15N Chemical Shifts and JNN-Couplings as Diagnostic Tools for Determination of the Azide–Tetrazole Equilibrium in Tetrazoloazines

Author(s):  
Sergey L. Deev ◽  
Tatyana S. Shestakova ◽  
Zakhar O. Shenkarev ◽  
Alexander S. Paramonov ◽  
Igor A. Khalymbadzha ◽  
...  
1997 ◽  
Vol 62 (11) ◽  
pp. 1747-1753 ◽  
Author(s):  
Radek Marek

Determination of 15N chemical shifts and heteronuclear coupling constants of substituted 2,2-dimethylpenta-3,4-dienal hydrazones is presented. The chemical shifts were determined by gradient-enhanced inverse-detected NMR techniques and 1H-15N coupling constants were extracted from phase-sensitive gradient-enhanced single-quantum multiple bond correlation experiments. Stereospecific behaviour of the coupling constants 2J(1H,15N) and 1J(1H,13C) has been used to determine the configuration on a C=N double bond. The above-mentioned compounds exist predominantly as E isomers in deuteriochloroform.


1987 ◽  
Vol 252 (4) ◽  
pp. C441-C449 ◽  
Author(s):  
L. A. Levy ◽  
E. Murphy ◽  
R. E. London

Fluorine 19 nuclear magnetic resonance (NMR) studies of intracellular fluorinated calcium chelators provide a useful strategy for the determination of cytosolic free calcium levels in cells and perfused organs. However, the fluorinated chelator with the highest affinity for calcium ions which has been described to date. 1,2-bis-(2-amino-5-fluorophenoxy)ethane-N,N,N',N'-tetraacetic acid (5FBAPTA), exhibits a dissociation constant (Kd) value 5- to 10-fold greater than the intracellular calcium concentration levels in most cell types, thus limiting the ability of fluorine NMR to report these concentrations reliably. We have consequently designed and synthesized several fluorinated calcium chelators with higher affinity for calcium. The best of these, 2-(2-amino-4-methyl-5-fluorophenoxy)-methyl-8 aminoquinidine-N,N,N',N'-tetraacetic acid (quinMF), has a Kd value approximately 10 times lower than that of 5FBAPTA. Several of the newly synthesized indicators have different chemical shifts for the calcium complexed and uncomplexed chelators to allow the simultaneous use of two indicators. In addition to providing information about the level of cytosolic free calcium, chelators containing a quinoline ring exhibit considerable sensitivity to magnesium levels and hence have potential application for the determination of cytosolic-magnesium concentrations. Application of these chelators is illustrated by determination of the cytosolic-free calcium level in erythrocytes. Use of quinMF, the chelator with the lowest Kd value, gives a calcium value of 25-30 nM.


1992 ◽  
Vol 30 (4) ◽  
pp. 312-319 ◽  
Author(s):  
Jürgen Lauterwein ◽  
Jürgen Schulte ◽  
Martin Schumacher ◽  
Miloslav Černý

2011 ◽  
Vol 133 (16) ◽  
pp. 6288-6298 ◽  
Author(s):  
Nikolaos G. Sgourakis ◽  
Oliver F. Lange ◽  
Frank DiMaio ◽  
Ingemar André ◽  
Nicholas C. Fitzkee ◽  
...  

Holzforschung ◽  
2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Lucas Lagerquist ◽  
Jani Rahkila ◽  
Patrik Eklund

Abstract A small library of 6-substituted syringyl model compounds with aliphatic, carboxylic, phenylic, benzylic alcohols and brominated substituents were prepared. The influence of the substituents on the chemical shifts of the compounds was analyzed. All of model compounds showed a characteristic increase in the 13C NMR chemical shift of the methoxy group vicinal to the substitution. This 13C NMR peak and its corresponding correlation peak in HSQC could potentially be used to identify 6-condensation in syringylic lignin samples.


1970 ◽  
Vol 25 (5) ◽  
pp. 451-461 ◽  
Author(s):  
Doureid Houalla ◽  
Raymond Marty ◽  
Robert Wolf

Over 100 δH values of H- (P) obtained in our laboratory, as well as values from the literature, have been tabulated and discussed. These data are useful, not only in the study of molecules containing a P-H bond but also, more generally, in the determination of the factors which influence the value of proton chemical shifts.


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