Mono-(3-β-aminoethylamino-3-deoxy)-β-cyclodextrin (CD-3-en) was synthesized by the tosylation of one of the secondary hydroxyl groups of β-cyclodextrin, followed by the substitution of the tosyl group with an aminoethylamino group. The pK_a values for the conjugate acids of CD-3-en were determined to be 5.18 and 9.25, each of which is significantly smaller than the corresponding value for ethylenediamine (6.85 and 9.93 respectively).
The complexation of CD-3-en with a few metal ions was examined in a buffer solution at pH 10.5 and 25℃. It was revealed that copper(II), cobalt(II), and nickel(II) form 1:2, 1:2 and 1:4 complexes, respectively, with CD-3-en.