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Inorganic and nuclear chemistry
Enantioselectivity towards several amino acids by metallo-6A-deoxy-6A-hydroxyethylamino-β-cyclodextrins (metallo- β CDea’s) was investigated by potentiometric titration of the various amino acid/metallo- β CDea systems with NaOH solution. It was shown that the cyclodextrin derivative is capable of distinguishing between enantiomers of amino acid species in the presence of certain metal ions (Co, Ni, Cu and Zn). Ni- β CDea complexes show the most enantioselectivity,whereas for Cu and Co2C-_CDea complexes less selectivity is observed. As expected, Zn- β CDea complexes exhibit no enantioselectivity. Stability and selectivity, however, do not go hand in hand, since the most stable complexes are formed with Cu2C. Several factors play a role in determining stability and selectivity in binary and ternary complexes and further study is required to gain a more comprehensive understanding of these.
Van Hoof, N., Russell, N., McNamara, M. Darch, R.: Enantioselective Complexation of Amino Acids by 6A-Deoxy-6A-hydroxyethylamino- β -Cyclodextrin and its Metallo-Derivatives in Aqueous Solution. Journal of Inclusion Phenomena and Macrocyclic Chemistry, 2000, Vol. 36, pp.179-189