Photosynthesis mimicking

Benniston AC, Mackie PR, Harriman A (1998) Artificial photosynthesis mimicking redox asymmetry. Angew Chem Int Ed 37 354—356... 

Electron transfer reactions constitute an ubiquitous class of chemical reactions. This is particularly true in biological systems where these reactions often occur at interfaces, in photosynthesis for instance. It is therefore challenging to use the surface specificity and the time resolution of the SHG technique to investigate these processes. At liquid-liquid interfaces, these processes are mimicked through the following scheme ... 

From a fundamental viewpoint, carbon dioxide reduction is a model reaction which can help us to understand better the mechanism of natural photosynthesis.11 Development of artificial photosynthetic systems, by mimicking functions of green plants, is one of... 

Gust., D. and T.A. Moore Mimicking Photosynthesis, Science. 35 (April 7, 1989). Horspool, W.M., and F. Leuci CRC Handbook of Organic Photochemistry ami Photcbbiogy, CRC Press LLC, Boca Raton, EL, 2003. 

Sayama et al.9) and Lincous et al.10) have proposed systems in which water is split by a combination of two photocatalytic and photochemical reactions. The present authors have also studied the water splitting system based on combined photocatalytic systems.u 15) Our goal is the construction of a water splitting system by mimicking the photosynthesis of green plants. 

With a view to achieving a system mimicking tne photosynthesis of green plants, we have studied the processes required to construct the whole system. These processes are discussed below. 

Several approaches to artificial photosynthesis involve the mimicking of membranes to effect charge separation. An easy extension of the micellar effects described above to systems amenable to study as photosynthetic models can be encountered in the charge separation derived on synthetic vesicles or membranes (275). Sonic dispersal of long chain ammonium halides, phosphates, sulfonate, or carboxylates produces prolate ellipsoidal vesicles with long term stabilities which can entrain and trap molecules in their compartments. With donor-acceptor photosystems, four physical arrangements about the vesicle are important, Fig. 6. 

The second article also deals with PET in arranged media, however, this time by discussing comprehensively the various types of heterogeneous devices which may control supramolecular interactions and consequently chemical reactions. Before turning to such applications, photosynthetic model systems, mainly of the triad type, are dealt with in the third contribution. Here, the natural photosynthetic electron transfer process is briefly discussed as far as it is needed as a basis for the main part, namely the description of artificial multicomponent molecules for mimicking photosynthesis. In addition to the goal to learn more about natural photosynthetic energy conversion, these model systems may also have applications, which, for example, lie in the construction of electronic devices at the molecular level. 

Hammarstrom L (2003) Towards artificial photosynthesis ruthenium-manganese chemistry mimicking photosystem II reactions. Curr Opin Chem Biol 7 666-673... 

Photophysical processes are commonly encountered and can participate in such important phenomena as energy harvesting (antenna effect), which is the basis for natural photosynthesis and artificial systems mimicking it [4-21] (see below). 

Lomoth R, Magnuson A, Sjodin M, Huang P, Styring S, Hammarstrom L. Mimicking the electron donor side of Photosystem II in artificial photosynthesis. Photosynth Res 2006 87 25 10. 

Sykora M, Maxwell KA, DeSimone JM, Meyer TJ. Mimicking the antenna-electron transfer properties of photosynthesis. Proc Natl Acad Sci USA 2000 97 7687-91. 

The reaction sequence shown in Scheme 2 mimicks a step of chlorophyll biosynthesis as well as hydrogen formation as a part of photosynthesis (82AG(E)132). 

Sayama K, Mukasa K, Abe R, Abe Y, Arakawa H (2002) Photo-catalytic water splitting system into H2 and 02 under visible light irradiation mimicking a Z-scheme mechanism in photosynthesis. Solar Light Energy Conversion Team, Photoreaction Control Research Center, Advanced Industrial Science and Technology (AIST), Ibaraki, Japan... 

A Z-scheme system mimicking the plant photosynthesis model developed with Pt-loaded Ti02 for HER and rutile Ti02 for OER. A IO3 /I shuttle was used as redox mediator. 330... 

An interesting aspect of the new work on Ti02, namely that of combining two photosystems (in a Z scheme) mimicking plant photosynthesis (see Entries 6 and 10 in Table 7) also has its roots in early work in this field (see, for example, Entry 2 in Table 1). Further elaboration of this strategy is contained in Ref. 96. 

The p-n photoelectrolysis approach,60 on the other hand, simply combines a n-type semiconductor photoanode and a p-type semiconductor photocathode in an electrolysis cell (Fig. 2c). The pros and cons of this twin-photosystem approach (which mimicks plant photosynthesis) were enumerated earlier in this Chapter (see Section 2). Table 16 provides a compilation of the semiconductor photocathode and photoanode combinations that have been examined. Reference 67 may also be con suited in this regard for combinations involving n WSe2, n MoSe2, n WS2, n TiCH, p InP, p GaP and p Si semiconductor electrodes. 

Energy Conversion - Photosynthesis During the process of photosynthesis, a well-organized dye array in the cell membrane accomplishes pho-toinduced charge separation that eventually leads to ATP synthesis. This system has been mimicked by immobilizing a fimctional dye molecule and ATP synthase in a lipid bilayer membrane. 

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