Foldamer-tuned switching kinetics and metastability of [2]rotaxanes.

Slip sliding away: foldamers can function as modular stoppers to regulate the slippage and de-slippage of pseudorotaxanes and the switching kinetics and metastability of bistable rotaxanes. By simply changing the solvent or the length of the hydrogen-bonded foldamer, the lifetime of the metastable co-conformation state can be increased dramatically, from several minutes to as long as several days.

Hydrogen bonding-directed quantitative self-assembly of cyclotriveratrylene capsules and their encapsulation of C60 and C70.

Under the direction of intramolecular three-center hydrogen bonding, two cyclotriveratrylene (CTV)-based capsules are assembled quantitatively from C(3)-symmetric CTV precursors by forming three imine bonds from arylamide-derived foldamer segments. (1)H and (13)C NMR and UV/vis experiments reveal that the capsules strongly encapsulate C(60) and C(70) in discrete solvents.

Vesicle self-assembly by tetrathiafulvalene derivatives in both polar and nonpolar solvents and pseudo-rotaxane mediated vesicle-to-microtube transformation.

This paper reports the self-assemblies of vesicles from two tetrathiafulvalene (TTF) derivatives (T1 and T2), that bear four or two amphiphilic side chains, in both polar and nonpolar solvents. The formation of vesicles is evidenced by scanning electron microscopy (SEM), atomic force microscopy (AFM), transmission electron microscopy (TEM), and dynamic light scattering (DLS) experiments, while the microstructural aspects of the vesicles are investigated by UV-vis, (1)H NMR, and high resolution TEM, which support a monolayer model for the vesicles. It is revealed that the formation of vesicles is driven by the combination of multiple noncovalent interactions, including pi-pi stacking, hydrogen-bonding, van der Waals force, and S.

Folding of aromatic amide-based oligomers induced by benzene-1,3,5-tricarboxylate anion in DMSO.

In this paper, we describe the folding of a series of linear arylamide oligomers in DMSO that is induced by benzene-1,3,5-tricarboxylate anion. The oligomers are comprised of naphthalene-2,7-diamine and 1,3,5-benzenetricarboxylic acid segments with two (tert-butoxycarbonylamino) groups at the ends and two to four hydrophilic N,N-bis(2-(2-(2-methoxyethoxy)ethoxy)ethyl)amino groups at one side of the backbones. (2D NOESY) (1)H NMR, fluorescence and UV-vis studies indicate that the oligomers do not adopt defined conformations in DMSO but fold into compact structures in the presence of the anion.

A click chemistry approach for the synthesis of macrocycles from aryl amide-based precursors directed by hydrogen bonding.

This paper describes the synthesis of four aryl amide-based macrocycles through the 1 + 1 formation of two 1,2,3-triazole units by click chemistry. Two series of aryl amide-based precursors that bear two azide or acetylene units have been prepared. Intramolecular hydrogen bonding has been utilized to induce them to adopt a U-styled conformation, which remarkably promotes the macrocyclization of two structurally matched precursors.

Self-assembly of vesicles from amphiphilic aromatic amide-based oligomers.

A novel class of linear arylamide oligomers has been designed and synthesized from naphthalene-2,7-diamine and benzene-1,3,5-tricarboxylic acid segments. The molecules carry two (tert-butoxycarbonylamino) groups at the ends and one to three hydrophilic N,N-bis(2-(2-(2-methoxyethoxy)ethoxy)ethyl)amino groups at one side of the backbone. The oligomers self-assembled into vesicular structures in methanol as a result of ordered stacking of the oligomeric amide backbones, which were evidenced by SEM, AFM, TEM, and fluorescent micrography experiments.

Hydrogen-bonding-mediated dynamic covalent synthesis of macrocycles and capsules: new receptors for aliphatic ammonium ions and the formation of pseudo[3]rotaxanes.

This paper describes a novel, highly efficient approach to the self-assembly of monomacrocycles and two-layered capsules by using dynamic covalent chemistry. Intramolecular hydrogen-bonding was used to preorganize aromatic amide-based monomers that contain aldehyde and tert-butoxycarbonylamino units. As a result, in the presence of an excess of trifluoroacetic acid (TFA), four monomers could self-couple to produce macrocycles selectively through the formation of three imine or hydrazone bonds.

Cholesterol-appended aromatic imine organogelators: a case study of gelation-driven component selection.

This letter describes a novel approach for developing organogelators through the formation of reversible imine bonds from two molecular components and the enriching behavior of the gelating imines. Cholesterol-appended aniline 1 and 4-substituted benzaldehydes 2a-d did not gelate any solvents. Their condensation products, imines 3a-d, however, could gelate alcohols because of the enhanced stacking interaction of the imine unit.

Foldamer organogels: a circular dichroism study of glucose-mediated dynamic helicity induction and amplification.

This paper reports a systematic study of the dynamic process for the self-assembly of chiral organogels from achiral hydrogen bonded hydrazide foldamers by induction of chiral glucose. Six foldamers incorporated with six decyl chains and two benzene, naphthalene, anthracene, or pyrene units at the ends are revealed to strongly gelate apolar and polar solvents, including alkanes, arenes, esters, alcohols, and 1,4-dioxane. The gels are characterized by UV-vis, fluorescent, XRD, SEM, and AFM methods, based on which a dislocated "tail-to-tail" stacking pattern is proposed.

Vesicles and organogels from foldamers: a solvent-modulated self-assembling process.

Nonamphiphilic, hydrogen-bonded hydrazide foldamers appended with four or six long flexible chains were revealed to spontaneously assemble to form vesicles in methanol and organogels in aliphatic hydrocarbons. SEM, AFM, TEM, DLS, and fluorescence microscopy were all used to identify the structures of the vesicles. It was proposed that intermolecular pi stacking of the folded frameworks and hydrogen bonding of the amide units in the appended chains induced the molecules to produce cylindrical aggregates.

Diastereomeric recognition of chiral foldamer receptors for chiral glucoses.

[reaction: see text] Three chiral aromatic hydrazide foldamers have been designed and synthesized, in which two R- or S-proline units were incorporated at the terminals of their backbones. The 1H NMR, circular dichroism (CD), and fluorescent experiments and molecular dynamics simulations revealed that the foldamers adopted a chiral helical conformation and complexed alkylated glucoses in chloroform with a good diastereomeric selectivity.