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The objective of molecular systems engineering is to move beyond functional components and primary systems, towards cumulate emergent properties in interfaced higher-order systems of unprecedented multifunctionality and sophistication.

In a multi-disciplinary team effort we gather experts on light-to-chemical energy conversion, artificial metalloenzymes, and bio-inspired polymer vesicles in order to construct molecular factories which produce added-value chemicals in an overall process fueled by solar energy. We outline our long-term vision and discuss specific challenges associated with this endeavor.

The interdisciplinary projects in bioinorganic and bioorganic chemistry of the Department of Chemistry, University of Basel led to the preparation of new systems that mimic biologically important processes and to the discovery of compounds from natural sources which are very promising with respect to medical applications. The advances in these areas are reported here.

With the aim of exploring the role of the second coordination sphere in enantioselective catalysis, achiral organometallic catalyst precursors are anchored in proteins via non-covalent interactions. A chemogenetic procedure allows the activity and the enantioselectivity of the artificial metalloenzymes to be optimized, to yield hybrid catalysts with features reminiscent both of enzymatic and homogeneous catalysts.

Avidin and structurally related streptavidin are attractive host proteins for the creation of artificial metalloenzymes displaying features reminiscent both of homogeneous catalysts and enzymes. The main advantages are that both proteins have been cloned and expressed in several organisms and possess a deep hydrophobic binding pocket capable of hosting biotinylated catalyst precursors. An optimized artificial avidin gene in Pichia pastoris is expressed. The high level of active protein produced in the extracellular medium is suitable for the performance of high-throughput screening in 96-well plate format. Biologically active recombinant streptavidin is expressed in E. coli. Mutations have been introduced both in avidin and streptavidin genes and both wild type and mutated proteins have been utilized to explore the role of the second coordination sphere in enantioselective catalysis.

Three different topics are presented herein. With the help of molecular-orbital analysis, the unique geometry and catalytic properties of d0 bent-metallocenes was analyzed in search for cyclopentadienyl substitutes.To overcome the inherent racemization of coordinatively unsaturated piano-stool complexes, a ten-electron donor ligand was designed. This ligand incorporates an arene bearing two tethers: a phosphine and an imine (abbreviated PArN). It was shown that upon ?6:?1:?1-coordination of PArN to ruthenium, a configurationally stable piano-stool complex results [Ru(?6:?1:?1-PArN)L]n+.A tripodal dodecadentate ligand, incorporating three soft bipyridine donors as well as three harder salicylamide chelates, was synthesized. This ligand allowed the investigation of the iron release from ferric enterobactin, suggesting a protonation/translocation into a salicylate-binding mode. In the presence of a single iron ion and depending on its oxidation mode, it was shown that this system displays switch-like properties.