bluuebunny/crossref_metadata_2025 huggingface dataset:
Functional domain mapping of peroxin Pex19p: interaction with Pex3p is essential for function and translocation
Authors: Matsuzono Yuji , Matsuzaki Takashi , Fujiki Yukio
Published: August 2006

The peroxin Pex19p functions in peroxisomal membrane assembly. Here we mapped functional domains of human Pex19p comprising 299 amino acids. Pex19p mutants deleted in the C-terminal CAAx farnesylation motif, the C-terminal 38 amino acid residues and the N-terminal 11 residues, maintained peroxisome-restoring activity in pex19 cells. The sequence 12-261 was essential for re-establishing peroxisome activity. Pex19p was partly localized to peroxisomes but mostly localized in the cytosol. Pex19p interacted with multiple membrane proteins, including the other two membrane biogenesis peroxins, Pex3p and Pex16p, those involved in matrix protein import such as Pex14p, Pex13p, Pex10p, and Pex26p, peroxisome morphogenesis factor Pex11pβ, and a PMP70 peroxisome-targeting signal region at residues 1-123. In yeast two-hybrid assays, Pex10p and Pex11pβ interacted only with full-length Pex19p. Of various truncated Pex19p variants active in translocating to peroxisomes, the mutants with the shortest sequence (residues 12-73 and 40-131) were localized to peroxisomes and competent in binding to Pex3p. Furthermore, membrane peroxins were initially discernible in a cytosolic staining pattern in pex19 cells only when co-expressed with Pex19p and were then localized to peroxisomes in a temporally differentiated manner. Pex19p probably functions as a chaperone for membrane proteins and transports them to peroxisomes by anchoring to Pex3p using residues 12-73 and 40-131.
ATP, phosphorylation and transcription regulate the mobility of plant splicing factors
Authors: Ali Gul Shad , Reddy Annireddy S. N.
Published: August 2006

Serine-arginine-rich (SR) proteins, a family of spliceosomal proteins, function at multiple steps in the assembly of the spliceosome in non-plant systems. Limited studies with metazoan SR splicing factors (ASF/SF2 and SC35) indicated that their mobility is not dependent on ATP and phosphorylation. In addition, inhibition of transcription slightly increased their mobility. Here, we analyzed the mobility of SR45, a plant-specific SR protein with unique domain organization, and SR1/SRp34, a plant homolog of metazoan ASF/SF2, using fluorescence recovery after photobleaching (FRAP) and fluorescence loss in photobleaching (FLIP). Our results show that, in contrast to metazoan SR splicing factors, the movement of the plant SR proteins is dependent on ATP, phosphorylation and transcription. To understand the underlying mechanism for these observations, we carried out mobility analyses with the domain-deletion mutants of SR45 in ATP-depleted cells and in the presence of inhibitors of transcription or phosphorylation. Our results show that the sensitivity of SR45 to these inhibitors is conferred by an RNA-recognition motif (RRM) and the serine-arginine-rich (RS) domain 2. These results provide important insights into the mechanisms of plant SR protein movement and suggest fundamental differences in the regulation of the mobility of plant and animal SR splicing factors.
Heterogeneous Rate Parameters of Multi-Step Charge-Transfer Processes for 9,9′-Bianthryl-10,10′-dicarbonitrile. Application of ac Voltammetry with Unusual Phase-Angle Behavior
Authors: Rashwan Farouk , Mohran Hossnia
Published: August 2006

Cyclic and ac voltammetric studies of a 9,9′-bianthryl-10,10′-dicarbonitrile/tetrabutylammonium hexafluorophosphate system in superdry aprotic solvents are presented. The rate parameters were obtained for successive one-electron transfer reactions at a hanging mercury drop electrode (HMDE) and/or a Pt disk electrode. The results of electrode processes were found to be in agreement with the predictions of the Marcus theory for heterogeneous charge-transfer reactions. Quite rare behavior of the phase angle of the Faradaic fundamental alternating currect was observed and is discussed in detail.
Structure-Retention Correlation on Methyl Phenyl Polysiloxane Phases in Capillary Gas Chromatography
Authors: Yamane Yasuhiro , Miyaji Kazuo , Hanafusa Kumi , Hanai Toshihiko , Hatano Hiroyuki
Published: August 2006

The selectivity of phenyl methyl polysiloxane phases was examined from the structure-retention correlations of alkanes, alkanols, alkylbenzenes, chlorobenzenes, and polycyclic aromatic hydrocarbons. Selectivity R* was obtained from plots of van der Waals volume vs. the difference of their logarithm of capacity ratios, and enthalpy of these compounds was calculated from van’t Hoff plot. The enthalpy −ΔH of polycyclic aromatic hydrocarbons was greater on phenyl methyl phases compared to those obtained on 100% methyl polysiloxane phase. The retention time of homologue series of compounds can be predicted from the selectivity or enthalpy, but not for chlorinated benzenes due to the difficulty of the estimation of electron donner effect of chloro group.
Crystal Structure of the Adduct of Thiourea with 2,6-Diethylnaphthalene
Authors: Shindo Takayoshi , Shindo Manabu , Ohnuma Hiroshi , Kabuto Chizuko
Published: August 2006

The crystal structure of 2,6-diethylnaphthalene thiourea adduct was solved by single crystal X-ray diffraction method. The crystal is monoclinic, space group P2l/c, with a = 12.571(3), b = 9.282(2), c = 14.634(3) Å, β = 92.14(2)°, V = 1706.3(6) Å3 and Z = 2. The final R value was 0.083. The structure was composed of thiourea (host) molecules enclosing channels with hexagonal-prism and 2,6-diethylnaphthalene (guest) molecules in the channels. The cross-section of the channel was deformed hexagon. In the channel, the occupying channel length of the guest molecule was 12.571(3) Å
1H NMR Response of Mono[6-(1-pyridinio)-6-deoxy]-α-cyclodextrin to Inorganic Anions
Authors: Mu Ping , Okada Takuya , Iwami Nakamasa , Matsui Yoshihisa
Published: August 2006

The chemical shifts (δ) of some 1H NMR signals given by mono[6-(1-pyridinio)-6-deoxy]-α-cyclodextrin (1) in D2O were significantly changed by the addition of alkali salts of chaotropic anions such as Br−, I−, SCN−, N3−, NO3−, and ClO4−. However, only small changes in δ were brought about by the addition of alkali salts of antichaotropic anions such as F−, Cl−, SO42−, H2PO4−, and HPO42−. The addition of the chaotropic anions caused a marked downfield shift in the signal of a C(5)–H located in the interior of the cavity of 1, and a marked upfield shift in the signal of one of the C(6)–H’s involved in the unsubstituted glucopyranose rings of 1. These facts indicate that the anions are included within the cavity and attract the pyridinio group of 1 close to the C(6)–H. The signal of the α-H’s in the pyridinio group showed a significant downfield shift with the addition of the alkali salts of Br−, I−, and SCN−, which form charge-transfer complexes with 1.
Electrochemical Characteristics of an Insulating Polymer-Modified Electrode Prepared by Electrochemical Polymerization
Authors: Kawai Tsuyoshi , Nagame Seigo , Nakazono Masahiro , Yoshino Katsumi
Published: August 2006

The electrochemical polymerization of 1,4-bis(2-methylstyryl)benzene and the electrochemical behavior of the resulting polymer-modified electrode have been studied. The rapidly decreasing polymerization current of the 1,4-bis(2-methylstyryl)benzene can be attributed to the passivation effect of the resulting polymer coating. The polymer-modified electrode showed an electrochemical response in an aqueous electrolyte solution corresponding to solute electroactive ions. The electrochemical behavior was dependent on the polymerization charge and the size of the electroactive ions. The polymer-modified electrode is applicable as the selective electrode for electroactive ions and molecules in an electrolyte solution containing electroactive bacterial cells.
Theoretical Study of the Rates and Mechanism of the Gas-Phase Reaction H + HN3 → NH2 + N2
Authors: Fueno Takayuki , Takane Shin-ya
Published: August 2006

Reaction of the hydrogen atom with hydrazoic acid HN3 in the gas phase has been investigated theoreticallly. Tracing of the reaction path by the SCF procedure based on the 6-31G (d,p) basis functions has shown that the reaction proceeds through an initial rate-determining hydrogen atom addition to HN3 giving a doublet radical H2N3, which is subsequently self-decomposed into NH2 + N2. The barrier height for the initial addition step calculated by the MRD-CI method employing the [4s2p1d] basis sets is 21 kJ mol−1 (with the vibrational zero-point energy correction). The bimolecular rate constants for the overall reaction calculated by the conventional transition state theory combined with appropriate tunneling corrections are found to agree well with the experimental data reported over the temperature range 300 to 500 K.
Aromaticity of Multiply Charged Fullerene Ions
Authors: Aihara Jun-ichi , Hosoya Haruo
Published: August 2006

The topological resonance energies (TREs) indicate that mono- to hexaanions of C60 are as aromatic as the neutral species. The tendency of multiply charged C60 anions to retain their own spherical conjugated systems can be attributed to aromatic character. Tetraanions of C28, C36, and C44 are likewise predicted to be highly aromatic. Thus, the formation of metallofullerenes, such as U@C28, U@C36, and U@C44, can be rationalized in terms of aromaticities of the ligands.
Thermal Condensation of Phosphorodiamidic Acid: HPO2(NH2)2
Authors: Kowalczyk K , Parent Y , Palavit G
Published: August 2006

Phosphorodiamidic acid disappears when it is heated at 110 °C. It condenses, giving the ammonium salt of P,P′-diamidoimidodiphosphoric acid. The value of the enthalpy for this reaction is −3.6 kJ mol−1. We determined the apparent activation energy for the condensation reaction by two different methods: -Differential Scanning Calorimetry, -Measuring out ammonium. We obtained by these two methods the same apparent activation energy: 120 kJ mol−1.
The Preparations, Properties and Structures of trans-[Rh(CN)2(tn)2]+
Authors: Odano Naomi , Harada Kazumasa , Urushiyama Akio
Published: August 2006

The title dicyano-complex of Rh(III) was newly synthesized. Stepwise ligand substitutions in an aqueous medium through trans-[RhCl2(tn)2]+, trans-[Rh(SO3)2(tn)2]−, trans-[Rh(CN)(SO3)(tn)2], and trans-[Rh(CN)Cl(tn)2]− were studied. The final substitution of Cl− of trans-[Rh(CN)Cl(tn)2]− by CN− was effected in a mixed medium of DMSO, ethanol, and H2O (8 : 1 : 1). The ligand field tetragonal parameters of Dt ca. −380 cm−1 were estimated based on the lower d–d absorption maximum at 36100 cm−1. The sharp IR peaks of ν (C≡N) were observed at 2115 cm−1 (nitrate) and 2116, 2131 cm−1 (perchlorate). The slight splitting detected for solid compound of the perchlorate was attributed to the presence of a structurally different complex species with respect to the Rh–C≡N bondings in the crystal. The X-ray crystal data are: trans-[Rh(CN)2(tn)2](NO3): monoclinic, space group P21/n, a = 11.626(4), b = 6.3624(6), c = 10.026(3) Å, β = 113.54(4)°, Dm = 1.78, Dc = 1.784 g cm−3, Z = 2; trans-[Rh(CN)2(tn)2](ClO4): triclinic, space group , a = 9.230(5), b = 12.690(3), c = 6.861(2) Å, α = 101.36(3)°, β = 106.10(3)°, γ = 76.42(3)°, Dm = 1.80, Dc = 1.800 g cm−3, Z = 2. In these two crystal lattices, the trans-[Rh(CN)2(tn)2]+ cations occupy the special positions of the inversion center, and the Rh-tn six-membered chelate rings appear in the chair form. While all of the bond distances and angles were well conserved, an appreciable variation appeared in the dihedral angles defined in the chair chelate rings (N–Rh–N : N–C···N–C and N–C···N–C : C–C–C). This structural variation in the Rh-tn chelate rings is responsible for the complicated splittings of the IR bands of the perchlorate, especially, in the CH2 rocking region of 880—970 cm−1. Other important geometrical data of the complex are (in mean values): Rh–N = 2.09, Rh–C = 2.03 Å, N–Rh–N (in chelate ring) = 91.8°
Reaction of the Group 15 Metalloid Amides with Diketene by 1,4-Addition Mode
Authors: Ando Fumio , Mio Ryosuke , Koketsu Jugo
Published: August 2006

(Dialkylamino)dimethylarsines, (dimethylamino)diphenylarsine, and (dialkylamino)dimethylstibines react with diketene to yield N,N-dialkyl-4-dimethylarsino-3-oxobutanamides, N,N-dimethyl-4-diphenylarsino-3-oxobutanamide, and N,N-dialkyl-4-dimethylstibino-3-oxobutanamides, respectively. These group 15 metalloid-substituted 3-oxobutanamides exist as keto-enol tautomers and the keto isomers are predominant in solution or in neat state. This reaction is the first example of 1,4-addition of heteroatom-nitrogen bond to diketene.
The Influence of β-Alanine and 4-Aminobutyric Acid Residues on the Solubility of Peptides Containing Them
Authors: Lee Jin-Shik , Murakawa Yuka , Hanami Akira , Narita Mitsuaki
Published: August 2006

The influence of unnatural amino acid residues, i.e., β-alanine (β-Ala) and 4-aminobutyric acid (γ-Aba) residues, on the solubility of peptides containing them was studied in organic solvents. The difference between the solubilities of peptides containing β-Ala, γ-Aba, Pro, Gly, Leu, and Asp(OBzl) was investigated by the solvent titration method by use of IR absorption spectra. The order of their solubilities is as follows, peptides containing Pro > β–Ala > γ–Aba > Asp(OBzl) > Leu > Gly. The extreme high solubility of peptides containing Pro residues is explained by the concept of “Peptide Segment Separation” caused by the tertiary peptide bond of the Pro residue. The high solubility of peptides containing β-Ala or γ-Aba residues is believed to be due to the difference of the geometries of the Gly, β-Ala, and γ-Aba residues. Their effective concentration seemed to be less important than their geometry. The role of β-Ala and γ-Aba residues in the solubility of peptides is similar to the role of Pro residues rather than Asp(OBzl), Gly, and Leu residues.
Simple One-Pot Synthesis of Thieno[2,3-b]thiophene Derivatives under Solid–Liquid PTC Conditions. Useful Starting Material for the Synthesis of Biological Active Compounds
Authors: El-Saghier Ahmed M M
Published: August 2006

A variety of thieno[2,3-b]thiophenes were prepared under phase-transfer catalysis conditions. The reaction of diethyl 3,4-dimethylthieno[2,3-b]thiophene-2,5-dicarboxylate with hydrazine hydrate gave the corresponding hydrazide derivative which was also subjected to react with acetylacetone, ethyl acetoacetate, malononitrile, CS2, phenyl isothiocyanate, p-chlorobenzaldehyde and diazotization to afford the described compounds. Treatment of 2,5-bis(azidocarbonyl)-3,4-dimethylthieno[2,3-b]thiophene with ethyl cyanoacetate, diethyl malonate or malononitrile gave the corresponding triazole derivatives.
Syntheses, Structures, and Properties of 2,3,6,7-Tetrathiabenzo[1,3-cd:4,6-c′d′]dipentalene and Its Methyl, Ethyl, Methylthio, and Ethylthio Derivatives: Novel Fused Polynuclear Heteroarenes
Authors: Otsubo Tetsuo , Kono Yasuhiro , Hozo Norio , Miyamoto Hisakazu , Aso Yoshio , Ogura Fumio , Tanaka Takanori , Sawada Masami
Published: August 2006

The title heteroarene (TBD) isoelectronic with perylene was synthesized by way of a dimerization of thieno[2,3-b]thiophene. In addition, 1,4,5,8-tetramethyl, tetraethyl, tetrakis (methylthio), and tetrakis (ethylthio) derivatives were readily obtained from TBD. An X-ray crystallographic analysis of TBD demonstrated that the molecular structure is quite planar and symmetrical, but strained in the bond angles. The crystal structure comprises herringbone-type column stacking with intercolumnar heteroatomic interactions. TBD showed the same oxidation potential as did perylene, and like perylene, formed an iodine complex with a relatively high electrical conductivity of 0.11 S cm−1. On the other hand, all of the TBD derivatives gave poorly conductive iodine complexes. In addition, TBD and the derivatives formed charge-transfer complexes with strong electron acceptors, such as 7,7,8,8-tetracyanoquinodimethane (TCNQ), 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (TCNQF4), 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ), and 1,1,2,3,4,4-hexacyano-1,3-butadiene (HCBD). These π-complexes, however, were mostly of low conductivity. The electrolyses of TBP gave powdery conductive polymers, whereas those of tetrakis (methylthio) TBD gave crystalline radical cation salts with conductivities of the order of 10−3 S cm−1.
Base-Promoted Rearrangement of 1,5-Dibromopentacyclo[5.3.0.02,5.03,9.04,8]decane-6,10-dione: Easy Entry of a Novel Cage System, 10-Oxa-9-oxopentacyclo[5.3.0.02,4.03,6.05,8]decane
Authors: Nigo Tomohiro , Hasegawa Takeshi , Kuwatani Yoshiyuki , Ueda Ikuo
Published: August 2006

The Diels-Alder dimerization of 2-bromo-2,4-cyclopentadienone ethylene acetal (2) gave endo-2,7-dibromodicyclopentadiene-1,8-dione 1,8-bis (ethylene acetal) (3) as a minor product in a 4.5% yield. Ultraviolet irradiation of 5 led to dimerization product 7. Deacetalization was accomplished by treating with concentrated sulfuric acid to give 1,5-dibromopentacyclo[5.3.0.02,5.03,9.04,8]decane-6,10-dione (9). Compound 9 was converted into a new cage system, 10-oxa-9-oxopentacyclo[5.3.0.02,4.03,6.05,8]decane, in a high yield by treating with 5% aqueous potassium hydroxide at 80 °C.
Mechanistic Study of Acid-Catalyzed Proton Exchange in Thioamide and Thiolactams
Authors: Wang Wei-Hsien , Cheng Pai-Hui , Hsieh Hsing-Ching
Published: August 2006

The kinetics of acid-catalyzed proton exchange in a series of thiolactams (5- to 7-membered ring) and N-methylthioacetamide were studied. Kinetic data were observed by NMR line-broadening and computer simulation methods. The second-order rate constants of all the thiolactams and N-methylthioacetamide are within the same order of magnitude. It is concluded that the imidic acid mechanism is dominant in thiolactams and N-methylthioacetamide.
Lability of Soluble Copper(II) Complex in River Waters in the Urban Area
Authors: Kawamoto Hiroshi , Yokoyama Ryo , Tsunoda Kin-ichi , Akaiwa Hideo
Published: August 2006

Hourly variation of the lability of soluble copper(II) complex in water samples from the Kiryu River in Gunma prefecture was investigated. By considering the relationship between the lability of soluble copper(II) complexes and the copper(II) complexing capacity, the lability was found to reflect the presence of weak CuII complexes.
Phase-Change Behavior of a Dialkoxo-Bridged Dinuclear Copper(II) Complex: X-Ray Crystal Structure of {2-[2-(Dimethylamino)ethylthio]ethanolato}isothiocyanatocopper(II) at 210 K
Authors: Mikuriya Masahiro , Toriumi Koshiro
Published: August 2006

The crystal structure of {2-[2-(dimethylamino)ethylthio]ethanolato}isothiocyanatocopper(II) at 210 K was determined by the single-crystal X-ray diffraction method. The unusual magnetic property was examined in terms of the temperature dependence of the magnetic susceptibility (85—290 K) and a differential scanning calorimetric analysis.
A Distorted Trigonal Bipyramidal Manganese(II) Complex of the Schiff Base Ligand (L) Derived from 2,6-Pyridinedicarboxaldehyde and (1R,2S)-Norephedrine; the X-Ray Structure of MnBr2L
Authors: Nakajima Kiyohiko , Kojima Masaaki
Published: August 2006

The title complex was synthesized and the structure was determined by the X-ray method. The oxygen atoms of the (1R,2S)-norephedrine moieties do not coordinate to manganese and the coordination polyhedron is a distorted trigonal bipyramid. The steric interactions between the bound bromide ions and the methyl and phenyl groups of the (1R,2S)-norephedrine moieties are suggested to influence the structure of the complex.
Preparation and Properties of the Dinuclear Copper(II) Complexes Containing the Derivatives of N,N,N′,N′-Tetrakis(2-benzimidazolyl)-2-hydroxy-1,3-diaminopropane and an Exogenous Bridging Ligand
Authors: Nakao Yasuo , Oohata Yasuko , Fujiwara Rika , Itadani Masumi , Sakurai Takeshi , Ichimura Akio , Mori Wasuke
Published: August 2006

The dinuclear copper(II) complexes of HL-Et or HL-Me and a bridging ligand (X (X = N3−, NCS−, NCO−, OH−, OAc−, (CH3)3CCOO− (OPi−), o-C6H4 (CH3)COO− (OTo−), pyrazolate (Pz−), and imidazolate (Im−))) have been prepared and characterized, where HL-Et = N,N,N′,N′-tetrakis[(1-ethyl-2-benzimidazolyl)methyl]-2-hydroxy-1,3-diaminopropane and HL-Me = N,N,N′,N′-tetrakis[(1-methyl-2-benzimidazolyl)methyl]-2-hydroxy-1,3-diaminopropane. The magnetic moments of these complexes differ depending upon their bridging groups. The electrochemistry in N,N-dimethylformamide showed that only one-electron reduction(Cu2+–Cu2+ → Cu+–Cu2+) can occur for the dinuclear complexes bridged by X = N3−, OAc−, OPi−, OTo−, Pz−, whilst the other complexes showed irreversible processes.
Crystal Structure of an Alternated Stacking Charge-Transfer Complex of 2,7-Bis(methylthio)-1,6-dithiapyrene (MTDTPY) with Tetracyano-2,6-naphthoquinodimethane (TNAP)
Authors: Toyoda Jiro , Oda Akio , Murata Ichiro , Kawamoto Atsushi , Tanaka Jiro , Nakasuji Kazuhiro
Published: August 2006

The charge-transfer complex of 2,7-bis(methylthio)-1,6-dithiapyrene (MTDTPY) with tetracyano-2,6-naphthoquinodimethane (TNAP) showed an alternated stacking mode of crystal structure. There are no short intermolecular contacts. The ionicity was estimated to be neutral based on an analysis of the IR stretching frequency of the CN groups and the transition energy of the charge-transfer band.
Reactions of 1,1-Diamino-2-nitroethylenes with Dimethyl Acetylenedicarboxylate
Authors: Tokumitsu Takao , Nagao Satomi
Published: August 2006

1,1-Diamino-2-nitroethylenes reacted with dimethyl acetylenedicarboxylate (2) to give an electrophilic adduct (dimethyl 2-[(2-imidazolidinylidene)nitromethyl]-2-butenedioate) as well as cyclocondensation products derived from the electrophilic adducts. The reaction of 1,1-dimorpholino-2-nitroethylene with 2 afforded dimethyl 2-(2,2-dimorpholino-1-nitroethenyl)-2-butenedioate or dimethyl 2-(dimorpholinomethylene)-3-(nitroethylene)butanedioate derived from the [2+2] cycloadduct.
Desulfonylative Iodination of Naphthalenesulfonyl Chlorides with Zinc Iodide or Potassium Iodide Catalyzed by Dichlorobis(benzonitrile)palladium(II) in the Presence of Lithium Chloride and Titanium(IV) Isopropoxide
Authors: Satoh Tetsuya , Itoh Kenji , Miura Masahiro , Nomura Masakatsu
Published: August 2006

Iodination of naphthalenesulfonyl chlorides accompanied by desulfonylation efficiently proceeded on treatment with either zinc iodide or potassium iodide using a catalyst system of [PdCl2(PhCN)2]/LiCl/Ti(OPri)4.
Free Radical Reaction of 1,3-Dimethyluracils and Caffeine with Benzoyl Peroxide in γ-Butyrolactone
Authors: Itahara Toshio , Ide Naoko
Published: August 2006

Treatment of 1,3-dimethyluracil, 1,3-dimethylthymine, and caffeine with benzoyl peroxide in γ-butyrolactone at 80 °C resulted in a free radical alkylation.
Studies of Collectors. XIII. The Selective Flotation of Cesium Ion with Resorcinol-Type Calix[4]arenes with Alkyl Side Chains
Authors: Koide Yoshifumi , Oka Tetsushi , Imamura Akemi , Shosenji Hideto , Yamada Kimiho
Published: August 2006

The resorcinol-type calix[4]arenes with alkyl side chains, [4]Ar-Rn, were prepared and then investigated as flotation collectors of Cs+. Alkali metal ions (Na+, K+, Rb+, and Cs+) were extracted in the pH range of 9.5—12.5 with [4]Ar-Rn. Moreover, the surface-active [4]Ar-Rn had competence to float Cs+ as a complex in a foam film (adsorbates) when short-chain [4]Ar-Rn (n = 4—8) were used for foam fractionation, and as scum when long-chain [4]Ar-Rn (n = 8—16) were used for ion flotation. The Cs+ was floated selectively with [4]Ar-Rn from a mixture of Na+, K+, Rb+, and Cs+, due to the strong binding to Cs+.
Deuterium Isotope Effects on Aromatic 13C Chemical Shifts. V. Nonadditivity of Methyl Substituent Effects on One-Bond Isotope Shifts for Methylpyridine N-Oxides
Authors: Nakashima Yasuki , Fukunaga Moritaka , Suzuki Keiko , Takahashi Kensuke
Published: August 2006

One- and two-bond deuterium isotope effects (1Δ and 2Δ) on 13C chemical shifts for methylpyridines and their N-oxides were investigated. The 1Δ values for methylpyridines agree with the calculated values, which are based on a simple additive rule of the methyl substituent effects. On the other hand, the additive rule was not satisfied in 1Δ for their N-oxides. This is attributed to a steric interaction between the substituent and the N-oxide group.
Phase Studies of a Mixed Trimethyltetradecylammonium Bromide–Hexadecyltrimethylammonium Bromide System
Authors: Suhaimi Hamdan , Rose Laili Che , Kassim Anuar
Published: August 2006

A phase studies was carried out on the phase equilibria in the three component systems of single and binary mixture (1 : 1) of trimethyltetradecylammonium bromide (TTAB) and hexadecyltrimethylammonium bromide (HTAB) with water and 1-hexanol at 30 °C. The phases were separated by repeated centrifugation. The birefringence was observed under cross polarizers and their consistency, texture and optical pattern were examined under the polarizing microscope. On the basis of the results obtained, a phase diagram was drawn that consists of two phases of isotropic solution and two mesophases. Results also showed a larger region for the lamellar liquid crystalline in the mixed system. The critical micelle concentration for the micellar region of the mixture was found at 0.0014 mol dm−3.
Structures of Sodium Hydrogen l-Tartrate Monohydrate and Potassium Hydrogen l-Tartrate
Authors: Kubozono Yoshihiro , Hirano Akiko , Nagasawa Shinichi , Maeda Hironobu , Kashino Setsuo
Published: August 2006

Crystals of sodium hydrogen l-tartrate monohydrate (NaHC4H4O6·H2O) were grown from the aqueous solution, while potassium hydrogen l-tartrate (KHC4H4O6) crystallized as anhydrate. Their crystal structures were determined by X-ray diffraction method. The hydrogen bonds between the carboxyl and carboxylate groups in these crystals are rather long; O···O 2.533(3) and 2.531(1) Å for the sodium and potassium compounds, respectively. The sodium and potassium ions are coordinated by eight O atoms at the corners of distorted square antiprism, Na+···O 2.404(2)—2.826(3) Å and K+···O 2.718(1)—3.059(1) Å. The crystal and molecular structures have been compared with those of the corresponding rubidium, caesium, and ammonium salts, and discussed with the aid of semiempirical and ab initio MO methods.
Molecular and Crystal Structure of Azobenzene-Containing Amphiphile, C3AzoC5N+Br−
Authors: Xu Guiqing , Okuyama Kenji , Shimomura Masatsugu
Published: August 2006

An azobenzene-containing odd-number amphiphile, C3AzoC5N+Br−, was crystallized by the vapor-diffusion method. The crystal is monoclinic with the space group P21, a = 25.866(3), b = 7.3560(9), c = 6.4833(7) Å, β = 96.255(9)°, and Z = 2. The structure was solved by the direct method and refined by the full-matrix least-squares method: R = 0.03 for 2116 observed reflections (2θ < 130°, Cu Kα, λ = 1.5418 Å). The molecules are arranged in an antiparallel fashion and interdigitated mutually. The azobenzene chromophores are aligned at the center part of the hydrophobic layer (the H-aggregation state) and inclined about 65° to each other. In the hydrophilic layer, detailed structures are different from those of even-number compounds with the H-aggregation state, resulting in an odd-even effect on their transition temperature.
Numbers of Isomers of Some Classes of Pentacyclic Conjugated Hydrocarbons
Authors: Cyvin Björg Nygaard , Brunvoll Jon , Cyvin Sven Josef
Published: August 2006

The pentacyclic structures are considered within the initiated studies of polycyclic conjugated hydrocarbons. A complete mathematical solution (in terms of generating functions) is presented for the numbers of CnHs isomers of these structures. Some details of the analysis are given for the doubly-branched catafused structures of the category in question, a subclass to which C16H8 cyclic bicalicene and C24H16 tetraphenylene belong.
Topochemical Studies. XVI. Direct Observation of the Solid-State Photoreaction of α-(Acetylamino)cinnamic Acid Dihydrate by Single Crystal X-Ray Diffraction
Authors: Iwamoto Tetsuyuki , Kashino Setsuo
Published: August 2006

The crystal structure at an intermediate stage in the solid-state photodimerization of α-(acetylamino)cinnamic acid dihydrate has been analyzed at the conversion rate of 12%: C11H11NO3·2H2O, Mr = 241.24, monoclinic, P21/a, a = 18.346(5), b = 6.072(2), c = 11.310(4) Å, β = 105.90(2)°, V = 1211.8(6) Å3, Z = 4, Dx = 1.323 Mg m−3, Cu Kα (λ = 1.5418 Å), μ = 0.89 mm−1, F(000) = 512, T = 295 K, R = 0.108 for 1678 unique reflections with |Fo| larger than σ(Fo). The present study revealed the structures of the monomer and photodimer components at the intermediate stage. The results made possible the discussion on the role of intermolecular hydrogen bonds and on the feature of the atomic movements accompanied by the reaction.
Vibrational Spectra of N-Acyl-l-Glutamic Acid Oligomers and the Long N-Acyl Chain Effect
Authors: Uehara Toshiyuki , Okabayashi Hirofumi , Taga Keijiro , Yoshida Tadayoshi , Kojima Hiroshi , Nishio Etsuo
Published: August 2006

Trimers and tetramers of N-acyl-l-glutamic acid oligomers (Glu-oligomers) with various acyl chains have been prepared. For these Glu-oligomer molecules the vibrational spectra were measured and compared with those of two β-forms (β1 and β2) and the α-helical form of poly(l-glutamic acid). For these samples the molecules take up a β2-type structure in the solid state. The long acyl chain in the oligomers induces stronger hydrogen bonds between the side-chain COOH and the amide linkages; this effect is due to the close packing of the long acyl chains accompanying the reduction of the intersheet spacing. Moreover, the long acyl-chain effect strongly depends upon the residue number of the oligomer. For cast films of Glu-oligomers made onto an NaCl plate, these oligomer molecules assume an α-helical type structure. For the α-helical type oligomers, it is also found that the long acyl chain induces stronger hydrogen bonds in the side-chain COOH groups, and that the effect depends on the residue number.
Determination of Lead in Fish Tissues by Electrothermal Atomic Absorption Spectrometry Using Bismuth Nitrate as Chemical Modifier
Authors: Chakraborty Ruma , Bhattacharyya Shuvendu S , Das Arabinda K
Published: August 2006

The electrothermal atomic absorption spectrometry has been used to develop a routine and interference-free method for the determination of lead in fish tissues. Bismuth(III) nitrate was used as a chemical modifier. The analytical curves of lead were studied by using pyrolytically coated graphite tubes. The instrumental conditions, electrothermal atomizer programme, concentration of the modifier, the calibration and addition curves were studied. A comparative study was also made between Pd(NO3)2 and Bi(NO3)3 as chemical modifiers. Not only a better limit of detection value has been obtained in comparison to Pd(NO3)2 modifier but also a lower atomization temperature, hence an extension of the life period of the graphite tube compared to magnesium nitrate+ammonium dihydrogen phosphate mixed modifier could be achieved in the present method.
Solvent Extraction of Europium(III) with 1-Naphthoic Acid into Chloroform in the Absence and Presence of Tetrabutylammonium Ions or Trioctylphosphine Oxide
Authors: Noro Junji , Sekine Tatsuya
Published: August 2006

The solvent extraction of europium(III) in 0.1 mol dm−3 sodium nitrate solutions with 1-naphthoic acid (HA) into chloroform was studied in the absence and presence of tetrabutylammonium ions (tba+) or trioctylphosphine oxide (TOPO). In the absence of tba+ and TOPO the distribution ratio of europium(III) with 0.1 mol dm−3 1-naphthoic acid was higher when the initial concentration of the metal was higher under otherwise identical conditions. This could be explained in terms of the extraction of a polynuclear species, Eu2A6(HA)2, in addition to a mononuclear species, EuA3HA. Furthermore, by the addition of tba+ or TOPO, the extraction of europium(III) was greatly enhanced. This could be explained in terms of the extraction of the ternary complex, EuA4−tba+, or the adducts, EuA3TOPO and EuA3(TOPO)2, like that found in the extraction of this metal ion with β-diketones. In these systems the extracted anionic complex with tba+ or the adducts with TOPO were only mononuclear, even under conditions in which the polynuclear species were extracted in the absence of these.
Structural Change in Lithium Intercalation of Defect Perovskite LiCuM3O9 (M = Ta, Nb)
Authors: Sato Mineo , Jin Tetsuro , Hama Yoshiki , Uematsu Kazuyoshi
Published: August 2006

The chemical lithium intercalation of defect perovskite LiCuM3O9 (M = Ta, Nb) compounds has been performed by using butyllithium. The content of the inserted lithium ions in the compounds was found to be ca. 1 mol per unit formula for M = Ta and ca. 4 mol per unit formula for M = Nb. The crystal structure of the intercalated compound was determined based on the powder X-ray diffraction pattern. The intercalated product was well crystallized for M = Ta, but almost amorphous for M = Nb. The Rietveld refinement confirmed that the intercalated tantalate, Li2CuTa3O9, adopts a rhombohedrally distorted perovskite structure with a = 5.4896(8) Å, α = 56.544(8)° and Z = 2 for the R3c space group. The Li and Cu atoms are statistically distributed over an identical crystallographic site with an atomic ratio of Li : Cu = 2 : 1. The coordination of the nearest-neighbor oxygen atoms around the (Li,Cu) site was changed from square-planar four-fold to triangular three-fold, accompanied by an intercalation reaction. This structural change could be reasonably explained as being due to the occurrence of a reduction of strong Jahn-Teller Cu2+ ions to Cu+ ions as a result of the lithium insertion.
Evaluation of the β-Sheet-Structure-Stabilizing Potential of 20 Kinds of Amino Acid Residues in Protected Deca- and Pentadecapetides
Authors: Lee Jin-Shik , Murakawa Yuka , Fujino Kentarou , Narita Mitsuaki
Published: August 2006

The β-sheet-structure-stabilizing potential of 20 kinds of guest amino acids has been evaluated by solvent titration for the protected pentapeptide, Boc–X–Ala–Glu(OBzl)–Leu–Gly–OPac, described previously. It has been proved that the  value was effective in evaluating the β-sheet-structure stability of protected tri- to heptapeptide in organic solvents. In order to widen the application range of the  value, deca- and pentadecapeptides were synthesized by fragment condensation of pentapeptides. The β-sheet-structure-stabilizing potentials of individual guest amino acids determined from deca- and pentadecapeptides showed different results from the  value. Circular dichroism showed that deca- and pentadecapeptides adopted helix and random coil structures in organic solvents. The helix structure influences the solvation mechanism of these protected peptides.
Steric and Electronic Effects on the Dehydration Step in Cyclohexanone and Bicyclic Ketones Oxime Formation
Authors: Brighente Ines Maria Costa , Vottero Leonor Rosa , Terezani Alberto Jose , Yunes Rosendo Augusto
Published: August 2006

Between pH 4 and pH 13, oxime formation from hydroxylamine with cyclohexanone and bicyclic ketones proceeds with rate limiting dehydration of the addition intermediate which is in equilibrium with the ketone and hydroxylamine. The dehydration step exhibits catalysis by oxonium ion (pH 4 to ca. 8), a pH independent pathway (pH 8 to ca. 10) and catalysis by hydroxide ion (pH ca. 10 to 13). The steric and electronic effects give important insights into the structure of the transition state of the mechanisms of oxonium ion, hydroxide ion catalyzed and spontaneous reaction.
Synthesis of 1,1-Dialkoxy Derivatives of 2,5-Diphenylsilacyclopent-3-ene and 2,5-Diphenylsilacyclopentane
Authors: Nagao Yukinori , Takahashi Masahiro , Abe Yoshimoto , Misono Takahisa , Jung Michael E
Published: August 2006

The 1,1-dialkoxy derivatives of 2,5-diphenylsilacyclopent-3-ene were prepared by a one-pot reaction of magnesium with (E,E)-diphenyl-1,3-butadiene and dialkoxydichlorosilanes. The trans content in each silacyclopentene was higher than the cis content. Hydrogenation of these silacyclopentenes gave the corresponding silacyclopentanes in high yields.
Synthesis of a Stereoisomer of Frullanolide Utilizing the Intramolecular Cyclization of ω-Formyl-2-alkenylsilane
Authors: Kuroda Chiaki , Shimizu Shigeru , Haishima Takahiro , Satoh James Y
Published: August 2006

Synthesis of 10-epi-frullanolide (3) is reported via the intramolecular cyclization of ω-formyl-α-trimethylsilylmethyl-α,β-unsaturated ester. The cyclization precursor, ethyl (Z)-5-(2-formyl-1,3-dimethyl-2-cyclohexenyl)-2-trimethylsilylmethyl-2-pentenoate (17), was prepared from 2,6-dimethyl-2-cyclohexen-1-one through the dialdehyde monoacetal as the key intermediate. Cyclization of 17 with tetrabutylammonium fluoride produced the hydroxy ester having C(6α)–H and C(7β)–H, which was hydrolyzed, then subjected to Fujisawa’s lactonization to afford 3.
Reactions of Cyclic C7H6-System: Reactions of a Tautomer of Cycloheptatetraene and Cycloheptatrienylidene with Tropone, Heptafulvene, and 1,3,5-Cycloheptatriene Derivatives
Authors: Saito Katsuhiro , Suzuki Satoshi , Watanabe Tetsuya , Takahashi Kensuke
Published: August 2006

Reactions of a cyclic C7H6-system, a tautomer of 1,2,4,6-cycloheptatetraene and 2,4,6-cycloheptatrienylidene, with tropone derivatives and 8,8-dicyanoheptafulvene afforded exo-[4π+2π] cycloadducts. Similar reactions with 1,3,5-cycloheptatriene derivatives gave exo-[6π+2π] cycloadducts. These reactions are considered to proceed through zwitter ionic intermediates containing tropylium ion moieties.
Stereoselectivity in the Preparation of 5,6-Dideoxy-5-dimethoxyphosphinyl-d- and -l-hexofuranoses, and an Efficient Synthesis of 5,6-Dideoxy-5-hydroxyphosphinyl-l-galactopyranose (a P-in-the-Ring l-Fucose Analogue)
Authors: Hanaya Tadashi , Yasuda Kiyomi , Yamamoto Hiroshi , Yamamoto Hiroshi
Published: August 2006

The addition of dimethyl phosphonate to five kinds of 6-O-tosyl-hexofuranos-5-uloses 3a—e (α-d-xylo, α-d-ribo, β-d-arabino, α-d-lyxo, and β-d-ribo) in the presence of DBU, followed by the catalytic hydrogenolysis in the presence of Raney-Ni (W-4), afforded (5S)- and (5R)-5,6-dideoxy-hexofuranose derivatives in the ratios of 1 : 0—2 : 1, depending upon the kinds of substituents on the β-side of the furanose ring of the intermediate 5,6-dideoxy-hex-5-enofuranoses. A P-in-the-ring sugar analogue of l-fucose type, 5,6-dideoxy-5-hydroxyphosphinyl-l-galactopyranoses, was efficiently prepared from 3-O-benzyl-5,6-dideoxy-1,2-O-isopropylidene-5-dimethoxyphosphinyl-α-l-galactofuranose readily obtained by the selective preparation mentioned above.
Synthesis of Dibenzotrisdehydro[16]annulene-1,4-dione and the Related Compounds
Authors: Higuchi Hiroyuki , Yamamoto Hiroyuki , Ojima Juro , Yamamoto Gaku
Published: August 2006

Synthesis of 7,8:13,14-dibenzo-2,9,11-trisdehydro[16]annulene-1,4-dione is described. Attempts to prepare diaza[18]annulene derivatives by ring expansion of the dibenz[16]annulenedione and its dimethyl analog are also described. Examination of 1H NMR spectra indicates that the dibenz[16]annulenedione shows no ring current effect.
Favorskii Rearrangement and Carbon–Carbon Bond-Cleavage of α-Chloro-α-sulfonyl Ketones: A Synthesis of Carboxylic Acids and Their Derivatives from Aldehydes and Ketones
Authors: Satoh Tsuyoshi , Oguro Kazuko , Shishikura Jun-ichi , Kanetaka Naomi , Okada Reiko , Yamakawa Koji
Published: August 2006

A method for synthesizing carboxylic acids and their derivatives from aldehydes and ketones via α-chloro-α-sulfonyl ketones is described. Acyclic α-chloro-α-sulfonyl ketones were synthesized from aldehydes and 1-chloroalkyl p-tolyl sulfoxides with carbon–carbon coupling in good overall yields. Cyclic α-chloro-α-sulfonyl ketones were synthesized from cyclic ketones in three steps in high overall yields. The Favorskii rearrangement of both acyclic- and cyclic α-chloro-α-sulfonyl ketones with sodium hydride in the presence of amine gave β-sulfonyl amides with skeletal rearrangement in good to excellent yield. Amides and α,β-unsaturated amides were synthesized from the β-sulfonyl amides. Treatment of the cyclic α-chloro-α-sulfonyl ketones with alkoxides and hydroxide gave carboxylic esters and acids with cleavage of the ring in good to excellent yields.
Triethylborane Induced Stereoselective Radical Addition of R3SiH to Acetylenes and Stereoselective Reduction of Alkenyl Iodides with Tris(trimethylsilyl)silane
Authors: Miura Katsukiyo , Oshima Koichiro , Utimoto Kiitiro
Published: August 2006

Triethylborane induced radical addition of various organosilanes (R3SiH) to acetylenes has been studied. Among them, tris(trimethylsilyl)silane (TTMSS) proved to be the best reagent for the hydrosilylation of acetylenic compounds in terms of yield and stereoselectivity. For instance, reaction of 1-dodecyne with TTMSS at room temperature for 3 h under Et3B catalyst provided (Z)-1-tris(trimethylsilyl)silyl-1-dodecene selectively in 98% yield. The stereochemical course of reduction of alkenyl iodides with TTMSS–Et3B or n-Bu3SnH–Et3B has been examined. Treatment of 1-dimethylphenylsilyl-2-iodo-1-dodecene with TTMSS–Et3B at room temperature afforded (Z)-1-dimethylphenylsilyl-1-dodecene selectively (Z/E > 30/1). On the other hand, treatment with n-Bu3SnH-Et3B gave (E)-1-dimethylphenylsilyl-1-dodecene exclusively.
Bis(η5-methylcyclopentadienyl)dihydridomolybdenum(IV). Synthesis and Reactions with Nucleophiles in the Presence of Protonic Acids
Authors: Ito Takashi , Yoden Tohru
Published: August 2006

[Mo(η5-MeCp)2H2] (3) (MeCp = C5H4Me) which was prepared by the reaction of MoCl5 with Na(MeCp) in the presence of NaBH4 was treated with p-toluenesulfonic acid (TsOH) to give [Mo(η5-MeCp)2H(OTs)]. Reactions of 3 with allyl alcohol in the presence of TsOH yielded [Mo(η5-MeCp)2(η3-C3H5)]+TsO− whereas the similar reaction with 2-methyl-2-propen-1-ol yielded . When the reactions of 3 with protonic acid HA (HA = TsOH and AcOH) were carried out in the presence of acetone or 4-t-butylcyclohexanone, [Mo(η5-MeCp)2A2] were formed accompanied by the reduction of ketones to the corresponding alcohols. The results are compared with the similar reactions with cyclopentadienyl analog of 3.
Interactions of Some Cationic Cobalt(III) Complexes with Anions Studied by the 59Co NMR Chemical Shifts
Authors: Iida Masayasu , Miyagawa Yasuko , Kohri Sachiko
Published: August 2006

The NMR peak of 59Co(III) cationic complexes shifts upfield upon interacting with anions when the interaction is mainly electrostatic; it shifts downfield when the hydrophobic interaction acts additively with the electrostatic interaction. These trends are enhanced in micellar solution systems.
Effect of Pressure on the Solubility of Sodium Bromide in Water
Authors: Sawamura Seiji , Yasuhara Shigeo , Sugi Shigeru , Egoshi Nobuaki
Published: August 2006

The solubility (ms) of sodium bromide (NaBr·2H2O) in water was measured at 283.15—313.15 K and 0.1—300 MPa. The ms decreases with increasing pressure and the coefficient, θ ( = (∂ms/∂p)T/ms), is −10 × 10−5 MPa−1 at 298.15 K and 0.1 MPa. This sign of θ is opposite to that (7 × 10−5 MPa−1) calculated using a thermodynamic equation.
Anion-Exchange Separation and Estimation of Thorium in Niobite-Tantalite Type Minerals: A New Approach
Authors: Premadas A
Published: August 2006

A simple, rapid and quantitative anion-exchange separation of microgram to milligram quantities of thorium has been achieved from milligram quantities of niobium, tantalum, and titanium in citric acid-nitric acid medium. This method is successfully applied for the separation and estimation of thorium in niobite-tantalite type minerals. Sample (0.500 g) is fused with ca. 8 g KHSO4and is taken in ca. 7% citric acid medium. To a suitable aliquot ca. 8 M (1 M = 1 mol dm−3) nitric acid acidity is maintained in ice cold condition, and is passed through a column of Dowex-lX8 (100—200 mesh size). Thorium is eluted with ca. 6 M HCl and estimated spectrophotometrically with arsenazo III. The RSD obtained by this method is 2—3%.
Comparison of High-Resolution Scanning Electron Microscopy with Transmission Electron Microscopy for the Characterization of Ultrafine Palladium Particles Embedded on Active Carbon
Authors: Takasu Yoshio , Kaneko Fuminori , Tsutsui Tsuyoshi , Nakagawa Mine , Yamada Mitsuo , Yahikozawa Kiyochika
Published: August 2006

Ultrafine palladium particles supported on powdery active carbon have been characterized by high-resolution scanning electron (secondary and reflection electron images) and transmission electron microscopies. The former was advantageous for the simultaneous observation of metal catalyst particles (smaller than 1.5 nm in diam.) as well as the surface morphology of their support.
Synthesis and Properties of Two Simplified Peptides of PA1-14, the N-Terminal 1-14 Residues of Adrenodoxin Precursor
Authors: Waki Koji , Tani Ayako , Kato Tamaki , Aoyagi Haruhiko
Published: August 2006

Two simplified peptides of PA1-14, which corresponds to the N-terminal 1-14 residues of adrenodoxin precursor, were synthesized and examined by circular dichroism and dye leakage measurements. Both peptides showed a tendency to form α-helices and exhibited moderate dye leakage.
Synthesis and Adiabatic Photochemistry of a 1,4-Difluorobenzene – Naphthalene Biplanemer
Authors: Okamoto Hideki , Kimura Masaru , Satake Kyosuke , Morosawa Shiro
Published: August 2006

A naphtalene-1,4-difluorobenzene biplanemer 1a has been prepared through the electrolytic oxidative didecarboxylation. The direct irradiation of 1a gave 1,4-difluorobenzene and excited naphthalene in both a singlet state (Φf = 0.098) and a triplet state (Φp = 0.029) at 77 K in EPA. In the triplet-sensitized reaction, the biplanemer 1a underwent intramolecular [2π+2π] cycloaddition to give a cage compound instead of the formation of the triplet naphthalene.
Reaction of N″-Cyanoguanidine with Formaldehyde (VII). Preparation of New Flocculants for Anionic Colloidal Particles
Authors: Shiba Ryuichi , Takahashi Miyuki , Ebisuno Toichi , Takimoto Michiaki
Published: August 2006

New flocculants for anionic colloidal particles were prepared from the reaction of the free bases of N,N-(diaminomethylene)urea (DU) and N,N′-methylenebis[N′-(diaminomethylene)urea] (Bis-DU) with formaldehyde. These are superior to the resinous product of N″-cyanoguanidine with formaldehyde regarding coagulation activity. The gelpermeation chromatograms of these resinous products elucidate that the components of the resin having higher molecular weights as well as the cationic charges play an important role in flocculation.