Carbon‐13 NMR relaxation studies of gluconate and manganese—gluconate interactions
1988; Wiley; Volume: 26; Issue: 7 Linguagem: Inglês
10.1002/mrc.1260260711
ISSN1097-458X
AutoresDavid Coffin, W. Robert Carper,
Tópico(s)Molecular spectroscopy and chirality
ResumoAbstract The effect of temperature on the spin–lattice ( R 1 ) and spin–spin ( R 2 ) 13 C relaxation rates of gluconate and manganese (II)–gluconate interactions was determined in D 2 O. An R 2 vs T −1 minimum was observed for gluconate similar to that observed in solid‐liquid phase transitions. Nuclear Overhauser enhancement factors indicated predominately dipolar relaxation mechanisms for all atoms except the carbonyl carbon. Activation energies and chemical shifts indicated a molecular reorientation involving the carbonyl carbon which resulted in changes in solvation effects. Addition of manganese(II) to gluconate in D 2 O resulted in an observed minimum in the R 1 vs T −1 plots for all carbon atoms except the carbonyl species. The activation energies further supported the concept of changes in solvent‐manganese‐gluconate interactions produced by variations in intramolecular structure.
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