New multinuclear metal catalysts for the light-driven activation of water and reduction of CO2

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First hetero-oligonuclear metal-organic compounds for the activation of water and carbon monoxide have been prepared. Their (photo)catalytic properties are currently investigated and reaction conditions are optimized. With the experiences gained new optimized catalysts for the production of hydrogen and oxygen (hydrogen fuel cell fuels) as well as CO or HCOOH as C1 building blocks shall be synthesized. In those systems, the connection of a photoactive unit with a catalytic active unit plays a major role. A well-directed photo-electron-transfer (PET) enables the provision of the required electron equivalents or holes in these photo-catalysts.The oxidation of oxid-ions to O2 and its backreaction (O2 to H2O or H2O2), respectively, are to be investigated especially with compounds of the Hangman- and Pacman-type. The specific introduction of substituents and catalytic metal center will determine the direction of the reaction. On the one hand, ruthenium polypyridyl compounds and on the other hand high-valent manganese and iron porphyrinoids shall be employed as catalytic active unit. Studies on reduction processes, especially the light-activated reduction of CO2, are to happen using supramolecular compounds. Extended porphyrinic macrocycles function as a bridging ligand and are arranged in a way to connect a photoactive center capturing light energy with a catalytic active metal center.The investigation of the controllability of the planned organic transformations by light, pH value, substituents and other parameters is supposed to lead to a precise product selectivity. Additionally, new insights into the elapsing processes and mechanisms shall be provided by isolation and characterization of reactive intermediates.