109Ag NMR-Studies of the Selective Solvation of the Ag+ -Ion in Water-Ethylamine-Mixtures and of the Coordination of Halide-Anions to the Silver-Ethylamine Solvate Complexes

1980 ◽  
Vol 35 (3) ◽  
pp. 319-328 ◽  
Author(s):  
J. Kronenbitter ◽  
U. Schweizer ◽  
A. Schwenk
Keyword(s):  
Chemical Shift ◽  
Chemical Exchange ◽  
Chemical Shifts ◽  
Equilibrium Constants ◽  
Relaxation Times ◽  
Solvent Mixtures ◽  
Nmr Studies ◽  
Selective Solvation ◽  
Halide Anions ◽  
Chlorine Ion

Abstract109Ag chemical shift measurements of 0.02 up to 3 molar solutions of AgNO3, AgCl, and AgBr in solvent mixtures of H2O (W) and ethylamine (ea) were performed. The extremely long relaxation times T1 and T2 were determined with new techniques. The Ag+ -ion in solvent mixtures of W and ea shows a strongly selective solvation by ea. The 109Ag chemical shift of the solvate complex [Ag ea2]+ surrounded solely by W is δ2 = (335 ± 2) ppm (referred to the Ag+-ion in W). A further solvation in addition to the inner solvation sphere was determined; this solvation is not or only weakly selective. There is a rapid chemical exchange; the lifetime of the inner solvation sphere is long compared with the Larmor period, whereas the solvation outside this sphere is changed in times shorter than the Larmor period. In contrast to the NO3- -anion, the halide anions Cl- and Br- are partly coordinated to the [Ag ea2]+ complex. The equilibrium constants for this coordination were determined as well as the chemical shifts of the [Ag ea2 · Cl] and the [Ag ea2 · Br] complexes. The bromine ion is coordinated for shorter times than the Larmor period, whereas the time of the coordination of the chlorine ion may be comparable to the Larmor period or shorter.

109Ag NMR-Study of the Selective Solvation of the Ag+ Ion in Solvent Mixtures of Water and the Organic Solvents: Pyridine, Acetonitrile, and Dimethyl Sulfoxide

1984 ◽  
Vol 39 (1) ◽  
pp. 83-94 ◽  
Author(s):  
L. Guinand. K. L. Hobt. E. Mittermaier ◽  
E. Rößler ◽  
A. Schwenk ◽  
H. Schneider
Keyword(s):  
Chemical Shift ◽  
Dimethyl Sulfoxide ◽  
Organic Solvents ◽  
Mole Fraction ◽  
Chemical Exchange ◽  
Chemical Shifts ◽  
Equilibrium Constants ◽  
Solvent Mixtures ◽  
Nmr Study ◽  
Solvent Molecules

In mixtures of water (W) and one of the organic solvents pyridine, acetonitrile, and dimethyl sulfoxide (O), the silver ion forms the following solvate complexes: AgW2, AgWO, and Ag02. The chemical shift of 109Ag is strongly affected by the ligating solvent molecules, and replacing the ligand W by one of the three organic ligands yields a higher Larmor frequency. In solvent mixtures, only a single resonance line has been observed because of rapid chemical exchange. The measured chemical shifts in the range up to 400 ppm are mean values of the chemical shifts of the different solvate species in a given mixture, weighted with their relative concentrations. The 109Ag chemical shifts were determined for 0.05 to 0.15 molal solutions of AgNO3, as functions of the mole fractions of the solvent components. Using a Gaussian least squares fitting routine, the individual chemical shifts of the Ag+ solvate complexes and the corresponding equilibrium constants were determined. This fit was successful for the whole mole fraction range of DMSO, while in the solvent systems with acetonitrile and with pyridine at higher concentrations of the organic component the chemical shift is influenced by more than two solvent molecules. In these cases equilibrium constants were calculated from chemical shift data for solutions of low mole fraction of acetonitrile and pyridine.

NMR studies of tandem WW domains of Nedd4 in complex with a PY motif-containing region of the epithelial sodium channel

1998 ◽  
Vol 76 (2-3) ◽  
pp. 341-350 ◽  
Author(s):  
Voula Kanelis ◽  
Neil A Farrow ◽  
Lewis E Kay ◽  
Daniela Rotin ◽  
Julie D Forman-Kay
Keyword(s):  
Chemical Shift ◽  
Sodium Channel ◽  
Chemical Shifts ◽  
Epithelial Sodium Channel ◽  
Chemical Shift Assignment ◽  
Nmr Studies ◽  
Ww Domains ◽  
Ww Ii ◽  
Py Motif ◽  
Shift Assignment

Nedd4 (neuronal precursor cell-expressed developmentally down-regulated 4) is a ubiquitin-protein ligase containing multiple WW domains. We have previously demonstrated the association between the WW domains of Nedd4 and PPxY (PY) motifs of the epithelial sodium channel (ENaC). In this paper, we report the assignment of backbone 1Hα, 1HN, 15N, 13C', 13Cα, and aliphatic 13C resonances of a fragment of rat Nedd4 (rNedd4) containing the two C-terminal WW domains, WW(II+III), complexed to a PY motif-containing peptide derived from the β subunit of rat ENaC, the βP2 peptide. The secondary structures of these two WW domains, determined from chemical shifts of 13Cα and 13Cβ resonances, are virtually identical to those of the WW domains of the Yes-associated protein YAP65 and the peptidyl-prolyl isomerase Pin1. Triple resonance experiments that detect the 1Hα chemical shift were necessary to complete the chemical shift assignment, owing to the large number of proline residues in this fragment of rNedd4. A new experiment, which correlates sequential residues via their 15N nuclei and also detects 1Hα chemical shifts, is introduced and its utility for the chemical shift assignment of sequential proline residues is discussed. Data collected on the WW(II+III)-βP2 complex indicate that these WW domains have different affinities for the βP2 peptide.Key words: WW domain, PY motif, Nedd4, ENaC, NMR.

Nuclear Magnetic Relaxation by Anisotropy of the Chemical Shift

1972 ◽  
Vol 27 (10) ◽  
pp. 1456-1458 ◽  
Author(s):  
J Blicharski
Keyword(s):  
Chemical Shift ◽  
Magnetic Relaxation ◽  
Chemical Shifts ◽  
Relaxation Times ◽  
Nuclear Magnetic Relaxation ◽  
Nuclear Magnetic

Abstract The relaxation times T1 , T2 , T1Q and T2Q are calculated in the weak collision case in the presence of anisotropy of the chemical shifts.

Chemical shifts for compounds of the group IV elements silicon and tin

1968 ◽  
Vol 46 (8) ◽  
pp. 1399-1414 ◽  
Author(s):  
B. K. Hunter ◽  
L. W. Reeves
Keyword(s):  
Chemical Shift ◽  
Complex Formation ◽  
Chemical Shifts ◽  
Equilibrium Constants ◽  
Lattice Relaxation ◽  
Lattice Relaxation Time ◽  
Spin Lattice Relaxation ◽  
Shielding Effect ◽  
Spin Lattice ◽  
Group Iv Elements

Chemical shifts for 29Si in seven series of molecules of the type XnSiY4−n have been measured where Y is an alkyl group and X varies widely in electronegativity. A considerable amount of proton and fluorine chemical shift data has been obtained for the same compounds and in one series (CH3)nSiCl4−n the 13C chemical shifts in the methyl groups have been measured.The gross features of the 29Si chemical shifts are understood by considering the series (Alkyl)3SiX with the electronegativity of X widely varied. The hybridization at silicon is approximately conserved in these series and the theoretically anticipated linear dependence on electronegativity of X is demonstrated. The ligands X = O, N, and F are exceptional and these 29Si chemical shifts have a high field shift. This additional shielding has been associated with (p → d)π bonding. The approximate nature of present chemical shift theories is not likely to provide a measure of the order of (p → d)π bonding.The 29Si chemical shifts in the series XnSiY4−n are discussed and also indicate a net shielding effect with (p → d)π bonding. A comparison is always made with corresponding 13C chemical shifts. A long range proton–proton coupling in molecules Me3SnX and Me2SnX2, H—C—Si—C—H, is observed when and only when X = O, (N?), F.119Sn chemical shifts in a series of alkyltin compounds have been measured. The same dependence on the electronegativity of X in the series (Alkyl)3SnX is noted, but the variation of X is much more limited. Some shielding due to (p → d)π bonding in the series (n-Butyl)nSnCl4−n is suggested. The tin chemical shift has been measured as a function of concentration and solvent for simple methyltin bromides and chlorides. In donor solvents, it has been possible to obtain equilibrium constants for complex formation from tin dilution chemical shifts. The nature of the bonding in complexes suggested previously is consistent with the variations in the coupling constant |JSn–C–H| with concentration. The distinction between ionization and complex formation with the solvent for (CH3)2SnCl2 can be made on the basis of the concentration dependence of |JSn–C–H|The spin–lattice relaxation time T1for 13C and 29Si in natural abundance in several pure degassed compounds has been measured. These are not in the case of 13C (as has been suggested) of the order several minutes, but are always less than 50 s and in one case as low as 3–4 s. Both 29Si and 13C T1 values follow what might be expected on the basis of a dipole–dipole mechanism from the closest protons. The short value of 35 s in CS2 is probably a result of spin–rotation interaction in the liquid state.

scholarly journals Variable-pressure dynamic NMR studies: effects of paramagnetic metal ions on NMR parameters in nonexchanging systems

1994 ◽  
Vol 72 (10) ◽  
pp. 2188-2192 ◽  
Author(s):  
Hideo D. Takagi ◽  
Kayoko Matsuda ◽  
Sen-Ichi Aizawa ◽  
Shigenobu Funahashi ◽  
Stephen D. Kinrade ◽  
...  
Keyword(s):  
Ligand Exchange ◽  
High Pressures ◽  
Activation Volume ◽  
Chemical Exchange ◽  
Chemical Shifts ◽  
Variable Pressure ◽  
Exchange Reactions ◽  
Nmr Studies ◽  
Nmr Parameters ◽  
Paramagnetic Metal

The possible effects of paramagnetic relaxation on the apparent volumes of activation for exchange reactions in solution, as measured by NMR at high pressures, are considered. Two model paramagnetic systems that do not undergo ligand exchange on the NMR time scale were examined: tri(acetylacetonato)chromium(III) in various perdeuterated solvents, and tris(ethylenediamine)nickel(II) ion in ethylenediamine solvent. No pressure dependence was discernible up to 200 MPa for the chemical shifts of 1H (exemplifying nuclei of spin 1/2) in the Cr(III) complex, or of solvent 14N (representing quadrupolar nuclei) in the Ni(II)–ethylenediamine case. The line widths Δv1/2, however, were significantly dependent on pressure. For 1H in the Cr complex, the increase of Δv1/2 with pressure was less than expected from the theory of scalar interactions, and was small enough to imply that any contribution from this source to the observed volume of activation in exchanging systems may be neglected. For 14N in liquid ethylenediamine, the increase of Δv1/2 with pressure was significantly greater when a paramagnetic solute was present. Thus, before the observed Δv1/2 at a pressure P (in MPa) measured by the NMR of a quadrupolar nucleus can be used to obtain a chemical exchange rate for a paramagnetic solute, it should be reduced by an amount Δv1/20 exp{θ(P − 0.1)(ΔVV‡/RT + κ)}, where ΔVV‡ is the activation volume for viscous flow and κ the compressibility of the solvent, Δv1/20 is the linewidth at 0.1 MPa in the absence of chemical exchange, and θ is a scaling factor between 0 and 1. The factors Δv1/20 and θ(ΔVV‡/RT + κ) are obtainable from measurements with a chemically equivalent, nonexchanging, paramagnetic solute.

31P-NMR Studies on ATP·Mg2⊕, p21·Nucleotide, and Adenylate Kinase·Nucleotide Complexes. Chemical Shifts, Rate and Equilibrium Constants

1986 ◽  
Vol 367 (2) ◽  
pp. 781-786 ◽  
Author(s):  
Werner KLAUS ◽  
Ilme SCHLICHTING ◽  
Roger S. GOODY ◽  
A. WITTINGHOFER ◽  
Paul RÖSCH ◽  
...  
Keyword(s):  
31P Nmr ◽  
Chemical Shifts ◽  
Equilibrium Constants ◽  
Nmr Studies

scholarly journals Oxygen-17 NMR spectroscopy of water molecules in solid hydrates

2016 ◽  
Vol 94 (3) ◽  
pp. 189-197 ◽  
Author(s):  
Sherif Nour ◽  
Cory M. Widdifield ◽  
Libor Kobera ◽  
Kevin M. N. Burgess ◽  
Dylan Errulat ◽  
...  
Keyword(s):  
Solid State ◽  
Chemical Shift ◽  
Density Functional ◽  
Chemical Shifts ◽  
Sodium Perchlorate ◽  
Coupling Constants ◽  
Water Molecules ◽  
Potassium Oxalate ◽  
Nmr Studies ◽  
Quadrupolar Coupling

17O solid-state NMR studies of waters of hydration in crystalline solids are presented. The 17O quadrupolar coupling and chemical shift (CS) tensors, and their relative orientations, are measured experimentally at room temperature for α-oxalic acid dihydrate, barium chlorate monohydrate, lithium sulfate monohydrate, potassium oxalate monohydrate, and sodium perchlorate monohydrate. The 17O quadrupolar coupling constants (CQ) range from 6.6 to 7.35 MHz and the isotropic chemical shifts range from –17 to 19.7 ppm. The oxygen CS tensor spans vary from 25 to 78 ppm. These represent the first complete CS and electric field gradient tensor measurements for water coordinated to metals in the solid state. Gauge-including projector-augmented wave density functional theory calculations overestimate the values of CQ, likely due to librational dynamics of the water molecules. Computed CS tensors only qualitatively match the experimental data. The lack of strong correlations between the experimental and computed data, and between these data and any single structural feature, is attributed to motion of the water molecules and to the relatively small overall range in the NMR parameters relative to their measurement precision. Nevertheless, the isotropic chemical shift, quadrupolar coupling constant, and CS tensor span clearly differentiate between the samples studied and establish a ‘fingerprint’ 17O spectral region for water coordinated to metals in solids.

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