Nuclear Magnetic Resonance Studies of the Solution Chemistry of Metal Complexes. II. Protonation of the Peptide Linkages of Bis(glycylglycinato)cobaltate(III)

1971 ◽  
Vol 49 (23) ◽  
pp. 3767-3771 ◽  
Author(s):  
Dallas L. Rabenstein
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Proton Magnetic Resonance ◽  
Proton Magnetic Resonance Spectroscopy ◽  
Equilibrium Constants ◽  
Solution Chemistry ◽  
Resonance Spectroscopy ◽  
Ph Titration ◽  
Magnetic Resonance Studies ◽  
Protonation Equilibria

Protonation of bis(glycylglycinato)cobaltate(III) in acidic aqueous solutions has been investigated by proton magnetic resonance spectroscopy. Chemical shift measurements indicate that the site of protonation is the peptide oxygen rather than the Co(III)-coordinated, deprotonated peptide nitrogen as previously proposed, and that the two peptide linkages are protonated in a stepwise fashion rather than simultaneously. Equilibrium constants for the stepwise protonation equilibria have been derived from the n.m.r. data. The equilibrium constant for the first protonation step has also been determined by pH titration.

Metal – Aminopolycarboxylic Acid Complexes. II. Studies of Triethylenetetraaminehexaacetic Acid and its Lead(II) Complexes in Aqueous Solution by Proton Magnetic Resonance Spectroscopy

1971 ◽  
Vol 49 (12) ◽  
pp. 2086-2095 ◽  
Author(s):  
P. Letkeman ◽  
J. B. Westmore
Keyword(s):  
Magnetic Resonance ◽  
Proton Magnetic Resonance ◽  
Proton Magnetic Resonance Spectroscopy ◽  
Equilibrium Constants ◽  
The Other ◽  
Resonance Spectroscopy ◽  
Carboxylate Groups ◽  
Triethylenetetraaminehexaacetic Acid ◽  
Nitrogen Bonds ◽  
Aminopolycarboxylic Acid

Nuclear magnetic resonance (n.m.r.) spectroscopy was used to determine the preferred protonation sites in TTHA. For its 1:1 complex with Pb(II) the following equilibrium constants for protonation were obtained (triethylenetetraaminehexaacetic acid ≡ H6A)[Formula: see text]The non-protonated complex is considered to have four coplanar (or nearly coplanar) metal–nitrogen bonds with the center carboxylate groups coordinated above and below this plane, and with the terminal carboxylate groups playing only a small part in the coordinate bonding. The first and second protonations of the complex occur preferentially at the terminal and center nitrogen atoms, respectively, on the same side of the complex, accompanied by breaking of the respective metal–nitrogen bonds. This causes partial unwrapping of the complex from one side. Rapid interconversion between configurations in which unwrapping and rewrapping occurs first from one side of the molecule and then from the other leads to simplified n.m.r. spectra.

Nuclear magnetic resonance studies of the solution chemistry of metal complexes. XIV. The aqueous chemistry of trimethyllead(IV) and its carboxylic acid complexes

1977 ◽  
Vol 55 (18) ◽  
pp. 3255-3260 ◽  
Author(s):  
T. L. Sayer ◽  
S. Backs ◽  
C. A. Evans ◽  
E. K. Millar ◽  
D. L. Rabenstein
Keyword(s):  
Carboxylic Acid ◽  
Magnetic Resonance ◽  
Proton Magnetic Resonance ◽  
Ph Dependence ◽  
Equilibrium Constants ◽  
Formation Constants ◽  
Solution Chemistry ◽  
Resonance Spectroscopy ◽  
Coupling Constant ◽  
Proton Coupling

The aqueous solution chemistry of the trimethyllead(IV) species and the trimethyllead(IV) complexes of six carboxylic acids of pKa values ranging from 2.75 to 4.95 has been investigated by proton magnetic resonance spectroscopy. Equilibrium constants for the reaction of (CH3)3Pb+ with hydroxide ion to form (CH3)3PbOH and ((CH3)3Pb)2OH+, and the formation constants of the carboxylic acid complexes were determined from the pH dependence of the chemical shift of the methyl protons of trimethyllead. The formation constants of the complexes increase as the pKa of the ligand increases. The lead-207-proton coupling constant was found to be insensitive to complexation.

scholarly journals Imaging intelligence with proton magnetic resonance spectroscopy

Intelligence ◽  
2009 ◽  
Vol 37 (2) ◽  
pp. 192-198 ◽  
Author(s):  
Rex E. Jung ◽  
Charles Gasparovic ◽  
Robert S. Chavez ◽  
Arvind Caprihan ◽  
Ranee Barrow ◽  
...  
Keyword(s):  
Magnetic Resonance ◽  
Magnetic Resonance Spectroscopy ◽  
Proton Magnetic Resonance ◽  
Proton Magnetic Resonance Spectroscopy ◽  
Resonance Spectroscopy

Disulfiram Determination by Proton Magnetic Resonance Spectroscopy and by Colorimetry

1973 ◽  
Vol 56 (1) ◽  
pp. 124-127 ◽  
Author(s):  
Eric B Sheinin ◽  
Walter R Benson ◽  
Myron M Smith
Keyword(s):  
Magnetic Resonance ◽  
Magnetic Resonance Spectroscopy ◽  
Proton Magnetic Resonance ◽  
Proton Magnetic Resonance Spectroscopy ◽  
Colorimetric Method ◽  
Drug Substance ◽  
Resonance Spectroscopy ◽  
Pmr Spectroscopy ◽  
Label Claim ◽  
Tablet Excipients

Abstract Disulfiram was determined in disulfiram drug substance and tablets by proton magnetic resonance (PMR) spectroscopy at the 100–480 mg level and by a colorimetric technique involving cuprous iodide at the 50 mg level. The tablet excipients do not interfere in the analysis. The average result for disulfiram in a tablet composite was 100.8±1.4% of label claim by PMR and 100.7±0.4% by the colorimetric method.

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