Tunable Energy Landscapes to Control Pathway Complexity in Self‐Assembled N‐Heterotriangulenes: Living and Seeded Supramolecular Polymerization

Abstract

Herein, the synthesis and self-assembling features of N-heterotriangulenes 1-3 decorated in their periphery with 3,4,5-trialkoxy-N-(alkoxy)benzamide moieties that enable kinetic control of the supramolecular polymerization process are described. The selection of an appropriate solvent results in a tunable energy landscape in which the relative energy of the different monomeric or aggregated species can be regulated. Thus, in a methylcyclohexane/toluene (MCH/Tol) mixture, intramolecular hydrogen-bonding interactions in the peripheral side units favor the formation of metastable inactivated monomers that evolve with time at precise conditions of concentration and temperature. A pathway complexity in the supramolecular polymerization of 1-3 cannot be determined in MCH/Tol mixtures but, importantly, this situation changes by using CCl . In this solvent, the off-pathway product is a face-to-face H-type aggregate and the on-pathway product is the slipped face-to-face J-type aggregate. The autocatalytic transformation of the metastable monomeric units, as well as the two competing off- and on-pathway aggregates allow the realization of seeded and living supramolecular polymerizations. Interestingly, the presence of chiral, branched side chains in chiral (S)-2 noticeably retards the kinetics of the investigated transformations. This work brings to light the relevance of controlling the pathway complexity in self-assembling units and opens new avenues for the investigation of complex and functional supramolecular structures.

C3‐Symmetrical π‐Scaffolds: Useful Building Blocks to Construct Helical Supramolecular Polymers

“…Pathway complexity in CBT derivatives has been elegantly exploited for compounds 18 a–c to realize living supramolecular polymerization (LSP) . The strategy of LSP allows the preparation of supramolecular polymers with low polydispersity and enhanced properties.…”

“…Furthermore, the addition of seeds of the thermodynamic J‐aggregates to a solution of the kinetic H‐aggregates accelerates the conversion of the kinetic to the thermodynamic product. This seeded growth method can be effectively repeated in three cycles …”

Consecutive Supramolecular Polymerization of a Rylene‐Based Twistacene

“…Considering the previous reports on referable self‐assembling systems endowed with the 3,4,5‐trialkoxy‐ N ‐(alkoxy)benzamide moiety, which favors the appearance of pathway complexity and the formation of metastable monomeric species (M*), and the strong influence that solvent can play in the stabilization of the energetic levels of the different species involved in supramolecular polymerizations, we have further investigated the self‐assembling features of 1 by using a more polar and aromatic solvent like toluene. VT‐ 1 H NMR experiments in deuterated Tol prove that the aggregated species are formed by the operation of π‐stacking interactions between the large aromatic moiety and the formation of a fourfold array of intermolecular H‐bonds between the amide functional groups.…”

Hierarchy of Asymmetry in Chiral Supramolecular Polymers: Toward Functional, Helical Supramolecular Structures

“…The results highlighted above for CBTs prompted us to search for LSP with this aromatic moiety. To accomplish this goal, we designed CBTs 17 endowed with peripheral side chains with ester and amide functional groups separated by an ethylene spacer (Figure a) . This distribution of complementary functional groups paves the way to the establishment of intramolecular hydrogen bonds that lead to the formation of trapped monomers, which enable kinetically controlled supramolecular polymerization .…”