Design and Synthesis of Biomimetic β-sheets Ferrocene Derivatives

yazhou liu [UCL] Singleton, Michael L. [UCL]

Well-ordered arrays of functional groups resulting from structural organization (folding) of peptides give rise to the important biological functions of proteins (protein-protein interactions, catalysis, etc….). Their replication could provide a powerful tool in the development of new catalysts and synthetic ligands for the recognition of biological molecules. Aromatic oligoamide foldamers can be a powerful tool towards this goal. While many of these molecules adopt helical structures, a greater surface area for interaction could potentially be provided by sheet-like structures. [1] To this end, ferrocene dicarboxylic acid could be a useful turn-unit in the design of beta-sheet like aromatic oligoamides. The two cyclopentadiene rings in ferrocene are separated by ~ 3.5 Å which provides an optimal separation for pi-pi stacking. However, ferrocene can act as a molecular ball bearing allowing rotation of the strands connected to each ring. Thus, before large sheet-like structures can be developed, the structural stability of molecules using ferrocene as a turn unit must be determined. To study this, we have synthesized a series of aromatic oligoamide strands using monomers with different sized aromatic surfaces and connected them using ferrocene dicarboxylic acid. We then studied their solid state and solution structural behavior with X-ray crystallography and NMR. These efforts and the ability of the ferrocene based aromatic oligoamides to interact with small organic molecules is described.