Concentration‐Dependent Self‐Assembly of an Unusually Large Hexameric Hydrogen‐Bonded Molecular Cage

Abstract

The sizes of available self‐assembled hydrogen‐bond‐based supramolecular capsules and cages are rather limited. The largest systems have volumes of approximately 1400–2300 Å3. Herein, we report a large, hexameric cage based on intermolecular amide–amide dimerization. The unusual structure with openings, reminiscent of covalently linked cages, is held together by 24 hydrogen bonds. With a diameter of 2.3 nm and a cavity volume of ∼2800 Å3, the assembly is larger than any previously known capsule/cage structure relying exclusively on hydrogen bonds. The self‐assembly process in chlorinated, organic solvents was found to be strongly concentration dependent, with the monomeric form prevailing at low concentrations. Additionally, the formation of host–guest complexes with fullerenes (C60 and C70) was observed.

Multiple hydrogen bonding driven supramolecular architectures and their biomedical applications

“…Tiefenbacher et al 128 reported a large hexameric cage (Fig. 12C) based on intermolecular amido-amide dimerization.…”

“…(B) Molecular recognition via hydrogen bonding and the covalent crosslinking forming disulfide bonds 127. (C) Hexameric hydrogen-bonded molecular cage 128. (D) Capsule structure formed via hydrogen bonding directed self-assembly 129.…”

Purely Covalent Molecular Cages and Containers for Guest Encapsulation

“…The cage was demonstrated to encapsulate spherical C 60 and C 70 fullerenes through favorable dispersive and π−π-interactions between the guest and the aromatic rings in the cage cavity (Figure 87). 204 Markiewicz, Jenczak, and co-workers prepared a robust enantiopure octameric cage (252) 8 held together by 48 cooperative hydrogen bonds between the 252 monomers. The capsule structure was retained in both the solid state, where crystals were obtained by the slow evaporation of a chloroform solution, and also in solution in nonpolar solvents, such as deuterated 1,1,2,2-tetrachloroethane (TCE-d 2 ).…”

Specific Noncovalent Association of Truncated exo-Functionalized Triangular Homochiral Isotrianglimines through Head-to-Head, Tail-to-Tail, and Honeycomb Supramolecular Motifs

“…Since the first works by Ružička, , macrocycles and, later on, covalent organic cage compounds have become essential compounds in chemistry, material chemistry, crystal engineering, and biochemistry. − The continuous development of supramolecular chemistry has resulted in macrocyclic compounds being employed as molecular building blocks in molecular tectonics. − This approach allows for the construction of capsules with large internal cavities and is capable of capturing neutral and charged species in addition polymeric structures, where the monomers are bound by noncovalent interactions. − …”