We are interested in integrating unorthodox, at best new interactions into catalysis. This is important because new ways to interact should lead to new reactivity. In this spirit, we have introduced catalysis with anion-π interactions in 2013, followed by catalysis with chalcogen bonds in 2017 and catalysis with pnictogen bonds in 2018.
The idea of anion-π catalysis is to stabilize anionic transitions states on π-acidic aromatic surfaces. This is complementary to conventional cation-π biocatalysis, just like nucleophilic aromatic substitution is complementary to electrophilic aromatic substitution. The first five years of anion-π catalysis have been summarized in Acc. Chem. Res. 2018, 51, 2255–2263.
Chalcogen and pnictogen bonds can be considered as complementary to the highly delocalized anion-π interactions, with focused sigma holes to operate at high precision in hydrophobic media. Arguably, they will emerge as the non-covalent counterpart of covalent Lewis acid catalysis, just like hydrogen-bonding catalysis is the non-covalent counterpart of Brønsted acid catalysis. One current topic with chalcogen, pnictogen and tetrel bonding catalysis is to work out distinct advantages compared to general Lewis acids.
With regard to reactions, we are interested in any transformation that could benefit from unorthodox interactions. Enolate chemistry and cycloadditions have been most attractive, current emphasis is on epoxide-opening polyether cascade cyclizations. As leading examples for access to new reactivity, violations of the Baldwin rules with pnictogen bonds and autocatalysis in π-acidic surfaces are of highest current interest.
Fundamental anion-π catalysis research focuses on anion-π catalysts, particularly naphthalenediimides (NDIs), perylenediimides (PDIs), fullerenes and higher carbon allotropes. We currently shift attention toward more complex systems, with emphasis on foldamers, lipid bilayer membranes, artificial enzymes and electrodes in microfluidics. Lipid bilayer membranes are fascinating to combine transport and catalysis in a solvent free environment, with confinement, directionality and compartmentalization for remote control. Systems catalysis on conducting surfaces in microfluidic devices aims for selectivity control and, ultimately, programmable multistep synthesis in electric fields. Artificial enzymes with unorthodox interactions are interesting to screen mutant libraries for asymmetric catalysis and new reactivity, ultimately also for use in live cells for metabolic engineering.
Methods: These projects generate expertise in synthetic methodology, in combination with total synthesis, supramolecular analysis and (optional) extension to molecular modeling, optoelectronic materials characterization, surface chemistry (heterogeneous catalysis on electrodes), and biocatalysis.
Collaborations: These projects offer optional in-house collaboration possibilities with regard to computational chemistry and ultrafast photophysics. They are loosely connected to the NCCR Molecular System Engineering, with possible collaboration with other members (artificial enzymes, device engineering), NCCR group meetings and retreats.
Some recent graphical abstracts: