Heteroleptic copper switches

Heteroleptic copper compounds have been designed and synthesized on solid supports. Chemical redox agents were used to change the oxidation state of the SiO₂-immobilized heteroleptic copper compounds from Cu(I) to Cu(II) and then back to Cu(I). Optical spectroscopy of a dimethyl sulfoxide suspension demonstrated the reversibility of the Cu(I)/Cu(II) SiO₂-immobilized compounds by monitoring the metal-to-ligand charge transfer peak at about 450 nm. Electron paramagnetic resonance spectroscopy was used to monitor the isomerization of Cu(I) tetrahedral to Cu(II) square planar. This conformational change corresponds to a 90° rotation of one ligand with respect to the other. Conductive atomic force microscopy and macroscopic gold electrodes were used to study the electrical properties of a p⁺ Si-immobilized heteroleptic copper compound where switching between the Cu(I)/Cu(II) states occurred at -0.8 and +2.3 V.