Kinetically Driven Cooperative Supramolecular Polymerization of Bisterpyridine Ligands in Aqueous Solution

Abstract

The kinetically controlled supramolecular polymerization is reported of bisterpyridine-based ligands bearing alanine moieties and alkyl chains, both in the absence and presence of Tb(NO3)(3), in a DMSO and H2O mixture (2:8 v/v). R-L-1 and R-L-2 exhibit helical fiber structures with lengths of several hundred micrometers, both without and with Tb3+ ions (3.0 equiv.). The supramolecular polymers form through a cooperative model with a nucleation-elongation mechanism and follow an "on-pathway" polymerization process. Thermodynamic parameters are calculated using the MATLAB of heating curves. The Gibbs free energy (Delta G) of the supramolecular polymer of R-L-1 is nearly identical to that of R-L-2. In contrast, the stability of the supramolecular polymers is significantly influenced by the presence of Tb3+ ions. Furthermore, the addition of seeds to monomeric species R-L-1 accelerated the supramolecular polymerization compared to the process without the seed.