THE LIGHT-DEPENDENT OXYGEN REDUCTION BY MONOLAYERS OF HYDRATED CHLOROPHYLL-A OLIGOMER

The phenomenon of light-dependent O2 uptake by monolayers of hydrated chlorophyll a oligomer deposited by the Langmuir-Blodgett technique on an SnO2 optically transparent electrode has been observed. Spectra of cathodic photocurrents coincided with the absorption spectrum of hydrated oligomer of chlorophyll a. In the presence of an artificial electron donor, hydroquinone, and an oxygen electron acceptor, both the cathodic and the anodic photocurrent caused by dry and wet chlorophyll a molecules of monolayer were measured under illumination in the range 400-800 nm. The effects of electrode potentials and redox reagents on the magnitude of solar energy conversion by the chlorophyll a monolayer at the optically transparent electrode are discussed. ESR and circular dichroism spectra show that hydrated oligomer of chlorophyll a consists of six molecules of chlorophyll a bonded with water molecules.