- Synthesis and investigation of catalytic affinities of water-soluble amphiphilic calix[n]arene surfactants in the coupling reaction of some heteroaromatic compounds
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Six water-soluble calix[n]arene-based Br?nsted acid-type catalysts with amphiphilic groups were successfully synthesized by incorporating sulfonic acid moieties. Their structures were characterized using FTIR,1H NMR,13C NMR, APT-NMR, and elemental analysis techniques. Moreover, their catalytic capabilities were evaluated in the coupling reaction of 2-methylfuran and/or N-methylindole with some sec-alcohols in aqueous media. The association of their surfactant abilities, and the effects of water amount used and reaction durations on the catalytic activities of these amphiphilic calix[n]arene derivatives were also investigated. Observations indicated that these amphiphilic calix[n]arene catalysts exhibited high catalytic activities in the coupling reactions of 2-methylfuran and N-methylindole with some alcohols in water.
- Sayin, Serkan,Yilmaz, Mustafa
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supporting information
p. 6528 - 6535
(2016/09/23)
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- Br?nsted acidic magnetic nano-Fe3O4-adorned calix[n]arene sulfonic acids: Synthesis and application in the nucleophilic substitution of alcohols
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Three magnetically recoverable Br?nsted acidic calix[n]arene derivatives were successfully constructed by immobilizing calix[n]arene sulfonic acids onto silica-coated magnetic nanoparticles, a process, which allows calix[n]arene derivatives to acquire magnetic properties. All of the magnetically recoverable Br?nsted acidic calix[n]arenes efficiently catalyze the coupling of electron-rich arenes with some alcohols in water. After separation and recovery from the reaction mixture by a simple magnet, these Br?nsted acidic calix[n]arenes can be recycled many times without losing their catalytic activity.
- Sayin, Serkan,Yilmaz, Mustafa
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p. 6669 - 6676
(2015/03/30)
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- Calixarene-based surfactants: Evidence of structural reorganization upon micellization
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The self-aggregation of five amphiphilic p-sulfonatocalix[n]arenes bearing alkyl chains at the lower rim was investigated by NMR spectroscopy and electrical conductivity. The critical micelle concentration was determined, and the tendency of this special class of surfactants to self-aggregate in aqueous solution was analyzed as a function of the alkyl chain length and the number of aromatic units in the macrocyclic ring. The structure of the surfactants in the monomeric and micellized states was elucidated by means of 1H NMR and, in the case of the calix[6]arene derivative, with 2D NMR experiments. While all amphiphilic calix[4]arenes studied here are blocked in the cone conformation, in the monomeric state the calix[6]arene adopts a pseudo-1,2,3-alternate conformation and the calix[8]arene is conformationally mobile. These calixarenes undergo an aggregation-induced conformational change, adopting the cone conformation in the micelles. The structure and size of the aggregates were studied by diffusion ordered spectroscopy (DOSY) experiments, and the results indicate that these surfactants self-assemble into ellipsoidal micelles.
- Basiilio, Nuno,Garcia-Rio, Luis,Martiin-Pastor, Manuel
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body text
p. 2404 - 2414
(2012/06/30)
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- Calix-arene silver nanoparticles interactions with surfactants are charge, size and critical micellar concentration dependent
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The interactions of silver nanoparticles capped by various calix[n]arenes bearing sulphonate groups at the para and/or phenolic faces with cationic, neutral and anionic surfactants have been studied. Changes in the plasmonic absorption show that only the calix[4]arene derivatives sulphonated at the para-position interact and then only with cationic surfactants. The interactions follow the CMC values of the surfactants either as simple molecules or mixed micelles.
- Tauran, Yannick,Brioude, Arnaud,Shahgaldian, Patrick,Cumbo, Alessandro,Kim, Beomjoon,Perret, Florent,Coleman, Anthony W.,Montasser, Imed
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supporting information
p. 9483 - 9485
(2012/11/06)
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- Complexation of the basic amino acids lysine and arginine by three sulfonatocalix[n]arenes (n = 4, 6 and 8) in water: Microcalorimetric determination of the Gibbs energies, enthalpies and entropies of complexation
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The complexes formed between three p-sulfonatocalix[n]arenes (n = 4, 6 and 8) and the amino acids lysine and arginine in water have been studied by microcalorimetry, at 298.15 K. For each system, both the apparent association constant and enthalpy of reaction have been extracted from the calorimetric data. The Gibbs energies, enthalpies and entropies of complexation have been determined both in acidic medium (pH 1) and in slightly basic medium (pH 8). The thermodynamic parameters for the complexation of arginine markedly differ from those for the complexation of lysine. The three hosts show very different thermodynamic behaviours. Our results are consistent with the formation of 1:1 complexes with the calix[4]arenesulfonate and the calix[6]arenesulfonate and with the formation of 1:1 and 1:2 complexes with the calix[8]arenesulfonate. Whereas the calix[4]arenesulfonate forms relatively strong complexes, the calix[6]arenesulfonate and the calix[8]arenesulfonate form only weak complexes. In all cases, the complexation is driven by a favourable enthalpy change. The enthalpies and entropies of complexing of arginine by the calix[6]arenesulfonate are remarkably negative. The enthalpies and entropies of complexation of the two amino acids by the cyclic tetramer and by the cyclic hexamer become more negative when the pH is changed from 8 to 1; the same effect is observed upon binding of the cyclic octamer with the first guest whereas the opposite effect is observed upon addition of the second guest.
- Douteau-Guevel, Nathalie,Coleman, Anthony W.,Morel, Jean-Pierre,Morel-Desrosiers, Nicole
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p. 629 - 633
(2007/10/03)
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- New Syntheses of Calixarene-p-sulphonates and p-Nitrocalixarenes
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Calixarene-p-sulphonates (tetramer, hexamer, and octamer) have been prepared (75-88percent) and used to give p-nitrocalixarenes (15-22percent yields based on the starting calixarenes).The novel nitration has two advatages: (i) calixarenes are protected from nitric acid oxidation by the electron-withdrawing sulphonate groups and (ii) the difference in the water-solubility of the p-nitrocalixarenes from the sulphonate-containing, lower nitration products, allows ready isolation of the former.The p-nitrocalixarenes thus obtained have potential as intermediates in the synthesis of a variety of functionalised calixarenes.
- Shinkai, Seiji,Araki, Koji,Tsubaki, Takayuki,Arimura, Takashi,Manabe, Osamu
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p. 2297 - 2300
(2007/10/02)
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