Unexpected Self‐Sorting Self‐Assembly Formation of a [4:4] Sulfate:Ligand Cage from a Preorganized Tripodal Urea Ligand

Abstract

The design and synthesis of tripodal ligands 1-3 based upon the N-methyl-1,3,5-benzenetricarboxamide platform appended with three aryl urea arms is reported. This ligand platform gives rise to highly preorganized structures and is ideally suited for binding SO 4 2À and H 2 PO 4 À ions through multiple hydrogen-bonding interactions.The solid-state crystal structures of 1-3 with SO 4 2À show the encapsulation of asingle anion within ac age structure,w hereas the crystal structure of 1 with H 2 PO 4 À showed that two anions are encapsulated. We further demonstrate that ligand 4,based on the same platform but consisting of two bis-urea moieties and asingle ammonium moiety,also recognizes SO 4 2À to form aself-assembled capsule with [4:4] SO 4 2À :4 stoichiometry in which the anions are clustered within acavity formed by the four ligands.This is the first example of as elf-sorting self-assembled capsule where four tetrahedrally arranged SO 4 2À ions are embedded within ah ydrophobic cavity.

Selective C70 encapsulation by a robust octameric nanospheroid held together by 48 cooperative hydrogen bonds

“…This design of the molecular substrate has provided a supramolecular nanocapsule with a precisely defined size and shape as well as an outstanding thermal and chemical stability in solution. In contrast to the previously described system based on the same central aromatic platform32, the formation of the capsule is independent of the presence of stabilizing template molecules. Thanks to small pore sizes, large internal cavity and sufficient dynamicity, the presented nanocapsule has been found to selectively recognize and encapsulate large aromatic guests such as fullerenes C 60 and C 70 .…”

“…The vast majority of hydrogen-bonded capsules are dimeric species which are constructed and/or exist only in the presence of stabilising template molecules1032. The formation of multimembered architectures via hydrogen bonds is much more challenging and rare, in part due to the potentially prohibitive entropic cost of creating large ordered objects303334.…”

Self‐Sorting Double‐Network Hydrogels with Tunable Supramolecular Handedness and Mechanical Properties

“…[1] To mimic the selfsorting function in nature, scientists have developed diverse strategies to construct artificial self-sorting systems with synthetic molecules or nanomaterials. [1a,b, 2] Most of the constructed self-sorting systems are manipulated by noncovalent interactions, such as hydrogen-bonding interactions, [3] solvophobic effects, [4] host-guest interactions, [5] and metal-ligand interactions. [6] However, self-sorting in biological systems and bioinspired self-assembly processes often rely on chiral molecules.…”

Size-Selective Urea-Containing Metal–Organic Frameworks as Receptors for Anions

“…Nature is the master key of anion recognition, and proteins are neutral receptors whose high selectivity is mainly due to noncovalent interactions, especially to hydrogen bonds. , The design and synthesis of anion receptors inspired by nature and based on specific noncovalent interactions are of central importance in supramolecular chemistry, attracting considerable attention from the scientific community and posing great challenges. , …”

“…3,4 The design and synthesis of anion receptors inspired by nature and based on specific noncovalent interactions are of central importance in supramolecular chemistry, attracting considerable attention from the scientific community and posing great challenges. 5,6 Selective anion recognition can be achieved by both neutral and positively charged hosts. Cationic charged hosts are, undoubtedly, the primary approach but, as the recognition process is based on nondirectional electrostatic interactions, they ensure poor anion selectivity, which is their main disadvantage.…”