Coordination of Cd(II) by N-alkylamino sugars in aqueous solution as studied by potentiometry and NMR spectroscopy

✍ Scribed by Hendrik Lammers; Herman van Bekkum; Joop A. Peters

• Publisher: Elsevier Science
• Year: 1996
• Tongue: English
• Weight: 501 KB
• Volume: 284
• Category: Article
• ISSN: 0008-6215
• DOI: 10.1016/0008-6215(96)00012-2

✦ Synopsis

The Cd(II) coordination of 1-(2-aminoethylamino)-l-deoxy-D-alditols (la-b) and of 1-(2aminopropylamino)-l-deoxy-D-alditols (2a-b) was investigated by means of J13Cd NMR spectroscopy and potentiometry. The influence of the sugar chains on the basicity of the amino groups was determined with 13C chemical shift pH titration curves. It appears that the inductive effects of the sugar moieties give rise to a decrease in pK a of the secondary amino function. The Cd(II) stability constants for ligands la-b and 2a-b and the Ni(II) stability constants for la were • • 113 determined by potentlometry. Cd NMR spectroscopy was employed to study the structures of 113 the Cd(II) complexes of la-b and 2a-b.

From the Cd chemical shifts for CdL and CdL 2, it could be concluded that at neutral pH both primary and secondary nitrogen atoms are involved in coordination• ~3C NMR shows that additional coordination of a hydroxyl group of the carbohydrate chain occurs at high pH (pH 12).