Chiral modified electrodes. Part 2. Marcus behaviour and high enantioselectivity in the photoelectrochemistry at a polymeric [Ru(4-methyl-4 '-vinyl-2,2 '-bipyridine)(3)](2+) electrode

Indium-tin-dioxide (ITO) and Pt electrodes can be modified with films of th e photo- and redox-active polymer of [Ru(4-methyl-4'-vinyl-2,2'-bipyridine) (3)](2+) ([Ru(vbpy)(3)](2+)). These modified electrodes show photocurrents when K-3[Co(ox)(3)] is reduced in a photoelectrochemical reaction. These ph otocurrents are, inter alia, dependent on the potential applied to the elec trode assembly. The photocurrent vs. voltage plots have maxima. Changing th e potential means changing the driving force of the electrode reaction and we can interpret the maximum plots by Marcus' theory for reactions in the n ormal and inverted region. For the investigation of a chemical reaction, el ectrodes with larger surfaces are necessary. In the photo-assisted reductio n of K-3[Co(ox)(3)] by means of a reticulated Ni-foam electrode modified by a chiral redox active polymer of [Ru(vbpy)(3)](2+) we have found enantio-s electivity with kappa=k(Lambda)/k(Delta) of up to 12, one of the highest va lues of asymmetry reported for photochemical reactions. Modified electrodes , where the optically excited electron transferring species in the polymer is the chiral element, represent a new type of chiral inductor.