- Tetrakis(phenylamidinium)-substituted resorcin[4]arene receptors for the complexation of dicarboxylates and phosphates in protic solvents
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Three bowl-type cavitand receptors (1-3), consisting of a resorcin[4]arene core with four convergent phenylamidinium groups, were prepared in gram quantities by efficient synthetic routes (Schemes 1 and 2) for the recognition of organic anions in CD3
- Sebo, Lubomir,Diederich, Francois,Gramlich, Volker
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- Trifluoromethanesulfonic acid-catalyzed synthesis of resorcinarenes: Cyclocondensation of 2-bromoresorcinol with aldehydes
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The resorcin[4]arenes bearing bromine substituents on their extraannular positions were directly prepared from 2-bromoresorcinol with aldehydes by trifluoromethanesulfonic acid-catalyzed cyclocondensation. In each case, a single stereoisomer was isolated. The main factors for the determination of the products are the reversibility of the C-C bond formation and the difference in the solubility of the isomers.
- Morikawa, Osamu,Ueno, Ryoji,Nakajima, Kazuki,Kobayashi, Kazuhiro,Konishi, Hisatoshi
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- Closed-surface hexameric metal-organic nanocapsules derived from cavitand ligands
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Assembly of cavitand ligands, 14-, and Zn2+ ions yields a one-dimensional polymer comprised of hexameric, closed-surface, metal-organic nanocapsules. The Royal Society of Chemistry.
- Ugono, Onome,Moran, Jason P.,Holman, K. Travis
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p. 1404 - 1406
(2008/12/21)
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- Guest release and capture by hemicarcerands introduces the phenomonen of constructive binding
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Two rigidly hemispherical cavitands containing three out of four phenolic hydroxyl regularly on their rims were shell by their with of CH2BrCl and K2CO3 in (CH3)2NCHO, (CH3)2NCOCH3, or (CH3)2SO to give 1·(CH3)2NCHO (20%), 1·(CH3)2NCOCH3 (42%), or 1·(CH3)2SO (51%), respectively. The crystal structure of 1·(CH3)2NCHO·2CH 3CN·2CHCl3 shows the (CH3)2NCHO guest to be firmly within the cavity, the other molecules acting as solvates. The guest's carbonyl group is pointed toward the portal connecting the inner and outer phases. Upon heating in solvents too large to occupy the cavity, these complexes released their guests to give free hemicarcerand 1. The t1/2 for decomplexation in 1,2,4-Cl3C6H3 at 140°C for 1·(CH3)2NCHO and 1·(CH3)2NCOCH2 were 14 and 34 h, respectively, and for 1·(CH3)2SO at 195°C, 24 h. When 1 was dissolved in the of small molecules such as CH3CN, CS2, CH2Cl2, or CH2Br2, new hemicarcerands 1·CH3CN, 1·CS2, 1·CH2Cl2, and 1·CH2Br2, respectively, were formed, isolated, and characterized. Complexes 1·O2, 1·N2, 1·H2O, and 1·Xe in CDCl3 solution were prepared and detected by the effect of on the 1H NMR of the host. Only 1·Xe was kinetically stable and subject to isolation and characterization. The association of 1 with N2 in CDCl3 at 22°C was estimated to be ~180 M-1, with O2 to be ~ 44 M-1, and with Xe to be ~200 M-1. The t1/2 value for 1·Xe dissociating in CDCl3 at 22°C was 47 h. Formation of 1·C6H6, 1·(CH2)4O, and 1middot;C5H5N of refluxing 1 in as solvent, and to 80, 100, and 100% completion, respectively. Heating 1 in a 5:1 solution of C6H5Cl-Et2NH at 65°C (4 h) a 70% conversion to 1·Et2NH. Heating 1 in 4:1 of C6H5Cl-CH3(CH2)3NH 2 at 105°C (24 h) gave a 90% conversion to 1·CH3(CH2)3NH2. No hemicarceplexes were when 1 was at in CHCl3, C6H5Cl, C6H5CH3, (CH3)2CHC6H5, or 1,2,4-Cl3C6H3. The 1H signal of incarcerated were moved upfield by 1-4 while the 129Xe signal of 1·Xe was moved upfield 101 ppm compared to free in CDCl3. We the term constructive binding to describe the steric forces that must be overcome for decomptexation of hemicarceplexes whose cross sectional sizes exceed those of the host's portals.
- Cram, Donald J.,Tanner, Martin E.,Knobler, Carolyn B.
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p. 7717 - 7727
(2007/10/02)
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- Guest Capture during Shell Closure1a-c
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The preparation and properties of seven new carceplexes 1-7 of general structure H·G are reported in which H is an enforced closed-shell molecule (carcerand) composed of linked anisyl moities to which are attached pendant R groups required to impart solubility to the complexes. The guest molecules (G) are incarcerated in the enforced hollow interior of the hosts: 1, R = CH2CH2C6H5 and G = CH3OH·HOCH3; 2, R = CH2CH2C6H5 and G = CH3CN·NCCH3; 3, R = CH2CH2C6H5 and G = CH3CN; 4, R = (CH2)4CH3 and G = (CH3)2NCHO; 5, R = (CH2)4CH3 and G = CH3CH2OH; 6, R = (CH2)4CH3 and G = CH3COCH2CH3; and 7, R = (CH2)4CH3 and G = CH3CH2COCH2CH3. The complexes were all thermally stable except that H·CH3CN·NCCH3 when heated gave H·CH3CN plus CH3CN. The critical shell-closing reactions used to prepare 1-7 involved a 4-fold substitution in which four CH2Cl groups attached to the rim of a cavitand reacted with a second cavitand with four CH2SH groups attached to its rim. The M2CO3-catalyzed reactions were run in solvents whose molecules fitted well into the interiors of the carcerands on the basis of an inspection of Corey-Pauling-Koltun (CPK) molecular models. The nonpolar complexes were purified by chromatography. The yields were high for the 4-fold reactions: 1, 22%; 2 + 3 mixture, 25%; 4, 20%; 5, 20%; 6, 32%; and 7, 23%. No shell closure occurred with benzene as solvent. When conducted in benzene-alcohol or benzene-acetonitrile, only the more polar component was incarcerated. All carceplexes except 2 gave strong molecular ions in their desorption chemical ionization mass spectra (DCI MS) ((CH3)3CH was the reagent gas), in both their positive and negative ion modes. The proton signals of the guests in 1-7 occurred 1-4 ppm upfield in their 1H NMR spectra in CDCl3, while the chemical shifts of the inward-turned protons of the OCH2O groups of the hosts were guest-sensitive. The 1H NMR spectra of 1 and 3-5 indicated that the guests rotated about both the C2 and C4 axes of the host rapidly on the 1H NMR time scales (360 and 500 MHz). The spectrum of 6 indicates the long axis of the CH3COCH2CH3 guest is aligned with the C4 axis of the host and rotates around this axis rapidly, but not about the shorter C2 axes.
- Bryant, Judi A.,Blanda, Michael T.,Vincenti, Marco,Cram, Donald J.
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p. 2167 - 2172
(2007/10/02)
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- Syntheses and Properties of Soluble Carceplexes
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The syntheses and characterizations of three soluble carceplexes (1-G, where G is guest) are reported. Carcerands are noncollapsible molecular cells whose interiors are large enough to contain molecules or ions (guests) and whose closed surfaces contain p
- Sherman, John C.,Knobler, Carolyn B.,Cram, Donald J.
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p. 2194 - 2204
(2007/10/02)
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