A series of triple-stranded complexes, [1a₃Ag]BF₄, [1b₃Ag]BF₄, [2a₃Ag₂](BF₄)₂, [2b₃Ag₂](BF₄)₂, and [3₃Ag₃](BF₄)₃, have been obtained through the self-assembly of Ag^I ions with p-phenylene ethynylpyridine ligands. X-ray crystallographic studies unambiguously demonstrated a Ag^I-directed monodentate triple-stranded helical structure in the solid state for 1b and 2b. A combination of NMR spectroscopy, HRMS (ESI), and isothermal titration microcalorimetry studies further confirmed that strands 1, 2, and 3 are also able to form triple-stranded helical structures in the presence of Ag^I ions in solution.

We synthesized and characterized a new kind of hydrazide oligomer that contains two different types of binding moieties for halide anions and saccharides. The addition of either halide anions or saccharides can induce the oligomers to adopt folded conformations. More interestingly, the oligomers are able to complex both chloride anions and saccharides in the cavity at the same time, implying a synergistic molecular recognition.

We synthesized and characterized a series of oligo(phenyl-amide-triazole)s that can fold into a helical conformation guided by halide ions. Their binding models and affinities are highly dependent on the length of the foldamer, media and the inducing capability of halide ions. The short foldamer with one helical turn shows a 1:1 binding stoichiometry to all halides, while the longer foldamer with two or three helical turns in principle can form 1:2 complexes with chloride anions even bromide anions with an enhancement on binding affinities. A result of quantitative NOE calculations imply that the longer foldamer should increase its helical pitch so as to release the electrostatic repulsion between halide ions.

Cationic aryl triazole oligomers have been synthesized through “click chemistry”. The results show that cationic aryl triazole oligomers adopt a helical conformation in water or in a mixture of water and methanol, but prevail as a random-coiled conformation in methanol. Importantly, circular dichroism spectroscopy and dynamic light scattering experiments revealed that cationic oligomers aggregated intermolecularly to form higher order architectures with a helical sense opposite to that of the individual helix, which eventually led to the formation of aggregates with sizes in the range 100–500 nm. The aggregation of cationic oligomers was governed by the concentration and polarity of the environment. More interestingly, cationic foldamers were able to recognize chloride and fluoride anions in aqueous solution. The recognition consequently destabilized intermolecular aggregation.

In this manuscript, we present supramolecular capsules based on a new design relying on both self-assembly and folding of oligomeric strands. We have designed an aromatic amide foldamer in which each monomer encodes three levels of information: a specific cavity size, recognition groups for guest binding, and a propensity to adopt a single or a double helical motif. Thus, a tetradecameric sequence based on four different monomers was encoded so that a wide double helical segment resulting from the hybridization of two strands creates a cavity in which guests, such as 1,10-decanediol, can be bound. Additionally two narrow single helical segments form end-caps and isolate the guest from the solvent. The design, synthesis, solid-state and solution-state characterization of duplex formation and guest binding are presented.