Y. Israeli et C. Detellier, MULTINUCLEAR MAGNETIC-RESONANCE STUDY OF THE COMPLEXATION OF LANTHANUM(III) BY D-GLUCITOL AND RIBITOL IN AQUEOUS-SOLUTION, Carbohydrate research, 297(3), 1997, pp. 201-207
A multinuclear magnetic resonance study (H-1, C-13, La-139) of the int
eractions of La(III) with D-glucitol and ribitol in aqueous solution i
s presented and is compared with recently published calorimetric data.
The thermodynamic data were determined by La-139 NMR, and are in exce
llent agreement with the calorimetric results: Delta H degrees = - 10.
3 +/- 1.2 kJ mol(-1) and Delta S degrees = - 25.7 +/- 3.9 J K-1 mol(-1
) (La-139 NMR); Delta H degrees = - 10.2 kJ mol(-1) and Delta S degree
s = - 25.8 J K-1 mol(-1) (calorimetry; from Rongere et al., op. cit.).
A conformational analysis of D-glucitol shows that the complexation o
f La(III) results from a 120 degrees rotation of the C-2-C-3 bond in t
he most stable conformation of D-glucitol, thus providing three hydrox
yl groups in a suitable spatial arrangement for the occupancy of the f
irst coordination sphere of La(III) and the concurrent replacement of
water molecules. (C) 1997 Elsevier Science Ltd.