| Abstract
| - A new complex [Ru(bpy)2(bpySH)](PF6)2, RuBpySH, has been prepared bearing two anchoring groups forsurface attachment, where bpy is 2,2‘-bipyridyl and bpySH is 5,5‘-bis(mercaptomethyl)-2,2‘-bipyridine.Monolayers of RuBpySH have been formed on micro and macro platinum electrodes by spontaneous adsorptionfrom micromolar solutions of the complex in 50:50 v/v water/acetone. The monolayers can be reversiblyswitched between the Ru2+ and the Ru3+ forms. Cyclic voltammetry is well-defined with a peak-to-peaksplitting of 30 ± 5 mV and a full width at half-maximum of 110 ± 10 mV being observed for scan rates upto 5 V s-1 where the supporting electrolyte is 0.1 M tetrabutylammonium tetrafluoroborate in acetonitrile.Adsorption is irreversible in this system, and the saturation coverage obtained is 8.1 ± 0.4 × 10-11 mol cm-2when the complex concentration in the deposition solution is between 10 μM and 1.0 mM. The dynamics ofadsorption depend markedly on the bulk concentration and are described in terms of irreversible adsorption.Dry monolayers display luminescence properties similar to those of powder samples of the complex, indicatingthat the monolayer has characteristics of the solid-state sample rather than the solution sample of the complex.Significantly, efficient electrochemiluminescence is generated using tripropylamine as the coreactant. Therate of electron transfer across the electrode/monolayer interface has been probed using high scan rate cyclicvoltammetry. The standard heterogeneous electron-transfer rate constant, k°, is 0.9 ± 0.1 × 104 s-1, andthere is weak adsorbate−electrode electronic communication.
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