ONE-WAY ELECTRON-TRANSFER FROM FLAVIN TO PORPHYRIN IN A LANGMUIR-BLODGETT MULTILAYER-MODIFIED ELECTRODE

Electron transfer between different redox molecules was studied using Langmuir-Blodgett (LB) multilayers. First, a model of the cyclic voltammetry (CV) for a modified electrode with a heterojunction of the LB multilayers was developed from the model for the multilayer given in the preceding paper. Next, porphyrin (hematoporphyrin(IX) bis (tridecanoyl ether) Ru(II) (pyridine)2 complex RuHP(PY)2) and flavin (7,8-dimethyl-3,10-dinonylisoalloxazine, DNI) LB multilayers were deposited on a gold electrode to form a porphyrin-flavin heterojunction, and the cyclic voltammograms were analysed based on the model. The electron diffusion coefficients for the electron transfer between porphyrin and flavin were determined according to the model to be ca. 1.9 × 10-12 cm2 s-1 from flavin to porphyrin and less than 1.5 × 10-14 cm2 s-1 for the reverse direction. This difference is considered to be based on the redox potential difference between DNI and RuHP(Py)2. This one-way electron transfer is the first step in the realization of molecular rectifying devices. © 1990.