Kinetically Controlled Seeded Living Supramolecular Polymerization of Tb(III) Complex

Abstract

We describe the synthesis of metallosupramolecular polymers using a Tb³⁺ complex as a primary building block. This synthesis is facilitated through the strategic manipulation of non-equilibrium self-assemblies, employing a living supramolecular polymerization method. Our extensive investigation into the metallosupramolecular polymerizations, which are both thermodynamically and kinetically regulated and centered around the Tb³⁺ complex with bisterpyridine-modified ligand (R-L ¹ ) incorporating R-alanine units, revealed noteworthy properties. These complexes initially form kinetically metastable aggregates, characterized by a coordination number of nine. This structure involves one Tb³⁺ cation and three NO₃⁻ anions at one terpyridine moiety, while the opposite terpyridine moiety remains unoccupied. Intriguingly, these aggregates can transition into a thermodynamically more stable state, also characterized by a nine-coordination number. In this state, each of the two terpyridine units is coordinated with one Tb³⁺ cation and three NO₃⁻ anions, respectively. This transformative process is expedited by seed-induced living polymerization. Therefore, we have successfully executed the seeded living supramolecular polymerization of the monomeric building unit under kinetically controlled conditions. This process yielded a metallosupramolecular polymer with a precisely regulated length and minimal polydispersity, demonstrating the potential of this approach in the design of advanced functional materials.