Nuclear magnetic resonance spin–lattice relaxation and the rotation of adamantane and hexamethylenetetramine in solution

Deuterium nmr spin–lattice relaxation times have been measured for dilute solutions of adamantane-d16 in CH2I2, CHBr3, CCl4, CHCl3, and CH2Cl2. The reorientation correlation times, τ2, calculated from the experimental data are used to calculate τJ, the angular momentum correlation times, assuming both the J-diffusion and Hubbard relations. The derived τJ values suggest that adamantane executes small step diffusion in CH2I2 and CHBr3, and large step diffusion in CCl4, CHCl3, and CH2Cl2. The calculated τJ values do not appear to be related to the mean times between collisions calculated using a hard sphere model. Both variable solvent and variable temperature experiments indicate 1 ps/cP for the viscosity dependence of the adamantane reorientation time, about 1/36th the value predicted using the familiar Stokes–Einstein equation.Carbon-13 and 1H nmr T1 data indicate that reorientation of hexamethylenetetramine in H2O (28 ps/cP), CHCl3 (27 ps/cP), and CHBr3 (18 ps/cP) is severely hindered because of inter-molecular hydrogen bonding.

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Bonded Hydrogen and Trapped H2 in a-Si1−xGex:H Alloys

MRS Proceedings ◽

10.1557/proc-149-503 ◽

1989 ◽

Vol 149 ◽

Cited By ~ 3

Author(s):

E. J. Vanderheiden ◽

G. A. Williams ◽

P. C. Taylor ◽

F. Finger ◽

W. Fuhs

Keyword(s):

Temperature Dependence ◽

Molecular Hydrogen ◽

Relaxation Times ◽

Lattice Relaxation ◽

Spin Lattice Relaxation ◽

Spin Lattice ◽

H Nmr ◽

Local Environments

ABSTRACT1H NMR has been employed to study the local environments of bonded hydrogen and trapped molecular hydrogen (H2) in a series of a-Si1−xGex:H alloys. There is a monotonic decrease of bonded hydrogen with increasing x from ≈ 10 at. % at x = 0 (a-Si:H) to ≈ 1 at. % at x = 1 (a-Ge:H). The amplitude of the broad 1H NMR line, which is attributed to clustered bonded hydrogen, decreases continuously across the system. The amplitude of the narrow 1H NMR line, which is attributed to bonded hydrogen essentially randomly distributed in the films, decreases as x increases from 0 to ≈ 0.2. From x = 0.2 to x ≈ 0.6 the amplitude of the narrow 1H NMR line is essentially constant, and for x ≥ 0.6 the amplitude decreases once again. The existence of trapped H2 molecules is inferred indirectly by their influence on the temperature dependence of the spin-lattice relaxation times, T1. Through T1, measurements it is determined that the trapped H2 concentration drops precipitously between x = 0.1 and x = 0.2, but is fairly constant for 0.2 ≤ x ≤ 0.6. For a-Si:H (x = 0) the H2 concentration is ≈ 0.1 at. %, while for x ≥ 0.2 the concentration of H2 is ≤ 0.02 at. %.

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A proton magnetic resonance relaxation study of molecular motions in trimethylamine-borane

Canadian Journal of Chemistry ◽

10.1139/v76-155 ◽

1976 ◽

Vol 54 (7) ◽

pp. 1087-1091 ◽

Cited By ~ 5

Author(s):

T. T. Ang ◽

B. A. Dunell

Keyword(s):

Magnetic Resonance ◽

Proton Magnetic Resonance ◽

Solid Phase ◽

Relaxation Times ◽

Lattice Relaxation ◽

Spin Lattice Relaxation ◽

Spin Lattice ◽

Free Induction ◽

Resonance Spin ◽

Resonance Relaxation

Proton magnetic resonance spin–lattice relaxation times T1 have been measured for trimethylamine-borane from 120 to 380 K, a few degrees above the melting point. Minima in T1 at 157 and 259 K are attributed to threefold reorientation of each of the three methyl groups and the borane group and to threefold reorientation of the whole molecule about the B—N axis, respectively. Activation energies for these processes were found to be 3.3 and 6.7 kcal/mol. Abrupt changes in T1 at 350 and 360 K correspond exactly with heat capacity transitions observed by other workers. The time constant for the decay of the free induction signal (FID curve) changes by two orders of magnitude at 360 K. Having a value of some 3 ms above 360 K, it shows that there must be rapid diffusion as well as molecular tumbling in the highest temperature solid phase.

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Solid-State Carbon-13 NMR Studies of Vulcanized Elastomers. VI. Relaxation in Sulfur-Vulcanized Natural Rubber

Rubber Chemistry and Technology ◽

10.5254/1.3536237 ◽

1989 ◽

Vol 62 (1) ◽

pp. 82-97 ◽

Cited By ~ 6

Author(s):

Mladen Andreis ◽

Juwhan Liu ◽

Jack L. Koenig

Keyword(s):

Experimental Data ◽

Solid State ◽

Variable Temperature ◽

Lattice Relaxation ◽

Spin Lattice Relaxation ◽

Relaxation Techniques ◽

Nmr Studies ◽

Time Curve ◽

Correlation Times ◽

Spin Lattice

Abstract Molecular motions in sulfur-vulcanized NR are investigated by solid state 13C NMR relaxation techniques. Since the high-resolution spectra of crosslinked samples exhibit overlapping in the aliphatic region, a combined application of variable temperature spin-lattice relaxation measurements and the computer simulation of the overlapped spectral region is used in order to detect resonance signals. Motional restrictions introduced by crosslinks are investigated from the temperature dependence of nT1 relaxation times for individual carbons. The V-curves for all polyisoprene signals and for the detectable signals arising from the network units exhibit a similar general trend with increased curing time: curve broadening, shift of the minima to higher temperatures, and increase of the T1 min values. All the backbone carbons show quantitatively similar effects of vulcanization on the spin-lattice relaxation. At shorter curing times, motional restrictions for the methyl side group are more pronounced compared to the main-chain carbons. The experimental data suggest that the isotropic motion is strongly affected by the crosslinking. Librational motion is less affected, while the change in rotational motion has no significant influence on the relaxation curve. Although experimental data cover a relatively narrow temperature range, not sufficiently wide for a more accurate quantitative analysis, the results indicate that concepts of plural correlation times and a distribution of correlation times are applicable.

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Molecular Motions in Halogen-Bridged One-Dimensional Pt Complexes, [PtII(en)2][PtIVX2(en)2](ClO4)4 (X = Cl, Br) Studied by 2H and 1H NMR

Zeitschrift für Naturforschung A ◽

10.1515/zna-2002-6-722 ◽

2002 ◽

Vol 57 (6-7) ◽

pp. 413-418 ◽

Cited By ~ 1

Author(s):

Noriyoshi Kimura ◽

Toru Hachisuka ◽

Yukitaka Nakano ◽

Ryuichi Ikeda

Keyword(s):

Relaxation Times ◽

Lattice Relaxation ◽

Energy Difference ◽

Spin Lattice Relaxation ◽

X Ray Diffraction ◽

Potential Wells ◽

One Dimensional ◽

X Ray ◽

Spin Lattice ◽

H Nmr

2H and 1H NMR measurements were performed on crystalline [Pt(en)2][PtX2(en)2](ClO4)4 (X = Cl, Br), where the protonated and partially deuterated ethylenediamines (en’s), NH2(CH2)2NH2, NH2(CD2)2NH2 and ND2(CH2)2ND2 were used as ligands. Measurements of 2H and 1H NMR spin-lattice relaxation times showed the presence of motions of en chelate rings at the temperatures near the phase transitions, whereas broad 2H NMR spectra and the reported X-ray diffraction data showed no marked motions. These results were consistently explained by introducing the en puckering motion between highly asymmetric potential wells with an energy difference of 10 - 13 kJ mol-1. This difference was shown to be much larger than 2 - 5 kJ mol-1, reported for the iodo-complex, [Pt(en)2][PtI2(en)2](ClO4)4

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Molecular determinants for drug–receptor interactions. Part 5. Anisotropic and internal motions in analgesic narcotics (morphine, oxymorphone) and related antagonists (nalorphine, naloxone) by carbon-13 nuclear magnetic resonance spin–lattice relaxation times

Journal of the Chemical Society Perkin Transactions 2 ◽

10.1039/p29850000955 ◽

1985 ◽

pp. 955-959 ◽

Cited By ~ 9

Author(s):

Giuseppe C. Pappalardo ◽

Lajos Radics ◽

Marcello Baldo ◽

Antonio Grassi

Keyword(s):

Nuclear Magnetic Resonance ◽

Relaxation Times ◽

Lattice Relaxation ◽

Spin Lattice Relaxation ◽

Spin Lattice ◽

Internal Motions ◽

Molecular Determinants ◽

Receptor Interactions ◽

Resonance Spin ◽

Drug Receptor

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Solitons, polarons and their dynamics in mixed-valence halogen-bridged MX-chains

Philosophical Transactions of The Royal Society A Mathematical Physical and Engineering Sciences ◽

10.1098/rsta.2007.2142 ◽

2007 ◽

Vol 366 (1862) ◽

pp. 93-100 ◽

Cited By ~ 3

Author(s):

Shinya Takaishi ◽

Masahiro Yamashita

Keyword(s):

Mixed Valence ◽

Relaxation Times ◽

Lattice Relaxation ◽

Spin Lattice Relaxation ◽

Relaxation Processes ◽

Spin Lattice ◽

H Nmr ◽

Spin Resonance ◽

1D Chain ◽

The One

This article describes the photo-generation processes of elementary excitations such as solitons and polarons, and their dynamics in the one-dimensional (1D) halogen-bridged Pt compound [Pt(en) 2 Br](ClO 4 ) 2 . Spin-solitons were photo-generated via relaxation processes of CT excitons and self-trapped excitons, made evident by photo-induced absorption and photo-induced electron spin resonance spectra. Polarons were not generated from CT excitons. Diffusion of spin-solitons on the 1D chain was studied quantitatively by analysing 1 H NMR spin-lattice relaxation times ( T 1 ).

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13C and 2H spin–lattice relaxation in neopentane-d12

Canadian Journal of Chemistry ◽

10.1139/v78-423 ◽

1978 ◽

Vol 56 (19) ◽

pp. 2576-2581 ◽

Cited By ~ 7

Author(s):

Brian A. Pettitt ◽

Roderick E. Wasylishen ◽

Ronald Y. Donc ◽

T. Phil Pitner

Keyword(s):

Melting Point ◽

Variable Temperature ◽

Relaxation Times ◽

Lattice Relaxation ◽

Spin Rotation ◽

Coupling Constants ◽

Spin Lattice Relaxation ◽

Spin Lattice ◽

Single Temperature ◽

Momentum Correlation

The results of a variable temperature study of the 2H and 13C spin–lattice relaxation times in neopentane-d12 are reported. along with those for the 13C's in neopentane at a single temperature. Orientational and angular momentum correlation times derived from these T1's exhibit the following: (i) τ2 is continuous through the melting point with an activation energy of 0.98 kcal/mol, (ii) τJ is more or less constant at 0.33 ± 0.03 ps within 40 K of either side of the melting point, and (iii) they do not conform to the theoretical relationships of extended diffusion, Fokker–Planck, or Langevin theories. The spin–rotation coupling constants are calculated to be −0.69 kHz for neopentane and −0.52 kHz for neopentane-d12

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Effect of stereosequence on carbon-13 nuclear magnetic resonance spin-lattice relaxation times of polypropylene

Macromolecules ◽

10.1021/ma50002a012 ◽

1981 ◽

Vol 14 (1) ◽

pp. 72-74 ◽

Cited By ~ 6

Author(s):

Tetsuo Asakura ◽

Yoshiharu Doi

Keyword(s):

Nuclear Magnetic Resonance ◽

Magnetic Resonance ◽

Relaxation Times ◽

Lattice Relaxation ◽

Spin Lattice Relaxation ◽

Spin Lattice ◽

Resonance Spin ◽

Nuclear Magnetic

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NMR Studies on Dynamics of Water Intercalated in Clay Minerals

Zeitschrift für Naturforschung A ◽

10.1515/zna-1999-6-714 ◽

1999 ◽

Vol 54 (6-7) ◽

pp. 431-436 ◽

Cited By ~ 7

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.

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