Supramolecular Chiral Assembly of Symmetric Molecules with an Extended Conjugated Core.

C3-symmetric molecules carrying a conjugated diacetylene (DA) core are found to self-assemble into well-defined supramolecular fibers with enhanced supramolecular chirality in both organic and aqueous solutions. The conjugated core affords these amphiphiles characteristic fluorescence properties, which can be quenched partially due to the aggregation. Integration of the C3-symmetry with the conjugation provides these novel molecules strong aggregation tendency through solvent-mediated π-π stacking with preferential supramolecular chirality, which is predominately related to steric hindrance from their dipeptide pendants. Highly uniform supramolecular fibers of P and M handedness with thickness consistent in the dimensions of individual C3 molecules are obtained. The increase of concentrations induces these fibers to wrap together to form supramolecular fibrous bundles. Topochemical polymerization of the DA moieties can transform these supramolecular fibers into stable covalent polymers. We therefore believe that self-assembly of these C3-symmetric molecules with extended conjugated DA cores provides new prospects for the construction of supramolecular helical fibers through enhanced π-π stacking and creates a convenient strategy to furnish covalent chiral polymers of hierarchical structures through supramolecular assembly.

Supramolecular Assembly of C3 -Peptides into Helical Fibers Stabilized through Dynamic Covalent Chemistry.

The supramolecular assembly of C3 -peptides carrying glycine-cysteine (Gly-Cys) dipeptide pendants into helical fibers is described. A Gly-Cys dipeptide sequence was selected to ensure the chirality, and at the same time, to provide a chance to crosslink the structure through oxidation of the thiol into dynamic covalent disulfide, and transfer supramolecular helical fibers into covalent ones. Supramolecular assembly in aprotic solvents affords long helical fibers with left-handedness, which can be stabilized through formation of disulfide. Transformation of supramolecular helical fibers into covalent ones was examined by NMR and FTIR spectroscopies as well as atom force microscopy.