Chiral Supramolecular Polymers Assembled from Conformationally Flexible Amino-Acid-Substituted Biphenyldiimides

Hydrogen-bonded polymers are a class of highly dynamic supramolecular aggregates, whose self-assembly may be tuned by very mild external or internal stimuli. However, the rational design of chiral supramolecules remains challenging especially when flexible components are involved. The combination of the inherent weakness and dynamic nature of the intermolecular bonds that hold together such assemblies with unrestricted molecular motions introduces additional factors which may affect the self-assembly process. In this report the self-assembly of four amino acid-derived chiral biphenyldiimides into open-chain 1D supramolecular polymers is presented. While the primary driving force, COOH center dot center dot center dot HOOC hydrogen bonding, is responsible for the polymer growth in all cases, the amino acid side chains play an important role in either stabilizing or destabilizing the assemblies obtained, as deduced from studies of the thermodynamics of the self-assembly process. Furthermore, substantial differences in the structural factors governing the polymerization process between dynamic liquid and static solid are found. This work demonstrates the potential of the rather unexplored class of diimide-based organic dyes in the formation of well-organized chiral supramolecular assemblies with tunable properties.

Automated summary

Hydrogen-bonded polymers are highly dynamic supramolecular aggregates that can self-assemble through external or internal stimuli. This study finds that chiral biphenyldiimides derived from amino acids can self-assemble into open-chain 1D supramolecular polymers, and the amino acid side chains play an important role in stabilizing or destabilizing the assemblies. Significant differences in the polymerization process are observed between dynamic liquid and static solid. This work demonstrates the potential of diimide-based organic dyes in the formation of chiral supramolecular assemblies with tunable properties.