnormally high relativistic correction was observed for phosphorus in PN, reaching ~20% of the CCSD(T)/CBS value, while the correction was less than 7% for other tested molecules.
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Affiliation(s)
- Kacper Rzepiela
- Faculty of Chemistry, University of Opole, 48 Oleska Street, 46-052 Opole, Poland
| | - Jakub Kaminský
- Institute of Organic Chemistry and Biochemistry of the CAS, Flemingovo nám. 2, 166 10 Prague, Czech Republic
- Correspondence: (J.K.); (T.K.)
| | - Aneta Buczek
- Faculty of Chemistry, University of Opole, 48 Oleska Street, 46-052 Opole, Poland
| | - Małgorzata A. Broda
- Faculty of Chemistry, University of Opole, 48 Oleska Street, 46-052 Opole, Poland
| | - Teobald Kupka
- Faculty of Chemistry, University of Opole, 48 Oleska Street, 46-052 Opole, Poland
- Correspondence: (J.K.); (T.K.)
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Ukhanev SA, Fedorov SV, Rusakov YY, Rusakova IL, Krivdin LB. Fluorine spin-spin coupling constants of pentafluorobenzene revisited at the ab initio correlated levels. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2022; 60:901-914. [PMID: 35470458 DOI: 10.1002/mrc.5276] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/09/2022] [Revised: 04/22/2022] [Accepted: 04/22/2022] [Indexed: 06/14/2023]
Abstract
All possible spin-spin coupling constants, 19 F-19 F, 19 F-13 C, and 19 F-1 H, of pentafluorobenzene were calculated at five different levels of theory, HF, DFT, SOPPA (CCSD), CCSD, and the SOPPA (CCSD)-based composite scheme with taking into account solvent, vibrational, relativistic, and correlation corrections. Most corrections were next to negligible for the long-range couplings but quite essential for the one-bond carbon-fluorine coupling constants. Hartree-Fock calculations were found to be entirely unreliable, while DFT results were comparable in accuracy with the data obtained using the wave function-based methods.
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Affiliation(s)
- Stepan A Ukhanev
- A.E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences, Irkutsk, Russia
| | - Sergei V Fedorov
- A.E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences, Irkutsk, Russia
| | - Yuriy Y Rusakov
- A.E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences, Irkutsk, Russia
| | - Irina L Rusakova
- A.E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences, Irkutsk, Russia
| | - Leonid B Krivdin
- A.E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences, Irkutsk, Russia
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Makulski W, Aucar JJ, Aucar GA. Ammonia: the molecule for establishing 14N and 15N absolute shielding scales and a source of information on nuclear magnetic moments. J Chem Phys 2022; 157:084306. [DOI: 10.1063/5.0096523] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Multinuclear NMR studies of the gaseous mixtures 3He/14NH3 and 3He/15NH3 are reported. Precise analysis of the 3He, 14N, 15N and 1H resonance frequencies show linear dependence on the gas density. Extrapolation of these results to the zero-pressure limit gives ν0(1H), ν0(14N) and ν0(15N) resonance frequencies of the isolated ammonia molecule at 300K. The analogous value for 3He atoms in gaseous mixtures ν0(3He) was measured as well. The application of a new scheme to introduce the most important electronic effects on NMR shieldings, together with highly accurate quantum chemical calculations allow the 14/15N and 1H shielding of the isolated ammonia molecule to be obtained with the greatest accuracy and precision. For the first time, these studies were carried out on ammonia within the so-called four-component relativistic framework. The NMR frequency comparison method provides an approach for determining the 14N and 15N nuclear magnetic moments. The new shielding parameters in ammonia were used for reevaluation of the entire nitrogen absolute shielding scale. Additionally, the absolute shielding values of several gaseous compounds and secondary reference substances in liquids were presented. It was established that 14N and 15N absolute shielding constants in 14NH3 and 15NH3 are very similar, and only differ by less than 0.01 ppm, which is not usually measurable in NMR experiments. Precise calculations of 14N and 15N dipole moments were also made from these accurate shielding values.
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Affiliation(s)
| | - Juan J. Aucar
- Natural and Exact Science Faculty, Northeastern University of Argentina, Argentina
| | - Gustavo A. Aucar
- Natural and Exact Science Faculty, Northeastern University of Argentina, Argentina
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de Oliveira MT, Alves JMA, Braga AAC, Wilson DJD, Barboza CA. Do Double-Hybrid Exchange-Correlation Functionals Provide Accurate Chemical Shifts? A Benchmark Assessment for Proton NMR. J Chem Theory Comput 2021; 17:6876-6885. [PMID: 34637284 DOI: 10.1021/acs.jctc.1c00604] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
A benchmark density functional theory (DFT) study of 1H NMR chemical shifts for data sets comprising 200 chemical shifts, including complex natural products, has been carried out to assess the performance of DFT methods. Two new benchmark data sets, NMRH33 and NMRH148, have been established. The meta-GGA revTPSS performs remarkably well against the NMRH33 benchmark set (mean absolute deviation (MAD), 0.10 ppm; maximum deviation (max), 0.26 ppm) with the smallest MAD of all evaluated functionals. The best-performing double-hybrid density functional (DHDF), revDSD-BLYP (MAD, 0.16 ppm; max, 0.35 ppm), performs similarly to hybrid-GGA methods (e.g., mPW1PW91/6-311G(d) (MAD, 0.15 ppm; max, 0.36 ppm)), but at a considerably higher computational cost. The results indicate that currently available double-hybrid DFT methods offer no benefit over GGA (including hybrid and meta) functionals in the calculation of 1H NMR chemical shifts.
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Affiliation(s)
- Marcelo T de Oliveira
- Department of Chemistry and Physics, La Trobe Institute of Molecular Sciences, La Trobe University, Melbourne, Victoria 3086, Australia.,Chemistry Institute of São Carlos, University of São Paulo, Avenida Trabalhador São Carlense 400, 13566-590 São Carlos, São Paulo, Brazil
| | - Júlia M A Alves
- Chemistry Institute of São Carlos, University of São Paulo, Avenida Trabalhador São Carlense 400, 13566-590 São Carlos, São Paulo, Brazil
| | - Ataualpa A C Braga
- Instituto de Química, Universidade de São Paulo, Avenida Prof. Lineu Prestes 748, 05508-000 São Paulo, Brazil
| | - David J D Wilson
- Department of Chemistry and Physics, La Trobe Institute of Molecular Sciences, La Trobe University, Melbourne, Victoria 3086, Australia
| | - Cristina A Barboza
- Institute of Physics, Polish Academy of Sciences, Aleja Lotników 32/46, Warsaw 02-668, Poland
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Fedorov SV, Krivdin LB. Computational Protocols for the 19F NMR Chemical Shifts. Part 1: Methodological Aspects. J Fluor Chem 2020. [DOI: 10.1016/j.jfluchem.2020.109625] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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Jaszuński M, Sauer SPA, Faber R, Wilson DJD. NMR parameters of FNNF as a test for coupled-cluster methods: CCSDT shielding and CC3 spin-spin coupling. Phys Chem Chem Phys 2020; 22:21350-21359. [PMID: 32936148 DOI: 10.1039/d0cp02730h] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
NMR shielding and spin-spin coupling constants of cis and trans isomers of FNNF have been determined to near-quantitative accuracy from ab initio calculations. The FNNF system, containing multiple N-F bonds and fluorine atoms, provides a severe test of computational methods. Coupled-cluster methods were used with large basis sets and complete basis set (CBS) extrapolations of the equilibrium geometry results, with vibrational and relativistic corrections. Shielding constants were calculated with basis sets as large as aug-cc-pCV7Z, together with coupled-cluster expansions up to CCSDT, at the all-electron CCSD(T)/aug-cc-pCVQZ optimized geometries. Spin-spin coupling constants have been determined with specialized versions of the correlation consistent basis sets ccJ-pVXZ, further augmented with diffuse functions. All-electron coupled-cluster methods up to CC3 were applied in these calculations. The results of this work highlight the application of state-of-the-art theoretical techniques, and provide the most accurate NMR properties of FNNF to date, which can serve to guide and supplement NMR experimentation.
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Affiliation(s)
- Michał Jaszuński
- Institute of Organic Chemistry, Polish Academy of Sciences, Kasprzaka 44-52, 01-224 Warsaw, Poland
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Li J, Liu JK, Wang WX. GIAO 13C NMR Calculation with Sorted Training Sets Improves Accuracy and Reliability for Structural Assignation. J Org Chem 2020; 85:11350-11358. [DOI: 10.1021/acs.joc.0c01451] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- Jing Li
- Department of Pharmacy, Xiangya Hospital, Central South University, Changsha, Hunan 410083, PR China
| | - Ji-Kai Liu
- School of Pharmaceutical Sciences, South-Central University for Nationalities, Wuhan, Hubei 430074, PR China
| | - Wen-Xuan Wang
- Xiangya School of Pharmaceutical Sciences, Central South University, Changsha, Hunan 410083, PR China
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Vı́cha J, Novotný J, Komorovsky S, Straka M, Kaupp M, Marek R. Relativistic Heavy-Neighbor-Atom Effects on NMR Shifts: Concepts and Trends Across the Periodic Table. Chem Rev 2020; 120:7065-7103. [DOI: 10.1021/acs.chemrev.9b00785] [Citation(s) in RCA: 64] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
- Jan Vı́cha
- Centre of Polymer Systems, Tomas Bata University in Zlı́n, tř. Tomáše Bati 5678, CZ-76001 Zlı́n, Czechia
| | - Jan Novotný
- CEITEC - Central European Institute of Technology, Masaryk University, Kamenice 5, CZ-62500 Brno, Czechia
| | - Stanislav Komorovsky
- Institute of Inorganic Chemistry, Slovak Academy of Sciences, Dúbravská cesta 9, SK-84536 Bratislava, Slovakia
| | - Michal Straka
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Flemingovo nám. 2, CZ-16610 Prague, Czechia
| | - Martin Kaupp
- Institute of Chemistry, Technische Universität Berlin, Strasse des 17. Juni 135, D-10623 Berlin, Germany
| | - Radek Marek
- CEITEC - Central European Institute of Technology, Masaryk University, Kamenice 5, CZ-62500 Brno, Czechia
- Department of Chemistry, Faculty of Science, Masaryk University, Kamenice 5, CZ-62500 Brno, Czechia
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Krivdin LB. Recent advances in computational 31 P NMR: Part 1. Chemical shifts. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2020; 58:478-499. [PMID: 31703153 DOI: 10.1002/mrc.4965] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/18/2019] [Revised: 10/19/2019] [Accepted: 10/23/2019] [Indexed: 06/10/2023]
Abstract
This is the first part of two closely related reviews dealing with the computation of phosphorus-31 nuclear magnetic resonance chemical shifts in a wide series of organophosphorus compounds including complexes, clusters, and bioorganic phosphorus compounds. In particular, the analysis of the accuracy factors, such as substitution effects, solvent effects, vibrational corrections, and relativistic effects, is presented. This review is dedicated to the Full Member of the Russian Academy of Sciences Professor Boris A. Trofimov in view of his invaluable contribution to the field of synthesis, nuclear magnetic resonance, and computation studies of organophosphorus compounds.
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Affiliation(s)
- Leonid B Krivdin
- A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences, Irkutsk, Russia
- Angarsk State Technical University, Irkutsk Region, Russia
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Zhang Y, Qian Y, Li W, Gao X, Pan B. Fluoride uptake by three lanthanum based nanomaterials: Behavior and mechanism dependent upon lanthanum species. THE SCIENCE OF THE TOTAL ENVIRONMENT 2019; 683:609-616. [PMID: 31146065 DOI: 10.1016/j.scitotenv.2019.05.185] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/09/2019] [Revised: 04/29/2019] [Accepted: 05/13/2019] [Indexed: 06/09/2023]
Abstract
Excess fluoride in water can be efficiently removed by lanthanum based material, however, different lanthanum species exhibited distinct fluoride removal capability. In this study, three typical lanthanum based nanoparticles denoted as L1, L2 and L3 in the form of La(OH)3, La2O3·nH2O and LaCO3OH respectively were synthesized and well characterized for fluoride removal. They differ in terms of morphology, surface charge, water content, specific surface area and crystallinity. L2 (La2O3·nH2O) exhibited the highest adsorption capacity (~28.9 mg/g) and selectivity towards fluoride, followed by L3 (LaCO3OH) (~25.1 mg/g) and L1 (La(OH)3) (~6.03 mg/g). Despite the relatively low capacity for L1, it could be efficiently regenerated by alkaline solution for repeated use. However, both L2 and L3 suffered significant from capacity loss after regeneration. X-ray photoelectron spectroscopy (XPS), nuclear magnetic resonance spectroscopy (NMR) analysis and molecular configuration modelling suggested the distinct mechanism of fluoride adsorption onto the three materials. Fluoride was captured by L1 and L3 via electrostatic attraction and ligand exchange of different bond strength. However, a stronger LaF interaction via chemical adsorption by L2 was observed. This study provided new insights into the role of commonly used La species for fluoride removal.
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Affiliation(s)
- Yanyang Zhang
- State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210023, China; Research Center for Environmental Nanotechnology (ReCENT), Nanjing University, Nanjing 210023, China.
| | - Yue Qian
- State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210023, China
| | - Wei Li
- Research Center for Environmental Nanotechnology (ReCENT), Nanjing University, Nanjing 210023, China; Key Laboratory of Surficial Geochemistry, Ministry of Education, School of Earth Sciences and Engineering, Nanjing University, Nanjing 210023, China
| | - Xiang Gao
- State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210023, China
| | - Bingcai Pan
- State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210023, China; Research Center for Environmental Nanotechnology (ReCENT), Nanjing University, Nanjing 210023, China
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