Grundlagen der Goldkatalyse
Dr. Sarah Bay – Hector Fellow A. Stephen K. Hashmi
Dr. Jean-Francois Greisch – Hector Fellow Manfred Kappes
In dem Projekt der Hector Fellows A. Stephen K. Hashmi und Manfred Kappes arbeiten die HFA Postdoktorandin Dr. Sarah Bay (Ruprecht-Karls-Universität Heidelberg) und der HFA Postdoktorand Dr. Jean-Francois Greisch (Karlsruher Institut für Technologie). Sie untersuchen die Eigenschaften innovativer Goldkatalysatoren.
Following the development of new highly active catalyst systems in early 2013, it was shown that homogeneous gold catalysis might be well-suited for industrial application and economically efficient use. The key to achieve this goal lies in the fundamental understanding of highly reactive gold catalyst systems. Within this Hector Fellow project, the researchers want to determine the structures and reaction pathways of selected gold catalysts. Furthermore, their studies aim at characterizing reaction intermediates by combining organic synthetic strategies with elaborated mass spectrometric methods. The figure shows the current workhorse, a dual activation catalyst. Although many of these catalytic cycles are understood in general terms, direct activity assessment including the influence of byproducts (e.g. small clusters of various charge states) as well as the identification of reaction intermediates has been missing, which finally prevents efficient optimization. Since concentrations of the new highly active gold catalysts are typically low and the active species are fragile, characterization using analytic techniques is challenging.
Nevertheless, the combination of high-resolution mass spectrometry and mild ionization methods provides a unique opportunity to directly probe catalyst-substrate-intermediates using a broad range of spectroscopic techniques. Via ion mobility measurements, collision cross-sections can be inferred and structural information on the isolated intermediates of reactions obtained, which improves the assessment of the reaction pathways. Reaction of gas-phase species with vapors can also provide unique information on their reactivity, making it possible to assess how different isomers/conformers contribute to the reaction. Finally, optical spectroscopic techniques can be used to probe both the structure and the electronic states as well as to isolate species for further investigation via hole-burning spectroscopy.
In short, by analyzing the reaction mixture and developing new approaches to accessing transient species, the project aims at obtaining unprecedented information on the mechanisms and species involved in gold-catalyzed reactions in order to optimize the catalysts and their modes of action for potential industrial application.