Spontaneous Aminolytic Cyclization and Self-Assembly of Dipeptide Methyl Esters in Water

Dipeptides are known to spontaneously cyclize to diketopiperazines, and in some cases these cyclic dipeptides have been shown to self-assemble to form supramolecular nanostructures. Herein, we demonstrate the in situ cyclization of dipeptide methyl esters in aqueous buffer by intramolecular aminolysis, leading to the formation of diverse supramolecular nanostructures. The chemical nature of the amino acid side chains dictates the supramolecular arrangement and resulting nanoscale architectures. For c[LF], supramolecular gels are formed, and the concentration of starting materials influences the mechanical properties of hydrogels. Moreover, by adding metalloporphyrin to the starting dipeptide ester solution, these become incorporated through cooperative assembly, resulting in the formation of nanofibers able to catalyse the oxidation of organic phenol in water. The approach taken here, which combines the chemically activated assembly with the versatility of short peptides might pave the way for achieving the spontaneous formation of supramolecular order and function using simple building blocks.