Tryptophan anion complexes of β-cyclodextrin (cyclomaltaheptaose), an aminopropylamino-β-cyclodextrin and its enantioselective nickel(II) complex

6I-(3-Aminopropylamino)-6I-deoxy-cyclomaltaheptaose (βCDpn) exhibits enhanced complexation of tryptophan anion, by comparison with βCD, while the nickel(II) complex of βCDpn complexes tryptophan anion even more strongly and exhibits a tenfold enantioselectivity in favour of the (S)-tryptophan anion.