Comparative Cation Chelating Properties of Per (3,6-Anhydro),- And Per (3,6-Anhydro 2-Ome) α-Cyclodextrins

The cation chelating properties of per(3,6 anhydro) α-cyclodextrin, [A36] and of per(3,6 anhydro, 2-O methyl) α-cyclodextrin, [A36M] were investigated by mass and NMR spectroscopy. A36 forms 1: 1 complexes with lead (K=2500 M -1), and also with strontium and potassium with a fast exchange rate kinetics. However, the formation of A36-Pb complex results in a dramatic enhancement of the haemolytic properties. Permethylation at the position 2 (A36M) confers an extreme affinity for Ba2+, Pb2+, Sr2+ and Ca2+ following a slow rate exchange process and a 1: 1 stoichiometry. Besides, a weak 1:1 A36M-K complex is also found, with a fast exchange rate. By opposition with A36. A36M complexes showed no haemolytic properties.