Complexation of cyclohexanocucurbit[6]uril with cadmium ions: X-ray crystallographic and electrochemical study.

Complexation of cyclohexanocucurbit[6]uril (Q*[6]), a water-soluble cucurbit[n]uril derivative, with Cd(2+) ions has been studied by means of cyclic voltammetry and differential pulse voltammetry. The electrochemical experimental data prove the formation of a highly stable 1:6 Q*[6]/Cd(2+) complex. We also obtained the single-crystal X-ray structure of a cadmium ion complex with Q*[6], in which each portal of Q*[6] chelates three cadmium ions. The present study suggests the potential utility of Q*[6] as an effective cadmium ion chelator and extractant.