CONSPICUOUS EFFECTS DUE TO COMPLEX FORMATION AND CONTACT TERM UPON LANTHANIDE-INDUCED SHIFTS IN19F NMR OF SOME FLUOROAROMATIC COMPOUNDS

1973 ◽  
Vol 2 (11) ◽  
pp. 1205-1208 ◽  
Author(s):  
Katsumi Ajisaka ◽  
Masatsune Kainosho ◽  
Hiroko Shigemoto ◽  
Kazuo Tori ◽  
Z. W. Wolkowski ◽  
...  
Keyword(s):  
Complex Formation ◽  
Contact Term ◽  
Lanthanide Induced Shifts

Lanthanide Induced Shifts in the Proton Magnetic Resonance Spectra of Cyclic Amines

1973 ◽  
Vol 51 (24) ◽  
pp. 4080-4081 ◽  
Author(s):  
Donald L. Hooper ◽  
Alzbeta Kardos
Keyword(s):  
Magnetic Resonance ◽  
Complex Formation ◽  
Proton Magnetic Resonance ◽  
Steric Effect ◽  
Cyclic Amines ◽  
Lanthanide Induced Shifts ◽  
Magnetic Resonance Spectra

Complex formation between europium tris(dipivalatomethane), Eu(DPM)3, and cyclic amines is not accompanied by inversion of the amine configuration, even for 2-alkyl and 2,6-dialkylpiperidines, where inversion of the amine configuration accompanies formation of the usual amine derivatives. There is, however, a steric effect of C-2 or C-6 substitution, in that the magnitude of the lanthanide induced shifts is sharply reduced.

Structure et conformation du complexe du N-acétyl-aspartate avec un cation lanthanide. Étude par résonance magnétique nucléaire du 1H et du 13C

1986 ◽  
Vol 64 (7) ◽  
pp. 1267-1277 ◽  
Author(s):  
Daniel Baron ◽  
Nicole Lumbroso-Bader
Keyword(s):  
Nitrogen Atom ◽  
Axial Symmetry ◽  
Binding Constant ◽  
Contact Term ◽  
Lanthanide Induced Shifts ◽  
Résonance Magnétique ◽  
Geometrical Factors ◽  
A Minor ◽  
Main Factor

Lanthanide induced shifts by Lu3+, Yb3+, Tm3+, Er3+, Ho3+, and Dy3+ in NAcAsp (0.14 M in D2O, pH 5) are observed for ten magnetic sites (1H and 13C). The averaged binding constant for 1:1 complexes is 72 M−1 (for chloride solutions of ca. 0.05 M). Determination of the pseudo-contact geometrical factors (under axial symmetry approximation) requires taking into account a contact term and discarding the Tm3+ results. Data from the Asp residue are in agreement with 6 structures of this residue such that chelation occurs through the two carboxylates. Oβ−… Cα′ length seems to be the main factor while COOα− orientation is a minor one. The entire set of results is consistent with only three structures where the nitrogen atom is far from the carboxylates, and the Cα—N rotamers have extended conformations. Three oxygen atoms (two from the COOβ− group) appear to be involved in the chelation. However, the data do not exclude another minor conformational species.

Complexes of Muellitol [1,3,5-Tri(3-methylbut-2-enyl)-scyllo-inositol] with Metal Cations

1985 ◽  
Vol 38 (10) ◽  
pp. 1561 ◽  
Author(s):  
SJ Angyal ◽  
D Greeves ◽  
L Littlemore
Keyword(s):  
Complex Formation ◽  
Time Scale ◽  
Metal Cations ◽  
Lanthanide Induced Shifts

Complex formation of muellitol with dipositive cations is fast, with tripositive cations slow, on the n.m.r . time-scale. The lanthanide- induced shifts of the signals in the 1H and 13C n.m.r . spectra of these complexes vary greatly, in sign and magnitude, with the nature of the solvent.

Novel approaches to model-free analysis of lanthanide-induced shifts, targeted to the investigation of contact term behavior

2011 ◽  
Vol 40 (27) ◽  
pp. 7165 ◽  
Author(s):  
Alexander G. Martynov ◽  
Yulia G. Gorbunova ◽  
Aslan Yu. Tsivadze
Keyword(s):  
Contact Term ◽  
Lanthanide Induced Shifts ◽  
Model Free ◽  
Novel Approaches
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