Core Facility Gas Electron Diffraction and Small Molecule Structures Centre, Bielefeld (GED@BI)

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Accurate molecular structures are the key for understanding chemical reactivity and molecular properties. The international core facility GED@BI is dedicated to structure determination of small molecules by two specialized techniques: gas electron diffraction (GED) and X-ray diffraction (XRD) of in-situ grown crystals. We propose to extend the support GED@BI for a second funding period until it reaches a fully self-sustaining state. GED is the most powerful method for investigating free molecules, undistorted by intermolecular interactions. It is complementary to single-crystal XRD, the standard method for crystalline samples. XRD can be extended to liquids or gases, if they are crystallized directly (in situ) on a diffractometer. In addition, XRD allows determining electron density distributions for detailed bonding description. The proposed methods are in many cases the only applicable to determine the structure of new compounds. They find applications in fundamental and applied chemical science, in particular to study unusual bonding situations, conformational behaviour, cluster compounds, weak inter- or intramolecular interactions and many more. Comparing gas and solid state structures provides information on structural consequences of intermolecular interactions. GED data also serve to validate or disprove quantum-chemical single-molecule calculations. The core facility GED@BI runs the most modern instrument for high-resolution GED worldwide and the only one in the EU. It is one of few places for XRD of in-situ grown crystals. Many successful structure determinations have been carried out and published during the first funding period. The range of international users has changed and widened. Data quality and has been improved and new methods of sample handling have been developed. After the GED instrument has been modernized, widely improved and automated, the limits of its capacity have been reached. As a highly sustainable long-term investment, we plan now to build a new instrument (financed by a separate instrument grant, supported by Bielefeld University), to foster instrumental and data analysis development.During the first funding period GED@BI has demonstrated successful manage¬ment concepts and its ability to acquire a substantial part of the necessary funds to run full-cost financed. Some of the initially proposed financing schemes turned out to be more appropriate than others. An additional new scheme of small research proposals is suggested to be tried in this second period of support. An updated concept for sustainable staff management will be realized with support of Bielefeld University. With these concepts GED@BI has secured continuity in expertise in both fields of expertise and the ability to train PhD students as well as to associate an independent research group of a young academic in its periphery and will further provide a comprehensive structure-determination service of highest quality.