Molecular Structure – from precise structure determination to molecular recognition

We apply broadband rotational spectroscopy to study the inter- and intra-molecular forces that govern molecular recognition at the molecular level in the gas phase. Molecular recognition is mainly controlled via non-covalent interactions such as hydrogen bonds, metal coordination, van der Waals forces and dispersive interactions. Even though molecular recognition was observed many years ago by Emil Fischer, non-covalently bound molecular recognition processes are still not well understood yet. For example, it is still extremely difficult to a priori predict the outcome of a molecular recognition event. Important questions concerning the fundamental concepts of molecular recognition, such as which interaction forces do reinforce, which to impede each other, highlight the necessity of an accurate description of intermolecular interactions in substrate-template complexes. We are placing special emphasis on the competition between different non-covalent interactions that governs molecular recognition. Broadband rotational spectroscopy allows us to study the molecular properties of such complexes of molecular model systems in detail.

Recently, we were able to unravel the structure and internal dynamics of the benzene dimer, one of the prototype systems for non-covalent interactions in chemistry. Its gas-phase structure is strongly governed by its internal dynamics that had been an open question since 20 years, changing its rotational spectrum to become that of a symmetric top. Our joint theoretical and spectroscopy work on the benzene dimer was published in Angewandte Chemie International Edition as Very Important Paper [50] as well as in Physical Chemistry Chemical Physics in 2013 [53].