13C and 1H NMR investigation of pilocarpine hydrochloride in water solution

1993 ◽  
Vol 71 (5) ◽  
pp. 738-741 ◽  
Author(s):  
Elena Gaggelli ◽  
Nicola Gaggelli ◽  
Gianni Valensin ◽  
Antonio Vivi
Keyword(s):  
Water Solution ◽  
Lattice Relaxation ◽  
Spin Lattice Relaxation ◽  
Relaxation Rates ◽  
Spin Lattice ◽  
H Nmr ◽  
Ca 50 ◽  
Nuclear Overhauser ◽  
Nuclear Overhauser Effects ◽  
Motional Correlation Time

Dynamic and geometric features of pilocarpine in water solution were delineated by interpreting 13C and 1H NMR spin-lattice relaxation rates and nuclear Overhauser effects. The motional correlation time was evaluated at 53 ± 5 ps at 298 K. 1H—1H distances, as calculated from double-selective 1H spin-lattice relaxation rates, and 13C—1H distances, as calculated from selective 13C–{1H} Overhauser effects, gave evidence of a C7 puckered conformation of the furanone ring and of an angle of ca. 50° between the two rings.

Further justification for the exo-anomeric effect. Conformational analysis based on nuclear magnetic resonance spectroscopy of oligosaccharides

1982 ◽  
Vol 60 (1) ◽  
pp. 44-57 ◽  
Author(s):  
Henning Thøgersen ◽  
Raymond U. Lemieux ◽  
Klaus Bock ◽  
Bernd Meyer
Keyword(s):  
Hard Sphere ◽  
Relaxation Times ◽  
Lattice Relaxation ◽  
Spin Lattice Relaxation ◽  
Resonance Spectroscopy ◽  
Anomeric Effect ◽  
Spin Lattice ◽  
H Nmr ◽  
Nmr Study ◽  
Nuclear Overhauser

Hard-sphere (HS) calculations predict three conformers for the branched B human blood group antigenic determinant (α LFuc(1 → 2)[α DGal(1 → 3)]βDGal) and two conformers for the linear tetrasaccharide (αLRha(1 → 2)αLRha(1 → 3)αLRha(1 → 3)βDGlcNAc), which constitutes a part of the repeating unit of the Shigellaflexneri O-antigen, which differ in conformational energy by less than 0.7 and 0.2 kcal/mol, respectively. However, a detailed 1H nmr study of specific interunit deshielding effects, quantitative treatment of spin-lattice relaxation times, and nuclear Overhauser enhancements requires that only one of the conformers thus predicted be, in fact, conformationally preferred in solution. These conformers are those predicted by hard-sphere exo-anomeric (HSEA) calculations.

The stereochemistry of some 7-hydroxyindene dimers: applications of 1H nuclear magnetic resonance relaxation pathway analysis

1985 ◽  
Vol 63 (8) ◽  
pp. 2332-2338 ◽  
Author(s):  
Walter J. Chazin ◽  
Lawrence D. Colebrook ◽  
Brian R. Davis ◽  
I. Ross N. McCormick ◽  
Stephen J. Johnson
Keyword(s):  
Nuclear Overhauser Effect ◽  
Chemical Shifts ◽  
Lattice Relaxation ◽  
Spin Lattice Relaxation ◽  
Relaxation Rates ◽  
Difference Spectra ◽  
Spin Lattice ◽  
Relative Stereochemistry ◽  
Effect Difference ◽  
Nuclear Overhauser

1H spin-lattice relaxation rates and nuclear Overhauser effect difference spectra have been measured (at 400 MHz) for six dimers derived from methyl-substituted 7-hydroxyindenes. Used in combination, these measurements identify the relaxation pathways available to all of the protons in the molecules. Analysis of these pathways has permitted assignment of all chemical shifts, and identification of the relative stereochemistry at all chiral centres.

Conformation and dynamics in solution of an N-quaternarized benzophenone derivative: a molecule active as UV filter

1991 ◽  
Vol 69 (6) ◽  
pp. 913-918 ◽  
Author(s):  
Cecilia Anselmi ◽  
Marisanna Centini ◽  
Mirella Scotton ◽  
Alessandro Sega
Keyword(s):  
Alkyl Chain ◽  
Lattice Relaxation ◽  
Proton Spin ◽  
Spin Lattice Relaxation ◽  
Proton Relaxation ◽  
Relaxation Rates ◽  
Uv Filter ◽  
Spin Lattice ◽  
Nuclear Overhauser Enhancement ◽  
Nuclear Overhauser

The dynamics and conformation of N,N-dimethyl-N-|3-(benzoyl-4-phenoxy)|-N-n-dodecylammonium bromide, 1, have been established in two solvents (CDCl3 and DMSO-d6) by the use of 13C spin-lattice relaxation rates, non-selective and selective proton spin-lattice relaxation rates, and 1H–{1H} nuclear Overhauser enhancement (nOe) experiments. The data obtained are consistent with two main mean conformations for compound 1: a "linear" conformation in CDCl3 and a folded conformation in DMSO-d6 where the alkyl chain forms a loop toward the aromatic moiety. Key words: UV filter, carbon and proton relaxation rates, nuclear Overhauser enhancement experiments, solvent dependent conformations.

T1, Nuclear Overhauser Effects Measurements in 13C NMR Spectroscopy: Analytic Relations for Short Equilibration Delays

1983 ◽  
Vol 37 (4) ◽  
pp. 357-360
Author(s):  
Vladimir León
Keyword(s):  
Experimental Data ◽  
Pulse Sequence ◽  
Relaxation Times ◽  
Lattice Relaxation ◽  
13C Nmr Spectroscopy ◽  
Spin Lattice Relaxation ◽  
Spin Lattice ◽  
Nuclear Overhauser ◽  
Nuclear Overhauser Effects ◽  
Saturation Experiment

Analytic relations that describe magnetization as a function of time are given for several dynamic nuclear Overhauser effects (NOE) experiments. They allow the extraction of spin-lattice relaxation times ( T1) and NOE (η) from a three-parameter fitting of experimental data. These results are valid even for short equilibration delays if the saturated protons have a much shorter relaxation time than the observed 13C. A simple pulse sequence that combines a progressive saturation experiment with gate decoupling is proposed for measuring T1 and η values. The calculated η values are a good approximation even for short equilibration delays without any restrictive assumptions about relaxation times of the nuclei involved.

Analysis of Spin Polarisation Transients in Periodically Photo-excited Triplet States

1975 ◽  
Vol 30 (5) ◽  
pp. 571-582 ◽  
Author(s):  
C. J. Winscom
Keyword(s):  
Lattice Relaxation ◽  
Rectangular Pulse ◽  
Decay Rates ◽  
Spin Lattice Relaxation ◽  
Pulse Excitation ◽  
Triplet States ◽  
Relaxation Rates ◽  
Spin Sublevel ◽  
Spin Lattice ◽  
The Individual

Abstract The behaviour of spin sublevel populations with time following periodic photo-excitation is ex-amined. The treatment is limited to conditions of magnetic field strength and temperature for which the spin lattice relaxation rates dominate the individual spin sublevel decay rates. The response of the system to three modes of excitation is considered: (i) continuous excitation using a time-independent intensity (ii) periodic rectangular pulse excitation and (iii) periodic waveform excitation. A convenient correspondence between the various forms of solutions is pointed out. The requirements of an experiment to determine spin-lattice relaxation rates in organic triplets at 77 K are discussed.

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

1989 ◽  
Vol 149 ◽  
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. %.

Anion reorientations and cation diffusion in a carbon-substituted sodium nido-borate Na-7,9-C2B9H12: 1H and 23Na NMR studies

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Alexander V. Skripov ◽  
Olga A. Babanova ◽  
Roman V. Skoryunov ◽  
Alexei V. Soloninin ◽  
Terrence J. Udovic
Keyword(s):  
Lattice Relaxation ◽  
Activation Energies ◽  
Spin Lattice Relaxation ◽  
Relaxation Rates ◽  
Cation Diffusion ◽  
Relaxation Data ◽  
Nmr Studies ◽  
Spin Lattice ◽  
Jump Rate ◽  
Disordered Phase

Abstract Polyhydroborate-based salts of lithium and sodium have attracted much recent interest as promising solid-state electrolytes for energy-related applications. A member of this family, sodium dicarba-nido-undecahydroborate Na-7,9-C2B9H12 exhibits superionic conductivity above its order-disorder phase transition temperature, ∼360 K. To investigate the dynamics of the anions and cations in this compound at the microscopic level, we have measured the 1H and 23Na nuclear magnetic resonance (NMR) spectra and spin-lattice relaxation rates over the temperature range of 148–384 K. It has been found that the transition from the low-T ordered to the high-T disordered phase is accompanied by an abrupt, several-orders-of-magnitude acceleration of both the reorientational jump rate of the complex anions and the diffusive jump rate of Na+ cations. These results support the idea that reorientations of large [C2B9H12]− anions can facilitate cation diffusion and, thus, the ionic conductivity. The apparent activation energies for anion reorientations obtained from the 1H spin-lattice relaxation data are 314 meV for the ordered phase and 272 meV for the disordered phase. The activation energies for Na+ diffusive jumps derived from the 23Na spin-lattice relaxation data are 350 and 268 meV for the ordered and disordered phases, respectively.

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