Photorespiration of the Monolayers of Hydrated Chlorophyll-A Oligomer

The photoelectrochemical properties of wet chlorophyll-a in monolayers, multilayers and thin films at oil/water, gas/water and solid/water interfaces have been studied extensively in order to obtain a thorough understanding of its role in the primary events in plant photosynthesis, i.e., light harvesting, energy transfer and charge separation in the photosynthetic unit (Tang and Albrecht,1975; Volkov, 1984)

<title>Light energy conversion with pheophytin a and chlorophyll a monolayers at the optical transparent electrode</title>

The photoelectrochemical behavior of chlorophyll (alpha) and pheophytin (alpha) monolayers, deposited on SnO2 optically transparent electrodes by means of the Langmuir-Blodgett technique, has been investigated. Spectra of photocurrents coincided with the absorption spectra of photosynthetic pigment monolayers at the SnO2-solution interfaces. The anodic and cathodic photocurrents were measured at different electrode potentials. The effects of solution pH, electrode potentials and redox reagents on the conversion of solar energy in photocurrent by photosynthetic pigments in monolayers on optical transparent electrodes are discussed

<title>Artificial photosynthesis at octane/water interface in the presence of hydrated chlorophyll a oligomer thin film</title>

The interface between two immiscible liquids with immobilized photosynthetic pigments can serve as the simplest model of a biological membrane convenient for the investigation of photoprocesses that are accompanied by spatial separation of charges. Oxygen evolution with a quantum efficiency of 10 - 20% can be seen by illuminating the octane/water interface having hydrated oligomer of chlorophyll (alpha) with proton acceptors in octane and electron acceptors in water. Considering the importance of such a model of photosynthetic membranes, in the present communication we have investigated the optical and absorption properties of wet chlorophyll (alpha) . The absorption, circular dichroism, and fluorescence properties of chlorophyll (alpha) in a non-polar solvent and in thin films were studied. The adsorption isotherms of dry and wet chlorophyll (alpha) at octane/water interface were also measured. The difference in adsorption behavior of chlorophyll (alpha) dissolved in dry and wet octane is discussed

Hydrated chlorophyll a oligomers in solutions, monolayers, and thin films

The interfacial tension measurements of dry and wet chlorophyll a at an octane—water interface show differences in adsorption behavior of the pigment depending on its aggregation state. Optical properties were also investigated using absorption and Fourier transform-infrared spectroscopy, along with fluorescence (excitation and emission) measurements in non-polar solvents and in thin films. The absorption and fluorescence spectral characteristics, and fluorescence lifetime measurements of dry and wet samples clearly indicate the difference in aggregation properties of this photosynthetic pigment. A strong decrease in the energy of Q y electronic transitions (Δν = 1700cm −1), due to the formation of hydrated oligomers, was accompanied by a decrease in fluorescence lifetime from 5.75 ± 0.02 ns (diluted dry chlorophyll a in n-hexane) to 0.12 ± 0.03 ns (wet chlorophyll a in thin films). Discussion of these results is based on the key role of the central magnesium atom in the porphyrin ring in intermolecular interactions and self-organization of chlorophyll a molecules