Forschung im AK Giernoth
Ionic liquids are -- by definition -- salts that are liquid below 100 °C. In organic chemistry, they are interesting as solvents for synthesis, since ionic liquids show a couple of unique features: many have a very wide liquidus range, they do not evaporate (even in high vacuum), and the combination of many different anions and cations gives us access to a very large number of ionic liquids with very different physical and chemical properties.
Our group is developing so-called "task-specific ionic liquids" that actually need to be able to "do" more than "just being a solvent" -- for example, showing catalytic activity.
In Situ NMR Spectroscopy in Ionic Liquids
The chemistry of ionic liquids is a fairly novel field of research. Therefore, interactions in these novel media are still not well understood. To that end, in situ spectroscopic methods are needed that enable routine investigations in ionic liquids.
Our group is developing NMR spectroscopy for use in neat ionic media. In this respect, we are not so much interested in developing fundamentally new methodologies, but to enable standard and advanced NMR spectroscopy for ionic liquids being the NMR solvents. With this tool, we are investigating reaction mechanisms in ionic solvents as well as studying the liquid-phase structures of neat and diluted ionic liquids in themselves.
We are studying the interactions of ions with small to medium sized biologically relevant peptides using a variety of in situ spectroscopic methods. In particular, the focus of current studies lies on the influence of ions and ionic liquids on peptide conformations and on the development of novel antimicrobials and antibiotics.
New Chiral Anions
Although in the past many chiral solvents have been developed, only very few reports about stereoinduction in homogeneously catalysed reactions have surfaced. Many ILs with chiral cations have been used for this purpose to no avail. The main reason for this "failure" seems to be that these chiral solvents unsufficiently interact with the transition state of the reaction. To us, this seems logical, since the majority of organic transformations either pass through an unpolar (radical reactions, cycloadditions) or a cationic transition state. Thus, in the latter case ionic liquids with chiral anions are needed.
We are developing chiral anions for ionic liquids based on two structural motives: functionalised borates and derivatives of the common anion Tf2N. The source for the chiral information stems from naturally occuring molecules ("chiral pool"), e.g. amino acids or terpenes.
Ionic liquids are perfectly suited solvents for the synthesis of highly polar or even charged molecules. Nonetheless, the separation of products of this type can be highly demanding. We are developing "switchable solvents" that can reversibly be transformed into an uncharged molecule via change of pH, temperature, irradiation etc.