bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthesis and Characterization of Polynuclear Chain and Tetranuclear Complexes of Mixed-Valent Ruthenium(II,III) Pivalate with N,N′-Didentate Ligands
Authors: Yoshioka Daisuke , Mikuriya Masahiro , Handa Makoto 
Published: December 2004

Abstract
Polymeric chain complexes, [Ru2(piv)4(pyz)]n(BF4)n·3nH2O (1), [Ru2(piv)4(4,4′-bpy)]n(BF4)n·nH2O (2), [Ru2(piv)4(dabco)]n(BF4)n·2nH2O (3), [Ru2(piv)4(phz)]n(BF4)n (4), and [Ru2(piv)4(H2O)2(tmpyz)]n(BF4)n·nCH2Cl2 (6), (Hpiv = pivalic acid, pyz = pyrazine, 4,4′-bpy = 4,4′-bipyridine, dabco = 1,4-diazabicyclo[2.2.2]octane, phz = phenazine, and tmpyz = tetramethylpyrazine), were synthesized and characterized by elementary analyses, infrared and electronic spectroscopies, and variable-temperature magnetic susceptibilities (4.5–300 K). A tetranuclear complex, [{Ru2(piv)4(H2O)}2(phz)](BF4)2 (5), was also synthesized, and a “dimer of dimers” structure was confirmed by an X-ray structure analysis. The crystal structure of 6 shows that [Ru2(piv)4(H2O)2]+ units are linked by hydrogen bonds with tmpyz molecules, giving zigzag chains with Ru1–O5···N1 angle of 108.1(2)°. A red-shift of the δ*/π*(Ru2) → σ*(Ru–O), and δ(Ru2) → δ*(Ru2) transition bands of the RuII,III2 core was observed in polymeric chain adducts 1–4. All of the present complexes show a very weak antiferromagnetic interaction between the dinuclear units with a considerable zero-field splitting parameter.
Optimal Environment for Maximal Molecular Recognition against Temperature. Three Distinct Patterns in Temperature–Recognition Profiles as a Function of Composition of Aqueous Binary Solvents
Authors: Endo Tadashi , Sugio Keitaro , Kogure Sadahiro , Horikosi Suguru , Tojima Motohiro , Aono Yosihiro , Ito Masato M 
Published: December 2004

Abstract
Oxidation of a pair of associating thiols 1 and 2, each having a binding site [–C(=O)NHC(=O)NH–] and a recognition site (R1 or R2), is examined at various temperatures as a function of mole fraction of water (xw) in aqueous binary solvents with EtOH, CH3CN, and i-PrOH. The selectivity (r) — a measure of the degree of molecular recognition in the oxidation — is represented by the logarithmic ratio of the yield of the unsymmetrical disulfide 4 to twice that of the symmetrical one 3. It is found that three distinct patterns are present in temperature–recognition profiles, depending on composition of the aqueous binary solvents: (1) “progressive decrease” in the lower xw region; (2) “presence of a maximum” in the medium xw region; (3) “progressive increase” in the higher xw region. It is also clarified that aqueous mixed solvents in the medium xw region are indispensable for maximal recognition to occur against temperature (the presence of a maximum in the temperature–selectivity relationship). Dependence of the r on the xw at lower and higher temperatures, presence of three distinct patterns in the temperature–recognition profiles, and so on are discussed in relation to the maximal recognition.
Selective Oxidative Carbonylation of Amines to Oxamides and Ureas Catalyzed by Palladium Complexes
Authors: Hiwatari Kozo , Kayaki Yoshihito , Okita Koshi , Ukai Tomohiro , Shimizu Isao , Yamamoto Akio 
Published: December 2004

Abstract
A new process for converting secondary amines into N,N,N′,N′-tetraalkyloxamides under CO pressure, catalyzed by homogeneous palladium complexes in the presence of 1,4-dichloro-2-butene (DCB) as an oxidant, has been developed. The mechanism of the oxidative double-carbonylation process, consisting of the oxidation of Pd(0) to Pd(II) with DCB through a β-chloride elimination of the η3-(chloromethyl)allylpalladium(II) intermediate, the formation of mono- and bis(carbamoyl)palladium species, and a reductive elimination of the two carbamoyl ligands, is proposed based on studies of the behavior of carbamoylpalladium complexes. When primary amines are employed with DCB as the oxidant, N,N′-dialkyloxamide is catalytically produced, whereas urea is exclusively produced when iodine is used as the oxidant. The reaction of an N-monopropylcarbamoylpalladium complex with propylamine under CO gave N,N′-dipropylurea, whereas a treatment with diethylamine yielded unsymmetrical N,N-diethyl-N′-propylurea, implying the intermediate formation of propyl isocyanate that is converted into the urea upon a reaction with the added amine. A kinetic study on the reaction of chloro-N-propylcarbamoylpalladium with triethylamine suggested a process proceeding through a base-promoted deprotonation of the N-monoalkylcarbamoyl ligand to form propyl isocyanate.
Synthesis of Chroman Derivatives by the Ring Expansion Reaction of Spirodienones, and an Assessment of their Plant Growth Inhibition
Authors: Doi Fuminao , Ohara Taiga , Ogamino Takahisa , Higashinakasu Keiko , Hasegawa Koji , Nishiyama Shigeru 
Published: December 2004

Abstract
Lewis acid-promoted 1,2-shift rearrangement reactions of the spirodienones, generated by the anodic oxidation of phenol derivatives, provided corresponding chromans. In addition to steric repulsion, electron-donating or withdrawing characteristics of the arylic substituents controlled the direction of the rearrangements. The plant growth inhibitory activity of several chroman derivatives was evaluated. In contrast to apparent inhibitions of 21c and 22c against both cress and oat, the selective activity against coleoptile and root of oat was observed in 21a, 21b, and 22d. Interestingly, the regioisomer 22b of 21b showed no activity.
A New Route to 2,4,6-Trisubstituted-6H-1,3-Oxazines
Authors: Kidwai Mazaahir , Thakur Ruby , Mohan Richa 
Published: December 2004

Abstract
The Lewis acid (borontrifluoride etherate) catalyzed novel synthesis of 2,4,6-trisubstituted-6H-1,3-oxazines is described here. Also, a new route towards an environmentally benign synthesis of the title compounds has been developed using montmorillonite K-10 clay as a catalyst under microwave irradiation (MWI). The procedure replaces the Lewis acid, and the products are obtained in a high yield and shorter reaction time.
Halide-Bridged Zigzag Chain of Tetrakis(acetamidato)dirhodium Cationic Radical Assisted by Hydrogen Bond
Authors: Yang Zhiyong , Fujinami Tomoharu , Ebihara Masahiro , Nakajima Kiyohiko , Kitagawa Hiroshi , Kawamura Takashi 
Published: December 2004

Abstract
The reaction of a Rh25+ cationic radical salt, 2,2-cis-[Rh2(acam)4(H2O)2]ClO4 (Hacam = acetamide), with sodium halides in aqueous solution gave crystals of [Rh2(acam)4Cl]n·7nH2O and [Rh2(acam)4Br]n, both of which consist of zigzag chain of (–Rh–Rh–X–)n, which is supported by hydrogen bond between amidato–NH and amidato–O atoms for the chain of the bromide and between O atoms of amidato bridges through interstitial water molecules for the chloride chain.
Synthesis of AlPO4-5 and AlPO4-11 Molecular Sieves by Dry-Gel Conversion Method
Authors: Bandyopadhyay Mahuya , Bandyopadhyay Rajib , Kubota Yoshihiro , Sugi Yoshihiro 
Published: December 2004

Abstract
Synthesis of aluminophosphate molecular sieves AlPO4-5 and AlPO4-11 has been studied by dry-gel conversion method using triethylamine and dipropylamine as structure-directing agents (SDAs), respectively. Amount of SDAs and the bulk water as the source of steam played vital roles during the crystallization. SAPO counterparts of the AlPO4’s were also synthesized by this method.
Electrochemical Detection of Base Pair Mutation
Authors: Yamashita Kenichi , Takagi Makoto , Kondo Hiroki , Takenaka Shigeori 
Published: December 2004

Abstract
An electrochemical method for detecting base pair mutation was devised, which is based on higher affinity of ferrocenyl naphthalene diimide intercalator for (matched) DNA duplex than for (mismatched) single stranded DNA on the electrode surface.
Potential of Zero Charge of a Molybdenum Electrode by Laser Ablation Voltammetry
Authors: Nakamura Kiyoshi , Ohno Masashi , Umemoto Kisaburo , Hinoue Teruo 
Published: December 2004

Abstract
We found that a zero-current potential, ZCP, in the laser ablation voltammogram agreed with a potential at which a differential capacitance component showed a minimum in the corresponding phase-selective ac voltammogram at the Mo electrode in phosphate buffer. This fact suggests that the ZCP is identical with the potential of zero charge (pzc). A pH dependence of the ZCP for the Mo electrode is discussed in terms of specific adsorption of a hydroxide ion.
A High Thermal Stable Light-Emitting Complex Based on a Tridentate Ligand
Authors: Shao Yan , Qiu Yong , Hu Xiaoming , Hong Xiaoying 
Published: December 2004

Abstract
A new complex with a tridentate ligand, (salicylidene-o-aminophenolato)(8-quinolinoato)aluminum (Al(Saph-q)), bearing a high glass transition temperature of 226 °C, shows a strong potential as a stable light-emitting material for organic electroluminescence.
A New and Efficient Method for Oxidation of Various Alcohols by Using N-tert-Butyl Phenylsulfinimidoyl Chloride
Authors: Mukaiyama Teruaki , Matsuo Jun-ichi , Yanagisawa Manabu 
Published: December 2004

Abstract
Various primary and secondary alcohols were smoothly oxidized to afford the corresponding aldehydes and ketones in excellent yields by using N-tert-butyl phenylsulfinimidoyl chloride (1) in the presence of DBU (1,8-diazabicyclo[5.4.0]undec-7-ene). The oxidation of alcohols was carried out in a simple manner by using the isolable oxidizing agent 1 under basic conditions.
Photochemical Bahavior of Zinc(II) Tetraphenylporphyrin in Nanoscale-fibers Made of trans-1,2-Bis(alkylamide)cyclohexane Derivatives
Authors: Kimura Matsumi , Kitamura Takuya , Muto Tsuyoshi , Hanabusa Kenji , Shirai Hirofusa , Kobayashi Nagao 
Published: December 2004

Abstract
A zinc porphyrin dimer, in which two porphyrin moieties were linked with an optically active (1R,2R)-trans-1,2-bis(aklylamide)cyclohexane unit, was incorporated into nanoscale fibers made of organogelators and the fluorescence quenching of zinc porphyrin moieties was diminished by the incorporation.
Control of the Photoisomerization Mode of Carbon–Carbon Double Bond by Intramolecular Hydrogen Bond; One-way Photoisomerization of 2′-Hydroxychalcone Induced by Adiabatic Intramolecular Hydrogen Atom Transfer
Authors: Norikane Yasuo , Itoh Hiroki , Arai Tatsuo 
Published: December 2004

Abstract
To investigate the effect of intramolecular hydrogen bonding on the photoisomerization of carbon–carbon double bond, photoisomerization of 2′-hydroxychalcone has been studied. Based on the quantum yield measurements and laser flash photolysis studies, it was found that 2′-hydroxychalcone isomerized only from cis- to trans-isomer. The one-way cis-trans isomerization is induced by the adiabatic hydrogen atom tranfer in the triplet state.
The Mild Hydrothermal Synthesis of Complex Fluorides of AZnF3 (A = Na, K)
Authors: Li Hong , Jia Zhihong , Shi Chunshan 
Published: December 2004

Abstract
The complex fluorides of AZnF3 (A = Na, K), which are isostructural with perovskite phases were obtained by the method of hydrothermal synthesis at 160–220 °C. Compared with traditional high-temperature solid-state method, the products were pure and contained lower amount of oxygen.
Preparation and Characterization of Mono-Imidazole Ligated (meso-Tetramesitylporphyrinato)iron(III) Complexes: Model for Cytochromes c’
Authors: Ikezaki Akira , Nakamura Mikio 
Published: December 2004

Abstract
A series of mono-imidazole ligated (meso-tetramesitylporphyrinato)iron(III) complexes have been prepared. The spin states of these complexes are presented as the admixed intermediate (S = 3/2, 5/2) on the basis of the 1H NMR, 13C NMR, EPR, and magnetic moments. The S = 3/2 character has increased as the axial imidazole ligand becomes bulkier.
Actinide chemistry: from weapons to remediation to stewardship
Authors: Choppin Gregory R. 
Published: December 2004

SummaryAn integral part of the international conferences on the Chemistry and Migration of Actinides has been the separation science of these elements. Separations involving actinide elements began with the discovery of radioactivity when Crookes reported that addition of carbonate ions to a solution of uranium caused formation of a soluble uranium carbonate complex and of a precipitate which contained most of theβ,γradioactivity. Subsequently, the Curies separated components of pitchblend to isolate the different radioactive elements which led, in 1898, to the discovery of the new element, polonium. The separation method used by these pioneers was precipitation which remained the dominant separation technique for the first 40 years of actinide research. This paper reviews actinide separation science to the present time.
Solubility and colloid formation of Th(IV) in concentrated NaCl and MgCl2solution
Authors: Altmaier M. , Neck Volker , Fanghänel Thomas 
Published: December 2004

SummaryThe solubility of crystalline ThO2(cr) and amorphous hydrated Th(IV) oxyhydroxide ThOn(OH)4-2n·xH2O(am) has been measured in dilute to concentrated NaCl and MgCl2solutions equilibrated with magnesium hydroxide or hydroxychloride at 22±2 °C. The contributions of colloids to the total thorium concentrations observed in both over- and undersaturation experiments with amorphous Th(IV) precipitates have been analysed by ultracentrifugation. The solubility increasing effect of long-time stable Th(IV) eigencolloids, previously investigated in 0.5 M NaCl solutions, is also observed in concentrated 5 M NaCl. Ionic strength and chloride concentration have no effect on the stability of these hydrophilic Th(IV) oxyhydroxide eigencolloids, which are the predominant species in solution. They cause relatively high total thorium concentration in neutral to alkaline steady state solutions, independent of ionic strength: log[Th]tot≈log[Th]coll=-6.3±0.5. In concentrated MgCl2solutions saturated with magnesium hydroxychloride colloids, the formation of pseudocolloids,i.e., Th(IV) sorbed onto Mg2(OH)3Cl·4H2O(coll), leads to a further increase of the total thorium concentration up to 10-5M. The present results are discussed with regard to maximum Th(IV) and Pu(IV) concentrations in performance assessment calculations.
On Mo-Ru-Tc-Pd-Rh-Te alloy particles extracted from spent fuel and their leaching behavior under Ar and H2 atmospheres
Authors: Cui Daqing , Low Jeanett , Sjöstedt Cecilia J. , Spahiu Kastriot 
Published: December 2004

Summary
In the present work, we extracted Mo-Tc-Ru-Pd-Rh-Te alloy particles from spent fuel by a non-oxidative selective leaching of the fuel matrix, characterized them and studied their leaching behavior under different redox conditions. After selecting the optimal experimental conditions by using a synthetic alloy, the radioactive alloy particles were extracted from spent fuel and characterized by using SEM (scanning electron microscopy)-WDS (wavelength dispersive spectra). Micrometer sized alloy particles display very similar compositions, on average (wt.%): 32.7% Mo, 40.5% Ru, 7% Tc, 4.4% Rh, 12.2% Pd and 3.8% Te. The alloy particles were leached in 10 mM NaCl and 2 mM NaHCO3 solutions, purged with two kinds of gas mixtures. It was observed that, under purging with Ar + 0.03% CO2, the leaching rates of 99Tc and 100Mo were similar, about 1.5 ppb/day. The results obtained under purging with 89.97% Ar + 0.03% CO2 + 10% H2 indicate that the 4d alloy particles are very effective catalysts for reduction caused by hydrogen: the concentrations of 99Tc and 100Mo dropped to levels below 1 ppb. No significant leaching of Ru, Rh, Pd and Te was observed during purging with both gas mixtures.
Application of the NICA-Donnan model for proton, copper and uranyl binding to humic acid
Authors: Saito Takumi , Nagasaki S. , Tanaka S. , Koopal L. K. 
Published: December 2004

SummaryHumic acids are natural organic materials that play an important role in the migration of heavy metal and actinide ions in aquatic and soil systems. In the present study, the binding of protons, copper ions and uranyl ions to the purified Aldrich humic acid (PAHA) is investigated and the results are modeled with the Non-Ideal Competitive Adsorption (NICA) model extended with electrostatic interactions according to the Donnan model (NICA-Donnan model). The NICA part of the model enables one to describe the competitive ion binding to a heterogeneous substrate taking into account a different stoichiometry per ion. The NICA-Donnan model can describe the binding of the ions to PAHA in large concentration ranges (3<pH<11; 3<pCu<13; 4<pUO2<18) and over a wide range of environmental conditions (pH, ionic strength). From the model description it follows that the affinity distribution of PAHA is bimodal with about equal numbers of "carboxylic"- (low logKH) and "phenolic"-type (high logKH) sites. The stoichiometry parameters of the binding reactions for copper and uranyl indicate both mono- and bi-dentate binding. Some specific attention is paid to the distribution of the bound uranyl ions over the "carboxylic" and "phenolic"-type sites. Such information is useful for comparison with spectroscopic information on the binding.
The redox behaviour of plutonium in humic rich groundwater
Authors: Marquardt Christian M. , Seibert A. , Artinger Robert , Denecke Melissa A. , Kuczewski B. , Schild D. , Fanghänel Thomas 
Published: December 2004

SummaryExperiments with different oxidation states of Pu in GoHy-532 groundwater under reducing conditions reveal that Pu(VI) and Pu(V) are reduced rapidly to Pu(IV) at pH 7. The half-life of the redox reactions Pu(VI)/(V) and Pu(V)/(IV) are in the range of minutes. The rates of both reduction reactions decrease with decreasing pH values. A portion of the Pu(IV) is not stable in the same groundwater and is reduced slowly to Pu(III) in the range of weeks. Ultrafiltration experiments show Pu to be totally bound to the humic substances in the groundwater. At Pu concentrations of 10-5to 10-4M, most of the Pu occurs as a Pu-colloid and/or Pu-colloid bound to humic substances (Pu-colloid-HS) in solution, which is indicated by EXAFS/XANES and XPS measurements.
Trivalent actinide coprecipitation with powellite (CaMoO4): Secondary solid solution formation during HLW borosilicate-glass dissolution
Authors: Bosbach Dirk , Rabung Thomas , Brandt Felix , Fanghänel Thomas 
Published: December 2004

SummaryPowellite (CaMoO4) is one of the various crystalline secondary alteration phases which form during the corrosion of high level waste (HLW) glasses. Due to their structural variability, powellite can accommodate considerable chemical substitutions including trivalent actinides. Batch adsorption and coprecipitation experiments in mixed flow reactors have been used to study quantitatively the uptake of Cm(III) and Eu(III) (as a nonradioactive chemical homologue for trivalent actinides) from aqueous solution under repository relevant conditions. A metal ion concentration-independentKdof 1200 ml/g has been determined for adsorption above pH 4 up to 3 μmol/L Eu(III). The partition coefficient for coprecipitation varies between 10 and 800 depending on the precipitation rate. Time-resolved laser fluorescence spectroscopy has been used to study the aqueous complexation of Cm(III)/Eu(III) and MoO42-as well as their incorporation into the powellite crystal lattice during coprecipitation. A red shift of the Cm(III) fluorescence emission of the transition indicates the formation of aqueous CmMoO4+(598 nm) and Cm(MoO4)22-(601 nm) complexes. The incorporation of Cm(III) is indicated by a significant red shift. The corresponding lifetime of 165 μs indicates quench effects. A similar behaviour has been observed for Eu(III). The life time of the5D0-7F2transition is 350 μs for an incorporated Eu(III) species, suggesting also intrinsic quench effects, due to the local crystal field or impurities.
Contribution of minerals to the sorption of U(VI) on granite
Authors: Baik M. H. , Hyun S. P. , Cho W. J. , Hahn P. S. 
Published: December 2004

SummaryBatch sorption experiments of U(VI) onto the surfaces of granite rock were carried out. The distribution of the sorbed U(VI) on crushed granite particles was investigatedviaa sequential chemical extraction method to quantify the amount of U(VI) sorbed on the mineral phases and by X-ray diffraction characterization of dried samples of the remaining minerals after each extraction step to determine the significant mineral phases that sorb U(VI). Chlorite among the constituent minerals, even though being present in a small amount, is assumed to contribute to the strong U(VI) sorption and most of the sorbed U(VI) was weakly bound to the granite surfaces. However, a discriminative amount of the sorbed U(VI) on granite particles was difficult to desorb, in particular, when sorption took place in the alkaline region. The distribution of the sorbed U(VI) both on the fresh intact surface and on the natural fracture surface was also investigated by a X-ray image mapping technique. The result shows that dominant minerals hosting the majority of the sorbed uranium are mica for the intact surface of granite and chlorite for the fracture surface of the granite.
Distribution and geochemical association of actinides in a contaminated soil as a function of grain size
Authors: Lee M. H. , Yoon Y. Y. , Clark Sue B. , Glover S. E. 
Published: December 2004

Summary
The distribution of actinides in a contaminated soil as a function of grain size was investigated by determining 239,240Pu, 241Am, and 238U after size fractionation. The soil was contaminated as the result of a fire at a nuclear missile site in the US. In all cases, the activity of each isotope increased with decreasing particle size, although differences were observed for 238U. A simple spherical model was used to represent surface area as a function of grain size. Fitted values for the distributions of 239,240Pu and 241Am by this model correlated well with experimental values, suggesting that their association is a surface sorption phenomenon. Fitted values for 238U did not correlate with measured values, indicating that U association was not strictly a surface mechanism.
To further investigate the partitioning of these isotopes within each size fraction, sequential extractions were performed on the various size fractions. 239,240Pu, 241Am, and 238U are associated with primarily reducible, acid sulfide soluble, and refractory phases, with more total activity associated with the refractory phase for the smaller size fractions. Considering only the final refractory phase for each size fraction, the activity of 238U was greater than 239,240Pu and 241Am. In the context of the behavior of U as a function of grain size, this result suggests that a significant fraction of the U is primordial and incorporated into the refractory matrix, most likely the silicates and refractory clay minerals.
Luminescence properties of tetravalent uranium in aqueous solution
Authors: Kirishima Akira , Kimura Takaumi , Nagaishi Ryuji , Tochiyama Osamu 
Published: December 2004

Summary
The luminescence spectra of U4+ in aqueous solutions were observed in the UV-VIS region at ambient and liquid nitrogen temperatures. The excitation spectrum indicates that the luminescence is arising from the deexcitation of a 5f electron at the 1
S
0 level and no other emissions of U4+ in aqueous solutions were detected for other f–f transitions. All the luminescence peaks were assigned to the transitions from 1
S
0 to lower 5f levels. To estimate the luminescence lifetime, luminescence decay curves were measured using time-resolved laser-induced fluorescence spectroscopy. At room temperature, the decay curve indicated that the lifetime was shorter than 20 ns. On the other hand, the frozen sample of U4+ in aqueous solution at liquid nitrogen temperature showed the same emission spectrum as at room temperature and its lifetime was 149 ns in H2O system and 198 ns in D2O system. The longer lifetime at liquid nitrogen temperature made it possible to measure the spectrum of U4+ at the concentration as low as 10-6 M. The difference in the anion species (ClO4
-, Cl-, SO4
2-) affected the structure of the emission spectrum to some extent.