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-L¹ and R-L² 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 (ΔG) of the supramolecular polymer of R-L¹ is nearly identical to that of R-L². 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-L¹ accelerated the supramolecular polymerization compared to the process without the seed.