Heterodimeric capsule

Corbellini, R, van Leeuwen, R W. B., Beijleveld, H., etal., Multiple ionic interactions for noncovalent synthesis of molecular capsules in polar solvents , New J. Chem. 2005, 29, 243-248. 

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Fig. 9 A Calix[4]arene tetraurea dimeric capsules with a particular head-to-tail hydrogen bond network. B Achiral tetraurea units form achiral homodimeric capsules, while C two different achiral units forms chiral heterodimeric capsules...

Equimolar amounts of achiral urea 1 and the optically active calix[4]urea 5 give rise to the formation of a heterodimeric capsule with only one cyclic arrangement of the urea hydrogen bonds (Fig. 11), and in the presence of a chiral racemic substrate like norcamphor two diastereoisomeric complexes were present in a 1.3 to 1 ratio. 

Fig. 13 Chiral heterodimeric capsule held together by means of ionic interactions...

Kobayashi K, Ishii K, Sakamoto S, Shirasaka T, Yamaguchi K (2003) Guest-induced assembly of tetracarboxyl-cavitand and tetra(3-pyridyl)-cavitand into a heterodimeric capsule via hydrogen bonds and CH-halogen and/or CH-n interaction control of the orientation of the encapsulated guest. J Am Chem Soc 125 10615... 

Kobayashi K, Ishii K, Yamanaka M (2005) Orientational isomerism and binding ability of nonsymmetrical guests encapsulated in a self-assembling heterodimeric capsule. Chem Eur J... 

Reinhoudt and co-workers (51) targeted O2 and prepared water-soluble models of heme-protein active sites. These were self-assembling, heterodimeric capsules of cationic Co(II) porphyrin (27) and tetrasulfonato calix[4]arene (28) (Fig. 12). A millipore VMWP membrane, loaded with an aqueous solution of 27 (2 mA/), 28 (6mM), and 1-methyl imidazole (20 mM), showed a facilitated transport of O2. The facilitation factor of 1.15 and the O2/N2 selectivity of... 

Homodimeric hydrogen-bonded capsules have been successfully employed to bind and separate fullerenes (Section 3.1.2). A heterodimeric capsule 32 forms through charge-assisted hydrogen bonding between a carboxylic acid and an amine-appended CTV and encapsulates a number of small neutral guests (Scheme 15). ... 

Figure 15 Hydrogen-bonded heterodimeric capsule featuring orientational isomerism for encapsulated guests.

Figure 16 Hydrogen-bonded heterodimeric capsule featuring slow spinning for encapsulated tetrasubstituted aromatic guests.

Figure 17 Heterodimeric capsule between tetramide cavitand and resorcin[4]arene templated by the presence of suitable guests.

Figure 22 Ionic heterodimeric capsule based on tetraalkylamidinium-calix[4]arene with a tetracarboxylate-calix[4]arene as host for cationic and neutral guests.

Fig. 32.19 Line drawing structure of cavitand units 44, 45 and 46, energy minimized structures of self-assembled homodimeric capsules 47 and 48 and self-assembled heterodimeric capsule 49 and 50. A color code was used for the cavitand core, 44 (green), 45 (blue) and 46 (red)...

Fig. 32.22 Line drawing structure of cavitand units 57 and 58, and self-assembled heterodimeric capsules 59. The energy minimized structure of the encapsulation complex formed by three guests 60 in the cavity of the self-assembled container 59d (57d 58) stabilized by four halogen bond interactions is also shown...

Kataoka K, James TD, Kubo Y (2007) Ion ptiir-driven heterodimeric capsule based on boronate esterification construction and the dynamic behavior. J Am Chem Soc 129 15126-15127... 

The calix[4]arene-based ligand syntones 129-133 with either aryl urea or sulfonylurea fragments on the upper rims in their cone-conformation gave small hydrogen-bonded capsules 338-342 by Scheme 3.24, while their heterodimeric capsules have been exclusively formed when both aryl- and sulfonylureas-containing syntones are present in solution [25]. All these homo- and het-erodi- and tetrameric capsules are able to reversibly encapsulate suitable guests in organic media. 

Valdes C, Spitz UP, Toledo LM, Kubik SW, Rebek J Jr (1995) Synthesis and self-assembly of pseudo-spheiical homo- and heterodimeric capsules. J Am Chem Soc 117(51) 12733-12745... 

Thondorf I, Rudzevich Y, Rudzevich V, Bohmer V (2007) Reasons for the exclusive formation of heterodimeric capsules between tetra-tolyl and tetra-tosylurea calix[4]arenes. Org Biomol Chem 5 2775-2782... 

Simultaneous, multiple ester formation was employed to assemble larger multitopic assemblies. For example, self-assembled molecular capsules via boronate esterification have been demonstrated. Two calix[3]arenes, one having the upper rim functionalized with diols, the other functionalized with boronic acids, were combined in the presence of a templating agent to form the heterodimeric capsule (Fig. 25). Extensive NMR analysis was performed to show that the two calixarenes in solution by themselves do not interact. It is only when tetramethyl ammonium acetate is added that the capsule forms. NMR diffusion studies have further demonstrated that the ammonium cation is included within the cavity. In addition, reversible decomposition-reconstruction of the capsule was observed in response to pH. 

FIGURE 25. Heterodimeric capsules form upon the templated assembly of tris-diol and triboronic acid calixarenes (Reprinted with permission from Ref 57. Copyright 2007 American Chemical Society.)... 

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