Encapsulation of Halocarbons in a Tetrahedral Anion Cage

Abstract

Caged supramolecular systems are promising hosts for guest inclusion, separation, and stabilization. Well-studied examples are mainly metal-coordination-based or covalent architectures. An anion-coordination-based cage that is capable of encapsulating halocarbon guests is reported for the first time. This A4L4-type (A=anion) tetrahedral cage, [(PO4)4L4](12-), assembled from a C3-symmetric tris(bisurea) ligand (L) and phosphate ion (PO4(3-)), readily accommodates a series of quasi-tetrahedral halocarbons, such as the Freon components CFCl3, CF2Cl2, CHFCl2, and C(CH3)F3, and chlorocarbons CH2Cl2, CHCl3, CCl4, C(CH3)Cl3, C(CH3)2Cl2, and C(CH3)3Cl. The guest encapsulation in the solid state is confirmed by crystal structures, while the host-guest interactions in solution were demonstrated by NMR techniques.

Trapping White Phosphorus within a Purely Organic Molecular Container Produced by Imine Condensation

“…However, the use of purely organic cages self‐assembled by means of dynamic covalent reactions including imine condensation to stabilize P 4 and other highly reactive species is much less well‐developed compared to their coordination chemistry‐based counterparts. This could be explained by the fact that, compared to cage systems containing metal linkages that have specific coordination preferences or anion‐based linking “nodes” that can also control linkage geometries, the high‐yielding syntheses of purely organic cage with defined shapes and sizes presents different challenges. Even although a number of complex organic structures, including elegant cage systems prepared via dynamic covalent bond formation, such as imine condensations, are now known, examples where purely organic, imine‐based cages are used as so‐called “molecular flasks” to recognize guest molecules or control their reactivity in homogeneous solutions are rare.…”

Anion recognition by oligo-(thio)urea-based receptors

“…53 (3) Phosphate-coordination directed tetrahedral cages Based on the 3 : 1 binding mode between PO 4 3À and the orthophenylene connected bis-urea unit, more complex architectures such as tetrahedral cages could be constructed. 55 This work represents the first example of the (4) Phosphate-induced fluorescence ''turn on'' dimers By using the latter strategy, Wu and coworkers constructed the first anion-coordination directed tetrahedral cage, a face-based A 4 L 4 type complex [(PO 4 ) 4 L 4 ], where L is a C 3 spacer connecting tris(pbu), ligand 40a (Fig.…”

Anion-templated hexagonal nanotubes

“…Notably, the groups of Wu, and Kruger and Gunnlaugsson have prepared “tetranuclear” cages assembled through hydrogen bonding between four phosphate or sulfate anions and four bis-urea ligands. 10 Other anion-templated cages, helicates, 1-D coordination polymers and 2-D layered structures have also been reported. 11 …”