Multinuclear Nuclear Magnetic Resonance Research Articles

Multinuclear nuclear magnetic resonance relaxation investigations of poly(propylene oxide) complexed with sodium trifluoromethanesulphonate

Low molecular weight poly(propylene oxide), PPO, was complexed with varying amounts of sodium trifluoromethanesulphonate, NaCF 3SO 3. Bulk PPO and the PPO-NaCF 3SO 3 complexes were investigated using 13C, 19F and 23Na nuclear magnetic resonance spectroscopy. Spin-lattice relaxation time, T 1, measurements were made as a function of temperature. The T 1 minima are observed for the different nuclei at different temperatures and concentrations of complexed salt. The 13C T 1 data are interpreted in terms of a Cole-Cole distribution of correlation times. Polymer motion is discussed in the context of the nuclei probed.

ChemInform Abstract: Multinuclear Solid‐State NMR in Silicate and Zeolite Chemistry

Abstract High-resolution nuclear magnetic resonance (NMR) spectroscopy of solids has been developed into a powerful tool for the structural investigations of organic and inorganic solid materials. In this article a concise survey on the applicability of multinuclear solid-state NMR in structural studies of silicates, aluminosilicates and zeolites is presented, and the main information available from 29Si, 27Al and 1H NMR spectra is summarized

Multinuclear NMR study of the interaction of vanadate with mononucleotides, ADP, and ATP.

The interaction of vanadate with 5'-mononucleotides, ADP, ATP, and various molecules containing some of their chemical moieties was studied in aqueous solution in the pH region of 5-9 using proton, 13C, 31P, and 51V nuclear magnetic resonance (NMR) spectroscopy. All the compounds studied formed noncyclic vanadate esters through interaction of monovanadate or divanadate with the hydroxyl groups of the ribose ring. Noncyclic anhydrides were also formed with the phosphate groups of ribose 5-phosphate, the mononucleotides, ADP, ATP, phosphate, pyrophosphate, and tripolyphosphate. In particular, ADP and ATP analogs resulted from AMP (AMPV and AMPV2) and from ADP (ADPV). Cyclic esters of trigonal bipyramidal geometry resulted from the interaction of vanadate with two ribose ring cis hydroxyl groups. AMP, CMP, and UMP formed two such complexes of 1:1 and 1:2 stoichiometries, similar to what has been observed for uridine and other nucleosides. However, 2'-deoxy-AMP does not yield this type of complexes. ADP and ATP also form similar cyclic ester complexes with vanadate, which does not chelate their pyrophosphate and tripolyphosphate moieties. Nevertheless, the separate pyrophosphate (PP) and tripolyphosphate (PPP) ligands form cyclic anhydrides of octahedral geometry with vanadate. However, their binding to vanadate is weaker than that of the ribose ring of nucleotides. Competition experiments between ethylene glycol and phosphate (P), pyrophosphate (PP), or tripolyphosphate (PPP) show that the relative strength of the interaction of these ligands with vanadate is PP greater than ethylene glycol greater than PPP greater than P.

Intrauterine fetal brain NMR spectroscopy: 1H and 31P studies in rats

Fetal brain metabolism was investigated in utero noninvasively using multinuclear nuclear magnetic resonance spectroscopy in rats at two representative prenatal stages: early (17-18 days) and late (20-21 days) stages. Phosphorus-31 (31P) spectroscopy revealed that phosphocreatine is significantly lower in the early stage and increases to the level of early neonates by the late prenatal stage. Intracellular pH at the early stage was found to be strikingly high (7.52 +/- 0.21) and decreased to a level similar to that of neonates by the late stage (7.29 +/- 0.07). Phosphomonoester levels at both stages were similar to the values reported for early neonates. Water-suppressed proton (1H) spectroscopy demonstrated a distinctive in vivo fetal brain spectral pattern characterized by low levels of N-acetyl aspartate and high levels of taurine. High-resolution proton spectroscopy and homonuclear chemical-shift correlate spectroscopy of brain perchloric acid extracts confirmed these in vivo findings. In vitro 31P spectroscopy of acidified chloroform methanol extracts showed the characteristic membrane phospholipid profiles of fetal brain. The phosphatidylethanolamine (PE)-to-phosphatidylcholine (PC) ratio (PE/PC) did not show significant changes between the two stages at 0.40 +/- 0.11, a value similar to that of early neonates.

Multinuclear solid-state NMR in silicate and zeolite chemistry

High-resolution nuclear magnetic resonance (NMR) spectroscopy of solids has been developed into a powerful tool for the structural investigations of organic and inorganic solid materials. In this article a concise survey on the applicability of multinuclear solid-state NMR in structural studies of silicates, aluminosilicates and zeolites is presented, and the main information available from 29Si, 27Al and 1H NMR spectra is summarized

ChemInform Abstract: Recent Developments in NMR Spectroscopy of Organometallic Compounds

Publisher Summary This chapter discusses the recent developments in nuclear magnetic resonance (NMR) spectroscopy of organometallic compounds. The experimental aspects and some results from multinuclear NMR spectroscopy and some examples from solid-state NMR spectroscopy are examined. Modern NMR spectrometers have powerful routines to modify the free induction decay and hence the resolution and signal/noise ratio. Homonuclear decoupling has long been established as a valuable tool in determining which nuclei are coupled. The Nuclear Overhauser Enhancement (NOE) is one of the most valuable tools in determining the connectivity among protons and, to a lesser extent, between protons and other nuclei. The sensitivity of an NMR experiment depends on the population difference among the energy levels. The Incredible Natural Abundurice Double Quantum Transfer Experiment (in adequate) pulse sequence was originally designed to detect 13 C – 13 C coupling without the confusion of the 13 C singlets due to the species without adjacent 13 C atoms. The normal π /2 pulse excites nuclei over a wide range of frequencies. Broadband decoupling has been applied for many years to obtain X-nuclei NMR spectra without 1 H coupling. Until very recently, variable-temperature solid-state NMR spectroscopy with magic angle spinning has been restricted close to room temperature because of the great difficulty of spinning the sample at high speed.

Studies of the hydrolysis and condensation of tetraethylorthosilicate by multinuclear ( 1h, 17o, 29si) nmr spectroscopy

The early stages of the acid hydrolysis and condensation of tetraethylorthosilicate (TEOS) have been studied by multinuclear ( 1 H, 17 O, 29 Si) nuclear magnetic resonance spectroscopy. Sub-stoichiometric concentrations of water were used in order to limit the number and complexity of the species formed. TEOS reacts rapidly with water to form hydrolysed monomers that in turn condense at a lower rate to form polymeric products. Detailed peak assignments were made possible through correlations of the time dependence of the NMR spectra obtained for all three nuclei. 29 Si NMR spectroscopy provides the most quantitative information about this system. The importance of field strength for 1 H NMR studies of TEOS is discussed.

A multinuclear nuclear magnetic resonance study of methylammonium nitrate

Deuterium nmr line shapes in the solid II phase of methylammonium nitrate (MAN) indicate that motion of the cation is restricted to internal rotations of the ND3 group about the C—N axis. In the high temperature plastic phase, solid I, of MAN, 2H, 14N, and 17O nmr results demonstrate that both the cation and anion undergo rapid overall rotations that result in complete averaging of all nuclear quadrupolar interactions. Spin-lattice relaxation results imply that rotations of the cation and anion are anisotropic and that the overall rotations are strongly coupled in both the solid I and liquid phases. At the melting point, overall rotations of the cation are only slightly faster in the liquid phase than in the solid I phase. In the solid I phase, in-plane rotations of the nitrate ion are about twice as rapid as end-over-end rotations of the C3 axis. In the neat liquid, rotations of the NO3− ion are more isotropic, with overall rotations being slightly faster than rotations about the symmetry axis.

Determination of the bonding preference of borane (BH3) toward aminoarsines by multinuclear nuclear magnetic resonance spectroscopy

The reactions of BH3·thf (thf = tetrahydrofuran) with selected (dialkylamino)dimethylarsines, Me2AsNR2(R = Me, Et, Prn, or Pri) have been carried out as a function of temperature to determine the initial co-ordination site of boron and to elucidate the nature of any As–N, As–B, and N–B bond dissociation/formation processes in solution. The reactions were monitored by multinuclear (1H, 11B, and 13C) n.m.r. spectroscopy over a temperature range of –90 to 25 °C. With Me2AsNMe2, a N–B bonded adduct is formed at low temperature, which decomposes at 25 °C to yield (Me2NBH2)2, Me2NH·BH3, µ-Me2NB2H5, and Me2AsAsMe2. Equimolar amounts of As–B and N–B adducts are formed at low temperature when Me2AsNEt2 is reacted with BH3·thf. With increasing temperature, the As–B adduct converts to the N–B adduct, which subsequently decomposes at room temperature to µ-Et2NB2H5, Et2NH·BH3, (Et2NBH2)2, and Me2AsAsMe2. The reaction of Me2AsNPrn2 with BH3·thf yields more of the As–B adduct than of the N–B adduct at –90 °C, but the former rearranges to the latter on warming. Only the As–B adduct is formed in the reaction of Me2AsNPri2 with BH3·thf. These results suggest that the steric bulkiness of the R2N moiety plays an important role in determining the co-ordination site of the boron in this series of compounds.

Dynamic and structural properties of the calcium binding site of bovine serine proteases and their zymogens: A multinuclear nuclear magnetic resonance and stopped-flow study

The combined use of 43Ca and 113Cd nuclear magnetic resonance (n.m.r.) has provided information on the structural and dynamic properties of the calcium binding site located in homologous positions in bovine β-trypsin, α-chymotrypsin and their zymogens. The 43Ca and 113Cd n.m.r. chemical shifts are consistent with an octahedral symmetry of the binding site and with the substitution of one of the two carboxylate ligands present in trypsin(ogen) with a neutral ligand in chymotrypsin(ogen). The constancy of the 113Cd n.m.r. chemical shifts upon binding of the pancreatic trypsin inhibitor and/or the dipeptide Ile-Val to trypsinogen confirms that structural changes in the activation domain do not affect the calcium binding site. The exchange between bound and “free” (solvated) Ca 2+ is slow on the 43Ca n.m.r. time-scale for trypsin(ogen), but falls in the intermediate exchange region for chymotrypsin(ogen). In trypsin, the Ca 2+ off-rate was measured by stopped-flow making use of the calcium indicator 1,2-bis( o-aminophenoxy)-ethane- N, N′, N′, N′-tetraacetic acid and was found to be 3(±1) s −1. In chymotrypsin(ogen) the off-rates calculated from the 43Ca n.m.r. data are 70 s −1 and 350 s −1, respectively. The dynamic properties of the calcium binding site of serine (pro)enzymes have been related to the flexibility of the binding site itself and have been compared to those of other extracellular and intracellular calcium binding proteins.

Influence of dilution on the physical state of model bile systems: NMR and quasi-elastic light-scattering investigations.

Multinuclear (1H and 31P) nuclear magnetic resonance (NMR) spectroscopy and quasi-elastic light scattering have been used to characterize molecular aggregates formed in dilute sodium taurocholate--egg lecithin solutions. When mixed micelles (1.25 g/dL) are diluted with 150 mM aqueous sodium chloride, light-scattering measurements suggest a transformation from mixed micelles to unilamellar vesicle species. Decreased 1H NMR line widths for bile salt resonances are consistent with predominance of a monomer form. The concurrent appearance of a second phospholipid choline methyl resonance indicates two types of phospholipid environment in slow chemical exchange: this behavior is consistent with small unilamellar vesicles. The appearance of bilayer vesicles in dilute model bile solutions is confirmed by addition of a lanthanide shift reagent (Pr3+), which splits the 1H or 31P head-group peak into two components with distinct chemical shift sensitivities. These mixed micelle and vesicle aggregates are also distinguished by their susceptibility to the lipolytic enzyme phospholipase A2 from cobra venom.

ChemInform Abstract: REACTIONS OF BORON COMPOUNDS WITH DIFLUOROPHOSPHORIC ACID: CHARACTERIZATION OF THE TETRAKIS(DIFLUOROPHOSPHATO)BORATE ANION BY MULTINUCLEAR (BORON‐11, FLUORINE‐19, AND PHOSPHORUS‐31) NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY

Chemischer InformationsdienstVolume 16, Issue 11 Preparative Inorganic Chemistry ChemInform Abstract: REACTIONS OF BORON COMPOUNDS WITH DIFLUOROPHOSPHORIC ACID: CHARACTERIZATION OF THE TETRAKIS(DIFLUOROPHOSPHATO)BORATE ANION BY MULTINUCLEAR (BORON-11, FLUORINE-19, AND PHOSPHORUS-31) NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY M. F. A. DOVE, M. F. A. DOVESearch for more papers by this authorR. C. HIBBERT, R. C. HIBBERTSearch for more papers by this authorN. LOGAN, N. LOGANSearch for more papers by this author M. F. A. DOVE, M. F. A. DOVESearch for more papers by this authorR. C. HIBBERT, R. C. HIBBERTSearch for more papers by this authorN. LOGAN, N. LOGANSearch for more papers by this author First published: March 19, 1985 https://doi.org/10.1002/chin.198511035Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume16, Issue11March 19, 1985 RelatedInformation

Complexes of the platinum metals. Part 26. Multinuclear nuclear magnetic resonance studies on rhodium(II) carboxylate adducts

A multinuclear (1H, l3C, 31P, and 103Rh), variable-temperature, n.m.r. study on some [Rh2(O2CR)4]–P(OR′)3 systems (R = Me, Et, Pr, or Ph; R′= Me, Et, or Ph) is reported. The ambient-temperature (298 K) spectra, which generally display broad unresolved signals with no discernible internuclear couplings, are consistent with the establishment in solution of dynamic equilibria of the form [{(R′O)3P}Rh(O2CR)4Rh{P(OR′)3}]⇌[{(R′O)3P}Rh(O2CR)4Rh(solv)]+ P(OR′)3(solv = solvent). Low-temperature (ca. 213 K) spectra of the same solutions show fully resolved resonances indicative of a frozen equilibrium mixture containing mono and bis adducts together with free phosphorus-donor ligands. The large 31P chemical shift difference (ca. 50–60 p.p.m.) between the mono and bis adducts points to the operation of a strong trans influence across the binuclear metal centre. This has been confirmed by a study of ca. 30 mixed adducts [{(MeO)3P}Rh(O2CMe)4RhL] in which 31P chemical shifts and 2J(RhP) coupling constants have been employed to establish a trans-influence series for the ligands L.

Multinuclear nuclear magnetic resonance study of the interaction of some phosphorus(V) compounds with inorganic acids. The protonating abilities of HNO3, MeSO3H, and HPO2F2 towards the phosphoryl group

The influence of protonation upon 31P and 17O n.m.r. parameters of the phosphoryl compounds POCl3 and HPO2F2 has been investigated. For POCl3, δ(17O) and 1J(P–O) decrease whereas δ(31P) increases with increasing protonation of the phosphoryl group. For HPO2F2 the changes in δ(17O) and δ(31P) were less informative although 1J(P–F) appears to increase smoothly with increasing protonation. The same trend in 1J(P–F) is observed for solutions of Na2PO3F in some inorganic acids (MeSO3H, CF3CO2H, HNO3, HSO3Cl, and 25 oleum). The POCl3 results indicate that the ability of HNO3 to protonate the phosphoryl group is significantly greater than would be anticipated on the basis of Hammett acidity-function measurements, whereas the protonating ability of MeSO3H is as anticipated on the basis of its Hammett function and that of HPO2F2 is lower than those of HNO3 and MeSO3H, comparable with that of liquid HCl. The values of δ(31P) of POBr3 in HNO3, MeSO3H, and HPO2F2 are in agreement with the above conclusions.

Reactions of boron compounds with difluorophosphoric acid; characterisation of the tetrakis(difluorophosphato)borate anion by multinuclear (11B, 19F, and 31P) nuclear magnetic resonance spectroscopy

The tetrakis(difluorophosphato)borate anion, [B(PO2F2)4]–(1), has been identified and characterised in solution by means of 11B, 19F, and 31P n.m.r. spectroscopy. (1) is formed from H3BO3 and P2O3F4 in HPO2F2. It is also the initial product of the reaction of BBr3 or BCl3 with excess HPO2F2; however, it is gradually converted to (2), which is believed to be [BF(PO2F2)3]–. (2) is also generated directly from either BF3 or BF4– in P2O3F4–HPO2F2 mixtures, in which it is gradually converted to (1).

Multinuclear nuclear magnetic resonance study of ion pairing and solvation in the system sodium tetraethylaluminate/tetrahydrofuran/m-xylene

Multinuclear nuclear magnetic resonance study of ion pairing and solvation in the system sodium tetraethylaluminate/tetrahydrofuran/m-xylene

Multinuclear nuclear magnetic resonance study of lithium perchlorate-solvent-nitroxide radical systems

Etude de la solvatation du cation lithium dans des solvants non aqueux par RMN de 7 Li en utilisant le radical tetramethyl-2,2,6,6, piperidinyloxyle-1 (TEMPO) comme marqueur de spin. A partir de la variation des parametres RMN en fonction de la temperature l'enthalpie de formation du complexe lithium-TEMPO est de 4,6±0,2 kJ mol −s dans THF et −3,3±0,8 kJ mol −1 dans CH 3 CN

Lithium halide and lithium perchlorate binding to phosphate. A multinuclear nuclear magnetic resonance spectroscopic study

On etudie pour RMN l'interaction de LiX (X=F, Cl, B 2 , ClO 4 ) avec l'isopropoxy-2 methyl-5 oxo-2 oxaphosphole-1,2 ene-4, le dimethyl-4,5 methoxy-2 oxo-2 dioxaphosphole-1,3,2, le phosphate de triphenyle et le phosphate de triethyle

ChemInform Abstract: MULTINUCLEAR, MULTIFIELD, AND MULTIPHASE NUCLEAR MAGNETIC RESONANCE STUDY OF CADMIUM MESO‐TETRAPHENYLPORPHYRIN AND ITS PYRIDINE ADDUCT

Chemischer InformationsdienstVolume 14, Issue 14 Physical Organic Chemistry ChemInform Abstract: MULTINUCLEAR, MULTIFIELD, AND MULTIPHASE NUCLEAR MAGNETIC RESONANCE STUDY OF CADMIUM MESO-TETRAPHENYLPORPHYRIN AND ITS PYRIDINE ADDUCT H. J. JAKOBSEN, H. J. JAKOBSENSearch for more papers by this authorP. D. ELLIS, P. D. ELLISSearch for more papers by this authorR. R. INNERS, R. R. INNERSSearch for more papers by this authorC. F. JENSEN, C. F. JENSENSearch for more papers by this author H. J. JAKOBSEN, H. J. JAKOBSENSearch for more papers by this authorP. D. ELLIS, P. D. ELLISSearch for more papers by this authorR. R. INNERS, R. R. INNERSSearch for more papers by this authorC. F. JENSEN, C. F. JENSENSearch for more papers by this author First published: April 5, 1983 https://doi.org/10.1002/chin.198314063AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume14, Issue14April 5, 1983 RelatedInformation

Changes of biological significance induced by metal ions in the structure of nucleic acids and nucleotides

We have previously shown that the action of metal ions on nucleic acids leads to a variety of perturbations in secondary structure, including crosslinking, mispairing, and degradation. We have demonstrated that metal ions also have a profound effect on the way in which nucleic acid molecules are packed together into highly organized aggregates [1]. These studies, along with those that reveal that metals also influence the enzymes that act on nucleic acids (such as cleavage enzymes and RNA polymerase) indicate how changes in cellular concentrations of metal ions can impact on cellular processes that depend on genetic information transfer. Many of the effects of metals on nucleic acids or other biomacromolecules involve conformational changes. We have recently been concerned with the ability of metal ions or complexes to induce interconversions among at least four nucleic acid conformers [2]. These studies were carried out with poly(dGdC)·(dGdC), which can exist in the Z-conformation, and we have discovered that conversion to Z-DNA can lead to further conversions to other DNA structures. These structures are all in equilibrium with each other, but each can be stabilized under appropriate conditions of nucleic acid and metal concentration. These conformational transitions are important because the biological activity of nucleic acids depends on their conformation. We have shown that different conformations of DNA have different activities as template for RNA synthesis. It has been reported that the progress of Alzheimer's disease, the most prevalent form of senile dementia, is associated with the accumulation of aluminum in the chromatin of the brain [3, 4]. We have found that Al forms crosslinks between DNA strands and that Al binding to DNA in chromatin can be monitored by nuclear magnetic resonance (NMR). Al has also been implicated in dialysis dementia [5] through binding to ATP [6]. We have found by multinuclear NMR studies that Al forms four different complexes [7] with ATP. 27Al NMR is very sensitive to the chemical environment of Al and can be used in the identification of Al complexes in equilibrium with each other in a variety of systems of biological interest [8].