Self‐Assembly of a Highly Organized, Hexameric Supramolecular Architecture: Formation, Structure and Properties

Abstract

Two derivatives, (3)L and (9)L, of a ditopic, multiply hydrogen-bonding molecule, known for more than a decade, have been found, in the solid state as well as in solvents of low polarity at room temperature, to exist not as monomers, but to undergo a remarkable self-assembly into a complex supramolecular species. The solid-state molecular structure of (3)L, determined by single-crystal X-ray crystallography, revealed that it forms a highly organized hexameric entity (3)L6 with a capsular shape, resulting from the interlocking of two sets of three monomolecular components, linked through hydrogen-bonding interactions. The complicated (1)H NMR spectra observed in o-dichlorobenzene (o-DCB) for (3)L and (9)L are consistent with the presence of a hexamer of D3 symmetry in both cases. DOSY measurements confirm the hexameric constitution in solution. In contrast, in a hydrogen-bond-disrupting solvent, such as DMSO, the (1)H NMR spectra are very simple and consistent with the presence of isolated monomers only. Extensive temperature-dependent (1)H NMR studies in o-DCB showed that the L6 species dissociated progressively into the monomeric unit on increasing th temperature, up to complete dissociation at about 90 °C. The coexistence of the hexamer and the monomer indicated that exchange was slow on the NMR timescale. Remarkably, no species other than hexamer and monomer were detected in the equilibrating mixtures. The relative amounts of each entity showed a reversible sigmoidal variation with temperature, indicating that the assembly proceeded with positive cooperativity. A full thermodynamic analysis has been applied to the data.

Designing Foldamer–Foldamer Interactions in Solution: The Roles of Helix Length and Terminus Functionality in Promoting the Self‐Association of Aminoisobutyric Acid Oligomers

“…Crystals suitable for X-ray crystallographic study were obtained for peptides 4 and 3 from CHCl 3 and diethyl ether/methanol, respectively (Figures 8 and 9). [35] These structures show several features that are consistent with the inter-and intramolecular interactions inferred from studies in solution. Both compounds adopted 3 10 -helical structures in the solid state, the integrity of which was maintained by i!i + 3 intramolecular hydrogenbonding interactions between the carbonyl groups and NH protons, thus producing a series of type-III b turns.…”

“…Crystals suitable for X‐ray crystallographic study were obtained for peptides 4 and 3 from CHCl 3 and diethyl ether/methanol, respectively (Figures 8 and 9) 35. These structures show several features that are consistent with the inter‐ and intramolecular interactions inferred from studies in solution.…”

Surface Modification of ZnO Nanorods with Hamilton Receptors

“…There are two factors that explain such an observed multilayer formation. First, Hamilton receptors are very likely to form hydrogen bonding aggregates and second catechol is known to form multilayers if applied in too high concentrations during the functionalization process [ 31 , 35 ]. However, the high amount of adsorbed Hamilton receptor enabled a detection of mass fragments in a TGA-MS experiment ( Figure 4 ).…”

Unexpected dimerization of a tripeptide comprising a β,γ‐diamino acid

“…In this work, we show that another tripeptide with different configuration (Figure ) does no longer form any intramolecular hydrogen bond but induces intermolecular interaction. According to various nuclear magnetic resonance (NMR) studies, specially diffusion‐ordered spectroscopy (DOSY), we reveal herein the dimeric structure of this new hybrid tripeptide.…”