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Holmes ST, Iuliucci RJ, Mueller KT, Dybowski C. Critical Analysis of Cluster Models and Exchange-Correlation Functionals for Calculating Magnetic Shielding in Molecular Solids. J Chem Theory Comput 2015; 11:5229-41. [DOI: 10.1021/acs.jctc.5b00752] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Sean T. Holmes
- Department
of Chemistry and Biochemistry, University of Delaware, Newark, Delaware 19716, United States
| | - Robbie J. Iuliucci
- Department
of Chemistry, Washington and Jefferson College, Washington, Pennsylvania 15301, United States
| | - Karl T. Mueller
- Department
of Chemistry, Pennsylvania State University, University Park, Pennsylvania 16802, United States
- Physical
and Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland, Washington 99352, United States
| | - Cecil Dybowski
- Department
of Chemistry and Biochemistry, University of Delaware, Newark, Delaware 19716, United States
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Nitrogen-doped (6,0) carbon nanotubes: A comparative DFT study based on surface reactivity descriptors. COMPUT THEOR CHEM 2013. [DOI: 10.1016/j.comptc.2013.04.003] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Gawinecki R, Kolehmainen E, Dobosz R, Khouzani HL, Chandrasekaran S. Intramolecular interactions in nitroamines studied by 1H, 13C, 15N and 17O NMR spectral and quantum chemical methods. JOURNAL OF THE IRANIAN CHEMICAL SOCIETY 2013. [DOI: 10.1007/s13738-013-0269-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Arjunan V, Thillai Govindaraja S, Subramanian S, Mohan S. Conformational analysis, spectroscopic and quantum chemical investigations of 2-bromo-3-nitroacetophenone. J Mol Struct 2013. [DOI: 10.1016/j.molstruc.2012.12.035] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Feland BC, Bernard GM, Wasylishen RE. A solid-state NMR investigation of the colossal expansion material, Ag3Co(CN)6. CAN J CHEM 2012. [DOI: 10.1139/v2012-072] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Presented here is a solid-state NMR investigation of the so-called “colossal expansion” material, Ag3Co(CN)6, a compound that exhibits some of the largest positive and negative thermal expansion properties reported. This study explores the 13C, 15N, and 59Co NMR properties of this material at room temperature and at variable temperatures with the goal of probing the effects of this colossal expansion behaviour on these properties. We found that the flexible nature of the crystal framework leads to a distribution of electric field gradients, and that, oddly enough, no strong correlation is observed between the NMR parameters of Ag3Co(CN)6 and its colossal expansion nature. The 59Co isotropic chemical shift increased and the 59Co nuclear quadrupolar coupling constant decreased with increasing temperature, but neither of these relationships were extraordinary when compared to other octahedral Co(III) complexes. The link between the colossal expansion and the NMR properties of Ag3Co(CN)6 may be the distribution of lattice parameters and hence unusually broad features in the 59Co NMR spectra. The high order of symmetry at the cobalt site resulted in a small quadrupolar coupling constant less than 1 MHz in magnitude. We also observed a |1J(107/109Ag,15N)| value of 96 Hz, the largest 107/109Ag–15N coupling constant reported to date.
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Affiliation(s)
- Brett C. Feland
- Department of Chemistry, University of Alberta, 11227 SK Drive N.W., Edmonton, AB T6G 2G2, Canada
| | - Guy M. Bernard
- Department of Chemistry, University of Alberta, 11227 SK Drive N.W., Edmonton, AB T6G 2G2, Canada
| | - Roderick E. Wasylishen
- Department of Chemistry, University of Alberta, 11227 SK Drive N.W., Edmonton, AB T6G 2G2, Canada
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Casabianca LB, de Dios AC. Ab initiocalculations of NMR chemical shifts. J Chem Phys 2008; 128:052201. [DOI: 10.1063/1.2816784] [Citation(s) in RCA: 100] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
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Freedman DA, Kruger S, Roosa C, Wymer C. Synthesis, characterization, and reactivity of [Ru(bpy)(CH3CN)3(NO2)]PF6, a synthon for [Ru(bpy)(L3)NO2] complexes. Inorg Chem 2007; 45:9558-68. [PMID: 17083258 DOI: 10.1021/ic061039t] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We report a high yield, two-step synthesis of fac-[Ru(bpy)(CH3CN)3NO2]PF6 from the known complex [(p-cym)Ru(bpy)Cl]PF6 (p-cym = eta(6)-p-cymene). [(p-cym)Ru(bpy)NO2]PF6 is prepared by reacting [(p-cymene)Ru(bpy)Cl]PF6 with AgNO3/KNO2 or AgNO2. The 15NO2 analogue is prepared using K15NO2. Displacement of p-cymene from [(p-cym)Ru(bpy)NO2]PF6 by acetonitrile gives [Ru(bpy)(CH3CN)3NO2]PF6. The new complexes [(p-cym)Ru(bpy)NO2]PF6 and fac-[Ru(bpy)(CH3CN)3NO2]PF6 have been fully characterized by 1H and 15N NMR, IR, elemental analysis, and single-crystal structure determination. Reaction of [Ru(bpy)(CH3CN)3NO2]PF6 with the appropriate ligands gives the new complexes [Ru(bpy)(Tp)NO2] (Tp = HB(pz)3-, pz = 1-pyrazolyl), [Ru(bpy)(Tpm)NO2]PF6 (Tpm = HC(pz)3), and the previously prepared [Ru(bpy)(trpy)NO2]PF6 (trpy = 2,2',6',2' '-terpyridine). Reaction of the nitro complexes with HPF6 gives the new nitrosyl complexes [Ru(bpy)TpNO][PF6]2 and [Ru(bpy)(Tpm)NO][PF6]3. All complexes were prepared with 15N-labeled nitro or nitrosyl groups. The nitro and nitrosyl complexes were characterized by 1H and 15N NMR and IR spectroscopy, elemental analysis, cyclic voltammetry, and single-crystal structure determination for [Ru(bpy)TpNO][PF6]2. For the nitro complexes, a linear correlation is observed between the nitro 15N NMR chemical shift and 1/nu(asym), where nu(asym) is the asymmetric stretching frequency of the nitro group.
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Affiliation(s)
- Daniel A Freedman
- Department of Chemistry, State University of New York at New Paltz, New Paltz, New York 12561, USA.
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Koder RL, Walsh JD, Pometun MS, Dutton PL, Wittebort RJ, Miller AF. 15N solid-state NMR provides a sensitive probe of oxidized flavin reactive sites. J Am Chem Soc 2006; 128:15200-8. [PMID: 17117871 PMCID: PMC5993988 DOI: 10.1021/ja0648817] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Flavins are central to the reactivity of a wide variety of enzymes and electron transport proteins. There is great interest in understanding the basis for the different reactivities displayed by flavins in different protein contexts. We propose solid-state nuclear magnetic resonance (SS-NMR) as a tool for directly observing reactive positions of the flavin ring and thereby obtaining information on their frontier orbitals. We now report the SS-NMR signals of the redox-active nitrogens N1 and N5, as well as that of N3. The chemical shift tensor of N5 is over 720 ppm wide, in accordance with the predictions of theory and our calculations. The signal of N3 can be distinguished on the basis of coupling to 1H absent for N1 and N5, as well as the shift tensor span of only 170 ppm, consistent with N3's lower aromaticity and lack of a nonbonding lone pair. The isotropic shifts and spans of N5 and N1 reflect two opposite extremes of the chemical shift range for "pyridine-type" N's, consistent with their electrophilic and nucleophilic chemical reactivities, respectively. Upon flavin reduction, N5's chemical shift tensor contracts dramatically to a span of less than 110 ppm, and the isotropic chemical shift changes by approximately 300 ppm. Both are consistent with loss of N5's nonbonding lone pair and decreased aromaticity, and illustrate the responsiveness of the 15N chemical shift principal values to electronic structure. Thus. 15N chemical shift principal values promise to be valuable tools for understanding electronic differences that underlie variations in flavin reactivity, as well as the reactivities of other heterocyclic cofactors.
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Affiliation(s)
- Ronald L. Koder
- Department of Chemistry, University of Kentucky, Lexington KY 40506-0055
- Department of Biochemistry and Biophysics, The Johnson Research Foundation, University of Pennsylvania, Philadelphia, PA 19104
| | - Joseph D. Walsh
- Department of Chemistry, University of Kentucky, Lexington KY 40506-0055
| | - Maxim S. Pometun
- Department of Chemistry, University of Louisville, Louisville KY 40292
| | - P. Leslie Dutton
- Department of Biochemistry and Biophysics, The Johnson Research Foundation, University of Pennsylvania, Philadelphia, PA 19104
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Penner GH, McCullough A. Solid-State Nitrogen-15 NMR and Quantum Chemical Study of N, N-Dimethylaniline Derivatives. J Org Chem 2006; 71:8794-9. [PMID: 17081008 DOI: 10.1021/jo061491u] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
In this study the components of the nitrogen chemical shift (CS) tensor are examined for a series of para substituted N,N-dimethylaniline derivatives. This is done through measurement of the 15N NMR spectra of powder samples and through quantum chemical calculations on the isolated molecules. Experiments and calculations show that the isotropic CS, delta(iso), decreases with increasing electron donating ability of the para substituent, in agreement with previous solution studies. More importantly, this study shows that this decrease in the isotropic (solution) CS is due to decreasing values of the CS tensor component delta(11) and component delta(33). The component delta(22) is essentially invariant to the electron donating/withdrawing ability of the para substituent. Through Ramsey's theory of nuclear magnetic shielding, it can be seen that the variation in delta(11) and delta(33), and hence delta(iso), is due to changes in the n-pi* and the sigma-pi* energy gaps in N,N-dimethylaniline. This, in turn, is a result of the change in the energy of the pi* molecular orbital with change in the pi-electron donating ability of the para substituent. The effects of nitrogen inversion on the components of the nitrogen CS tensor components are also discussed. This study also shows the feasibility of performing 15N cross-polarization experiments on nonspinning powder samples at natural isotopic abundance.
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Affiliation(s)
- Glenn H Penner
- Department of Chemistry, University of Guelph, Guelph, Ontario N1G 2W1, Canada.
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Casabianca LB, Faller CM, de Dios AC. Carbon Chemical Shift Tensor Components in Quinolines and Quinoline N-Oxides. J Phys Chem A 2005; 110:234-40. [PMID: 16392860 DOI: 10.1021/jp055372e] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Chemical shift calculations are carried out for the quinoline carbons in 1,8-bis(2-isopropyl-4-quinolyl)naphthalene, 2-isopropylquinoline, amodiaquine, chloroquine, and quinine and the N-oxide of each compound. Ab initio calculations of the isotropic shielding values are in agreement with experimental chemical shifts. The calculations indicate that changes to the principal components of the shielding tensor upon N-oxidation are similar for each compound. Carbons 2, 4, 8, and 10 are largely shielded in each case as the nitrogen is oxidized. For C2, C4, and C10, this shielding is due to a large change in sigma11 and/or sigma22, indicating a change in pi-electron density. For C8, the large shielding change is due mainly to a change in sigma33, indicating a change in sigma-electron density. Upon examination and comparison of the calculated 13C shielding tensor components in the antimalarial drugs versus those in unsubstituted quinolines, it is found that amodiaquine and chloroquine have increased pi-electron density in the ring containing the amino side chain and quinine has increased pi-electron density in the opposite ring, containing the methoxy substituent.
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Affiliation(s)
- Leah B Casabianca
- Department of Chemistry, Georgetown University, 37th and O Streets NW, Washington, DC 20057, USA
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