Within living organisms in the natural world, highly complex systems have evolved over billions of years to carry out the specific synthetic functions required to support and propagate life. Nature’s use of biological machines for the synthesis of functional molecules has inspired synthetic chemists from a broad range of specialisms to design artificial molecular machines and systems capable of facilitating non-trivial synthetic tasks. Rotaxanes are favourable architectures around which to design molecular machines as their mechanically-interlocked structure provides the chemist with a unique handle by which to achieve molecular compartmentalisation and to control the effective molarity of non-covalently linked components.<br/><br/>An artificial, rotaxane-based molecular machine that operates in a processive manner on a polymeric track to assemble a catalytically active oligopeptide is reported. Polydispersity information is programmed into this device through its careful design and modular assembly; upon operation of the artificial molecular machine, this encoded information is translated into a pre-defined oligopeptide product. Furthermore, the produced oligoleucine species spontaneously adopts a secondary structure with α-helical character, enabling it to promote asymmetric organocatalysis in the Juliá-Colonna epoxidation of a chalcone derivative with excellent chiral control and efficiency. These results demonstrate that it is possible to use artificial molecular machines for the non-trivial synthesis of functional molecules in a manner reminiscent of the ribosome assembling the primary structure of an enzyme.

Artificial molecular machines that assemble oligomeric asymmetric catalysts

254th National Meeting (2017)

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