Electron transfer at Au surfaces modified by tethered osmium bipyridine-pyridine complexes

Chemically modified electrodes by the osmium complex [Os(bpy)(2)ClPy - X]+PF6- tethered to Au surfaces by (1) reaction of cysteamine with the aldehyde (X=CHO), (2) mercapto alkanoic acid reaction with amine [X=(CH2)(2)NH2], and (3) reduction of the diazonium salt of p-aminobenzoic acid and further amidation reaction with the amine derivative of the osmium complex [X=(CH2)2NH2] were performed to explore the electron transfer properties of these redox-modified surfaces. The modified Au surfaces were characterized by infrared reflection absorption spectroscopy and resonant Raman spectroscopy. Cyclic voltammetry was used to study the electrochemical properties of the osmium complexes covalently attached to the surface as a function of the type and length of the tether.