Professor Sijbren Otto, University of Groningen, Centre for Systems Chemistry, Groningen, The Netherlands

Systems Chemistry: Molecular Recognition, Catalysis and Self-Replication

How the immense complexity of living organisms has arisen is one of the most intriguing questions in contemporary science. We have started to explore experimentally how organization and function can emerge from complex molecular networks in aqueous solution1. We focus on networks of molecules that can interconvert, to give mixtures that can change their composition in response to external or internal stimuli. Molecular recognition between molecules in such mixtures leads to their mutual stabilization, which drives the synthesis of more of the privileged structures2.

In this talk I will focus on two systems. The first is based on a single building block that gives rise to a small but unusually rich molecular network that can be induced to form catenanes (in the absence of any added template)2a, a self-replicator (upon seeding), a catalyst (upon addition of its substrate),  a synthetic receptor (upon adding a single template) and an allosteric receptor (upon adding two separate templates).

The second part of the talk will focus on self-replicating systems, where replication is driven by self-recognition of a molecule in the dynamic network3. Oxidation of a peptide-functionalized dithiol building block gives rise to a mixture of different-sized macrocycles. Stacking of the macrocycles into fibers may result in the autocatalytic production of more of this particular macrocycle at the expense of the other material in the molecular network. The selection rules that dictate which (if any) replicator will emerge from such networks are starting to become clear.

We have observed that factors such as mechanical energy (stirring or shaking) and the presence of cosolvents can determine which replicator wins the competition for building blocks.

We have also witnessed a process akin to speciation in a system made from a mixture of two building blocks.

1. (a) R. F. Ludlow, S. Otto, Chem. Soc. Rev. 2008, 37, 101-108. (b) P. T. Corbett, J. Leclaire, L. Vial, K. R. West, J.-L. Wietor, J. K. M. Sanders, S. Otto Chem. Rev. 2006, 106, 3652-3711. (c) J. Li, P. Nowak, S. Otto, J. Am. Chem. Soc. 2013, 135, 9222-9239.
2. (a) K. R. West; R. F. Ludlow; P. Besenius; P. T. Corbett; P. A. G. Cormack; D. C. Sherrington; S. Otto, J. Am. Chem. Soc. 2008, 130, 10834-10835. (b) R. F. Ludlow; S. Otto, J. Am. Chem. Soc. 2008, 130, 12218-12219.
3. J. M. A. Carnall; C. A. Waudby; A. M. Belenguer; M. C. A. Stuart, J. J.-P. Peyralans, S. Otto, Science 2010, 327, 1502-1506.