Supramolecular Polymer Transformation: A Kinetic Study

Investigation of supramolecular kinetics is essential for elucidating self-assembly mechanisms. Recently, we reported on a noncovalent system involving a bolaamphiphilic perylene diimide dimer that is kinetically trapped in water but can rearrange into a different, more ordered assembly in water/THF mixtures (Angew. Chem. Int. Ed. 2014, 53, 4123). Here we present a kinetic mechanistic study of this process by employing UV–vis spectroscopy. The transformation exhibits a rapid decrease in the red-shifted absorption band, which is monitored in order to track the kinetics at different temperatures (15–50 °C) and concentrations. Fitting the data with the 1D KJMA (Kolmogorov–Johnson–Mehl–Avrami) model affords the activation parameters. The latter as well as seeding experiments indicates that the transformation occurs without the detachment of covalent units, and that hydration dynamics plays a significant role in nucleation, with entropic factors being dominant. Switching off the transformation, and the formati...