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 Cd2+ 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]/Cd2+ 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.