NMR Spectroscopy (nmr + spectroscopy)

Distribution by Scientific Domains
Distribution within Chemistry

Kinds of NMR Spectroscopy

  • ma nmr spectroscopy
  • multidimensional nmr spectroscopy
  • multinuclear nmr spectroscopy
  • solid-state nmr spectroscopy
  • solution nmr spectroscopy
  • spinning nmr spectroscopy
  • two-dimensional nmr spectroscopy

  • Terms modified by NMR Spectroscopy

  • nmr spectroscopy experiment

  • Selected Abstracts

    Mesomerization of S4 -Symmetric Tetrahedral Chelate Complex [In4(L3)4]: First-Time Monitored by Temperature-Dependent 1H NMR Spectroscopy,,

    Rolf W. Saalfrank
    Abstract VT 1H NMR spectroscopy proved that a non-dissociative and reversible mesomerization process links the tetranuclear indium(III) complexes meso -(,,,,,,,)(P,P,M,M)- 3 and meso -(,,,,,,,)(M,M,P,P)- 3,. During this process four tandem Bailar twists, resulting in the (,)/(,) isomerization at the indium centers, and the (P)/(M) inversion of the four coordinating face-centered, helical ligands (L3)3, are involved. In addition, gas-phase DFT calculations (B3LYP/LANL2DZp) revealed a C1 -symmetric transition state (+21.9 kcal,mol,1) for the mesomerization mechanism which connects 3 and 3,. [source]

    Characterization by NMR Spectroscopy, X-ray Analysis and Cytotoxic Activity of the Ruthenium(II) Compounds [RuL3](PF6)2(L = 2-Phenylazopyridine or o -Tolylazopyridine) and [RuL'2L"](PF6)2(L', L" = 2-Phenylazopyridine, 2,2'-Bipyridine)

    Anna C. G. Hotze
    Abstract Tris(ligand) complexes [RuL3](PF6)2 (L = 2-phenylazopyridine or o -tolylazopyridine) and mixed ligand [RuL'2L"](PF6)2 (L' and L" are 2-phenylazopyridine or 2,2'-bipyridine) have been synthesized, structurally characterized and investigated for cytotoxic activity. These complexes are important to study the hypothesis that the compound ,-[Ru(azpy)2Cl2] (azpy = 2-phenylazopyridine) exhibits a high cytotoxicity due to its two cis chloride ligands, which might be exchanged for biological targets as DNA. Molecular structures of mer -[Ru(azpy)3](PF6)2 (1) and mer -[Ru(tazpy)3](PF6)2 (5) (tazpy = o -tolylazopyridine) have been determined by X-ray diffraction. Series of complexes [RuL3](PF6)2 and [RuL'2L"](PF6)2 show interesting NMR spectroscopic data; e.g. the spectrum of mer -[Ru(azpy)3](PF6)2 (1) shows extremely broadened resonances at room temp. but sharpened resonances at low temperature. In the 1H NMR spectra of compounds [Ru(azpy)2(bpy)]2+ and [Ru(bpy)2(azpy)]2+ (bpy = 2,2-bipyridine), respectively, less broadened (room temp.) or completely sharp resonances (room temp.) occur in comparison to 1 (under same conditions). By selecting the right temperature and/or concentration, NMR spectra of these series of compounds have been resolved using 2D COSY and NOESY NMR spectroscopy. Remarkably, the cytotoxicity data against a series of human tumor cell lines (A498, EVSA-T, H226, IGROV, M19, MCF-7 and WIDR) show a moderate cytotoxicity for these series of tris(ligand) complexes. So, even though no chloride ligands are present in these tris(ligand) complexes, a considerable cytotoxic activity is observed. This would imply that the 2-phenylazopyridine ruthenium(II) complexes act by a completely different mechanism than the well-known cisplatin. This finding is important, because an anticancer compound acting via a different mechanism is a prerequisite in designing new anticancer drugs. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source]

    Application of Gel-Phase 195Pt NMR Spectroscopy in a Novel Solid-Phase Synthesis of a Primary Amine Dichloroplatinum(II) Complex

    Marc S. Robillard
    Abstract Gel-phase 195Pt NMR spectroscopy of dichloroplatinum peptide complexes attached to a solid support is described. The observed 195Pt chemical shifts of the support-bound platinum complexes are in good agreement with the solution-state 195Pt NMR spectra of the soluble and deprotected analogs. This non-destructive analytical method for on-resin-compound analysis was applied in the optimization of the solid-phase synthesis of the primary amine dichloroplatinum complex 6, which represents a new class of platinum complexes now available via solid-phase synthetic chemistry. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003) [source]

    Screening of Garlic Water Extract for Binding Activity with Cholera Toxin B Pentamer by NMR Spectroscopy , An Old Remedy Giving a New Surprise

    Matteo Politi
    Abstract Binding between a component of the crude hot water extract obtained from Allium sativum crushed bulbs (ASw) and cholera toxin B pentamer (CTB) was detected by STD NMR experiments. Bioassay-oriented fractionation allowed the partial identification of a high molecular weight polysaccharide mainly composed of galactose as the bioactive complex against CTB. This work represents the first example of screening of a medicinal plant by NMR against a specific disease, and corroborates traditional medical uses of the species. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source]

    Solid-State Structure and Tautomerism of 2-Aminotroponimines Studied by X-ray Crystallography and Multinuclear NMR Spectroscopy

    Rosa M. Claramunt
    Abstract Structural studies in the solid state by X-ray crystallography and by 13C and 15N CPMAS NMR spectroscopy carried out on a series of 2-aminotroponimine derivatives 2,5 has allowed to establish the existence of hydrogen bonding and to determine the most stable tautomer. Almost all the structures reflect the classical double-well potential function for the N,H···N hydrogen bonds. Only in the case of the compound N -(pyrrol-1-yl)-2-(pyrrol-1-ylamino)troponimine (5) the crystal structure shows two independent molecules, one with a classical hydrogen bond and another with either a single-well or a low-barrier hydrogen bond. The structure of this compound is discussed with the use of the solid-state NMR spectroscopic data. 2-Aminotropones, as intermediates to the 2-aminotroponimines, show the oxo-tautomer as the stable form. B3LYP/6-31G* calculations are used to rationalise the experimental results. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004) [source]

    In vitro Chemical Reactivity of Doped Bioactive Glasses: an Original Approach by Solid-State NMR Spectroscopy

    Elodie Dietrich
    The control of the in vitro and in vivo bioactivity, as well as the chemical reactivity of melt-derived glasses is an important state in the biomaterials field. The present work explores the local structure of bioactive glasses before and after in vitro assays in simulated body fluid. This study by solid-state MAS,NMR constitutes an original approach to the understanding of the bioactivity process. [source]

    , -Cyclodextrin as Inhibitor of the Precipitation Reaction between Berberine and Glycyrrhizin in Decoctions of Natural Medicines: Interaction Studies of Cyclodextrins with Glycyrrhizin and Glycyrrhetic Acid by 1H-NMR Spectroscopy and Molecular-Dynamics Calculation

    Miyoko Kamigauchi
    Abstract To prevent the precipitation reaction between glycyrrhizin (1) and berberine (3) in the decoctions of Glycyrrhiza/Coptis rhizome or Glycyrrhiza/Phellodendron bark, the presence of cyclodextrin (CD) in the mixture was proven to be effective. The preventing effect decreased in the order , -CD>, -CD, and no effect was observed for , -CD. On the other hand, the extraction degree of 1 from the natural medicine Glycyrrhia was considerably increased in the presence of , -CD, , -CD being much more effective than , - or , -CD. Thus, the blocking effect of CD on the precipitate formation between 1 and 3 is suggested to be primarily dependent on the stability of the inclusion complex of the CD with 1. To establish the structure of such a preferred inclusion complex, the interactions of 1 with , - and , -CDs were investigated by 1H-NMR spectroscopy and molecular-dynamics (MD) calculations. The 1H-NMR measurements showed that the increase in solubility of 1 in H2O is dependent on the degree of its inclusion into the CD, which depends on the molecular size of the CD. The MD calculations suggested that the H-bond interactions are sufficiently strong to form a stable [1/, -CD] complex, in which the lipophilic rings C, D, and E of 1 are fully inserted into the molecular cavity of , -CD, thus forming a kind of structure covered by a hydrophilic molecular capsule, while such an interaction mode is impossible for , - or , -CD. [source]

    Computational NMR Spectroscopy of Transition-Metal/Nitroimidazole Complexes: Theoretical Investigation of Potential Radiosensitizers

    The computed chemical shifts of transition-metal complexes with dimetridazole (=,1,2-dimethyl-5-nitro-1H -imidazole; 1), a prototypical nitro-imidazole-based radiosensitizer, are reported at the GIAO-BP86 and -B3LYP levels for BP86/ECP1-optimized geometries. These complexes comprise [MCl2(1)2] (M,=,Zn, Pd, Pt), [RuCl2(DMSO)2(1)2], and [Rh2(O2CMe)4(1)2]. Available ,(1H) and ,(15N) values, and ,,(1H) and ,,(15N) coordination shifts are well-reproduced theoretically, provided solvation and relativistic effects are taken into account by means of a polarizable continuum model and suitable methods including spin,orbit (SO) coupling, respectively. These effects are particularly important for the metal-coordinated N-atom, where the contributions from solvation and relativity can affect ,(15N) and ,,(15N) values up to 10,20,ppm. The 195Pt chemical shifts of cis - and trans -[PtCl2(1)2] are well-reproduced using the zero-order regular approximation including SO coupling (ZORA-SO). Predictions are reported for 99Ru and 103Rh chemical shifts, which suggest that these metal centers could be used as additional, sensitive NMR probes in their complexes with nitro-imidazoles. [source]

    Natural Abundance 43Ca NMR Spectroscopy of Tobermorite and Jennite: Model Compounds for C,S,H

    Geoffrey M. Bowers
    There are few effective methods for characterizing the molecular scale structural environments of Ca2+ in hydrated cements, which has limited our ability to understand the structure of, for example, Ca,silicate hydrate (C,S,H). 43Ca nuclear magnetic resonance (NMR) spectroscopy has long been considered too insensitive to provide useful data in this regard, but 43Ca magic angle spinning (MAS) NMR spectra reported here for synthetic tobermorite and jennite with naturally abundant levels of 43Ca demonstrate that this is a viable approach. We show that spectra with useful signal/noise ratios can be obtained in a reasonable acquisition period (,2 days) using an H0 field strength of 21.1 T, 5 mm rotors spinning at a frequency of 5 kHz, and a double frequency sweep preparatory pulse sequence. Tobermorite and jennite produce relatively broad resonances due to their complex structures and structural disorder, however, the chemical shift differences between six-coordinate 43Ca in jennite and seven-coordinate 43Ca in 11 Å tobermorite are large enough that the signals are entirely resolved at this field. These data suggest that signal from ideal tobermorite-like and jennite-like sites in cement C,S,H can most likely be distinguished by 43Ca NMR and that this method will be a powerful approach for studying cement-based ceramic materials in the coming decade. [source]

    Interaction of Epothilone,B (Patupilone) with Microtubules as Detected by Two-Dimensional Solid-State NMR Spectroscopy,

    ANGEWANDTE CHEMIE, Issue 41 2010
    Dr. Ashutosh Kumar
    Die Apoptose von Krebszellen ist die Folge, wenn Epothilone wie Patupilon nach einem bislang unbekannten Mechanismus die Polymerisation von ,,-Tubulindimeren zu Mikrotubuli auslösen. Durch Festkörper-NMR-Spektroskopie von Mikrotubuli-gebundenem Patupilon wurden nun Atompositionen des Wirkstoffs identifiziert, deren chemische Verschiebungen durch den Bindevorgang deutlich verändert werden (siehe Korrelationsspektren von freiem (schwarz) und komplexiertem Patupilon (rot)). [source]

    Technetium-99 MAS,NMR Spectroscopy of a Cationic Framework Material that Traps TcO4, Ions,

    ANGEWANDTE CHEMIE, Issue 34 2010
    Ping Yu Dr.
    Kein Entrinnen für Technetium: Nur wenige 99Tc-MAS-NMR-Spektren wurden bisher aufgenommen. Die hier vorgestellten Spektren zeigen, dass durch Kernspaltung gebildete, potenziell umweltgefährdende TcO4, -Ionen aus simulierten radioaktiven Abwässern in den Kanälen und Hohlräumen eines Materials mit kationischem Gerüst eingefangen werden (siehe Bild). [source]

    Dynamics of Benzene Rings in MIL-53(Cr) and MIL-47(V) Frameworks Studied by 2H,NMR Spectroscopy,

    ANGEWANDTE CHEMIE, Issue 28 2010
    Die Rotationsdynamiken von Benzolringen im flexiblen MIL-53- und im starren MIL-47-Gerüst wurden durch 2H-NMR-Spektroskopie untersucht. In beiden Fällen werden 180°-Flips beobachtet, wobei der Flip-Prozess in MIL-53 schneller ist. Zur Simulation der experimentellen Spektren (links) reicht die Berücksichtigung der quadrupolaren Wechselwirkung nicht aus (Mitte): Auch der paramagnetische Effekt muss einbezogen werden (rechts). [source]

    Elucidation of the Structure and Intermolecular Interactions of a Reversible Cyclic-Peptide Inhibitor of the Proteasome by NMR Spectroscopy and Molecular Modeling,

    ANGEWANDTE CHEMIE, Issue 23 2010
    Benjamin Stauch
    Komplexe Betrachtungen: Das Proteasom spielt bei Krankheiten eine entscheidende Rolle und reizt daher als Therapieziel. Ein Strukturmodell (siehe Bild) des Proteasoms im Komplex mit Argyrin, einem cyclischen Heptapeptid mit Antitumorwirkung, liefert eine Erklärung für die hohe biologische Aktivität dieses Naturstoffs. Die bekannten Struktur-Aktivitäts-Beziehungen dieses Wirkstoffs werden auf der Grundlage dieses Modells diskutiert. [source]

    Direct Visualization of Disulfide Bonds through Diselenide Proxies Using 77Se NMR Spectroscopy,

    ANGEWANDTE CHEMIE, Issue 49 2009
    Mehdi Mobli Dr.
    Selen als Sehhilfe: Viele Proteine enthalten verbrückende Disulfidbindungen, die häufig eine wesentliche Rolle für Proteinstruktur, -faltung und -funktion spielen. Doch die Methoden, um die Verknüpfungsmuster von Disulfidbindungen in Proteinen zu bestimmen, sind technisch schwierig und führen leicht zu Fehlinterpretationen. Nun ist es möglich, diese Verknüpfungen in nativen Proteinen direkt mithilfe der 77Se-NMR-Spektroskopie zu visualisieren. [source]

    Direct Detection of 3hJNC, Hydrogen-Bond Scalar Couplings in Proteins by Solid-State NMR Spectroscopy,

    ANGEWANDTE CHEMIE, Issue 49 2009
    Paul Schanda Dr.
    Allgegenwärtige Wasserstoffbrücken steuern die Faltung und Funktion von Proteinen. Die skalaren Kopplungskonstanten über Wasserstoffbrücken im Proteinrückgrat , mit Werten bis hinab zu 0.5,Hz , können im Festkörper direkt NMR-spektroskopisch bestimmt werden (siehe Bild). Die Kerne an beiden Seiten der Wasserstoffbrücke können identifiziert werden, und die Größe der Kopplungskonstanten lässt sich genau ermitteln. [source]

    Ranking of High-Affinity Ligands by NMR Spectroscopy,

    ANGEWANDTE CHEMIE, Issue 36 2009
    Xiaolu Zhang Dr.
    Das Protein wählt seinen Liganden, und NMR-Spektroskopie enthüllt, welchen es genommen hat (siehe Schema). So gelingen eine sehr genaue Bestimmung der relativen Bindungsaffinitäten zweier Liganden bezüglich eines Proteinrezeptors und zum ersten Mal die Bestimmung der Affinitäten fest bindender Liganden durch NMR-Spektroskopie. Dieser Ansatz sollte nützlich für die Leitstrukturoptimierung sein. [source]

    Real-Time Monitoring of Organic Reactions with Two-Dimensional Ultrafast TOCSY NMR Spectroscopy,

    ANGEWANDTE CHEMIE, Issue 34 2009
    Antonio Herrera Prof.
    Klarheit auf einen Blick: Ein ultraschnelles zweidimensionales TOCSY-Experiment mit nur einem Scan wurde für das Studium der Synthese von Pyrimidin aus einem aliphatischen Keton, einem Nitril und Tf2O genutzt. 525 dieser TOCSY-Experimente wurden aufgezeichnet, und Reaktanten, Intermediate und Produkte konnten verfolgt werden (siehe Bild; blau = Produkt; grau, grün und rosa = Zwischenstufen). [source]

    Long-Range Correlations between Aliphatic 13C Nuclei in Protein MAS NMR Spectroscopy,

    ANGEWANDTE CHEMIE, Issue 31 2009
    Ein hocheffizienter Polarisationstransfer in MAS-NMR-Experimenten (MAS: Rotation im magischen Winkel) ist möglich durch eine Kombination von alternierenden 13C-Markierungen und bandselektiver Radiofrequenz(RF)-getriebener Wiedereinkopplung (BASE RFDR). Dabei wird die Bandselektivität schwacher RF-Strahlung genutzt, um die homonucleare Dipolwechselwirkung wieder einzuführen. [source]

    Preparation of a Functional GABARAP,Lipid Conjugate in Nanodiscs and its Investigation by Solution NMR Spectroscopy

    CHEMBIOCHEM, Issue 14 2010
    Peixiang Ma
    The state you're in: GABARAP, a protein relevant for autophagic processes, has been enzymatically coupled to phosphatidylethanolamine in a ubiquitin-like modification cascade. The lipidation state of GABARAP defines its subcellular localization pattern and is crucial to its functional integrity. [source]

    NMR Spectroscopy of Paramagnetic Metalloproteins

    CHEMBIOCHEM, Issue 9 2005
    Ivano Bertini Prof.
    Abstract This article deals with the solution structure determination of paramagnetic metalloproteins by NMR spectroscopy. These proteins were believed not to be suitable for NMR investigations for structure determination until a decade ago, but eventually novel experiments and software protocols were developed, with the aim of making the approach suitable for the goal and as user-friendly and safe as possible. In the article, we also give hints for the optimization of experiments with respect to each particular metal ion, with the aim of also providing a handy tool for nonspecialists. Finally, a section is dedicated to the significant progress made on13C direct detection, which reduces the negative effects of paramagnetism and may constitute a new chapter in the whole field of NMR spectroscopy. [source]

    In-Cell NMR Spectroscopy

    CHEMBIOCHEM, Issue 9 2005
    Sina Reckel
    Keep it natural. NMR spectroscopy is a noninvasive spectroscopic technique that allows researchers to characterize the conformation and dynamics of proteins in their natural environment. Conformational changes, post-translational modifications or interaction with drugs can thus be studied inside living cells (see graphic). [source]

    ChemInform Abstract: Slow-Proton Dynamics within a Zirconium-Containing Sandwich-Like Complex Based on the Trivacant Anion ,-[SiW9O34]10- , Synthesis, Structure and NMR Spectroscopy.

    CHEMINFORM, Issue 4 2009
    Nathalie Leclerc-Laronze
    Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source]

    ChemInform Abstract: Facile Incorporation of Platinum(IV) into Polyoxometalate Frameworks: Preparation of [H2Pt(IV)V9O28]5- and Chararacterization by 195Pt NMR Spectroscopy.

    CHEMINFORM, Issue 18 2008
    Uk Lee
    Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source]

    ChemInform Abstract: Synthesis of CD3 -Labeled 11-cis-Retinals and Application to Solid-State Deuterium NMR Spectroscopy of Rhodopsin.

    CHEMINFORM, Issue 7 2008
    Katsunori Tanaka
    Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source]

    1,3-Alternate Calix[4]arene Nitronyl Nitroxide Tetraradical and Diradical: Synthesis, X-Ray Crystallography, Paramagnetic NMR Spectroscopy, EPR Spectroscopy, and Magnetic Studies.

    CHEMINFORM, Issue 49 2007
    Andrzej Rajca
    Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source]

    High-Resolution 17O NMR Spectroscopy of Wadsleyite (,-Mg2SiO4).

    CHEMINFORM, Issue 49 2003
    Sharon E. Ashbrook
    No abstract is available for this article. [source]

    The First Observation of Heteronuclear Two-Bond J-Coupling in the Solid State: Crystal Structure and Solid-State NMR Spectroscopy of Rb4(NbO)2(Si8O21).

    CHEMINFORM, Issue 4 2003
    Hsien-Ming Kao
    Abstract For Abstract see ChemInform Abstract in Full Text. [source]

    Determination of Absolute Configuration of Decipinone, a Diterpenoid Ester with a Myrsinane-Type Carbon Skeleton, by NMR Spectroscopy.

    CHEMINFORM, Issue 44 2002
    Amir Reza Jassbi
    No abstract is available for this article. [source]

    Towards a Molecular Understanding of Cation,Anion Interactions,Probing the Electronic Structure of Imidazolium Ionic Liquids by NMR Spectroscopy, X-ray Photoelectron Spectroscopy and Theoretical Calculations

    Till Cremer
    Abstract Ten [C8C1Im]+ (1-methyl-3-octylimidazolium)-based ionic liquids with anions Cl,, Br,, I,, [NO3],, [BF4],, [TfO],, [PF6],, [Tf2N],, [Pf2N],, and [FAP], (TfO=trifluoromethylsulfonate, Tf2N=bis(trifluoromethylsulfonyl)imide, Pf2N=bis(pentafluoroethylsulfonyl)imide, FAP=tris(pentafluoroethyl)trifluorophosphate) and two [C8C1C1Im]+ (1,2-dimethyl-3-octylimidazolium)-based ionic liquids with anions Br, and [Tf2N], were investigated by using X-ray photoelectron spectroscopy (XPS), NMR spectroscopy and theoretical calculations. While 1H,NMR spectroscopy is found to probe very specifically the strongest hydrogen-bond interaction between the hydrogen attached to the C2 position and the anion, a comparative XPS study provides first direct experimental evidence for cation,anion charge-transfer phenomena in ionic liquids as a function of the ionic liquid's anion. These charge-transfer effects are found to be surprisingly similar for [C8C1Im]+ and [C8C1C1Im]+ salts of the same anion, which in combination with theoretical calculations leads to the conclusion that hydrogen bonding and charge transfer occur independently from each other, but are both more pronounced for small and more strongly coordinating anions, and are greatly reduced in the case of large and weakly coordinating anions. [source]

    3-Mercapto-2,6-Pyridinedicarboxylic Acid: A Small Lanthanide-Binding Tag for Protein Studies by NMR Spectroscopy

    Bradley Man
    Abstract Paramagnetic effects from lanthanide ions present powerful tools for protein studies by nuclear magnetic resonance (NMR) spectroscopy provided that the lanthanide can be site-specifically and rigidly attached to the protein. A new, particularly small and rigid lanthanide-binding tag, 3-mercapto-2,6-pyridinedicarboxylic acid (3MDPA), was synthesized and attached to two different proteins via a disulfide bond. The complexes of the N-terminal domain of the E.,coli arginine repressor (ArgN) with seven different paramagnetic lanthanide ions and Co2+ were analyzed in detail by NMR spectroscopy. The magnetic susceptibility anisotropy (,,) tensors and metal position were determined from pseudocontact shifts. The 3MDPA tag generated very different ,, tensor orientations compared to the previously studied 4-mercaptomethyl-DPA tag, making it a highly complementary and useful tool for protein NMR studies. [source]