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Calix
Kinds of Calix Selected AbstractsDetermination of Trace Amounts of Copper in Tap Water Samples with a Calix[4]arene Modified Carbon Paste Electrode by Differential Pulse Anodic Stripping VoltammetryELECTROANALYSIS, Issue 10 2007Çelik Canpolat Abstract A calix[4]arene modified carbon paste electrode was used for trace determination of copper. The study of the preconcentration of copper as well as the other heavy metal ions at the modified electrode, with subsequent measurement by differential pulse anodic stripping voltammetry (DPASV), indicates the efficient open-circuit accumulation of the analytes onto the electrode. Many parameters such as the composition of the paste, pH, preconcentration time and stirring rate influence the response of the measurement. The procedure was optimized for copper determination. For a 10-minute preconcentration time at pH,6.5,7.5, the detection limit (LOD) was 1.1,,g L,1. The optimized method was successfully applied to the determination of copper in tap water sample by means of standard addition procedure. The copper content of the sample was comparable with the result obtained with AAS method. [source] Electrocatalysis and Voltammetric Determination of Dopamine at a Calix[4]arene Crown-4 Ether Modified Glassy Carbon ElectrodeELECTROANALYSIS, Issue 4 2007Guo-Song Lai Abstract A sensitive and selective electrochemical method for the determination of dopamine (DA) was developed using a calix[4]arene crown-4 ether (CACE) film modified glassy carbon electrode (GCE). The modified electrode exhibited good electrocatalytic activity for electrochemical oxidation of DA in the pH,6.00 Britton,Robinson buffer solution, and ascorbic acid (AA) did not interfere with it. The diffusion coefficient (D=2.7×10,5,cm2 s,1), and the kinetic parameter such as the electron transfer coefficient (,=0.54) of DA at the surface of CACE were determined using electrochemical approaches. The catalytic oxidation peak currents showed a linear dependence on the DA concentration and a linear analytical curve was obtained in the range of 2.0×10,5,1.0×10,3,M of DA with a correlation coefficient of 0.9990. The detection limit (S/N=3) was estimated to be 3.4×10,6,M. This method was also examined for the determination of DA in an injection sample. In addition, effects of possible interferences were investigated. The present work shows the potential of the proposed method for the fabrication of a modified electrode, as it can be effectively used for voltammetric detection of DA. [source] Silver(I)-Selective PVC Membrane Potentiometric Sensor Based on a Recently Synthesized Calix[4]areneELECTROANALYSIS, Issue 10 2006Ayça Demirel Abstract A new PVC membrane potentiometric sensor for Ag(I) ion based on a recently synthesized calix[4]arene compound of 5,11,17,23-tetra- tert -butyl-25,27-dihydroxy-calix[4]arene-thiacrown-4 is developed. The electrode exhibits a Nernstian response for Ag(I) ions over a wide concentration range (1.0×10,2,1.0×10,6 M) with a slope of 53.8±1.6,mV per decade. It has a relatively fast response time (5,10,s) and can be used for at least 2 months without any considerable divergence in potentials. The proposed electrode shows high selectivity towards Ag+ ions over Pb2+, Cd2+, Co2+, Zn2+, Cu2+, Ni2+, Sr2+, Mg2+, Ca2+, Li+, K+, Na+, NH4+ ions and can be used in a pH range of 2,6. Only interference of Hg2+ is found. It is successfully used as an indicator electrode in potentiometric titration of a mixture of chloride, bromide and iodide ions. [source] Soft Metal Ion-Selective Electrodes Based on ,-Coordinate Calixarene DerivativesELECTROANALYSIS, Issue 15-16 2003Setsuko Yajima Abstract Calix[4]arene derivatives incorporating ,-unsaturated alkenyl groups or saturated alkyl groups and their monomeric analogues were used as ,-coordinate neutral carriers for ion-selective electrodes (ISEs) of soft metals [silver and thallium(I)] ions. The EMF responses were excellent for most of the ISEs, among which there was no significant difference in the response. The ion selectivities of the ISEs depend on the structure of neutral carriers employed. 1H NMR study explains the difference in the ion selectivity. In the metal-ion complexation by the ,-coordinate calixarene derivatives, thallium ion is likely to interact with the calixarene skeleton, while silver ion tends to interact with both of the calixarene skeleton and the ,-unsaturated alkenyl groups. [source] Funnel Complexes with CoII and NiII: New Probes into the Biomimetic Coordination Ability of the Calix[6]arene-Based Tris(imidazole) SystemEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 9 2004Olivier Sénèque Abstract The coordination properties of the calix[6]arene-based tris(imidazole) ligand X6Me3Imme3 were further explored with CoII and NiII. This imidazole system stabilizes tetrahedral mononuclear CoII complexes with an exchangeable fourth exogenous ligand (water, alcohol, amide) located at the heart of the hydrophobic calixarene cavity. With a weak donor ligand such as a nitrile, both four-coordinate tetrahedral and five-coordinate trigonal bipyramidal complexes were obtained. The latter contains a second nitrile molecule trans to the included guest nitrile. These complexes were characterized in solution as well as in the solid state. The NiII complexes are square-based pyramidal five-coordinate edifices with a guest nitrile inside the cavity and a water molecule outside. A comparison with previously described ZnII and CuII complexes emphasizes the flexibility of this ligand. A comparison with carbonic anhydrase, a mononuclear zinc enzyme with a tris(histidine) coordination core, shows that X6Me3Imme3 displays many structural features of this enzyme except for the cis coordination of the exogenous ligands. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004) [source] A Bifunctional Chromogenic Calix[4]arene Chemosensor for Both Cations and Anions: A Potential Ca2+ and F, Switched INHIBIT Logic Gate with a YES Logic FunctionEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 24 2010Kai-Chi Chang Abstract A bifunctional chromogenic calix[4]arene 3, which contains both triazoles and hydroxy azophenols as both cationic and anionic recognition sites and the azophenol moiety as a coloration unit, was designed and synthesized. The recognition of Ca2+ by 3 gave rise to a marked colour change from greenish to bright yellow, whereas the recognition of F, by 3 showed a colour change from light green to bluish. The colour changes of 3 by the inputs of Ca2+ and F, have been implemented to construct a combinational logic circuit at the molecular level. [source] Synthesis of an Inherently Chiral Calix[4]arene Amino Acid and Its Derivatives: Their Application to Asymmetric Reactions as OrganocatalystsEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 12 2009Seiji Shirakawa Abstract The synthesis of an inherently chiral calix[4]arene amino acid as a chiral building block has been achieved in order for subsequent transformation to various types of inherently chiral calix[4]arenes. The optically pure, inherently chiral calix[4]arene amino acids were prepared by the separation of a diastereomeric mixture of calix[4]arene amino acid derivatives bearing a (R)-BINOL moiety. The separated optically pure calix[4]arene amino acid derivatives with a (R)-BINOL moiety were easily transformed to novel inherently chiral calix[4]arenes containing an amino alcohol structure or a quaternary ammonium moiety. These optically pure chiral calix[4]arenes were applied to asymmetric reactions as organocatalysts.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source] Oligophenylcalix[4]arenes as Potential Precursors for Funnelenes and Calix[4]triphenylenes: Syntheses and Preliminary Cyclodehydration StudiesEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 21 2006Michael Mastalerz Abstract The concept for a new class of nonplanar polyaromatic hydrocarbons , the funnelenes , is presented. Retrosynthetic considerations lead to polyphenyl- and oligophenylcalix[4]arenes as potential precursors. In this paper we describe the synthesis of these calixarenes and the first cyclodehydration studies on a model compound which leads to a hexabenzocoronene derivative. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source] Calix[4]arene-Based Chromogenic Chemosensor for the ,-Phenylglycine Anion: Synthesis and Chiral RecognitionEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 6 2006Guang-Yan Qing Abstract Calix[4]arene-based two-armed chiral anion receptors 3a and 3b have been synthesized and examined for their chiral anion-binding abilities by UV/Vis absorption and 1H NMR spectroscopy. The results of nonlinear curve fitting indicate that 3a and 3b form 1:1 stoichiometric complexes with the L - or D -,-phenylglycine anion by multiple hydrogen-bonding interactions and exhibit good enantioselective recognition for the enantiomers of the ,-phenylglycine anions (3a: Kass(L)/Kass(D) = 4.76; 3b: Kass(D)/Kass(L) = 2.84). The marked colour changes observed for the complexation of 3a with the chiral anions and the good enantioselective recognition reveal that receptor 3a could be used as a good chiral chromogenic chemosensor for the enantiomers of the ,-phenylglycine anion. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source] Novel Chiral (Salen)MnIII Complexes Containing a Calix[4]arene Unit as Catalysts for Enantioselective Epoxidation Reactions of (Z)-Aryl AlkenesEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 16 2005Maria E. Amato Abstract New asymmetric (salen)MnIII and UO2 complexes containing a calix[4]arene unit in the ligand framework were synthesized. The UO2 complexes were characterized by 1H-, 13C-, 2D TOCSY and T-ROESY NMR spectroscopy. Furthermore, the structure of one UO2 complex was determined by single-crystal X-ray analysis. The data showed that UO2 complexes, which can be considered in first approximation models of the Mn=O oxidant active species, possess a chiral pocket and adopt relevant conformations for the selectivity of the oxygen transfer process. Epoxidation data of model alkenes with the MnIII complexes showed moderate ee values and were not conclusive in indicating that the calix[4]arene unit might be able to influence the selectivity by a molecular recognition mechanism. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source] Synthesis and Conformation Analysis of New Perphosphorylated Calix[4]resorcinarenesEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 23 2004Vera I. Maslennikova Abstract The octaphosphorylation of calix[4]resorcinarenes 1 by 2-dialkylamino-1,3,2-diheterophosphorinanes 2 is described, and the effect of different factors on the structures of the resulting perphosphorylated products 3,5 was studied. Conformation analysis of these compounds by correlated 2D NMR spectroscopy and X-ray diffraction analysis was performed, and it was found that compounds 3,5, like the initial resorcinarenes 1, each have the all - cis configuration of the R groups in the methylidene bridges of the calixarene system, but different orientations of benzene rings and phosphorinane fragments with respect to one another and to the macrocycle plane. Perphosphorylated resorcinarenes 3a,c, 4a and 5a with R = alkyl exist in flattened cone conformations with the phosphorinane fragments on the same side of the macrocycle plane. The conformations of the perphosphorylated resorcinarenes 3d, 4b and 5b with R = Ph change to forms intermediate between flattened cone and 1,3 - alternate. The phosphorus fragments in these compounds are located on opposite sides of the macrocycle plane. It was shown that the oxidation and sulfurisation of phosphocalixarenes 3 proceed without any change in the spatial organisation of the macrocyclic system. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004) [source] A Fast Access to Non-Symmetrically Substituted 1,3-Alternate Conformers of Calix[4]arenesEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 13 2004Arjan W. Kleij Abstract A simple and direct protocol is reported for the synthesis of the first non-symmetrically substituted 1,3-alternate conformers of calix[4]arenes by selective mono-deacylation of a tribenzoyl precursor under basic conditions, followed by dialkylation. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004) [source] Micellar Effects in Olefin Hydroformylation Catalysed by Neutral, Calix[4]arene-Diphosphite Rhodium ComplexesADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 10 2009Laure Monnereau Abstract The combination of calixarene-derived surfactants and neutral rhodium complexes containing a hemispherical "1,3-calix-diphosphite" ligand led to efficient catalysts for the hydroformylation of octene and other olefins in water. While the surfactants allowed the formation of micelles that dissolve both the catalyst and the alkene, thereby resulting in high olefin:rhodium ratios, the diphosphite provided a tight envelope about the catalytic centre able to drive the reaction towards the linear aldehydes. Best results in the hydroformylation of 1-octene were obtained when using [tetra(p -sulfonato)]-(tetra- n -butoxy)-calix[4]arene as surfactant. With this additive remarkable linear to branched aldehyde ratios of up to 62 were obtained, the corresponding activities being higher than those observed when operating in an organic solvent [turnover frequencies (TOFs) up to 630 mol(converted 1-octene), mol(Rh),1,h,1]. [source] Efficient, Nickel-Catalysed Kumada,Tamao,Corriu Cross- Coupling with a Calix[4]arene-Diphosphine LigandADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 9 2009Laure Monnereau Abstract The dynamic complex cis - P,P,-(,5 -cyclopentadienyl)-{5,17-bis(diphenylphosphino)-25,26,27, 28-tetrabenzyloxycalix[4]arene}nickel(II) tetrafluoroborate (2) in which the PNiP plane undergoes a rapid fanning motion was assessed in the cross-coupling reacting between phenylmagnesium bromide (PhMgBr) and aryl halides (ArX). TOFs, of up to 21250 mol(converted ArBr),mol(2),1,h,1, were obtained with electron-rich as well as congested bromoarenes using catalyst loadings as low as 1×10,3,mol%, provided that the reactions were carried out at 100,°C in dioxane with a PhMgBr/ArX ratio of 2:1. The high activities observed contrast with those observed for triphenylphosphine-based catalysts and furthermore, outperforms the fastest diphosphine-based catalysts reported, a behaviour which is likely to rely on a bite angle effect. [source] Chromatographic partitioning of cesium by a macroporous silica-calix[4]arene-crown supramolecular recognition compositeAICHE JOURNAL, Issue 10 2010Anyun Zhang Abstract A macroporous silica-based 1,3-[(2,4-diethyl-heptylethoxy)oxy]-2,4-crown-6-calix[4]arene (Calix[4]arene-R14) supramolecular recognition polymeric composite, (Calix[4]+Oct)/SiO2 -P, was synthesized. It was performed by impregnating and immobilizing Calix[4]arene-R14 and n -octanol into the pores of the macroporous SiO2 -P particles support. n -Octanol was used to modify Calix[4]arene-R14 through hydrogen bonding. The effect of eight typical fission products contained in highly active liquid waste (HLW) on the adsorption of Cs(I), one of the heat generators, was investigated at 298 K by examining the effect of contact time and the HNO3 concentration in a range of 0.3,7.0 M. (Calix[4]+Oct)/SiO2 -P showed excellent adsorption ability and high selectivity for Cs(I) at 4.0 M HNO3 over the tested elements. The partitioning of Cs(I) from a simulated HLW was operated by (Calix[4]+Oct)/SiO2 -P packed column. Cs(I) was able to be effectively eluted by water and separated from the tested metals. It is demonstrated that (Calix[4]+Oct)/SiO2 -P is promising to apply in chromatographic separation of Cs(I) from HLW. © 2010 American Institute of Chemical Engineers AIChE J, 2010 [source] Synthesis and Characterization of Amphiphilic Star-Shaped Polymers With Calix[6]arene CoresMACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 9 2006Weipu Zhu Abstract Summary: The syntheses and characterizations of well-defined star-shaped amphiphilic polymers containing a hydrophobic p - tert -butyl-calix[6]arene core and six hydrophilic PPO or PPO- b -PDTC arms are described. The average number of PO units in each arm could be adjusted by choosing a suitable amount of raw material. Schematic structure of the amphiphilic star-shaped block copolymer containing a hydrophobic p - tert -butyl-calix[6]arene core and six PPO- b -PDTC arms. [source] A Calix[4]arene 3d/4f Magnetic Cooler,ANGEWANDTE CHEMIE, Issue 52 2009Georgios Karotsis Gut gekühlt: Der erste auf Calix[4]arenen basierende 3d/4f-Cluster (siehe Bild; violett,Mn, braun,Gd, rot,O, blau,N) hat eine hohe magnetische Isotropie und viele molekulare Spinzustände, die selbst bei niedriger Temperatur besetzt sind, während sein ferromagnetisches Limit erst bei hohem angelegtem Feld erreicht wird. Diese Eigenschaften machen ihn zu einem ausgezeichneten magnetischen Kühlmittel für Niedertemperaturanwendungen. [source] Calix[4]arene-Based Single-Molecule Magnets,ANGEWANDTE CHEMIE, Issue 44 2009Georgios Karotsis Schützende Haut: Einzelmolekülmagnete (SMMs), die durch zwei Calix[4]arene geschützt sind, wurden synthetisiert (siehe Bild: Mn violett, O rot, N blau, C grau). Das Calixaren isoliert die SMMs, und durch Modifizieren seines oberen Randes können die Abstände zwischen den Schichten und damit die Festkörperpackung verändert werden. [source] Trimeric Cyclic Assemblies of Calix[4]arene-Tethered Bismerocyanines,ANGEWANDTE CHEMIE, Issue 33 2009Andreas Lohr Dr. Ein cyclischer Komplex aus drei Calixaren-Bismerocyanin-Konjugaten entsteht durch Paarung der Chromophore (siehe Bild). Die Bildung der Trimere wird mit einem einfachen mathematischen Modell beschrieben, und das Potenzial der Aggregation von dipolaren Merocyanin-Farbstoffen als gerichtetes und spezifisches supramolekulares Bindungsmotiv wird aufgezeigt. (Calixarene: grün; Merocyanine: C,hellblau, N,dunkelblau, O,rot). [source] ChemInform Abstract: 1,2,3-Triazole-Strapped Calix[4]pyrrole: A New Membrane Transporter for Chloride.CHEMINFORM, Issue 42 2009Matthew G. Fisher Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] ChemInform Abstract: Synthesis of Novel Calix[4]arenocrowns via Ring-Closing Metathesis.CHEMINFORM, Issue 5 2009Lin-Gang Lu Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] ChemInform Abstract: Synthesis of Calix[4]arene,Crown-6 with Alkoxysilyl-Containing Substituents.CHEMINFORM, Issue 50 2008E. A. Alekseeva Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] ChemInform Abstract: Novel Pyrene-Armed Calix[4]arenes Through Triazole Connection: Ratiometric Fluorescent Chemosensor for Zn2+ and Promising Structure for Integrated Logic Gates.CHEMINFORM, Issue 49 2008Lin-Na Zhu Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] ChemInform Abstract: Synthesis of Novel Heterocyclic Calixarenes via the Diels,Alder Reaction of Calix[4]bis(spirodienones).CHEMINFORM, Issue 46 2008V. B. Ganga Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] ChemInform Abstract: Calix[n]arene Sulfonic Acids Bearing Pendant Aliphatic Chains as Recyclable Surfactant-Type Broensted Acid Catalysts for Allylic Alkylation with Allyl Alcohols in Water.CHEMINFORM, Issue 45 2008Yu-Liang Liu Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] ChemInform Abstract: Calix[4]arenes with Siloxanes Bridging Opposite RingsCHEMINFORM, Issue 1 2008Paul F. Hudrlik Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] Self-Assembly via Ionic Interactions of Calix[6]arene-Based Receptors Displaying Remarkable Host,Guest Properties Toward Neutral Guests.CHEMINFORM, Issue 49 2007Stephane Le Gac Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source] 1,3-Alternate Calix[4]arene Nitronyl Nitroxide Tetraradical and Diradical: Synthesis, X-Ray Crystallography, Paramagnetic NMR Spectroscopy, EPR Spectroscopy, and Magnetic Studies.CHEMINFORM, Issue 49 2007Andrzej Rajca Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source] Calix[6]arene Derivatives Selectively Functionalized at Alternate Sites on the Smaller Rim with 2-Phenylpyridine and 2-Fluorenylpyridine Substituents to Provide Deep Cavities.CHEMINFORM, Issue 14 2007Xianshun Zeng Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source] Fullerene Encapsulation with Calix[5]arenes.CHEMINFORM, Issue 18 2006Takeharu Haino Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source] | |||||||||||||||||||||||||||||||