Supramolecular polymerization of imine-based monomers driven by the dissipation of chemical fuels

Systems that alter their properties in response to chemical stimuli hold promise for partially mimicking the functions of living systems. Over the past decade, numerous supramolecular systems have been developed in which chemical composition and properties are controlled through the dissipation of chemical fuels. These typically rely on the transient conversion of a “dormant” species into an active, self-assembling supramolecular monomer. This process is driven by fuel consumption and ceases once the fuel is depleted, restoring the initial dormant state. Previously, out-of-equilibrium supramolecular polymerizations were achieved by activating dormant species through the addition or removal of small structural units to enable polymerization.

Here, we introduce an approach that integrates the reversibility of dynamic covalent chemistry with supramolecular chemistry to induce transient supramolecular polymerizations by “recycling” components from a dynamic combinatorial library (DCL). Treating an equilibrated DCL of aliphatic imines and aromatic amines with an activated carboxylic acid (ACA) produces a dissipative dynamic combinatorial library of aromatic imines and protonated aliphatic amines (Figure 1). The transient acidic conditions promote the formation of a supramolecular polymer featuring interactions between the protonated aliphatic amines and crown ether moieties within the aromatic imine scaffold (Figure 1). Consequently, fuel dissipation reorganizes chemical connectivity, temporarily converting a purely covalent (polymeric) system into a supramolecular polymer. We validate this strategy using two distinct covalent dormant feedstocks: a diimine macrocycle based on a calix[4]arene scaffold and a mixture of imine (cyclo)oligomers derived from an isophthalaldehyde skeleton.