Polar host-guest interaction.  Binding of nonionic polar compounds with a resorcinol-aldehyde cyclooligomer as a lipophilic polar host

Aoyama, Yasuhiro; Tanaka, Yasutaka; Toi, Hiroo; Ogoshi, Hisanobu

doi:10.1021/ja00210a073

Cited by 213 publications

(112 citation statements)

References 4 publications

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Section: Introductionmentioning

confidence: 99%

“…1), first introduced by Hö gberg 3 and developed for supramolecular applications by Cram, 4 Aoyama, 5 Reinhoudt, 6 and many others. Resorcinarenes can be synthesized from resorcinol and simple aldehydes in a single step and high yield, 5 and provide a versatile framework for systematic modifications to the headgroup or tailgroups. 6 However, the resorcinarenes' dispersant properties are not necessarily unique: other calixarenes, cyclodextrins, 7 and nonplanar macrocycles with dendritic features may also be developed for nanoparticle encapsulation and self-assembly.…”

Section: Introductionmentioning

confidence: 99%

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Calixarene‐Encapsulated Nanoparticles: Self‐Assembly into Functional Nanomaterials

Wei

2006

ChemInform

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Calixarenes are excellent surfactants for enhancing the dispersion and self-assembly of metal nanoparticles into well-defined structures, particularly those with unit length scales in the 10-100 nm size range. Particles within these ensembles are strongly coupled, giving rise to unique collective optical or magnetic properties. The self-assembled nanostructures described in this feature article include 2D arrays of colloidal Au nanoparticles with size-dependent plasmonic responses, and sub-100 nm Co nanoparticle rings with chiral magnetic states. These nanoparticle assemblies may be further developed for applications in chemical sensing based on surfaceenhanced Raman scattering (SERS) and as binary elements for nonvolatile memory, respectively.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Calixarene‐Encapsulated Nanoparticles: Self‐Assembly into Functional Nanomaterials

Wei

2006

ChemInform

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“…Two signals of hydroxyl protons are observed in the 1 H-NMR spectra of TUresorc [4]arene in C 6 D 6 and CDCl 3 (13,14). The lower-field signal is assigned to the hydroxyl protons forming the intramolecular hydrogen-bonding network and the other upper-field signal is assigned to "free" hydroxyl protons, which are in a nearly free state or in a intermolecular hydrogen-bonded state forming weak molecular assemblies (12). These signals are shifted slightly upfield in CDCl 3 compared with those in C 6 D 6 ; this may be owing to weakened intermolecular hydrogen bonds by a polar effect of CDCl 3 .…”

Section: Measurementsmentioning

confidence: 96%

“…These hydroxyl groups are also involved in the formation of molecular assemblies by making intermolecular hydrogen bonds in nonpolar solvents as shown in Fig. 1 (10)(11)(12). As shown by these examples, the state of the hydroxyl groups has great impact on the properties of resorc [4]arene.…”

Section: Introductionmentioning

confidence: 97%

Hydrogen-bonding Interactions of C-Tetraundecenylresorc[4]arene with Some Guest Molecules

et al. 2006

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“…encapsulation ͉ nanochemistry ͉ self-assembly R esorcinarenes 1 (1) feature a shallow, bowl-like shape that has intrinsic capabilities in molecular recognition (2)(3)(4)(5). Their gentle curvature and electronic properties attract cationic, convex molecules, but when the resorcinarene is deepened through synthesis, size selectivity can be seen and the molecules are regarded as cavitands (6)(7).…”

mentioning

confidence: 99%

Experimental and computational probes of the space in a self-assembled capsule

Ajami

Iwasawa²,

Rebek³

2006

Proc. Natl. Acad. Sci. U.S.A.

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Self-assembled capsules are hosts that recognize and surround smaller molecule guests of appropriate size, shape, and chemical surfaces. The space available inside is a cage of fixed solvent molecules, many of which are aromatic. These aromatics provide anisotropic shielding to guests, and a map of induced magnetic shielding for the inner space can be obtained through nucleusindependent chemical shift calculations. Experimental values of the magnetic environment can be determined by NMR spectra of the guests inside. We describe here the environment in a cylindrical capsule with tapered ends. A series of terminal acetylenes-the narrowest of organic structures-was synthesized and used to probe the magnetic shielding of the capsule's ends. Their NMR spectra showed that the acetylenic hydrogen experiences deshielding as it is forced deeper into the tapered end of the capsule where four benzene rings converge. Modeling and density functional theory calculations provided excellent agreement with the experimental values and established a molecular ruler to explore steric and magnetic environments inside the capsule.encapsulation ͉ nanochemistry ͉ self-assembly R esorcinarenes 1 (1) feature a shallow, bowl-like shape that has intrinsic capabilities in molecular recognition (2-5). Their gentle curvature and electronic properties attract cationic, convex molecules, but when the resorcinarene is deepened through synthesis, size selectivity can be seen and the molecules are regarded as cavitands (6-7). Such cavitands can maintain their conformations through intramolecular hydrogen bonds along the upper rim (8-9), or, when intermolecular hydrogen bonding is possible, the formation of capsules 2.2 can occur (10-12). This capsule presents guests with an electronic environment dominated by the eight benzene rings at each end (13-15). The four aryls at each of the resorcinarene ends impart an intense magnetic anisotropy: proton nuclei held near these ends show upfield shifts of up to 5 ppm in their NMR signals. Here we plot the details of these shifts within 2.2 using special probes (terminal acetylenes) capable of deep insertion. The results provide a test of predictions made by computational methods. Results and DiscussionThe shape and dimensions of the space inside the capsule are shown in Figs. 1 and 2. The calculated values are, inevitably, a function of the graphics software used, and we show results obtained by using GRASP (16). A cross section of the capsule appears in Fig. 2, and the section goes through the para position of two of the benzene rings that make up the tapered ends at the right side of the figure. These ends are hollow square pyramids, and the standard probe indicates a space Ϸ17 Å long from the centroids of the benzenes from one end to the other. But what can fit into these tapered ends? A hydrogen atom of a terminal acetylene is the smallest and narrowest organic substructure we could imagine, so it was selected as a slim probe for the steric and electronic properties of this space.We explored the inner ...

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Polar host-guest interaction. Binding of nonionic polar compounds with a resorcinol-aldehyde cyclooligomer as a lipophilic polar host

Cited by 213 publications

References 4 publications

Calixarene‐Encapsulated Nanoparticles: Self‐Assembly into Functional Nanomaterials

Calixarene‐Encapsulated Nanoparticles: Self‐Assembly into Functional Nanomaterials

Hydrogen-bonding Interactions of C-Tetraundecenylresorc[4]arene with Some Guest Molecules

Experimental and computational probes of the space in a self-assembled capsule

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