Complexes of praseodymium(III) with D-gluconic acid

The complexation of the praseodymium(III) ion with D-gluconic acid was stud ied by potentiometry. UV-Vis spectrophotometry, circular dichroism (CD) exp eriments and H-1 and C-13 NMR. In order to determine the coordination sites , the study of the complexation with D-galactonic and D-gulonic acids was a lso achieved. It was found that six different complexes are formed in solut ion from pH 2 to 11.5. The formation constants were determined. For four sp ecies among the six, D-gluconic acid binds the cation with deprotonated hyd roxylic group(s) in addition to the carboxylate group. On the basis of the spectroscopic results, the structures of the complexes are discussed. (C) 2 000 Elsevier Science Ltd. All rights reserved.