Self-assembly is widely used to generate large and elaborate assemblies such as coordination cages, which can have useful functions such as catalysis, sensing and transport.  Studying self-assembly, and the conditions under which different assemblies appear, is therefore of great importance as it provides insight into how we can control self-assembly pathways rather than relying on serendipity.We have synthesised a set of water soluble self-assembled coordination cages which are in equilibrium with each other in solution.   The three components of the 'library' are a M12L18 cage, a M4L6 cage and a M2L3 helix.  All three assemblies have been characterised by 1H NMR, Mass spectrometry and X-ray crystallography.The interconversion between the assemblies has been investigated as a function of temperature and concentration using NMR spectroscopy.  We find that variations in the balance between the components follow on the basis of what would be expected by the Le Chatelier principle, with the largest (entropically disfavoured) assembly dominating at low temperatures and high concentration, and the smallest (entropically favoured) assembly dominating at high temperatures and low concentration. 

Dynamic equilibrium between coordination cages of different sizes

248th National Meeting (2014)

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