bluuebunny/crossref_metadata_2025_split huggingface dataset:
Preparation, Structure, and Characterization of a Novel Diphosphoheptadecatungstate Complex, [(P2O7)W17O51]4−
Authors: Himeno Sadayuki , Katsuta Tadashi , Takamoto Masayo , Hashimoto Masato 
Published: January 2006

Abstract
A novel diphosphoheptadecatungstate complex, [(P2O7)W17O51]4− was prepared from a 200 mM (M = mol dm−3) W(VI)–10 mM P2O74−–0.6 M HCl–40% (v/v) CH3CN system, and characterized by IR, UV–vis, 31P NMR, and 183W NMR spectroscopy, and voltammetry. Single-crystal X-ray analysis was made on [(C2H5)4N]4[(P2O7)W17O51]·CH3CN, which crystallized in the monoclinic space group P21/n, with cell parameters a = 16.1877(8), b = 22.103(1), c = 22.670(1) Å, β = 90.847(1)°, V = 8110.3(7) Å3, and Z = 4. The anion consists of a PW8O31 fragment derived from a β-Keggin-type [PW12O40]3− structure, and two PW8O31 units are linked by five oxygen atoms and a WO5 square pyramid. The [(P2O7)W17O51]4− anion exhibited a four-step reversible one-electron redox wave in CH3CN, and a three-step two-electron redox wave resulted in the presence of acid. This is the first example of an electrochemically-active diphosphotungstate complex.
Comparison of Basicity of the Diimine and Quinoid Group of 1,10-Phenanthroline-5,6-dione Ligated on Pt(II)
Authors: Okamura Rei , Fujihara Tetsuaki , Wada Tohru , Tanaka Koji 
Published: January 2006

Abstract
A platinum(II) complex bearing 1,10-phenanthroline-5,6-dione (phenO2), [PtCl(phenO2-N,N′)(PPh3)]+ ([2]+) was newly prepared and characterized. An X-ray crystallographic study of [2](PF6) revealed that the phenO2 ligand coordinates to platinum with the N,N′-chelate form. The basicity of the quinoid part of phenO2 in [2]+ and of the diimine one in [Pt(phenO2-O,O′)(PPh3)2] with an O,O′-chelate ring (3) was evaluated in the absence and the presence of Li+ by means of UV–vis spectroscopy and cyclic voltammetry. The quinoid group in [2]+ practically had no ability to bind Li+, but induced on anodic potential shift of the phenO2 localized redox potential by 850 mV due to the strong interaction between the reduced form of [2]+ and Li+. Undeniably, a weak interaction of Li+ with the diimine moiety of free phenO2 (K = 3.6 M−1) is greatly enhanced in the interaction between Li+ and the diimine site in 3 because of the electron donation from the catecholato group of the complex.
Steric and Electronic Effects of Substituents on Planar Nickel(II) Complexes: Synthesis, NMR Spectral and Single Crystal X-ray Structural Studies on Nickel(II) Dithiocarbamates with NiS2PN, NiS2PC, and NiS2P2 Chromophores
Authors: Arul Prakasam Balasubramaniam , Ramalingam Kuppukkannu , Bocelli Gabriele , Cantoni Andrea 
Published: January 2006

Abstract
Four new dithiocarbamatonickel(II) complexes [Ni(dchdtc)(NCS)(PPh3)] (1), [Ni(dchdtc)(CN)(PPh3)] (2), [Ni(dchdtc)(PPh3)2]ClO4 (3), and [Ni(dchdtc)(dppe)]ClO4 (4) (dchdtc = N,N-dicyclohexyldithiocarbamate anion, PPh3 = triphenylphosphine, and dppe = 1,2-bis(diphenylphosphino)ethane) were prepared from the parent [Ni(dchdtc)2]. All four complexes were analyzed by CV, UV–vis, IR, and NMR (1H, 13C, and 31P) spectra. 13C NMR spectra of the complexes (1–4) show the most notable &gt;13CS2 signals at around 200 ppm. In the cyclohexyl ring, the α-CH carbon is deshielded to a greater extent on complexation. Extraordinary deshielding was observed for the 31P signal in all of the cases, indicating the effective bonding of phosphorus to the metal center. Single crystal X-ray structural analysis of the mixed ligand complexes (1–3) indicates a decrease in S–Ni–S bite angle when compared to that of the parent bis(dithiocarbamate), due to an increase in steric crowding around the central metal by the introduction of a bulky PPh3. The trans effects on Ni–S bonds can be arranged in the following order: NCS− &lt; PPh3 &lt; CN−. The S23, (1.306(3) Å), because of the steric effect exerted by two PPh3 groups and dchdtc. The observed negative reduction potentials follow the order: 1 &gt; 2 &gt; 3, indicating the presence of a higher relative electron density on 1 compared to 2 and 3.&lt; bond is very short for complex
Structural Characterization of Copper(I) Complexes Supported by β-Diketiminate Ligands with Different Substitution Patterns
Authors: Shimokawa Chizu , Tachi Yoshimitsu , Nishiwaki Nagatoshi , Ariga Masahiro , Itoh Shinobu 
Published: January 2006

Abstract
Copper(I) complexes generated by using a series of β-diketiminate ligands (R1,R2LR3−, [(R3)N–C(R2)–C(R1)–C(R2)–N(R3)]−, see Chart 1; “β-diketiminate” denotes enaminone imine analogs) have been structurally characterized by X-ray crystallographic analysis. In the α-nitro-ligand system (R1 = NO2 and R2 = H), the structure of the resulting products were largely affected by the nitrogen substituent R3, providing bis(β-diketiminato)copper(II) complex 1 [a product of the disproportionation reaction of copper(I)] (R3 = Ph), head-to-tail linear coordination polymer copper(I) complex 2 (R3 = Mes, (mesityl)), and mononuclear copper(I) complex 3 (R3 = Dipp (2,6-diisopropylphenyl)). On the other hand, α-cyano-ligand (R1 = CN and R2 = H or Me) always gave head-to-tail coordination polymer copper(I) complexes (4–8) regardless of the aromatic substituent R3. In both systems, β-diketiminate ligands exhibited a U-shaped closed conformation, forming a six-membered chelate ring with copper(I). Copper(I) complexes with a β-diketiminate ligand with a W-shaped open conformation were also obtained in the case of α-methyl and α-hydrogen derivatives (R1 = Me or H, R2 = H, and R3 = Dipp). In these cases, the dinuclear and tetranuclear copper(I) macrocyclic complexes 9 and 10 were obtained.
Intermolecular Association Model of Antifungal Polyene Macrolide via Concerted =C–H···O Interactions: X-ray Crystal Structure Analysis and Ab Initio Molecular-Orbital Calculations of Chainin
Authors: In Yasuko , Ohishi Hirofumi , Miyagawa Hiroo , Kitamura Kunihiro , Igarashi Yasuhiro , Ishida Toshimasa 
Published: January 2006

Abstract
The absolute configuration of chainin (1), a polyene macrolide antibiotic, was determined by X-ray crystal analyses, and the conformational stability of planar 28-membered ring was confirmed by an ab initio quantum chemical calculation. The most prominent feature observed in the crystal structure was the concerted =C–H···O interactions formed between four conjugated olefinic CH groups and five hydroxyl oxygen atoms of neighboring molecules. The character of the interaction was investigated by IR measurements and quantum chemical calculations, leading to the conclusion that these concerted interactions are powerful enough to form defined intermolecular association of polyene macrolide. Characteristically, this intermolecular association mode allows the proposal of a barrel-stave assembly, comprising eight parallel or antiparallel pairs of 1 via =C–H···O interactions, which serves as a possible ion-permeable membrane channel structure of polyene macrolide, which may be responsible for the antifungal activity in cell membranes.
Total Synthesis, Structural Revision, and Biological Evaluation of Calafianin, a Marine Spiroisoxazoline from the Sponge, Aplysina gerardogreeni
Authors: Ogamino Takahisa , Obata Rika , Tomoda Hiroshi , Nishiyama Shigeru 
Published: January 2006

Abstract
The reported structure of the natural calafianin (1) and its isomer in the epoxide region 13 were successfully synthesized through the cis- and trans-spiroisoxazoline compounds, which were produced by electrochemical oxidation of the hydroxyimino-phenol derivative 7, followed by Zn[BH4]2 reduction. Comparison of the spectroscopic data of the synthetic (±)-1 and (±)-13 resulted in structural revision of the natural calafianin to 13, possessing the trans-relationship between an epoxide and an oxygen of the isoxazoline. In addition, a significant difference of antimicrobial activity between 1 and 13 is discussed.
CsOH·H2O Promoted Areneselenenylation of Aryl Bromides and Iodides
Authors: Varala Ravi , Ramu Enugala , Adapa Srinivas R 
Published: January 2006

Abstract
We report a transition metal-free synthetic protocol for the cross-coupling reaction of aryl bromides and aryl iodides and diphenyl diselenide (Ph2Se2) using CsOH·H2O as a base in DMSO at 110 °C. Using this protocol, we show that a variety of diaryl selenides can be synthesized in moderate to good yields.
Direct and Convenient Synthesis of [Bis(trifluoroacetoxy)iodo]arenes from Iodoarenes
Authors: Hossain Md Delwar , Kitamura Tsugio 
Published: January 2006

Abstract
An easy, safe, and effective method for preparing [bis(trifluoroacetoxy)iodo]arenes, ArI(OCOCF3)2, in high yields from some iodoarenes are reported, using a K2S2O8/CF3COOH/CH2Cl2 system. This procedure avoids the use of high temperature and severe reaction conditions.
Decomposition of Chlorobenzene over Phosphate and Sulfate Catalysts Properties
Authors: Takita Yusaku , Sadatomi Yoshitaka , Nishiguchi Hiroyasu , Nagaoka Katsutoshi 
Published: January 2006

Abstract
The catalytic conversion of chlorobenzene (CB) over some metal phosphates and sulfate was studied in the presence of water vapor and oxygen. The conversion of CB proceeded in the order of AlPO4, Zr3(PO4)4, CePO4–AlPO4, and La2(SO3)3 above 673 K. The major products were CO, CO2, and HCl. The reaction proceeded in the absence of water vapor; however, the activity was greatly reduced in the absence of oxygen. Even in the presence of oxygen, 30 mol % of water vapor inhibited the reaction. No intermediate hydration products were observed. There was no correlation between each of the catalytic activity, the acidity, and the concentration of the surface hydroxys of the catalysts. These results suggest that the essential reaction for CB conversion is oxidation. The specific surface area (SSA) of the catalysts was not changed during the CB conversion.
Nano-Tribological Study on the Smoothness of Writing with a Ball-Point Pen Using Friction Force Microscopy
Authors: Okuo Hiroyasu , Asahi Toru , Onoue Takahiro , Osaka Tetsuya 
Published: January 2006

Abstract
The relationship between human sensation experienced in the use of a material and its physical properties was investigated for the case of writing with a ball-point pen containing water-based ink. Friction force microscopy (FFM) and a writing tester were used to measure friction in nano- and macro-scale, respectively, and their results were correlated with the smoothness of the act of writing. FFM allowed the determination of the optimum concentration of a specific lubricant to be incorporated in the ink to minimize the wear of the bearing material, although no significant relationship was observed with the writing tester. The nano-tribological measurements by FFM provide a significant means to understand the relationship between materials and the smoothness of the act of writing.
Improvement of Electrochemical Capability of Sputtered Silicon Film Anode for Rechargeable Lithium Batteries
Authors: Komaba Shinichi , Mikami Fuminobu , Itabashi Tatsuya , Baba Mamoru , Ueno Taku , Kumagai Naoaki 
Published: January 2006

Abstract
To improve the electrochemical properties of the silicon film anode in lithium cells, we prepared three types of silicon based-films, i.e., intrinsic silicon, n-type silicon, and Ag10Si90 binary films using r.f. magnetron sputtering. Based on galvanostatic charge–discharge tests and a.c. impedance measurements, the n-type silicon film and Ag10Si90 binary film cells exhibited a superior cycle life and lower electrochemical resistance compared with the intrinsic silicon film cell. The potential variation in the electrochemical alloying/de-alloying reactions of the Ag10Si90 binary film with lithium was different from that of the intrinsic silicon film, meaning that the Ag ingredient in the binary film affected the charge–discharge reaction. Furthermore, when a Ni plate roughened by chemical etching was used as a substrate, the Ag10Si90 film anode demonstrated an excellent capacity retention during 400 cycles with a high discharge capacity of &gt;200 μA h cm−2 (corresponding to 1500 mA h g−1) at 0.5 mA cm−2 (2.5 C).
Physico-Chemical Properties of New Liquid Crystals Incorporating a Benzofuran-2-one Skeleton
Authors: Morita Yuki , Zhang Fusheng , Tasaka Takeyasu , Yamaguchi Remuto , Okamoto Hiroaki , Takenaka Shunsuke 
Published: January 2006

Abstract
The liquid crystal properties of 3H-2-oxobenzofuran-6-yl 4-(n-CnH2n+1O)benzoates (1-n, n = 5–12), 4′-(n-CnH2n+1O)biphenyl-4-carboxylates (2-n, n = 6–10), and 4-(n-CnH2n+1)benzoates (3-n, n = 4–6) are described. The n = 5–8 homologues of 1-n exhibit a nematic (N) phase, and the n = 8–12 homologues exhibit a smectic A (SmA) phase, where the layer spacing is ca. 1.3 times of the calculated molecular length. The homologues of 2-n show a complex phase-transition behavior involving a smectic C (SmC), two kinds of SmA, reentrant nematic, and N phases, where the SmC phase is exhibited by the n = 6–8 homologues. The layer spacings of SmA phases formed at high and low temperature regions correspond to 1.3 and 1.0 times of the molecular lengths, respectively. The polar interactions around the terminal lactone moiety are assumed to play important roles for the complex polymesomorphism and diversity of the smectic layer structure.
Synthesis, Properties, and Application as Emitters in Organic Electroluminescence Devices of Quinacridone- and Squarylium-Dye-Centred Dendrimers
Authors: Matsui Masaki , Tanaka Saori , Funabiki Kazumasa , Kitaguchi Toru 
Published: January 2006

Abstract
The UV–vis absorption and fluorescence spectra, solubility, and application as emitters in single-layer organic electroluminescence (EL) devices of novel quinacridone- and squarylium-dye-centred dendrimers (Gn-QAs and Gn-SQs) were examined. The respective dendrimers showed no remarkable differences in the UV–vis absorption (λmax) and photoluminescence (PL) maxima (λem). The solubility of dendrimers drastically increased at higher generation. The EL maxima of Gn-QAs and Gn-SQs were observed at 522 and 710 nm, respectively. In the case of Gn-QAs, the EL intensity under the fixed bias voltage decreased at higher generation due to a decrease in energy transfer from the host molecules to QA. Meanwhile, in the case of Gn-SQs, the EL intensity increased upon higher generation because of increased current density and the improvement of concentration quenching.
Multi-Dimensional Crystal Structures and Unique Solid-State Properties of Heterocyclic Thiazyl Radicals and Related Materials
Authors: Awaga Kunio , Tanaka Toshiyuki , Shirai Takahiro , Fujimori Masato , Suzuki Yosuke , Yoshikawa Hirofumi , Fujita Wataru 
Published: January 2006

Abstract
The crystal structures and magnetic properties of heterocyclic thiazyl radicals and related materials have been examined. TTTA (=1,3,5-trithia-2,4,6-triazapentalenyl) exhibited a first-order phase transition between a paramagnetic high-temperature (HT) phase and a diamagnetic low-temperature (LT) phase, with a wide thermal hysteresis loop over the temperature range 230–305 K. The phase control of TTTA was achieved by pressure and by light irradiation. BDTA (=1,3,2-benzodithiazolyl) also exhibited a diamagnetic–paramagnetic phase transition above room temperature. However, fresh samples always exhibited a superheating of the LT phase that resulted in a double melting (melt–recrystallization–melt process) and supercooling of the HT phase, which in turn led to an antiferromagnetic ordering at 11 K. The molecular compounds of thiazyl radicals were prepared; TTTA formed a coordination polymer structure in the TTTA·[Cu(hfac)2 (=bis(hexafluoroacetylacetonato)–copper(II))] crystal, where a ferromagnetic coupling was found between the organic and inorganic species. The cation radical salts, [BBDTA (=benzo[1,2-d:4,5-d′]bis[1,3,2]dithiazole)]·MCl4 (M = Ga and Fe), exhibited ferromagnetic ordering at 7 K and ferrimagnetic ordering at 44 K after evaporation of crystal solvents. We also grew crystals of M–TTDPz (TTDPz = tetrakis(thiadiazole)porphyrazine and M = H2, Fe, Co, Ni, Cu, and Zn) and performed their structural analyses. Their crystal structures were found to depend strongly on the central metal ion and could be classified into three forms: α, β, and γ.
Design and Synthesis of Bis(Zn(II)–Dipicolylamine)-Based Fluorescent Artificial Chemosensors for Phosphorylated Proteins/Peptides
Authors: Ojida Akio , Hamachi Itaru 
Published: January 2006

Abstract
Protein phosphorylation represents a ubiquitous mechanism for controlling diverse protein functions and plays central role in signal transduction cascades in living cells. In order to elucidate the complex network of phosphorylation-based signaling, it is desirable to develop versatile methods and molecular probes that can selectively recognize and detect the phosphoprotein of interest. We present herein the molecular recognition and fluorescence sensing of phosphorylated proteins/peptides by synthetic small molecules. The chemosensors are designed to utilize metal–ligand interaction as a main binding force and thus possess two Zn(II)–dipicolylamine(dpa)s as the binding sites for phosphate group(s) on the protein/peptide surface. We propose the two strategies for recognition of phosphorylated protein/peptide surface; (i) cooperative-binding strategy and (ii) cross-linking strategy. The binuclear anthracene-type chemosensors are designed to interact with a phosphate group on protein/peptide surface based on the cooperative-binding mode, in which the single phosphate group is recognized by the two Zn(II)–dpa sites of the chemosensor. The binding affinity of the chemosensors sensitively depends on the sequence of the phosphopeptide, and reaches to nearly 107 M−1 for a highly negatively charged peptide. In addition, the chemosensors increase their fluorescence upon binding to the phosphorylated proteins/peptides. Therefore, they can distinguish between phosphorylated and non-phosphorylated state of proteins/peptides by their fluorescence intensities. Detailed experiments clarify that the phosphate anion-assisted binding of the second Zn(II) to the binuclear chemosensors is crucial for the fluorescence increase upon binding to the phosphorylated derivatives. The other approach to recognize phosphorylated protein surface by synthetic small molecule is based on the cross-linking strategy. The chemosensors possess bipyridine as a spacer unit between two Zn(II)–dpa sites, which are arranged at appropriately distal position, thereby make possible the cross-linking interaction with two phosphate groups on protein surface. The chemosensors shows higher affinity for the bis-phosphorylated peptide than for the mono-phosphorylated one, indicating that the cross-linking interaction is effective for recognition of multisite phosphorylation domains of a protein. The results presented in this article are regarded as the first step toward detection of specific phosphorylation event of a protein in complicated biological systems using synthetic small molecules. The bioanalytical application of these chemosensors, such as the fluorescence detection of phosphatase catalyzed dephosphorylation and the selective staining of phosphoprotein in SDS-PAGE, are also discussed.
Electromagnetophoretic Measurements of Adsorption Forces of Polystyrene Microparticles on Silica Surfaces in Surfactant Solutions
Authors: Iiguni Yoshinori , Watarai Hitoshi 
Published: January 2006

Abstract
An electromagnetophoretic force has been applied for the measurement of the adsorption force of a single polystyrene particle to a silica surface in electrolyte solutions. By the electromagnetophoretic buoyancy, polystyrene microparticles in a fused-silica capillary were made to migrate perpendicular to the wall of the capillary. A switching of the current direction and a gradual increase of the current under a homogeneous magnetic field of 10 T could desorb the single particle from the wall and allowed us to measure the adsorption force from the desorbing current with a sensitivity of pN. By this method, the adsorption forces of polystyrene particles on a bare surface and on a squalane-coated fused-silica surface were measured in the absence and the presence of surfactants such as Triton X-100, cetyltrimethylammonium bromide, and sodium dodecyl sulfate. The observed adsorption forces showed that the roles of the surfactants included not only the reduction of the adsorption force as a spacer, but also the production of a characteristic force due mainly to electrostatic interaction.
DFT Calculations of Cubane-Type Mo2Ru2S4 Clusters. Stability of a Possible Dinitrogen Cluster and an Isolable Acetonitrile Cluster
Authors: Yoshizawa Kazunari , Kihara Naoki , Shiota Yoshihito , Seino Hidetake , Mizobe Yasushi 
Published: January 2006

Abstract
The electronic properties of cubane-type mixed-metal sulfido clusters with an Mo(V)2Ru(II)2S4 core and possible dinitrogen activation on it are described from DFT computations. The cluster [(CpRu)2{MoCl2(MeCN)}2(μ3-S)4] (Cp = η5-C5H5), whose Cp* analogue (Cp* = η5-C5Me5) was isolated and fully characterized by X-ray crystallographic analysis, has a closed-shell singlet ground state. Upon release of the acetonitrile ligands, the ground state remains in a closed-shell singlet state, the corresponding open-shell singlet and triplet states lying 2 kcal mol−1 above the closed-shell singlet state. Dinitrogen can hardly coordinate to this neutral [(CpRu)2(MoCl2)2(μ3-S)4] cluster. However, upon reduction by two electrons the binding energy for two N2 molecules to the resultant anionic cluster [(CpRu)2{MoCl2(N2)}2(μ3-S)4]2− increases to 4 kcal mol−1. This interaction, which still seems too weak to become isolable, is analyzed in terms of molecular orbitals to increase our understanding of dinitrogen activation by synthetic systems. The HOMO of [(CpRu)2(MoCl2)2(μ3-S)4]2− is pointing toward missing ligands and can interact effectively with the πg* orbitals of dinitrogen. This orbital might play a role in the binding of dinitrogen.
Self-Organization Properties and Microstructures of Sodium N-(11-Acrylamidoundecanoyl)-l-valinate and -l-threoninate in Water
Authors: Roy Sumita , Dey Joykrishna 
Published: January 2006

Abstract
A new class of N-acylamino acid surfactants, sodium N-(11-acrylamidoundecanoyl)-l-valinate (SAUV) and -l-threoninate (SAUT), were synthesized and characterized in aqueous solutions. The self-assembly properties were studied by surface tension, fluorescence probe, light scattering, and microscopic techniques. The interfacial properties of the amphiphiles have been investigated at the air/water interface. The critical aggregation concentration (cac) and free energy change of aggregation for both amphiphiles were determined. The results of fluorescence probe and surface tension studies have indicated that initially flat bilayer structures are formed, which upon a further increase of surfactant concentration transform into closed vesicles. The pH and temperature dependence of the bilayer aggregates have been studied. The role of intermolecular hydrogen bonding between amide groups upon aggregation towards microstructure formation in solution has been elucidated. The micropolarity of the hydrophobic domains of the bilayer self-assemblies was estimated by fluorescence probe methods. Dynamic light scattering measurements were performed to determine the mean size of the aggregates. The circular dichroism spectra of SAUV and SAUT suggested the formation of chiral aggregates in dilute solution. The transmission electron micrographs revealed the presence of closed vesicles and twisted ribbons in the aqueous solutions of the amphiphiles. Optical microscopic images also showed the existence of twisted ribbons and rope-like helical structures in the case of SAUV.