Cooperation Research Unit

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The interdisciplinary research group FOR1405 focuses the efforts of physicists and chemists to utilize cutting edge photon sources for the dedicated research in the area of charge transfer processes in bioinorganic copper model systems that are relevant for catalytic and enzymatic reactions.The concerted approach merges advanced bioinorganic copper chemistry and sophisticated spectroscopy that makes use of the tremendous potential of pulsed laser, free-electron laser and 3rd-generation-synchrotron applications. At its most ambitious level - for which the FOR is the most important prerequisite -, it provides us with fundamental insights into charge transfer dynamics with a time resolution between femtoseconds to nanoseconds with large relevance for bioinorganic chemistry.The technical foundation for the use of soft and hard X-ray free-electron lasers in connection with high-end synchrotron sources such as PETRA III is complemented by the use of high-end lab-based laser sources to implement and validate new experimental techniques such as modern jet technologies. The full range of modern Raman spectroscopy (resonance and pump-probe Raman) as well as of X-ray absorption spectroscopy (XAS, HERFD, XES, pump-probe XAS) is herefore applied throughout.Charge transfer comprises multiple elementary steps: Firstly, an electron is removed from the metal to a ligand (inner-sphere process) leading to a charge separation over small distances. In a next step this electron can be transferred to an external oxidant during an outer-sphere process. Subsequently, the electron is transferred over longer distances to other redox partners (charge transport).In the first funding period, we focused on Tyrosinase and CuA models. In order to investigate more thoroughly the underlying inner-sphere electron transfer processes, we chose to complement these studies on bi- and polynuclear model complexes by studying mononuclear copper complexes as models for Type Zero copper proteins. All three types of models allow for investigating specific questions on electron transfer in a controlled environment with each subproject focusing on two basic charge/electron transfer phenomena. We will use our knowledge on the dynamics of the excited state to allow a detailed microscopic and quantum mechanical understanding of the involved charge transfer dynamics. On the computational side, methodological developments as well as theoretical spectroscopy are planned for the second funding period. In order to achieve a more realistic description of the molecular electronic structure we will extend our studies towards full relativistic calculations including non-collinear spin polarization. In conjunction with broken symmetry calculations we hope in particular to explore and rationalize the spin structure of the dicopper complexes.