Supramolecular Block Copolymers from Tricarboxamides. Biasing Co‐assembly by the Incorporation of Pyridine Rings

Abstract

The synthesis of a series of triangular‐shaped tricarboxamides endowed with three picoline or nicotine units (compounds 2 and 3, respectively) or just one nicotine unit (compound 4) is reported, and their self‐assembling features investigated. The pyridine rings make compounds 2–4 electronically complementary with our previously reported oligo(phenylene ethynylene)tricarboxamides (OPE‐TA) 1 to form supramolecular copolymers. C3‐symmetric tricarboxamide 2 forms highly stable intramolecular five‐membered pseudocycles that impede its supramolecular polymerization into poly‐2 and the co‐assembly with 1 to yield copolymer poly‐1‐co‐2. On the other hand, C3‐symmetric tricarboxamide 3 readily forms poly‐3 with great stability but unable to form helical supramolecular polymers despite the presence of the peripheral chiral side chains. The copolymer poly‐1‐co‐3 can only be obtained by a previous complete disassembly of the constitutive homopolymers in CHCl3. Helical poly‐1‐co‐3 arises in a process involving the transfer of the helicity from racemic poly‐1 to poly‐3, and the amplification of asymmetry from chiral poly‐3 to poly‐1. Importantly, C2v‐symmetric 4, endowed with only one nicotinamide moiety and three chiral side chains, self‐assembles into a P‐type helical supramolecular polymer (poly‐4) in a thermodynamically controlled cooperative process. The combination of poly‐1 and poly‐4 generates chiral supramolecular copolymer poly‐1‐co‐4, whose blocky microstructure has been investigated by applying the previously reported supramolecular copolymerization model.

Supramolecular copolymerization of hydrophobic and hydrophilic monomers in liquid crystalline media

“…44 In the previous examples, the formation of supramolecular block copolymers is governed by the balance between the association energies between the monomers (homo- and hetero-interactions). 30–34 In the present case, compatibilizing 5OCB seems to contribute to controlling this energy balance to realize a block sequence with the two monomers, which otherwise undergo self-sorting supramolecular polymerization.…”

“…Considering that the supramolecular block copolymer is usually formed under kinetic conditions, 20–29 our system is one of the rare examples of the formation of a block sequence under thermodynamic conditions. 30–34 The present study may serve as a guiding principle for the control of the block sequence in supramolecular copolymers, that can lead to controlled microphase-separated structures as in conventional covalent copolymers.…”

Electronically and geometrically complementary perylenediimides for kinetically controlled supramolecular copolymers

“…In thermodynamically controlled supramolecular copolymers, it is difficult to control such microstructure but the recently reported mass-balance model reported by ten Eikelder and coworkers 15 has allowed to unravel the microstructure of thermodynamically controlled heteropolymers once they are formed. 16 On the other hand, kinetically controlled supramolecular copolymerizations have been reported to yield alternating supramolecular copolymers. The sequential addition of metastable monomers, able to undergo nucleation–elongation growth, is crucial to produce seeded supramolecular copolymerizations affording such alternating coassemblies.…”

Red Circularly Polarized Luminescence from Dimeric H-Aggregates of Acridine Orange by Chiral Induction

“…More recently, chiral scaffolds (template) have been used for generating chiroptical signals through chiral induction to achiral molecules on their surface. − Other approaches include: (i) suppression of nonradiative decay induced by the aggregation of achiral molecules − and (ii) energy transfer to coassembled achiral chromophores. − Coupling between the transition dipoles of template-bound molecules contributes to the emergent chiroptical properties. The nature of exciton coupling (on- or off-resonance) is reflected as mono- or bisignation in the CD/CPL spectrum.…”