Studies on Chloroplast Membranes. I. 13C Chemical Shifts and Longitudinal Relaxation Times of Carboxylic Acids

1977 ◽  
Vol 30 (4) ◽  
pp. 813 ◽  
Author(s):  
S Johns ◽  
D Leslie ◽  
R Willing ◽  
D Bishop
Keyword(s):  
Carboxylic Acid ◽  
Chemical Shift ◽  
Carboxylic Acids ◽  
Chemical Shifts ◽  
Relaxation Times ◽  
Segmental Motion ◽  
Unsaturated Carboxylic Acids ◽  
Longitudinal Relaxation ◽  
13C Chemical Shift ◽  
The Individual

The 13C chemical shift and longitudinal relaxation time (T1) of the individual carbon atoms in a series of carboxylic acids in CDCl3 solution have been determined. Substituent shift parameters have been derived from the chemical shift data. The relaxation times have been interpreted in terms of increasing segmental motion along the methylene chains of the carboxylic acid molecules which are associated at the carboxylic acid groups in the form of inverted micelles. Differences in the segmental motion between saturated and unsaturated carboxylic acids are rationalized on the grounds of intermolecular interactions between adjacent molecules in the inverted micelle structures.

Studies on chloroplast membranes. III. 13C chemical shifts and longitudinal relaxation times of 1,2-Diacyl-3-(6-sulpho-α-quinovosyl)-sn-glycerol

1978 ◽  
Vol 31 (1) ◽  
pp. 65 ◽  
Author(s):  
SR Johns ◽  
DR Leslie ◽  
RI Willing ◽  
DG Bishop
Keyword(s):  
Chemical Shifts ◽  
Relaxation Times ◽  
Acid Group ◽  
Vesicular Structure ◽  
13C Chemical Shifts ◽  
Longitudinal Relaxation ◽  
Monomeric Structure ◽  
13C Chemical Shift ◽  
Nuclear Overhauser ◽  
The Individual

13C Chemical shifts, longitudinal relaxation times and some nuclear Overhauser enhancement factors of the individual carbon atoms in the chloroplast lipid, 1,2-diacyl-3-(6-sulpho-α-quinovosyl)-sn-glycerol (sl), have been measured in the three solvents: methanol[D4], chloroform[D] and water[D2]. Correlation times for the individual carbon atoms calculated from these results have been interpreted in terms of different secondary structures: a monomeric structure in methanol[D4], an inverted micellar structure in chloroform[D] and a bilayer vesicular structure in water[D2]. Substituent shift parameters have been determined for the sulphonic acid group from a series of alkanesulphonic acids and these have been used in the 13C chemical shift assignments in sl and a series of model compounds.

Studies on Chloroplast Membranes. II. 13C Chemical Shifts and Longitudinal Relaxation Times of 1,2-Di[(9Z,12Z,15Z)-octadeca-9,12,15-trienoyl]-3-galactosyl-sn-glycerol and 1,2-Di[(9Z,12Z,15Z)-octadeca-9,12,15-trienoyl]-3-digalactosyl-sn-glycerol

1977 ◽  
Vol 30 (4) ◽  
pp. 823 ◽  
Author(s):  
S Johns ◽  
D Leslie ◽  
R Willing ◽  
D Bishop
Keyword(s):  
Relaxation Time ◽  
Chemical Shifts ◽  
Relaxation Times ◽  
Longitudinal Relaxation Time ◽  
Time Data ◽  
Longitudinal Relaxation ◽  
Monomeric Structure ◽  
13C Chemical Shift ◽  
Nuclear Overhauser ◽  
The Individual

The 13C chemical shift and longitudinal relaxation time (T1) of the individual carbon atoms in the two major lipids of chloroplast thylakoids, 1,2-di[(9Z,12Z,15Z)-octadeca-9,12,15-trienoyl]-3- galactosyl-sn-glycerol and 1,2-di[(9Z,12Z,15Z)-octadeca-9,12,15- trienoyl]-3-digalactosyl-sn-glycerol, have been measured in the three solvents: methanol[D4], chloroform[D] and water[D2]. The longitudinal relaxation time data are interpreted in terms of different secondary structures in the different solvents, a monomeric structure in methanol[D4], an inverted micellar structure in chloroform[D] and a bilayer structure in water[D2]. Two possible correlations times can be obtained from the longitudinal relaxation times of the galactosyl and glyceryl carbon atoms in chloroform[D] and water[D2] and nuclear Overhauser enhancement values have been used to assign the correlation times to these carbon atoms.

Nuclear Magnetic Relaxation by Anisotropy of the Chemical Shift

1972 ◽  
Vol 27 (10) ◽  
pp. 1456-1458 ◽  
Author(s):  
J Blicharski
Keyword(s):  
Chemical Shift ◽  
Magnetic Relaxation ◽  
Chemical Shifts ◽  
Relaxation Times ◽  
Nuclear Magnetic Relaxation ◽  
Nuclear Magnetic

Abstract The relaxation times T1 , T2 , T1Q and T2Q are calculated in the weak collision case in the presence of anisotropy of the chemical shifts.

Carbon magnetic resonance studies of some phenyl, furyl and thienyl organometallics. Some comments on carbon-metal scalar coupling

1974 ◽  
Vol 27 (2) ◽  
pp. 417 ◽  
Author(s):  
D Doddrell ◽  
KG Lewis ◽  
CE Mulquiney ◽  
W Adcock ◽  
W Kitching ◽  
...  
Keyword(s):  
Chemical Shift ◽  
Chemical Shifts ◽  
Substituent Effects ◽  
Coupling Constants ◽  
Scalar Coupling ◽  
Coupling Constant ◽  
Aryl Substituent ◽  
Magnetic Resonance Studies ◽  
Thienyl Group ◽  
13C Chemical Shift

13C chemical shift variations within a series of phenyl, furyl and thienyl Group IVB organometallics appear to be best understood in terms of the usual alkyl and aryl substituent effects on 13C chemical shifts and not variations in dπ ?pπ metal-aryl interactions. Large changes in 13C-metal scalar coupling constants have been observed suggesting that other factors besides the s-character of the carbon-metal bond is responsible in determining the coupling constant.

Determination of Alcohols, Phenols, and Carboxylic Acids Using Phosphorus-31 NMR Spectroscopy

1986 ◽  
Vol 40 (3) ◽  
pp. 348-351 ◽  
Author(s):  
David E. Schiff ◽  
John G. Verkade ◽  
Robert M. Metzler ◽  
Thomas G. Squires ◽  
Clifford G. Venier
Keyword(s):  
Free Radical ◽  
Nmr Spectroscopy ◽  
Carboxylic Acids ◽  
Chemical Shifts ◽  
Relaxation Times ◽  
Oh Groups

Derivatization of compounds containing -OH groups can be accomplished quantitatively with 1,3,2-dioxaphospholanyl chloride. The chemical shifts of phosphorus in the derivatives clearly differentiate alcohols from phenols and carboxylic acids. Quantitation is obtained by use of 31P FT-NMR spectroscopy in the presence of 2,2,6,6-tetrameth-ylpiperidinyloxy free radical to shorten relaxation times. Compounds with phosphorus chemical shifts differing by as little as 0.1 ppm can be separately determined.

scholarly journals Powder Crystallography by Combining NMR and Crystal Structure Predictions

2014 ◽  
Vol 70 (a1) ◽  
pp. C136-C136 ◽  
Author(s):  
Cory Widdifield ◽  
Maria Baias ◽  
Jean-Nicolas Dumez ◽  
Per H. Svensson ◽  
Hugh Thompson ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Chemical Shift ◽  
Structure Determination ◽  
Structure Prediction ◽  
Density Functional ◽  
De Novo ◽  
Chemical Shifts ◽  
2D Nmr ◽  
Other Information ◽  
13C Chemical Shift

State-of-the-art work in the field of NMR crystallography for molecular systems at natural abundance has recently focused on the accurate measurement of 1H chemical shift values. We will show how when coupled with crystal structure prediction (CSP) methods, this protocol is well-suited for solving the crystal structures of small to medium sized organic molecules, including cocaine and the de-novo structure determination of AZD8329.[1,2] As complementary 1D and 2D NMR experiments are needed for the 1H assignment process, other information, such as isotropic 13C chemical shift values (δiso) are measured. Unfortunately, 13C chemical shifts are not generally useful for structure determination. Additional NMR parameters that are sensitive to structure would ensure that the structure determination procedure is robust, and would provide more accurate refinements when studying larger or more challenging systems. Here, we measure 13C chemical shift tensors for a variety of prototypical organic pharmaceuticals and use density functional theory computations under the gauge-including projector augmented-wave (GIPAW) formalism to probe whether these parameters may be discriminatory for unit cell determinations and structure determination (notably when added to the CSP + 1H chemical shifts protocol).

Copper-catalyzed regioselective synthesis of furan via tandem cycloaddition of ketone with an unsaturated carboxylic acid under air

2015 ◽  
Vol 13 (1) ◽  
pp. 309-314 ◽  
Author(s):  
Monoranjan Ghosh ◽  
Subhajit Mishra ◽  
Kamarul Monir ◽  
Alakananda Hajra
Keyword(s):  
Carboxylic Acid ◽  
Carboxylic Acids ◽  
Ambient Air ◽  
Regioselective Synthesis ◽  
Unsaturated Carboxylic Acid ◽  
Unsaturated Carboxylic Acids

A catalytic decarboxylative annulation has been developed for the regioselective synthesis of furans by the cycloaddition of ketones with α,β-unsaturated carboxylic acids in ambient air.

Stable carboxylic acid derivatized alkoxy silanes

2015 ◽  
Vol 51 (12) ◽  
pp. 2339-2341 ◽  
Author(s):  
A. Feinle ◽  
S. Flaig ◽  
M. Puchberger ◽  
U. Schubert ◽  
N. Hüsing
Keyword(s):  
Carboxylic Acid ◽  
Carboxylic Acids ◽  
One Pot ◽  
Hydrosilylation Reaction ◽  
Unsaturated Carboxylic Acids ◽  
Organofunctional Silanes ◽  
Alkoxy Groups

A convenient and straightforward one-pot hydrosilylation reaction of different unsaturated carboxylic acids with trialkoxysilanes in the presence of catalytic amounts of platinum(iv) dioxide resulted in excellent yields in organofunctional silanes combining carboxy- and alkoxy groups within one molecule.

Origin and Nature of Transmission Modes of Anomalous Effects of meta-Substituents on the 13C Chemical Shift of the Carboxyl Carbon (δCO) of Benzoic Acid

2010 ◽  
Vol 63 (2) ◽  
pp. 321 ◽  
Author(s):  
Susanta K. Sen Gupta ◽  
Rajendra Prasad
Keyword(s):  
Chemical Shift ◽  
Benzoic Acid ◽  
Chemical Shifts ◽  
Substituent Effects ◽  
Basis Set ◽  
Benzoic Acids ◽  
Anomalous Effect ◽  
Atomic Orbitals ◽  
13C Chemical Shift ◽  
Carboxyl Carbon

Studies of substituent effects on NMR chemical shifts are of great benefit in determining fine details of electron distribution in molecules. Interestingly, NMR substituent effects are often different and even opposite to those associated with chemical reactivity. Among molecules exhibiting anomalous (reverse) substituent effects is benzoic acid, the standard model for studying substituent effects. The substituent effect on the 13C chemical shift of its carboxyl carbon (δ CO) is just the opposite of that on its acid strength or reactivity. To develop insights into the origin of the anomalous effect of a substituent on δ CO, occupancies of natural atomic orbitals at the carboxyl and ring carbons of a set of 10 meta-substituted benzoic acids have been calculated at the density functional theory level using the B3LYP function with split valance 6–311G++** basis set. Statistical correlations obtained for the 13C chemical shifts, δ CO and δ C-ring of these benzoic acids with the natural atomic orbital occupancies calculated for respective carbon atoms on one hand and with Taft’s inductive and resonance parameters (σ I and σ R BA ) of the substituents on the other hand have been critically analyzed. The findings have established firmly that a meta-substituent’s anomalous effect on δ CO is caused by the substituent-induced changes in the total occupancy of only the p z natural atomic orbitals at the carboxyl carbon. The study has demonstrated further that the transmission of the anomalous effect can be successfully interpreted by a 5.5:–2.5:1 combination of the localized, extended, and resonance-induced π-polarization effects.

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