Aromatic oligoamide macrocycles exhibit strong preference for highly directional association. Aggregation happens in both nonpolar and polar solvents but is weakened as solvent polarity increases. The strong, directional assembly is rationalized by the cooperative action of dipole-dipole and π-π stacking interactions, leading to long nanotubular assemblies that are confirmed by SEM, TEM, AFM, and XRD. The persistent nanotubular assemblies contain non-collapsible hydrophilic internal pores that mediate highly efficient ion transport observed with these macrocycles and serve as cylindrical sites for accommodating guests such as metal ions.

A unique supramolecular two-component gelation system was constructed from amphiphilic shape-persistent cyclo[6]aramides and diethylammonium chloride (or triethylammonium chloride). This system has the ability to discriminate native arginine from 19 other amino acids in a specific fashion. Cyclo[6]aramides show preferential binding for the guanidinium residue over ammonium groups. This specificity was confirmed by both experimental results and theoretical simulations. These results demonstrated a new modular displacement strategy, exploring the use of species-binding hydrogen-bonded macrocyclic foldamers for the construction of two-component gelation systems for selective recognition of native amino acids by competitive host-guest interactions. This strategy may be amenable to developing a variety of functional two-component gelators for specific recognition of various targeted organic molecular species.

An intramolecularly hydrogen‐bonded crescent aromatic oligoamide 1 bearing two coumarin residues was synthesized. The results from UV‐vis and fluorescent spectra upon metal ions complexation demonstrated that the two fluorophores serving as parts of the shape‐persistent backbone provided the molecule with high selectivity and sensitivity for recognition of Th4+ over other lanthanide and uranyl ions. A 48‐fold fluorescent enhancement in the intensity was observed at 505 nm upon adding Th4+, while other metal cations failed to induce such a significant change. A visual detection for Th4+ was achieved by color change. The stoichiometry of the complex formed by 1 and Th4+ was found to be 1:1 with the stability constant of (2.0±0.6)×106 L·mol−1.

A unique supramolecular two-component gelation system was constructed from amphiphilic shape-persistent cyclo [6]aramides and diethylammonium chloride (or triethylammonium chloride). This system has the ability to discriminate native arginine from 19 other amino acids in a specific fashion. Cyclo[6]aramides show preferential binding for the guanidinium residue over ammonium groups. This specificity was confirmed by both experimental results and theoretical simulations. These results demonstrated a new modular displacement strategy, exploring the use of species-binding hydrogen-bonded macrocyclic foldamers for the construction of two-component gelation systems for selective recognition of native amino acids by competitive host-guest interactions. This strategy may be amenable to developing a variety of functional two-component gelators for specific recognition of various targeted organic molecular species.

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