The hydroxonium perchlorate complex of cis-syn-cis-dicyclohexano 18-crown-6 ether: conformational analysis in the solid state and in solution at low temperature as studied via 13C NMR methods

1991 ◽  
Vol 69 (12) ◽  
pp. 1964-1969 ◽  
Author(s):  
G. W. Buchanan ◽  
C. Morat ◽  
R. A. Kirby ◽  
J. S. Tse
Keyword(s):  
Solid State ◽  
Title Complex ◽  
Torsional Angle ◽  
Free Energy Barrier ◽  
Inversion Process ◽  
Ring Inversion ◽  
Nmr Methods ◽  
Perchlorate Complex ◽  
C Nmr ◽  
Coalescence Temperature

From 100.6-MHz 13C NMR coalescence temperature measurements, the title complex is shown to undergo a single degenerate ring inversion process with a free energy barrier of [Formula: see text]. This is ca. 5 kJ/mol higher than the barrier in the free crown. The solid state 13C CPMAS spectrum is indicative of a totally unsymmetrical conformation and the shift trends in the solid are analyzed in terms of local torsional angle variations. Comparisons of experimental vs. calculated (GIAO) 13C chemical shift ranges for the CH2O carbons in the solid are made and satisfactory agreement with respect to the overall range and magnitude of the 13C shielding differences is obtained. Key words: crown ethers, stereochemistry, NMR.

The sodium perchlorate complex of cis-syn-cis dicyclohexano-24-crown-8 ether. X-ray crystal structure and solution conformations as studied by variable temperature 13C NMR spectroscopy at 125 MHz. An example of eight-coordinate sodium

1992 ◽  
Vol 70 (6) ◽  
pp. 1688-1695 ◽  
Author(s):  
G. W. Buchanan ◽  
Y. Lear ◽  
C. Bensimon
Keyword(s):  
Crystal Structure ◽  
Variable Temperature ◽  
Sodium Perchlorate ◽  
13C Nmr Spectroscopy ◽  
Ring Inversion ◽  
X Ray ◽  
Free Energy Of Activation ◽  
Perchlorate Complex ◽  
C Nmr ◽  
Coalescence Temperature

The major isomer obtained by hydrogenation of dibenzo-24-crown-8 ether is shown to have the cis-syn-cis configuration as determined from the crystal structure of its sodium perchlorate complex. This material possesses eight-coordinate sodium with Na—O distances ranging from 2.54 to 2.78 Å. The complex is shown to exist in a single asymmetric conformation below 240 K as determined by 13C NMR at 125 MHz. From NMR coalescence temperature measurement, the free energy of activation for cyclohexane ring inversion in this complex has been determined to be 51.0 ± 0.6 kJ/mol.

Solid state stereochemistry of crown ethers: X-ray crystal structure and 13C NMR studies of the LiNCS complex of 1,4,7,11-tetraoxacyclotetradecane

2000 ◽  
Vol 78 (3) ◽  
pp. 316-321
Author(s):  
G W Buchanan ◽  
A B Driega ◽  
G PA Yap
Keyword(s):  
Crystal Structure ◽  
Solid State ◽  
Crown Ether ◽  
13C Nmr ◽  
Title Complex ◽  
Nmr Studies ◽  
Nmr Spectrum ◽  
X Ray ◽  
Large Amplitude Motion ◽  
C Nmr

The title complex is asymmetric in the crystal due to the spatial orientation of the NCS function. The space group has been determined to be P21 with a = 9.496(3), b = 8.736(3), c = 9.676(3) Å, β = 117.859(5)°, and Z = 2. The solid state 13C NMR spectrum is consistent with the lack of symmetry in the crystal and there is little evidence for large amplitude motion in the macrocycle as determined from the dipolar dephased spectrum.Key words: macrocyclic crown ether, lithium complex.

scholarly journals Structural Investigations of C-Nitrosobenzenes. Part 3.1 Solid-state and Solution 13C NMR Studies, and Crystal Structure of E-(4-CIC6H4NO)2

1999 ◽  
Vol 23 (3) ◽  
pp. 202-203
Author(s):  
Daniel A. Fletcher ◽  
Brian G. Gowenlock ◽  
Keith G. Orrell ◽  
David C. Apperley ◽  
Michael B. Hursthouse ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Solid State ◽  
13C Nmr ◽  
Nmr Studies ◽  
Structural Investigations ◽  
Nmr Data ◽  
C Nmr

Solid-state and solution 13C NMR data for the monomers and dimers of 3- and 4-substituted nitrosobenzenes, and the crystal structure of E-(4-CIC6H4NO)2 are reported.

Solid state NMR of membrane proteins: methods and applications

2021 ◽  
Author(s):  
Vivien Yeh ◽  
Boyan B. Bonev
Keyword(s):  
Solid State ◽  
High Resolution ◽  
Membrane Proteins ◽  
Solid State Nmr ◽  
Lipid Membrane ◽  
Cell Function ◽  
Membrane Lipid ◽  
Pharmacological Intervention ◽  
Nmr Methods ◽  
Informative Approach

Membranes of cells are active barriers, in which membrane proteins perform essential remodelling, transport and recognition functions that are vital to cells. Membrane proteins are key regulatory components of cells and represent essential targets for the modulation of cell function and pharmacological intervention. However, novel folds, low molarity and the need for lipid membrane support present serious challenges to the characterisation of their structure and interactions. We describe the use of solid state NMR as a versatile and informative approach for membrane and membrane protein studies, which uniquely provides information on structure, interactions and dynamics of membrane proteins. High resolution approaches are discussed in conjunction with applications of NMR methods to studies of membrane lipid and protein structure and interactions. Signal enhancement in high resolution NMR spectra through DNP is discussed as a tool for whole cell and interaction studies.

47,49Ti NMR in Metals, Inorganics, and Gels

2000 ◽  
Vol 55 (1-2) ◽  
pp. 291-297 ◽  
Author(s):  
T. J. Bastow
Keyword(s):  
Solid State ◽  
Titanium Oxide ◽  
Recent Progress ◽  
Titanium Isopropoxide ◽  
Metallic State ◽  
X Ray Diffraction ◽  
X Ray ◽  
Hydrolysis Of ◽  
C Nmr

Some recent progress in solid state 47,49Ti NMR is described and reviewed. The metallic-state work described covers metals such as hep titanium, TiB2 , a number of intermetallics such as TiAl2 and TiAl3· The inorganic work covers the various titanium oxide based materials including the TiO2 polymorphs, anatase, rutile and brookite. The gel work covers the evolution of crystalline titania from gels formed by hydrolysis of titanium isopropoxide. Some complementary data from 17O and 13C NMR and powder X-ray diffraction is also included.

scholarly journals Simple Methylcadmium Alkoxides

2007 ◽  
Vol 62 (10) ◽  
pp. 1339-1342 ◽  
Author(s):  
Surajit Jana ◽  
Tania Pape ◽  
Norbert W. Mitzel
Keyword(s):  
Mass Spectrometry ◽  
Solid State ◽  
Molecular Formula ◽  
Equimolar Ratio ◽  
X Ray ◽  
X Ray Crystallography ◽  
Elemental Analyses ◽  
Solid State Structures ◽  
Structural Aspects ◽  
C Nmr

The reaction of dimethylcadmium with alcohols R-OH in equimolar ratio leads to the formation of tetrameric methylcadmium alkoxides with molecular formula [(MeCd)4 (OR)4] [R = Me (1), Et (2) and iPr (3)]. These compounds have been characterised by 1H, 13C NMR and IR spectroscopy, by mass spectrometry, elemental analyses and by X-ray crystallography (for 2 and 3). The solid state structures show distorted cubane-type aggregates with Cd4O4 cores. The structural aspects and the spectroscopic characterisations of these compounds are discussed.

Etude par résonance paramagnétique électronique de la radiolyse en phase solide de composés cycliques perfluorés

1970 ◽  
Vol 48 (3) ◽  
pp. 435-446 ◽  
Author(s):  
Claude Chachaty ◽  
Alain Forchioni ◽  
Masaru Shiotani
Keyword(s):  
Electron Spin Resonance ◽  
Solid State ◽  
Relative Intensity ◽  
Transition Point ◽  
Γ Irradiation ◽  
Ring Inversion ◽  
Spin Resonance ◽  
The Matrix ◽  
Γ Rays ◽  
Transition Points

Perfluorocyclohexane (PFCH) and perfluoromethylcyclohexane (PFMCH) have been irradiated in the solid state by γ rays of 60Co. The electron spin resonance (e.s.r.) spectrum of PFCH irradiated at 77 °K corresponds mainly towhich is tumbling in the matrix above 160 °K and disappears at the transition point (180 °K). When γ irradiation is carried out at 200 °K, C6F11• is also produced, but reacts with PFCH giving a radicalsupposed to be [Formula: see text]The e.s.r. spectrum of PFMCH γ irradiated at 77 °K has not been identified; it might be attributable in part to (•C6F11CF3)−. Above 160–170° K, the e.s.r. spectrum corresponds only toThe equal coupling of the four γ fluorines and also the relative intensity 1:4:1 of the three main groups of lines observed above 210 °K suggest that ring inversion occurs with a high rate.We have also studied the radicals [Formula: see text]produced by γ irradiation in the presence of oxygen. The variation of their spectra with temperature, particularly near the transition points, is very characteristic of the motion involved.

High-resolution solid-state C NMR study of per(3,6-anhydro)-α-cyclodextrin based polymers and of their chromium complexes

2005 ◽  
Vol 61 (1) ◽  
pp. 88-94 ◽  
Author(s):  
S CADARS ◽  
M FORAY ◽  
A GADELLE ◽  
G GERBAUD ◽  
M BARDET
Keyword(s):  
Solid State ◽  
High Resolution ◽  
Chromium Complexes ◽  
Nmr Study ◽  
C Nmr
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