By a News Reporter-Staff News Editor at Life Science Weekly -- A new study on Supramolecular Research is now available. According to news reporting originating in Stockholm, Sweden, by NewsRx journalists, research stated, "Human society faces a fundamental challenge as energy consumption is projected to increase due to population and economic growth as fossil fuel resources decrease. Therefore the transition to alternative and sustainable energy sources is of the Utmost importance."
The news reporters obtained a quote from the research from Stockholm University, "The conversion of solar energy into chemical energy, by splitting H2O to generate molecular O-2 and H-2, could contribute to solving the global energy problem. Developing such a system will require the combination of several complicated processes, such as light-harvesting, charge separation, electron transfer, H2O oxidation, and reduction of the generated protons. The primary processes of charge separation and catalysis, which occur in the natural photosynthetic machinery, provide us with an excellent blueprint for the design of such systems. This Account describes our efforts to construct supramolecular assemblies capable of carrying out photoinduced electron transfer and to develop artificial water oxidation catalysts (WOCs). Early work in our group focused on linking a ruthenium chromophore to a manganese-based oxidation catalyst. When we incorporated a tyrosine unit into these supramolecular assemblies, we could observe fast intramolecular electron transfer from the manganese centers, via the tyrosine moiety, to the photooxidized ruthenium center, which clearly resembles the processes occurring in the natural system. Although we demonstrated multi-electron transfer in our artificial systems, the bottleneck proved to be the stability of the WOCs. Researchers have developed a number of WOCs, but the majority can only catalyze H2O oxidation in the presence of strong oxidants such as Ce-IV, which is difficult to generate photochemically. By contrast, illumination of ruthenium(II) photosensitizers in the presence of a sacrificial acceptor generates [Ru(bpy)(3)](3+)-type oxidants. Their oxidation potentials are significantly lower than that of Ce-IV, but our group recently showed that incorporating negatively charged groups into the ligand backbone could decrease the oxidation potential of the catalysts and, at the same time, decrease the potential for H2O oxidation. This permitted us to develop both ruthenium- and manganese-based WOCs that can operate under neutral conditions, driven by the mild oxidant [Ru(bpy)(3)](3+). Many hurdles to the development of viable systems for the production of solar fuels remain."
According to the news reporters, the research concluded: "However, the combination of important features from the natural photosynthetic machinery and novel artificial components adds insights into the complicated catalytic processes that are involved in splitting H2O."
For more information on this research see: Artificial Photosynthesis: Photosynthesis: From Nanosecond Electron Transfer to Catalytic Water Oxidation. Accounts of Chemical Research, 2014;47(1):100-111. Accounts of Chemical Research can be contacted at: Amer Chemical Soc, 1155 16TH St, NW, Washington, DC 20036, USA. (American Chemical Society - www.acs.org; Accounts of Chemical Research - www.pubs.acs.org/journal/achre4)
Our news correspondents report that additional information may be obtained by contacting M.D. Karkas, Stockholm University, Dept. of Organ Chem, Arrhenius Lab, SE-10691 Stockholm, Sweden. Additional authors for this research include E.V. Johnston, O. Verho and B. Akermark (see also Supramolecular Research).
Keywords for this news article include: Sweden, Europe, Stockholm, Ruthenium, Nanotechnology, Transition Elements, Emerging Technologies, Supramolecular Research, Supramolecular Assemblies
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