NMR studies of hydrocarbons solubilized in aqueous micellar solutions

1991 ◽  
Vol 69 (5) ◽  
pp. 822-833 ◽  
Author(s):  
Roderick E. Wasylishen ◽  
Jan C. T. Kwak ◽  
Zhisheng Gao ◽  
Elisabeth Verpoorte ◽  
J. Bruce MacDonald ◽  
...  
Keyword(s):  
Alkyl Chain ◽  
Chemical Shifts ◽  
Nmr Relaxation ◽  
Spin Lattice Relaxation ◽  
Ionic Surfactant ◽  
Nmr Studies ◽  
Unsaturated Hydrocarbons ◽  
Saturated Hydrocarbons ◽  
Surfactant Micelle ◽  
H Nmr

Information concerning the solubilization of hydrocarbons in ionic surfactant micelles was obtained from 2H NMR relaxation, 1H NMR chemical shifts, and 1H NMR paramagnetic relaxation measurements. The rotational motion of deuterated hydrocarbons, which is related to the micellar microviscosity at the location of the hydrocarbons, was probed by 2H NMR relaxation. The relaxation data are interpreted using both the two-step and the single-step models, and the results are discussed in terms of the micellar microviscosity and the location of the hydrocarbons in micelles. The location of the hydrocarbons in micelles was further investigated by determining the aromatic ring current-induced 1H chemical shifts along the surfactant alkyl chain and by comparing the 1H spin-lattice relaxation enhancement of the hydrocarbons and the surfactant alkyl chain, induced by Mn2+ on the micellar surface. The hydrocarbons used include benzene, naphthalene, acenaphthalene, triphenylene, cyclohexane, cyclododecane, and tert-butylcyclohexane and the surfactants studied are hexadecyl-, tetradecyl-, and dodecyltrimethylammonium bromide; hexadecyl-, tetradecyl-, and dodecylpyridinium halide; and sodium dodecyl sulfate. The results indicate that the micellar microviscosity at the location of saturated hydrocarbons is approximately 5 cP for both the cationic and anionic micelles, whereas the micellar microviscosity at the location of unsaturated hydrocarbons is much higher. The unsaturated hydrocarbons are found to reside primarily near the surfactant headgroup in the cationic micelles, but are distributed evenly throughout the anionic SDS micelles. The saturated hydrocarbons appear to be located in the interior of the micelles. Key words: NMR, relaxation, solubilization, surfactant, micelle.

1H NMR studies on the solution conformation of contulakin-G and analogues

2002 ◽  
Vol 80 (8) ◽  
pp. 1022-1031 ◽  
Author(s):  
Lill Kindahl ◽  
Corine Sandström ◽  
A Grey Craig ◽  
Thomas Norberg ◽  
Lennart Kenne
Keyword(s):  
Hydrogen Bond ◽  
Chemical Shifts ◽  
Torsional Rigidity ◽  
Peptide Chain ◽  
Random Coil ◽  
Amide Proton ◽  
Solution Conformation ◽  
Nmr Studies ◽  
H Nmr ◽  
Intramolecular Hydrogen

The conformation of contulakin-G, a bioactive 16 amino acid O-linked glycopeptide (ZSEEGGSNAT*KKPYIL) with the disaccharide β-D-Gal(1[Formula: see text]3)α-D-GalNAc attached to the threonine residue in position 10, has been investigated by 1H NMR spectroscopy. The 1H NMR data for the non-glycosylated peptide and for two glycopeptide analogues, one with the monosaccharide α-D-GalNAc at Thr10 and one with the disaccharide β-D-Gal(1–>3)α-D-GalNAc at Ser7, all of lower bioactivity than contulakin-G, have also been collected. The chemical shifts, NOEs, temperature coefficients of amide protons, and 3JNH,αH-values suggest that all four compounds exist mainly in random coil conformations. Some transient populations of folded conformations are also present in the glycopeptides and turns, probably induced by the sugars, are present in the peptide chain around the site of glycosylation. In the two peptides O-glycosylated at Thr10, the rotation of α-D-GalNAc around the linkage between the sugar and the peptide is restricted. There is evidence for a hydrogen bond between the amide proton of α-D-GalNAc and the peptide chain that could contribute to this torsional rigidity. An intramolecular hydrogen bond between the carbohydrate and the peptide chain does not exist in the peptide O-glycosylated at the Ser7 residue. Key words: conformation, contulakin-G, NMR, O-linked glycopeptide.

scholarly journals NMR Studies on Dynamics of Water Intercalated in Clay Minerals

1999 ◽  
Vol 54 (6-7) ◽  
pp. 431-436 ◽  
Author(s):  
Shin’ichi Ishimaru ◽  
Ryuichi Ikeda
Keyword(s):  
Nmr Spectra ◽  
Relaxation Times ◽  
Lattice Relaxation ◽  
Axial Rotation ◽  
Spin Lattice Relaxation ◽  
Water Molecules ◽  
Nmr Studies ◽  
Spin Lattice ◽  
H Nmr ◽  
Clay Layers

Abstract The dynamics of water molecules intercalated in D2O saturated synthetic and natural smectites, and a synthetic Na-fluormica were studied by measurements of solid state 2H NMR spectra and spin-lattice relaxation times at 150 - 370 K. The obtained results could be explained by the 2-site flip, the C2 rotation and the isotropic rotation of the D2O molecules in smectites. In fluormica, the isotropic motion was undetectable, but the axial rotation of the hydration sphere as a whole was observed. The activation energies and correlation times of the C2 rotation were almost independent of the interlayer cations but depended on the character of clay-layers.

1H and 2H NMR Studies of Mixtures 2,6-Lutidine/Water Near the Lower Critical Solution Point

1992 ◽  
Vol 47 (4) ◽  
pp. 583-587 ◽  
Author(s):  
Vytautas Balevicius ◽  
Norbert Weiden ◽  
Alarich Weiss
Keyword(s):  
Phase Region ◽  
Spin Lattice Relaxation ◽  
Nmr Studies ◽  
Two Phase ◽  
H Nmr ◽  
Coexisting Phases ◽  
Critical Solution Point ◽  
Solution Point ◽  
Concentration Changes ◽  
Nmr Signals

AbstractDeuteron spin-lattice relaxation time (TJ measurements of binary mixtures 2,6-lutidine/D20 have been done near the lower critical solution point (TC, L), ε = (T - TC, L)/TC, L ≧10-5. Singularities are observed at TC, L. The changes in the slope of T1 (2H) = ƒ ( T ) can be interpreted as due to the effect of concentration changes on Ty and simultaneously strong overlaping of 2H NMR signals from coexisting phases. In the two-phase region, ca. 2°C above TC, L two D2O signals with very strong temperature evolution have been detected. Similar doubling of 2,6-lutidine 1H NMR signals has been observed already at T - TC, L ≦ 1 °C. It is shown that the two signals arise from the nuclei in two coexisting phases; they are not due to pecularities of hydrogen bond. The difference between chemical shifts of both D2O signals δ’ - δ” possess the property of an order parameter, i.e. δ’ - δ” ~ εβ with β = 0.336±0.030

scholarly journals NMR Studies into the Potential Interactions of Fullerene C60 with Tetraphenylporphyrin and Some of Its Derivatives

2010 ◽  
Vol 2010 ◽  
pp. 1-9
Author(s):  
C. Obondi ◽  
A. A. Rodriguez
Keyword(s):  
Stationary Phases ◽  
Nmr Relaxation ◽  
Interaction Process ◽  
Relaxation Rates ◽  
Electronic Effects ◽  
Nmr Studies ◽  
Noticeable Effect ◽  
H Nmr ◽  
Electron Donating Groups ◽  
Potential Interactions

1H NMR relaxation studies were employed to investigate potential interactions between C60 and tetraphenylporphyrin, H2[TPP], and parasubstituted tetraphenylporphyrins, H2[(p-X)4TPP], where X = CN and OCH3 in solution. The substituted porphyrins provided a means by which to investigate the role that electronic effects play in the interaction process. A comparison of the relaxation rates, R1, and correlation times, τC, of the pyrrole and phenyl hydrogens in these complexes, without and with the presence of C60, revealed that the introduction of C60 into solution did not have a noticeable effect on R1 and τC of these protons in H2[TPP], indicating the absence of long-term intermolecular interaction at either of these two sites. A similar analysis of the two protons in the other two substituted tetraphenylporphyrin analogs revealed slower molecular dynamics indicating the presence of intermolecular interactions. Stronger interactions were observed in H2[(p-OCH3)4TPP] indicating that the electron-donating abilities of the -OCH3 group promote the interaction process. Our results indicate that it is very likely that enhanced selectivity in the chemical purifications of fullerenes and metallofullerenes can be achieved by employing tetraphenylporphyrin-silica stationary phases which have been modified with electron-donating groups.

NQR and NMR Studies of Phase Transitions in R2Pb[Cu(NO2)6] (R = K, Rb, Tl, Cs, and NH4)

1996 ◽  
Vol 51 (5-6) ◽  
pp. 721-725
Author(s):  
Motohiro Mizuno ◽  
Tetsuo Asaji ◽  
Masahiko Suhara ◽  
Yoshihiro Furukawa
Keyword(s):  
Transition Point ◽  
Relaxation Times ◽  
Lattice Relaxation ◽  
Incommensurate Phase ◽  
The Other ◽  
Spin Lattice Relaxation ◽  
Nmr Studies ◽  
Spin Lattice ◽  
H Nmr ◽  
The Difference

Abstract39K, 87, 85Rb, 133Cs, 205T1, and 1, 2H NMR spin-lattice relaxation times T1 and 14N NQR spin-lattice relaxation times T1Q were determined for R2Pb[Cu(NO2)6] (R = K, Rb, Tl, Cs, and NH4). T1 of 39K and 87Rb showed very short values in the incommensurate phase as compared with those in the other phases. When the commensurate-incommensurate phase transition point is approached from below, 14N T1Q of the R = K, Rb, Tl, and NH4 compounds showed rapid decrease. On the other hand, that of the R = Cs compound began to decrease first after passing beyond the corresponding transition point. The difference of the T1Q behavior may be ascribed to the difference of the condensed phonon mode in the incommensurate phase.

scholarly journals Applications and evaluation of IGAIM 13C and 1H chemical shift calculations for unsaturated hydrocarbons and organolithium compounds

1996 ◽  
Vol 74 (6) ◽  
pp. 875-884 ◽  
Author(s):  
Nick Henry Werstiuk ◽  
Jiangong Ma
Keyword(s):  
Chemical Shifts ◽  
Special Importance ◽  
Unsaturated Hydrocarbons ◽  
Nmr Chemical Shifts ◽  
Organolithium Compounds ◽  
H Nmr ◽  
Lithium Complexes ◽  
Experimental Values ◽  
Chemical Shift Calculations ◽  
C Nmr

Wave functions obtained at the RHF/6-31+G(d) level of theory were used with the new method IGAIM (individual gauges for atoms in molecules) developed by Keith and Bader to calculate the isotropic 13C and 1H NMR chemical shifts of a group of neutral molecules (bicyclo[3.2.1]octa-2,6-diene (1), bicyclo[3.2.1]oct-6-ene (2), bicyclo[2.2.1]hepta-2,5-diene (3), benzene (4)), carbanions (prop-2-en-1-yl (allyl) (5), bicyclo[3.2.1]octa-3,6-dien-2-yl (8)), and lithium complexes (prop-2-en-1-yllithium (6) and its dimer 7, bicyclo[3.2.1]octa-3,6-dien-2-yllithium (9)). The theoretical isotropic 13C NMR chemical shifts of the neutral molecules, relative to the calculated value for TMS(tetramethylsilane), are in excellent agreement with the experimental values, with differences between the sets of data ranging from +4.9 to −7.1 ppm. For the same group of compounds the theoretical 1H shifts are lower than the experimental values by increments ranging between 0.4 and 1.29 ppm. For allyllithium, which exists as an unsymmetrical fluxional dimer, the theoretical averaged 13C shifts are larger, 2.6 ppm for the terminal carbons and 16.7 ppm for the central carbon, than the experimental values. In the case of 8, originally considered to be a bishomoaromatic species, the theoretical 13C chemical shifts of its Li+ complex 9 differ from the experimental ones for THF-solvated 9 by values that range from +6.2 to −15.0 ppm. Yet, the relative theoretical chemical shifts — of special importance is the fact that the carbons of the vinylene bridge of this compound are unusually shielded relative to the parent diene 1 — correlate with the experimental data. The 1H chemical shifts calculated for the hydrocarbons 1, 2, 3, 4 and the lithium complexes 7 and 9 range from 0.08 to 1.38 ppm less than the experimental values. To gain information on whether variations in charge density play a significant role in determining the magnitudes of the chemical shifts, we used AIMPAC calculations to obtain the atom electron populations of diene 1, 5, 6, dimer 7, 8, and 9. We find no obvious correlation between the charges on the carbon atoms and the 13shifts for this set of compounds. Key words: IGAIM, calculations, 13C and 1H chemical shifts, unsaturated hydrocarbons, organolithium compounds.

NMR studies of alkali intercalted carbon nanotubes

2003 ◽  
Vol 772 ◽  
Author(s):  
M. Schmid ◽  
C. Goze-Bac ◽  
M. Mehring ◽  
S. Roth ◽  
P. Bernier
Keyword(s):  
Carbon Nanotubes ◽  
Lattice Relaxation ◽  
Spin Lattice Relaxation ◽  
Energy Storage Devices ◽  
Nmr Studies ◽  
Storage Devices ◽  
Spin Lattice ◽  
Relaxation Measurements ◽  
Resonance Spin ◽  
Walled Carbon Nanotubes

AbstractLithium intercalted carbon nanotubes have attracted considerable interest as perspective components for energy storage devices. We performed 13C Nuclear Magnetic Resonance spin lattice relaxation measurements in a temperature range from 4 K up to 300 on alkali intercalated Single Walled Carbon Nanotubes in order to investigate the modifications of the electronic properties. The density of states at the Fermi level were determined for pristine, lithium and cesium intercalated carbon nanotubes and are discussed in terms of intercalation and charge transfer effects.

1H NMR Conformational Studies in Water of Angiotensin II Analogues Modified at the N- and C-Termini: Interactions of the Aromatic Side Chains and Folding of the N-Terminal Domain

1994 ◽  
Vol 59 (11) ◽  
pp. 2523-2532 ◽  
Author(s):  
John Hondrelis ◽  
John Matsoukas ◽  
George Agelis ◽  
Paul Cordopatis ◽  
Ning Zhou ◽  
...  
Keyword(s):  
Shielding Effect ◽  
Resonance Spectroscopy ◽  
Nmr Studies ◽  
Previous Suggestion ◽  
Aminoisobutyric Acid ◽  
H Nmr ◽  
Neutral Ph ◽  
Angiotensin Ii Analogues ◽  
Proton Resonances ◽  
Cosy Nmr

The conformation of [Sar1]angiotensin II in water at neutral pH has been examined by proton magnetic resonance spectroscopy at 400 MHz and in particular by comparing its 1H NMR spectral data with those of analogues modified at positions 1,4 and 6, namely [Sar1,Cha8]ANGII, [Des Asp1,Cha8]ANGII, [Aib1,Tyr(Me)4]ANGII, [Aib1,Tyr(Me)4,Ile8]ANGII, [N-MeAib1,Tyr(Me)4]ANGII, [N-MeAib1,Tyr(Me)4,Ile8]ANGII, ANGIII and [Sar1,Ile8]ANGII. Assignment of all proton resonances in these analogues was made possible by 2D COSY NMR experiments. The H-2 and H-4 protons for the histidine ring in [Sar1]ANGII, ANGII and ANGIII were shielded compared with the same protons in [Sar1,Ile8]ANGII, [Sar1,Cha8]ANGII and [Des Asp1,Cha8]ANGII; this shielding effect was not disturbed upon methylation of the tyrosine hydroxyl and/or replacement of residue 1 (sarcosine or aspartic acid) with aminoisobutyric acid (Aib) or N-methyl aminoisobutyric acid (N-MeAib). These data are consistent with our previous suggestion based on NMR studies in neutral DMSO that a characteristic folded conformation for ANGII previously observed in non-polar solvents can also be detected in water at neutral pH, but to a lesser degree.

scholarly journals 13C and 1H NMR Spectra of Synthetic (25R)-5α-Spirostanes

1999 ◽  
Vol 23 (1) ◽  
pp. 48-49
Author(s):  
Martín A. Iglesias Arteaga ◽  
Carlos S. Pérez Martinez ◽  
Roxana Pérez Gil ◽  
Francisco Coll Manchado
Keyword(s):  
1H Nmr ◽  
Nmr Spectra ◽  
Chemical Shifts ◽  
1H Nmr Spectra ◽  
H Nmr ◽  
C 23 ◽  
Main Effects ◽  
Nmr Signals

The assignment of 13C and 1H NMR signals of synthetic (25 R)-5α-spirostanes is presented; the main effects on chemical shifts due to substitution at C-23 are briefly discussed.

scholarly journals Physicochemical properties and structural dynamics of organic–inorganic hybrid [NH3(CH2)3NH3]ZnX4 (X = Cl and Br) crystals

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Ae Ran Lim ◽  
Sun Ha Kim ◽  
Yong Lak Joo
Keyword(s):  
Structural Dynamics ◽  
Chemical Shifts ◽  
Lattice Relaxation ◽  
Magic Angle Spinning ◽  
Spin Lattice Relaxation ◽  
Resonance Spectroscopy ◽  
Magic Angle ◽  
Scanning Calorimetry ◽  
Inorganic Hybrid ◽  
Halogen Atoms

AbstractThe physical properties of the organic–inorganic hybrid crystals having the formula [NH3(CH2)3NH3]ZnX4 (X = Cl, Br) were investigated. The phase transition temperatures (TC; 268K for Cl and 272K for Br) of the two crystals bearing different halogen atoms in their skeletons were determined through differential scanning calorimetry. The thermodynamic properties of the two crystals were investigated through thermogravimetric analysis. The structural dynamics, particularly the role of the [NH3(CH2)3NH3] cation, were probed through 1H and 13C magic-angle spinning nuclear magnetic resonance spectroscopy as a function of temperature. The 1H and 13C NMR chemical shifts did not show any changes near TC. In addition, the 1H spin–lattice relaxation time (T1ρ) varied with temperature, whereas the 13C T1ρ values remained nearly constant at different temperatures. The T1ρ values of the atoms in [NH3(CH2)3NH3]ZnCl4 were higher than those in [NH3(CH2)3NH3]ZnBr4. The observed differences in the structural dynamics obtained from the chemical shifts and T1ρ values of the two compounds can be attributed to the differences in the bond lengths and halogen atoms. These findings can provide important insights or potential applications of these crystals.

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