bluuebunny/crossref_metadata_2025_split huggingface dataset:
Optimization of a Regression Model for a Quantitative Structure. Mutagenicity Relationship of Some Natural Amino Acids
Authors: Kuanar Minati , Mishra Bijay K 
Published: August 2005

Abstract
Multivariate statistical tools, such as principal-component analysis and multiple-regression analysis, were used for a large number of structural and empirical parameters of some eleven natural amino acids for predicting mutagenicity. An optimized regression model was derived from some selective principal components and solubility data. Plots related to the principal components resulted in the ordination of amino acids as well as the structural and empirical parameters.
Rearrangement Approaches to Cyclic Skeletons. XIII. Total Synthesis of Triquinane Sesquiterpenes, (±)-Modhephene, and (±)-Isocomene, on the Basis of Formal Substitution at Both Bridgeheads of a Bicyclo[2.2.2]oct-5-en-2-one
Authors: Uyehara Tadao , Murayama Tomohiro , Sakai Katsunori , Onda Kayoko , Ueno Masako , Sato Toshio 
Published: August 2005

Abstract
A reaction of 1,4-dimethoxybicyclo[2.2.2]oct-5-en-2-one and R1MgX, followed by treatment with p-toluenesulfonic acid in benzene, gave the 5-methoxybicyclo[3.2.1]oct-6-en-2-one having a substituent (R1) at the C-1 bridgehead. This ketone was converted into the 5-methoxybicyclo[3.2.1]oct-3-en-2-one. By treatment with Li[CuR2], a second bridgehead substituent (R) was introduced at the C-4 position of the conjugated ketone. The product was converted into the corresponding α,β-unsaturated ketone, and then treated with R2Li or DIBAL-H (R2 = H). Acid treatment of the resulting allyl alcohols gave the bicyclo[2.2.2]oct-5-en-2-one having substituents R, R1, and R2 at the C-1, 4, and 5 positions, respectively. This procedure was successfully applied to a formal total synthesis of (±)-modhephene, a propellane-type triquinane sesquiterpene, and that of (±)-isocomene, an angular triquinane sesquiterpene, on the basis of an oxa-di-π methane rearrangement of the bicyclo[2.2.2]oct-5-en-2-ones.
Transition Metal-Catalyzed Intramolecular Cyclization of 1,5- and 1,6-Dienes via Direct Cleavage and Addition of the Carbon–Hydrogen Bond
Authors: Fujii Naoaki , Kakiuchi Fumitoshi , Yamada Airi , Chatani Naoto , Murai Shinji 
Published: August 2005

Abstract
Ruthenium- and rhodium-catalyzed intramolecular C–H/olefin coupling reactions of 1-(2-pyridyl)-, 1-(2-imidazolyl)-, and 1-(2-oxazolyl)-1,5-dienes proceeded in a regiospecific manner to give 5-membered ring products. Their 1,6-diene analogues are also applicable to the cyclization reaction to give the corresponding 5- and 6-membered carbocycles. For the cyclization of the pyridine derivatives, [RhCl(PPh3)3] showed the highest catalytic activity with respect to efficiency and selectivity. When the imidazole derivatives were employed to the cyclization reaction, the combination of the rhodium(I) complex and the relatively sterically bulky phosphine (e.g., PCy3 and PPFOMe) was a quite effective catalyst system. In the case of the oxazoles, the ruthenium complex, [Ru(H)2(CO)(PPh3)3], showed the highest activity among the catalysts examined. These catalytic reactions usually proceed at 120 °C. The [RhCl(PPh3)3]-catalyzed cyclization reaction of 2-[(1E)-4,4-dimethyl-1,5-hexadienyl]pyridine smoothly proceeded even at room temperature to give the corresponding cyclized product in 93% yield after 24 h. A hybrid catalyst system containing the rhodium(I) and both PPh3 and P(o-tolyl)3 had a slightly better catalytic activity compared with that of [RhCl(PPh3)3]. The intramolecular cyclization can be also applied to the C–H/CO/olefin coupling reactions. These carbonylation reactions gave the 5-membered ring ketones exclusively. The intramolecular C–H/olefin coupling reactions provide a new entry for constructing carbocyclic compounds from 1,n-dienes.
Electronic Transitions of Ternary Copper(II) Naphthalenediolate Complexes
Authors: Yamada Yasunori , Hasegawa Miki , Kobayashi Michio , Fukuda Yutaka , Hoshi Toshihiko 
Published: August 2005

Abstract
The electronic structure and nature of the electronic transitions of copper(II) naphthalenediolate complexes, (2,2′-bipyridine) (2,3-naphthalenediolato) copper(II) ([Cu(ndo)(bpy)]) and (2,3-naphthalenediolato) (1,10-phenanthroline) copper(II) ([Cu(ndo)(phen)]), have been studied from the viewpoints of the polarization spectra and MO theory. The 339.0 and 296 nm bands of [Cu(ndo)(phen)] have been assigned to localized transitions of the naphthalenediolate (ndo) skeleton, and the 308, 275, and 269 nm bands on the phenanthroline (phen) skeleton. It has been clarified experimentally that the 400 nm band can be assigned to the CT transition between ndo and Cu(II). The total state wavefunctions show that the 293 and 282 nm bands are due to the intramolecular interligand CT (LL′CT) transitions from ndo to phen, thus indicating that the two π-electronic systems, separated by the central metal ion, can directly interact. The complex [Cu(ndo)(bpy)] shows the electronic transitions at 339.0, 256.0, 245, 238, and 210 nm localized on ndo, and at 315, 295, and 264 nm localized on the bipyridine (bpy) moiety. The 400 nm band of [Cu(ndo)(bpy)] is due to the intramolecular CT transition between ndo and Cu(II). In the case of [Cu(ndo)(bpy)], the LL′CT transition is not observed.
Infrared Spectroscopic Observation of Intermediate Species on Ni and Fe Electrodes in the Electrochemical Reduction of CO2 and CO to Hydrocarbons
Authors: Koga Osamu , Matsuo Tadanori , Yamazaki Hiroki , Hori Yoshio 
Published: August 2005

Abstract
Adsorbed species on Ni and Fe electrodes were investigated by in-situ infrared spectroscopy in the electrochemical reduction of CO2 or CO. Two types of adsorbed CO on the Ni electrode and one type on the Fe electrode were detected in a CO atmosphere. The two types, assigned to linear and bridged CO molecules, were also formed on the Ni electrode in CO2 reduction. The negative polarization decreased the coverage of the adsorbed CO on Ni. The decay rate constants were evaluated from the spectroscopic data; the rate constant for the linear type was three times higher than that for the bridge one. Both constants agreed well with those determined from the formation rate of hydrocarbons in CO reduction, confirming that both adsorbed CO molecules were intermediate species to hydrocarbons. The high electrocatalytic activity of Cu in hydrocarbon formation from CO2 and CO was rationalized in terms of the adsorption strength of CO on metals by comparing the activity of Ni, Fe, and Cu electrodes with the infrared bands of adsorbed CO on these electrodes. The weaker adsorption of CO on Cu led to higher activity.
Solid-State Photodimerization of Methyl (RS)-1-Phenyl-2-piperidinoethyl (RS)-1,4-Dihydro-2,6-dimethyl-4-(2-thiazolyl)pyridine-3,5-dicarboxylate Hydrochloride Controlled by the Buffer Zone
Authors: Marubayashi Nobuhiro , Ogawa Takayuki , Hirayama Noriaki 
Published: August 2005

Abstract
The solid-state photodimerization of three polymorphic crystal forms (forms I, II, and III) of a bulky olefin, methyl (RS)-1-phenyl-2-piperidinoethyl (RS)-1,4-dihydro-2,6-dimethyl-4-(2-thiazolyl)pyridine-3,5-dicarboxylate hydrochloride, was studied. Forms I and II are anhydrous crystals and form III is an isomorphous hydrate of form II. X-Ray analyses of these forms showed that forms II and III have the same geometrical characteristics suggesting high susceptibility to photodimerization according to the well-known topochemical rule. Although UV irradiation of from II affords a photodimer, 4a,8a-dimethoxycarbonyl-2,4b,6,8b-tetramethyl-3-[(RS)-1-phenyl-2-piperidinoethoxycarbonyl]-7-[(SR)-1-phenyl-2-piperidinoethoxycarbonyl]-(4RS,8SR)-4,8-di(2-thiazolyl)-1,4,4a,4b,5,8,8a,8b-octahydro-cis-transoid-4a,4b-cis-cyclobuta[1,2-b : 3,4-b′]dipyridine, in high yield, the photolysis of form III proceeds much more slowly than that of form II. A detailed inspection of the crystal structures revealed that there is a space to afford the mobility of molecules for dimerization in form II, whereas the space is occupied by the incorporated water molecule in form III. We have previously proposed that a buffer zone, which is a space in the crystal structure, controls the photodimerization of bulky olefins. The present study demonstrates that the buffer zone is an essential controlling factor for the solid-state photodimerization of bulky olefins.
Electronic Structure and UV Absorption Spectra of 2-Pyridylacetylenes: An Intramolecular Orbital Interaction between the n Orbital on the Nitrogen Atom of the Pyridine Ring and the In-plane π Orbital of the Ethynylene Group
Authors: Okubo Jun , Shinozaki Hiraku , Koitabashi Toshiyuki , Yomura Ryo 
Published: August 2005

Abstract
The UV absorption spectra of some pyridylacetylenes were measured in various media at room temperature and 77 K, and the origin of the electronic absorption bands of these compounds was clarified compared with the results of MO calculations. For instance, it has been found that the 304.6, 271.7, 221, and 216 nm bands of 1-(2-pyridyl)-2-phenylethyne in cyclohexane can be assigned to the calculated S1 ← S0, S5 ← S0, S9 ← S0, and S10 ← S0 transitions, respectively, in which the observed 271.7 nm band (S5 ← S0) is ascribed as a new type transition from the n orbital on the aza-nitrogen atom of the pyridine ring to the in-plane π* orbital on the sp-carbon atoms of the ethynylene group. Furthermore, it is revealed that the observed 259.6 nm band of 1,2-di(2-pyridyl)ethyne (D2PE) can also be assigned to a new type of transition caused by weak interactions between the n orbitals and the in-plane π orbital of the ethynylene group. This result indicates that two n orbitals of the terminal pyridine rings of D2PE may interact with each other via the central in-plane π orbital.
Temperature Effect on the Depolarization Degree of the Raman Active Totally Symmetric Vibrations of Some Benzene Derivatives Belonging to Point Groups D6h and D3h
Authors: Yumura Tetsuji , Koga Makoto , Hoshikawa Hironori , Nibu Yoshinori , Shimada Ryoichi , Shimada Hiroko 
Published: August 2005

Abstract
The temperature effect on the depolarization degree of the Raman bands of the totally symmetric vibrations of some benzene derivatives belonging to point groups D6h and D3h was studied. In these molecules a direct field due to incident light gives rise to an intrinsic depolarization, and an indirect field causes by dipoles induced in the surrounding molecules by the incident light gives rise to depolarization due to intermolecular interactions. It was observed that although the depolarization degree increases with increasing temperature for all vibrational modes, the relationship between the temperature and depolarization degree is different, depending on the vibrational modes as well as the substituents. These observations are qualitatively explained by a change in the intermolecular interaction due to thermal fluctuations of the intermolecular distance caused by molecular vibrations.
Effect of Copper(I) on Hydrogenase Activity from Desulfovibrio vulgaris (Miyazaki)
Authors: Kamachi Toshiaki , Okura Ichiro 
Published: August 2005

Abstract
Effect of copper ion on the activity of the hydrogenase from Desulfovibrio vulgaris (Miyazaki) was studied. When the hydrogenase was incubated with Cu(II) ion, the hydrogenase activity did not change. The hydrogenase activity was inhibited when the hydrogenase was incubated with copper ion in the presence of sodium ascorbate, suggesting the effect of Cu(I) ion. ESR studies indicate that the signal intensity attributed to [3Fe–4S] cluster decreased with decreasing the activity. Copper contents of hydrogenase increased, but the contents of iron and nickel did not change. Results obtained demonstrate that incorporated Cu(I) affects the hydrogenase a activity by the perturbation of [3Fe–4S] cluster.
A Thermolytic Azulene Synthesis from Dimethyl 4-Morpholino-3,3a,8,8a-tetrahydroazulene-5,6-dicarboxylates and Its 1-Substituted Derivatives
Authors: Kuroda Shigeyasu , Hirooka Syuzi , Oda Mitsunori , Iwaki Hiroyuki , Teranishi Syuki , Matsushita Noriko , Hongou Tamotsu , Ikeda Mariko , Hayashi Syuichi , Miyatake Ryuta , Izawa Mayumi , Yamada (the late) Masaki , Shimao Ichiro 
Published: August 2005

Abstract
The thermolysis of 1-substituted 4-morpholino-3,3a,8,8a-tetrahydroazulene-5,6-dicarboxylates derivatives (7a—c) under catalytic dehydrogenation conditions was studied. The reaction substrates were prepared by a several-step sequence involving the [2+2] cycloaddition of bicyclc morpholino enamines with dimethyl acetylenedicarboxylate, and a subsequent electrocyclic opening of the cyclobutene ring as a key skeletal construction, starting from bicyclo[3.3.0]octane-2,6-dione mono(ethylene acetal). Refluxing of a diphenyl ether solution of dimethyl 4-morpholino-3,3a,8,8a-tetrahydroazulene-5,6-dicarboxylate (7a) containing a catalytic amount of Pd–C gave a 10% yield of dimethyl azulene-5,6-dicarboxylate (8a), accompanied by a 10% yield of dimethyl azulene-4,6-dicarboxylate (9a), trace amounts of dimethyl azulene-5,7-dicarboxylate (10a), methyl azulene-5-carboxylate (12a), and methyl azulene-6-carboxylate (13a). Under the same thermolytic conditions, a 1-phenyl-substituted compound 7b gave corresponding similar types of phenyl-substituted azulenes (8b, 9b, 10b, 11b, and 14b), and a 1-cyano-substituted compound 7c gave a mixture of corresponding similar types of cyano-substituted azulenes (8c, 9c, 10c, and 11c). This sequence provides a new method for synthesizing substituted azulenes suffering from migration and removal of one ester group. Also the thermolysis of a similar system of dimethyl 3-(1-pyrrolidinyl)-2,7-cycloheptadiene-1,2-dicarboxylate (15), even in the absence of a catalyst, gave cycloheptatriene derivatives of dimethyl 1,3,5-cycloheptatriene-dicarboxylate (16, 17, 18, and 19), bearing no morpholine molecule.
Palladium-Catalyzed Arylation of Azole Compounds with Aryl Halides in the Presence of Alkali Metal Carbonates and the Use of Copper Iodide in the Reaction
Authors: Pivsa-Art Sommai , Satoh Tetsuya , Kawamura Yoshiki , Miura Masahiro , Nomura Masakatsu 
Published: August 2005

Abstract
The reactions of iodobenzene with azole compounds, 1,2-disubstituted imidazoles and 2-substituted oxazoles and thiazoles, were examined in the presence of catalytic amounts of Pd(OAc)2 and PPh3 in DMF using alkali metal carbonates as bases. It was found that the coupling products, 5-arylazoles, could be selectively produced in good yields by using Cs2CO3. In the case that their 2-position is unsubstituted, the site could also be arylated. In reactions using bromobenzene in place of iodobenzene, K2CO3 was also as effective as Cs2CO3. The addition of a stoichiometric amount of CuI appeared to specifically promote the reactions of thiazoles as well as those of thiophene derivatives. The reactions of 2-unsubstituted azole compounds with aryl iodides could be mediated by CuI to some extent without using the palladium species to give 2-arylazoles.
Preparations of Furans from α-Bromo Ketones and Enol Ethers Catalyzed by a Rhenium(I) Nitrogen Complex
Authors: Koga Yuji , Kusama Hiroyuki , Narasaka Koichi 
Published: August 2005

Abstract
By the catalytic use of a rhenium(I) nitrogen complex, [ReCl(N2)(PMe2Ph)4], α-keto radicals are generated from α-bromo ketones and react with vinyl ethers and silyl enol ethers intermolecularly. Various substituted furans, including tetrasubstituted furans such as furoguaiacin, are prepared by this method.
Norbornadiene-Fused Heterocycles: Synthesis of 5,8-Dihydro-5,8-methanophthalazines and Regioselective Ring Cleavage and Skeletal Rearrangement of 6,7-Epoxy-5,6,7,8-tetrahydro-5,8-methanophthalazine 2-Oxides in Trifluoroacetic Acid
Authors: Kobayashi Tomoshige , Sugawara Hideki , Nikaeen Behrooz 
Published: August 2005

Abstract
5,8-Dihydro-5,8-methanophthalazine, prepared by the reaction of bicyclo[2.2.1]hepta-2,5-diene-2,3-dicarbaldehyde with hydrazine, reacted with MCPBA to give an N-oxide. Further oxidation with MCPBA afforded the corresponding exo-6,7-epoxy derivative. Treatments of the epoxide and its diphenyl-substituted derivative with trifluoroacetic acid gave 6,9-bis(trifluoroacetoxy) derivatives by a regioselective ring-opening of the oxirane, accompanied by Wagner–Meerwein rearrangement. The bis(trifluoroacetoxy) derivatives were converted to the corresponding diols for elucidation of their regio- and stereochemistry.
Electrochemical Lithium Intercalation within Carbonaceous Materials: Intercalation Processes, Surface Film Formation, and Lithium Diffusion
Authors: Ogumi Zempachi , Inaba Minoru 
Published: August 2005

Abstract
Electrochemical lithium intercalation within carbonaceous materials has attracted much attention for use to produce anodes in rechargeable lithium batteries. Although small-size rechargeable lithium cells using carbon anodes have been already commercialized, there still remain a lot of problems to be solved. Furthermore, recent global environmental issues require carbon anodes with high energy densities for use in electric energy storage and electric vehicles in the near future. This review article covers recent topics of the lithium intercalation, focusing on three fundamental aspects: intercalation processes, surface film formation, and lithium diffusion within carbons.
Some Theoretical Considerations Concerning Ion Hydration in the Case of Ion Transfer between Water and 1,2-Dichloroethane
Authors: Sánchez C , Leiva E , Dassie S A , Baruzzi A M 
Published: August 2005

Abstract
Some aspects of direct ion transfer across water/1,2-dichloroethane have been analyzed using a very simple model based on thermodynamic considerations. It was concluded that ion solvation by water molecules may occur in some particular cases in the organic phase, delivering an important contribution to the Gibbs free energy of ion transfer between the aqueous and the organic phase. In general terms, this particular type of transfer should be favored in the case of highly charged small ions at interfaces with a relatively low surface tension and a large difference between the reciprocal of the corresponding dielectric constants.
Catalytic Reforming of Methane with Carbon Dioxide on LaBO3 (B = Co, Ni, Fe, Cr) Catalysts
Authors: Wu Yunying , Kawaguchi Osamu , Matsuda Tsuneo 
Published: August 2005

Abstract
The reforming reactions of CH4 with CO2 diluted with He on perovskite structural oxides, LaBO3 (B = Co, Ni, Fe, Cr), were examined. The reaction activity at 1073 K followed the order LaCoO3 &gt; LaNiO3 &gt; LaFeO3 &gt; LaCrO3, and the highest selectivities to CO and H2 were obtained on a LaCoO3 catalyst. The reaction on the LaCoO3 catalyst under the reaction condition of CH4/CO2 = 1 showed a H2/CO ratio of 1; the ratio was less than 1 on other catalysts. In the initial stage of the reactions of CH4 + CO2 on LaCoO3 and LaNiO3 catalysts, an induction period accompanying the reduction of the catalysts was observed. During the reforming reaction, both the LaCoO3 and LaNiO3 catalysts were decomposed by reduction to Co to Ni metal and La2O3. No induction period, however, was observed in the reaction on the LaFeO3 and LaCrO3 catalysts, which were stable during the reaction. The high activity of the decomposed LaCoO3 catalyst is ascribed here —as a result of EPMA, SEM analysis and of comparison with the reaction behaviors of Co catalysts supported on La2O3 — to the high concentration of metallic cobalt uniformly dispersed as fine particles on the catalyst surface. The reaction mechanism on the cobalt metal was inferred from the results of the reaction of CH4 or CO2 alone on the decomposed LaCoO3 catalyst.
Kinetics and Mechanisms of Hydrogen Peroxide Disproportionation Catalyzed by Mononuclear Schiff Base Manganese(III) Complexes: Effects of Chelate and Hydroxide Ion on Hydrogen Peroxide Disproportionation in N,N-Dimethylformamide
Authors: Uehara Minori , Urade Mika , Abe Yuriko 
Published: August 2005

Abstract
The preparation of [Mn(saltnOCOPh)Cl]·DMF (H2saltnOCOPh: N,N′-(2-benzoyloxypropane-1,3-diyl)bis(salicylideneamine)) and kinetics and mechanisms of H2O2 disproportionation catalyzed by mononuclear Schiff base manganese(III) complexes, such as [Mn(salen)Cl] (H2salen: N,N′-ethylenebis(salicylideneamine)), [Mn(saltn)Cl] (H2saltn: N,N′-propane-1,3-diylbis(salicylideneamine)), [Mn(saltnOH)Cl] (H2saltnOH: N,N′-(2-hydroxypropane-1,3-diyl)bis(salicylideneamine)), and [Mn(saltnOCOPh)Cl] in N,N-dimethylformamide (DMF), have been investigated. The disproportionation of H2O2 to O2 and H2O proceeds coupled with the redox cycle between the Mn(III) complex and the Mn(IV) intermediate: the first step is the fast equilibrium (Km) of the Mn(III) complex and the Mn(IV) intermediate formed by the reaction of the Mn(III) complex with H2O2, followed by a slow reaction (k1) of the Mn(IV) intermediate with H2O2 to produce O2 and H2O recovering the original Mn(III) complex. The Km values decrease in the following order: [Mn(salen)Cl] (728 mol−1 dm3) &gt;&gt; [Mn(saltnOH)Cl] (28.0 mol−1 dm3) &gt; [Mn(saltn)Cl] (6.28 mol−1 dm3) &gt; [Mn(saltnOCOPh)Cl] (1.83 mol−1 dm3), reflecting an increased distortion along the axis containing the coordination of H2O2 to the Mn(III) complex. On the other hand, the rate constants (k1) fall into the following sequences: [Mn(saltnOH)Cl] (4.29 × 105 mol−2 dm6 s−1) &gt; [Mn(salen)Cl] (1.67 × 105 mol−2 dm6 s−1) &gt; [Mn(saltnOCOPh)Cl] (3.34 × 104mol−2 dm6 s−1) &gt; [Mn(salen)Cl] (6.15 × 103 mol−2 dm6 s−1). In spite of the small Km values for saltnOH, saltnOCOPh, and saltn complexes with the 1,3-diamine ligand, compared to that for the salen complex, the large k1 value for the saltnOH complex strongly suggests stabilization of the transition state for the formation of hydrogen-bondings among the Mn(IV) intermediates and H2O2. Futhermore, the effect of the OH− ion on the H2O2 disproportionation catalyzed by [Mn(salen)Cl] has been reported. On account of the formation of [Mn(salen)OH] coordinated by the OH− ion, the appearance of the reaction path involving not only the Mn(III)–Mn(IV) cycle, but also the Mn(II)–Mn(III) cycle, is shown based on the ESR and visible spectral studies. The activity for the Mn(II)–Mn(III) cycle is 20 times larger than that for the Mn(III)–Mn(IV) cycle.
Determination of Ultratrace Gallium in River Water by Electrothermal Atomic Absorption Spectrometry after Preconcentration with Solvent Extraction and Back Extraction
Authors: Kawaguchi Hiroshi , Shimizu Tokuo , Shirakashi Takashi , Shijo Yoshio 
Published: August 2005

Abstract
A method for the determination of gallium at ng dm−3 levels in river water is described. Gallium is extracted into carbon tetrachloride as an ion pair of gallium–5-sulfo-8-quinolinol (H2QS) chelate anion with tetradecyldimethylbenzylammonium chloride (Zephiramine), and subsequently back-extracted into 0.3 cm3 of a nitric acid solution. The high efficiency of extraction and back extraction allows gallium to be concentrated about 5000-fold with a combined single extraction and back extraction. The back-extracted solution, containing 250 μg cm−3 of nickel as a matrix modifier, is suitable for the determination of gallium by electrothermal atomic absorption spectrometry (ETAAS). The detection limit (3σ) for gallium is 0.29 ng dm−3 based on a 1500-fold preconcentration. The concentration of dissolved gallium in river water was found to be 5.3—9.2 ng dm−3 by the proposed method.
Calix[4]arene-Modified Oligosiloxane as a Quasi-Immobilized Neutral Carrier for Silicone-Rubber-Membrane Sodium Ion-Selective Electrodes
Authors: Kimura Keiichi , Tsujimura Yutaka , Yokoyama Masaaki , Maeda Takumi 
Published: August 2005

Abstract
An oligo(dimethylsiloxane) carrying ionophorous calix[4]arene moieties at the side chain was synthesized as a Na+ neutral carrier for highly durable silicone-rubber membranes of ion-selective electrodes by reacting calix[4]arene tetraallyl ester with an oligo(methylsiloxane). This medium-molecular-weight calix[4]arene ionophore alleviated the drawback of chemically-modified calixarene-based silicone-rubber membranes, such as a high membrane impedance and a slow electrode response.