This project focuses on functional systems that are relevant for the chemical sciences.  Recently, we discovered that synthetic transport systems can serve as unique analytical tools to explore exotic interactions that are otherwise difficult to detect.  This approach provided unprecedented evidence for the functional relevance of anion-π interactions, the underrecognized counterpart of cation-π interactions that operates on π-acidic aromatic surfaces with positive quadrupole moments.  With the same strategy, the unique power of halogen bonds for anion transport was discovered, and other less common interactions were use to create function (anion-macrodipole interactions, aromatic donor-acceptor interactions, dynamic covalent bonds).

With evidence for anion stabilization in the ground state in hand, there was no reason to doubt that anion-π interactions could also stabilize anionic transition states.  The complementary cation-π interactions are known stabilize reactive carbocation intermediates, particularly in steroid biosynthesis.  The first example for catalysis with anion-π interactions has just been published.  Increasing stabilization of an anionic transition state with increasing π-acidity of the catalyst is provided as experimental evidence.

Based on this breakthrough, we currently focus on refined anion-π catalysts (naphthalenediimide tweezers, macrocycles, etc; perylenediimides, calixarenes, calixpyrroles, chiral catalysts).  Considering the many attractive anionic transitions states we all know of, we are also most interested to achieve anion-π catalysis for reactions of outstanding interest (enolate chemistry, asymmetric catalysis, etc).  Moreover, catalysis with exotic interactions other than anion-π interactions is very attractive (halogen bonds, macrodipoles, etc), and background studies on ion transport with exotic interactions naturally continue.

Methods:  This project is ideal for students interested synthetic methodology combined in relatively light multistep synthesis (reaction kinetics by NMR, UV, HPLC, GC, Michaelis-Menten kinetics, asymmetric catalysis, X-ray.  In addition:  Retrosynthetic analysis, modern synthetic methods (organometallics, µW, etc), purification techniques (TLC, flash, LC-MS, HPLC, etc), compound characterization (NMR, ESI, MALDI, HRMS, UV, IR, CD, mp, optical rotation, etc).

Collaborations:  Computational simulation is essential (with Jiri Mareda).

Some recent references:  Angew. Chem. Int. Ed. 2013, 52, 9940; J. Am. Chem. Soc. 2013, 135, 8324; J. Am. Chem. Soc. 2013, 135, 5302; Nature Commun. 2012, 3, 905; Angew. Chem. Int. Ed. 2011, 50, 11675; Nature Chem. 2010, 2, 533.