Synthesis and studies of a water-soluble and air-stable Cu(I)/Cu(II) open-shell funnel complex.

The derivatization of the large rim of a TMPA-capped calix[6]arene (TMPA = tris(2-pyridylmethyl)amine) with three trimethylammonium groups enables the water-solubilization of two air-stable Cu(I)/Cu(II) complexes. These two complexes present a vacant coordination site shielded from the aqueous environment by the calixarene core. The spectroscopic and electrochemical data recorded in pure water indicate that the host-guest properties of the funnel complex are retained in both oxidation states of the copper cation.