ALGORITHM FOR NMR SIGNAL SHAPE ANALYSIS FOR DETERMINING THE ACTIVATION PARAMETERS OF THE MOLECULAR DYNAMICS OF PARAMAGNETIC COMPLEXES OF LANTANIDS: CONFORMATION DYNAMICS IN COMPLEXES OF THULYUM WITH MACROCYCLIC DOTA LIGAND

2021 ◽  
Vol 62 (7) ◽  
Author(s):  
С.П. Бабайлов ◽  
Е.Н. Заполоцкий
Keyword(s):  
Molecular Dynamics ◽  
Shape Analysis ◽  
Activation Parameters ◽  
Signal Shape ◽  
Paramagnetic Complexes

Signal-shape analysis of a thermally cycled tin-oxide gas sensor

1991 ◽  
Vol 3 (1) ◽  
pp. 63-68 ◽  
Author(s):  
Stanislaw Wlodek ◽  
Konrad Colbow ◽  
Franco Consadori
Keyword(s):  
Gas Sensor ◽  
Shape Analysis ◽  
Tin Oxide ◽  
Signal Shape

The Barrier to Rotation About the N—N Bond in N-Nitrosamines as Determined by Nuclear Magnetic Resonance Total Line Shape Analysis

1974 ◽  
Vol 52 (17) ◽  
pp. 3028-3036 ◽  
Author(s):  
J. D. Cooney ◽  
S. K. Brownstein ◽  
J. W. ApSimon
Keyword(s):  
Shape Analysis ◽  
Line Shape ◽  
Energy Barrier ◽  
Activation Parameters ◽  
Substantial Contribution ◽  
Resonance Structure ◽  
Bond Rotation ◽  
Line Shape Analysis ◽  
Bond Character ◽  
Nitrogen Bond

The energy barrier to internal N—N bond rotation in five cyclic and two bicyclic N-nitrosamines [Formula: see text]has been determined using high temperature 100 MHz n.m.r. spectroscopy. A substantial contribution from the ionic resonance structure of [Formula: see text] produces considerable double bond character in the nitrogen–nitrogen bond and a concomitant increase in the rotational barrier about the N—N bond. The molecules were examined in the[Formula: see text]liquid state and had ring sizes varying from five to nine atoms. The Arrhenius and Eyring activation parameters for the energy barrier were determined using total line shape analysis and the intensity ratio approximation method. The energy barrier to N—N bond rotation was found to range from 23–29 kcal/mol depending on the molecular structure and the solvent.

Nuclear Magnetic Resonance Studies of Enantiomeric Internal Rotational Isomers of 1- and 3-Arylhydantoins in Achiral and Chiral Solvents

1975 ◽  
Vol 53 (11) ◽  
pp. 1556-1562 ◽  
Author(s):  
Lawrence D. Colebrook ◽  
Siddik Icli ◽  
Frank H. Hund
Keyword(s):  
Internal Rotation ◽  
Shape Analysis ◽  
Chemical Shifts ◽  
Activation Parameters ◽  
Methyl Groups ◽  
Solvent Interactions ◽  
Rotational Isomers ◽  
Line Shape Analysis ◽  
Solvent Dependence ◽  
Normal Probe

1H and 13C n.m.r. spectra have been determined for a number of 1- and 3-arylhydantoins in achiral and chiral solvents. These compounds, which have enantiomeric rotational isomers, show restricted internal rotation about the aryl C—N bond at normal probe temperatures. Chemical shifts between corresponding protons on the pairs of rotamers, induced by diastereomeric solute–solvent interactions in the chiral solvent, are strongly dependent on the location of the protons in the solute molecules. In conjunction with 1H and 13C chemical shifts, these data provide information on the geometry of the solvated species. No splitting of signals resulting from the presence of diastereomeric solvates was observable in the 13C spectra. Activation parameters for hindered internal rotation, determined by complete p.m.r. line shape analysis using signals of the diastereotopic methyl groups in the 5-position, show some solvent dependence.

A proton magnetic resonance study of trimethyl phosphate exchange on magnesium(II)

1973 ◽  
Vol 26 (6) ◽  
pp. 1227 ◽  
Author(s):  
J Crea ◽  
SF Lincoln ◽  
RJ West
Keyword(s):  
Shape Analysis ◽  
Methylene Chloride ◽  
Structural Rearrangement ◽  
Activation Process ◽  
Trimethyl Phosphate ◽  
Magnetic Resonance Study ◽  
Signal Shape ◽  
Dissociative Mechanism ◽  
Proton Magnetic Resonance Study ◽  
Phosphate Exchange

A 1H N.M.R. study of the exchange reaction Mg(tmp)62+ ↔ tmp (tmp, trimethyl phosphate) in methylene chloride and acetone diluents is reported. A complete signal shape analysis is used to derive kinetic parameters. The value for kex (193 K) in the rate law R = 6kex[Mg(tmp)62+] is 3.2�0.5 s-1, ΔH? = 70.7�3.8 kJ mol-1, and ΔS? = 135.1�12.6 J mol-1 K-1 when the Mg2+ : tmp : methylene chloride mole ratio is 1.00 : 12.1 : 34.9. Values of similar magnitude are obtained under different mole ratio and diluent conditions. The tmp exchange is considered to proceed through a dissociative mechanism involving solvent structural rearrangement in the activation process.

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