Contribution of kinetics and thermodynamics to the metal-mediated assembly of a flexible tripeptide into giant discrete structures

To develop sophisticated artificial systems that are comparable to those in nature, understanding the principles controlling the assembly of flexible molecules into giant structures is essential. In this study, the metal-mediated self-assembly of a flexible tripeptide into three giant discrete complexes was analyzed using small-angle X-ray scattering along with other experimental and simulation studies. We revealed the kinetic and thermodynamic contributions during the assembly process, which resulted in the selective formation of two giant discrete structures of similar sizes in a water/acetonitrile solution. We also identified the factors that open the kinetic pathway to giant [2]-catenane structures in aqueous solutions. The formation of structures containing multiple components is generally considered kinetically unfavorable. However, our results revealed that solvent molecules and counterions kinetically initiate the formation of giant, multicomponent catenane structures in aqueous solutions.