bluuebunny/crossref_metadata_2025 huggingface dataset:
Solubility Differences among Geometric and Optical Isomers of Tris(amino acidato)cobalt(III)
Authors: Yoshimura Yasuki
Published: September 2002

The solubilities of soluble mer-(-)-isomers of various tris(amino acidato)cobalt(III) ([Co(aa)3]) in water were determined over the temperature range 5 to 50 °C. From these data the standard free energy (ΔdisG°), enthalpy (ΔdisH°), and entropy of dissolution (ΔdisS°) at 25 °C were estimated and compared with the values reported for mer-(+)-, fac-(-)-, and fac-(+)-isomers of [Co(aa)3]. The solubilities of these isomers increase in the order fac-(+)- < fac-(-)- < mer-(+)- < mer-(-)-isomers for [Co(aa)3] synthesized from amino acids with longer side chains than 2-aminobutyric acid. On the other hand, the increasing sequence of the solubilities for tris(L-alaninato)cobalt(III) ([Co(L-ala)3]) and tris(L-serinato)cobalt(III) ([Co(L-ser)3]) is fac-(+)- < mer-(+)- < fac-(-)- < mer-(-)-isomers. The solubility differences between the mer- and fac-isomers and between the (-)- and (+)-isomers are discussed based on the differences of ΔdisH° and TΔdisS° among these isomers. Furthermore, the influence of introducing hydroxyl and methyl groups into the side chains of the amino acids on the dissolution behavior of [Co(aa)3] is discussed.
Interfacial Solubilization of (5,10,15,20-Tetraphenylporphyrinato)zinc(II) in Cetyltrimethylammonium Chloride Reversed Micellar Solutions
Authors: Nakashima Toshiyuki , Fujiwara Terufumi , Kumamaru Takahiro
Published: September 2002

The interaction between the zinc(II) complex of 5,10,15,20-tetraphenylporphyrin (Zn(tpp)) and cetyltrimethylammonium chloride (CTAC) at the interface of a CTAC reverse micelle in chloroform and 6 : 5 (v/v) chloroform–cyclohexane has been investigated spectrophotometrically. The spectra of Zn(tpp) in the CTAC reversed micellar solutions provide evidence of formation of the associated species Zn(tpp)CTAC; its Soret band is not influenced by solvent polarity. At a fixed molar ratio of water to surfactant (Rw = [H2O]/[CTAC]), the absorbance at the maximum of the Zn(tpp)CTAC band increases with an increase in the CTAC concentration. In the slope of the plot a discontinuity was found, due to formation of reverse micelles at this CTAC concentration, taken as the critical micelle concentration (cmc). The variations of the spectral data were interpreted quantitatively by applying the pseudophase model. Increasing Rw causes a decrease in the Zn(tpp)-solubilizing ability of reverse micelles, implying that the nucleophilicity of Cl- ion to the central zinc of the complex is dropped by the Cl- hydration at the interface. Furthermore, the standard free energy of micellization, calculated from the cmc data, indicates that the micellization is promoted by the Cl- hydration and by decreasing the chloroform fraction in the bulk organic phase.
Controlling Factors of Weak Acid and Base Concentrations in Urban Dewwater—Comparison of Dew Chemistry with Rain and Fog Chemistry—
Authors: Takeuchi Masaki , Okochi Hiroshi , Igawa Manabu
Published: September 2002

Dewwater was collected from January 1993 to December 2000 in Yokohama, Japan, and analyzed for weak acid anions with other major chemical components. The volume-weighted average and medium pH of the dewwater were 4.88 and 6.08, respectively, at our sampling site. Weak acids (carbonate, nitrite, sulfite, formate, and acetate ions) were the major species in the dewwater and were several times higher than those in the rain- and fogwater. The concentrations of these species and ammonium ion can be estimated by the resistance model. The estimated values of N(III) correlate relatively well with the measured values, which shows the origin of N(III) in dewwater is nitrous acid in the ambient air. On the other hand, ammonium ion in the dewwater originated from not only gaseous ammonia but also aerosol ammonium ions. Hydrogensulfite ions in the dewwater which originated from sulfur dioxide are an important species as the precursor of the sulfate and they were stabilized by forming hydroxyalkanesulfonate (HASA). Formic acid and acetic acid in the dewwater originated mainly from gas, while the oxalic acid is from aerosol.
The Treatment of Hazardous Substances in Scrubbing Water
Authors: Araya Hirotoshi
Published: September 2002

The scrubbing waters of the combustion exhaust gases containing low concentrations of cyanide ion, formaldehyde, phosphate ion and fluoride ion were treated by the methods for concentrated liquid wastes. Such methods were applicable to the scrubbing waters which did not contain fluoride ions.
High Axial Coordination in a cis-Coordinated Succinimidatocopper(II) Complex
Authors: Akitsu Takashiro , Komorita Seiko
Published: September 2002

A copper(II) complex [Cu(succim)2(N-Eten)(H2O)2] (succim = succinimidate and N-Eten = N-ethylethylenediamine) was prepared and characterized by X-ray crystallography and polarized crystal electronic spectra. The complex has a distorted octahedral [CuN4O2] chromophore. The π-donor succim ligands on cis-positions raise the potential of axial coordination up to six-coordination to maintain electroneutrality of the complex.
Photochemical Reactions of Hydroarenes with N-Bromosuccinimide
Authors: Zong Zhi-Min , Zhang Wei-Hong , Jiang Qun , Lu Jin , Wei Xian-Yong
Published: September 2002

The photochemical reactions of 1,2,3,4-tetrahydronaphthalene (THN), 9,10-dihydrophenanthrene (DHP), 9,10-dihydroanthracene (DHA), and acenaphthene (AN) with N-bromosuccinimide (NBS) were investigated under N2 atmosphere at room temperature. The results show that the relative reactivities of the hydroarenes toward a photochemical reaction with NBS are THN < DHP < AN << DHA, which is consistent with the stabilities of the radicals produced by benzylic hydrogen abstraction from the hydroarenes. Photochemical reactions of THN and DHP mainly afforded dehydrogenated products, while the photobrominations of the dehydrogenated products from AN and DHA with NBS proceeded readily.
Inclusion Complexes of Cyclodextrins with Methylene Blue and α-Naphthol Orange and Temperature Dependence of the Inclusion Complexation in Aqueous Solutions
Authors: Hamai Sanyo , Satou Hideyuki
Published: September 2002

Methylene Blue (MB) has been found to form a complex with α-Naphthol Orange (αNO) in aqueous solution. From a simulation concerning the fluorescence quenching of MB by αNO, an equilibrium constant for the formation of the 1 : 1 MB–αNO complex has been estimated to be 79900 mol-1 dm3. Upon the addition of γ-CD to MB solution containing αNO, the absorption of the MB monomer band is enhanced in intensity without an appearance of the MB dimer band, indicating the formation of a ternary γ-CD–MB–αNO inclusion complex. To determine a stoichiometry of the ternary inclusion complex, a continuous variation method using the fluorescence intensities has been performed under the condition that the sum of the initial concentrations of γ-CD and αNO has been kept constant. The result of the continuous variation method indicates the formation of a 2 : 1 : 1 γ-CD–MB–αNO inclusion complex. The equilibrium constant for the formation of the γ-CD–MB–αNO inclusion complex from γ-CD and the 1 : 1 MB–αNO complex has been evaluated to be 1.86 × 109 mol-2 dm6 from a simulation concerning the absorbance change. From the temperature dependence of the equilibrium constants, ΔH and ΔS values have been evaluated for the γ-CD–MB–αNO and γ-CD–MB–Acid Orange 7 systems. The ΔH and ΔS values for the formation of the γ-CD–MB–αNO inclusion complex have been positive in sign, in contrast to those for the formation of the MB–αNO and γ-CD–αNO complexes.
Preparation and Rearrangement of Arylhydroxymethano[3]orthocyclo[5](1,8)naphthalenophanes.
Authors: Isobe Shin-ichiro , Kubo Kanji , Thiemann Thies , Sawada Tsuyoshi , Yonemitsu Tadashi , Mataka Shuntaro
Published: September 2002

Arylhydroxymethano[3]orthocyclo[5](1,8)naphthalenophanes 11, which possess a rigid boat-chair conformation, were prepared by the reaction of 9,10-benzo-3,4,5-[1,8]naphthobicyclo[5.4.1]dodecan-3,9-dien-12-one 8c with aryllithium reagents and treated with hydrobromic acid in dioxane. The intermediary cation generated from 11 rearranged either to a benzo[cd]azulene system of type 12 or to a tricyclic system containing a cyclopropane-unit of type 13, depending on the nature of the aryl substituent on the bridging carbon atom.
Synthesis, Solution Chemistry, X-ray Structure and Biological Activity of Novel Pyridoxal Thiosemicarbazone Derivatives
Authors: Ferrari Marisa Belicchi , Bisceglie Franco , Leporati Enrico , Pelosi Giorgio , Tarasconi Pieralberto
Published: September 2002

Novel ligands were obtained by condensation of pyridoxal with thiosemicarbazides substituted with alkyl and aryl moieties on the aminic and/or hydrazinic nitrogen. The spectrophotometric characteristics of the various species are reported. The X-ray structure of two different dimethylthiosemicarbazones of pyridoxal — pyridoxal N1,N2-dimethylthiosemicarbazone monohydrate and pyridoxal N1,N1-dimethylthiosemicarbazone monohydrate — was determined. The change of methyl group position determines in the solid state strong differences which affect the ligand behavior of these compounds. In the first ligand, characterized by X-ray diffraction, the pyridoxal ring is in a zwitterion form, with the phenolic oxygen and the sulfur atoms in trans position to the iminic N atom. The second compound, with both methyl groups on the aminic nitrogen, shows the donor atoms SNO on the same side, making it potentially suitable for coordination to the metal. Biological studies have involved both inhibition of cell proliferation and apoptosis tests on human leukemia cell lines U937. Both ligands inhibited cell growth, but neither of them induced apoptosis. On the basis of the pKa values, the second ligand is more easily dissociable and this allows us to predict the formation of neutral complexes with it.
A Product Analytical Study of the Thermal and Photolytic Decomposition of Some Arenediazonium Salts in Solution
Authors: Canning Peter S J , Maskill Howard , McCrudden Katharine , Sexton Brian
Published: September 2002

Products of thermal and photochemical reactions of eleven arenediazonium tetrafluoroborates in various solvents have been analyzed. All compounds in most solvents undergo unimolecular heterolysis to give singlet aryl cations which are captured by solvent. This mechanism is dominant for arenediazonium ions without electron-withdrawing substituents in all solvents, and the only reaction observed in water. Additionally, appreciable yields of fluoroarenes are obtained by fluoride abstraction by the aryl cation from fluorinated solvents and from tetrafluoroborate in fluorinated solvents. Yields from photochemical processes are very similar to those from thermal reactions indicating that the main reactions proceed through common or very similar intermediates. Aryl cations formed from ion-paired diazonium ions may react with the counterion, but fragmentation of dissociated diazonium ions leads only to solvent-derived product. Some arenediazonium ions in some solvents undergo an alternative radical reaction leading principally to hydrodediazoniation. It is proposed that this reaction involves initial rate-limiting electron transfer from ethanol to the arenediazonium ion followed rapidly by homolysis of the resultant aryldiazenyl radical. Within the same solvent cage, the aryl radical then either abstracts an α-hydrogen from the ethanol radical cation generated in the first step to give the reduction product and protonated acetaldehyde, or combines with it at the oxygen to give a protonated aryl ethyl ether.
Construction of Fused Cyclooctanoid Ring Systems via Seven-Membered Ring Carbonyl Ylides
Authors: Muthusamy Sengodagounder , Babu Srinivasarao Arulananda , Gunanathan Chidambaram , Suresh Eringathodi , Dastidar Parthasarathi
Published: September 2002

A series of α-diazo carbonyl compounds tethered to cyclopentanone/cyclohexanone/1-tetralone units have been synthesized using a diazomethane solution to construct various fused cyclooctane ring systems via rhodium-generated carbonyl ylides. The reaction of rhodium(II) acetate dimer with various α-diazo carbonyl compounds generated transient cyclic seven-membered ring carbonyl ylides, which underwent facile 1,3-dipolar cycloadditions with dipolarophiles, like N-phenylmaleimide, p-benzoquinone, and DMAD to furnish a variety of fused epoxy-bridged cyclooctane ring systems in a tandem manner. Interestingly, an oxepine ring system was generated via an intramolecular proton transfer of a seven-membered ring carbonyl ylide. A tri-oxa polycyclic compound was obtained in the case of p-benzoquinone as dipolarophile. A single-crystal X-ray analysis of a fused cyclootanoid derivative is reported to decisively establish the structure and stereochemistry of the fused epoxy-bridged cyclooctane ring systems; a further analysis revealed the existence of a unique intermolecular C–H···π interaction motif in the solid-state architecture.
A Novel Reductase Participating in the Hydrogenation of an Exocyclic C–C Double Bond of Enones from Nicotiana tabacum
Authors: Shimoda Kei , Izumi Shunsuke , Hirata Toshifumi
Published: September 2002

A novel 74 kDa enone reductase which catalyzes the reduction of the exocyclic C–C double bond of enones was isolated from cultured cells of Nicotiana tabacum. The reductase was found to catalyze the enantiofacially selective reduction of the C–C double bond of 2-alkylidenecyclohexanone to give optically active (S)-2-alkylcyclohexanone.
Preparation and Conformational Analysis of 6,10-Diethyl[1,2,3]trithiolo- [4,5-h]benzopentathiepin Monoxides: Isolation and Optical Properties of Chiral Benzopentathiepin Derivatives
Authors: Kimura Takeshi , Hanzawa Masayuki , Tsujimura Kazuhiko , Takahashi Tatsuya , Kawai Yasushi , Horn Ernst , Fujii Takayoshi , Ogawa Satoshi , Sato Ryu
Published: September 2002

6,10-Diethyl[1,2,3]trithiolo[4,5-h]benzopentathiepin (1) was oxidized by mCPBA in dichloromethane to produce the corresponding four monoxides. The structures of the monoxides 2, 3, 4, and 5 were determined by X-ray crystallography to be 6,10-diethyl[1,2,3]trithiolo[4,5-h]benzopentathiepin 8-oxides (1,2,3-trithiole 2-oxides) for 2 and 3, and 6,10-diethyl[1,2,3]trithiolo[4,5-h]benzopentathiepin 7-oxides (1,2,3-trithiole 1-oxides) for 4 and 5, respectively. Compounds 2 and 3 are isomers with respect to the conformation of the 1,2,3,4,5-pentathiepin ring, and 4 and 5 are also the conformational isomers. These compound pair members, 2 and 3, and 4 and 5, were found to isomerize each other by inversion of the pentathiepin ring. The activation parameters of the isomerization, ΔG298≠, ΔH≠, and ΔS≠, were determined by 1H NMR spectroscopy. Because of the slow inversion of the pentathiepin ring, isolation of unsymmetrically substituted benzopentathiepin as a chiral molecule is possible. Asymmetric oxidation of 1 was performed by a Sharpless reagent [1/Ti(OiPr)4/R,R-DET/t-BuOOH = 1 : 2 : 4 : 4] to produce optically active monoxides 4a and 5a. The configuration of 4a and 5a was confirmed as R configuration on the sulfinyl sulfur atom, respectively. The specific rotation and the circular dichroism spectra of 4a and 5a were measured in chloroform; such data are apparently affected by the conformation of the pentathiepin ring.
Rhodium- and Ruthenium-Catalyzed Dehydrogenative Borylation of Vinylarenes with Pinacolborane: Stereoselective Synthesis of Vinylboronates
Authors: Murata Miki , Kawakita Koji , Asana Taichi , Watanabe Shinji , Masuda Yuzuru
Published: September 2002

The treatment of pinacolborane (4,4,5,5-tetramethyl-1,3,2-dioxaborolane) with vinylarenes in the presence of a catalytic amount of phosphine-free di-μ-chlorobis(1,5-cyclooctadiene)dirhodium(I) [RhCl(cod)]2, through dehydrogenative borylation, provides the corresponding regio- and stereodefined (E)-2-arylethenylboronates in high yields. Also, a ruthenium complex prepared in situ from (1,5-cyclooctadiene)(1,3,5-cyclooctatriene)ruthenium(0) [Ru(cod)(cot)] and P(4-CF3C6H4)3 showed considerable catalytic activity for dehydrogenative borylation.
Conformational Study of Isobutenylene Chains in Tandem Claisen Rearrangement Products. Insights from X-ray Crystallography and 1H NMR for Salicylideneaniline Derivatives
Authors: Houjou Hirohiko , Tsuzuki Seiji , Nagawa Yoshinobu , Hiratani Kazuhisa
Published: September 2002

A new variety of salicylideneaniline derivatives were prepared from a substituted aniline and a bis(hydroxybenzaldehyde) which has been synthesized through a tandem Claisen rearrangement reaction. X-ray crystal structures were obtained for many of the products. With respect to the conformation of their isobutenylene chain, the crystal structures can be classified into three groups: i.e., skew–skew (I), syn–skew (II), and syn–syn (III) conformers. The 1H NMR spectra were significantly different among these compounds, especially for the isobutenylene moiety. The set of the chemical shifts, (δ (Ha), δ (Hb)), of exo-methylene (Ha) and benzylic methylene (Hb) is a good index for classifying the NMR spectra, and these values also reflect the conformation of the isobutenylene chain found in the crystal state. Namely, each conformer of I, II, and III corresponds to the (δ (Ha), δ (Hb)) values (ppm) around (5.10, 3.43), (4.86, 3.43), and (4.74, 3.56), respectively. This result is verified by the complexation study of a 15-crown-5 derivative with alkali metal ions. The chemical shift change caused by the complexation is successfully explained by the conformation changes among I, II, and III.
Radical Addition of α-Halo Ester to Homoallylic Gallium or Indium Species: Formation of Cyclopropane Derivatives
Authors: Usugi Shin-ichi , Tsuritani Takayuki , Yorimitsu Hideki , Shinokubo Hiroshi , Oshima Koichiro
Published: September 2002

Treatment of benzyl bromoacetate with 3-butenylgallium dichloride in ether in the presence of a catalytic amount of Et3B as a radical initiator provided benzyl 3-cyclopropylpropanoate in 64% yield via a radical addition–substitution sequence. The use of 3-butenylindium dichloride in place of the gallium reagent also afforded the same product in good yield.
Synthetic Studies on Ceratospongamides, Cyclic Heptapeptides Containing Thiazole and Oxazoline Units: Total Synthesis of cis,cis-Ceratospongamide
Authors: Kutsumura Noriki , Sata Noriko U , Nishiyama Shigeru
Published: September 2002

A total synthesis of cis,cis-ceratospongamide 1a, a cycloheptapeptide isolated from the Indonesian red alga Ceratodictyon spongiosum and the symbiotic sponge Sigmadocia symbiotica, was accomplished. The heptapeptide chain 8 was produced by a stepwise connection of the following segments: (L-Phe-L-Pro)-thiazole residue, L-Phe-L-Pro-OMe, and L-Ile-L-aThr-OMe. Macrolactamization of 8, followed by cyclization to an oxazoline ring, provided cis,cis-ceratospongamide 1a along with its diastereomer 1c, which was different from the reported trans,trans-ceratospongamide 1b. The structural determination of 1c and its conversion to 1a were successfully achieved.
Collision Energy Dependence Measurement of the Total De-excitation and the CF3* Chemiluminescence Cross Sections in the Ar(3P) Reaction with CF3H
Authors: Kawaguchi Hisashi , Ohoyama Hiroshi , Kasai Toshio
Published: September 2002

The collision energy dependences of the total de-excitation and the CF3* chemiluminescence cross sections were measured in the reaction of Ar(3P) with CF3H using conventional and cross-correlation TOF methods. In the latter method, which is favorable for detecting weak signals, we employed a pseudorandom pulse discharge to generate a metastable argon beam. The collision energy dependence for the CF3* chemiluminescence channel gives a positive slope as a function of the collision energy with a threshold of 0.10 eV. The collision energy dependence of the total de-excitation in the entrance channel, on the other hand, shows a steep decrease as a function of collision energy without any threshold. These results provide insight into the detailed dynamics at crossing points of the potential energy surfaces.
Efficient and Selective Trimerization of Aryl and Alkyl Isocyanates Catalyzed by Sodium p-Toluenesulfinate in the Presence of TBAI in a Solvent-Free Condition
Authors: Moghaddam Firouz Matloubi , Dekamin Mohammad G , Khajavi Mohammad S , Jalili Seifollah
Published: September 2002

Aryl and alkyl isocyanates have been efficiently converted into symmetrical trisubstituted aryl and alkyl isocyanurates, catalyzed by sodium p-toluenesulfinate on its own or in the presence of tetrabutylammonium iodide (TBAI), in a solvent-free condition. The latter has been shown to have a higher catalytic activity.
Triethylborane-Induced Radical Reactions in Ionic Liquids
Authors: Yorimitsu Hideki , Oshima Koichiro
Published: September 2002

Some triethylborane-induced radical reactions were found to proceed in ionic liquids. The reactions include atom transfer radical cyclization, hydrostannylation of alkyne, and atom transfer radical addition. Benzyl bromoacetate participated in the bromine atom transfer addition reaction to 1-octene in 1-ethyl-3-methylimidazolium tetrafluoroborate to afford the corresponding adduct in excellent yield. The facile bromine atom transfer addition in the ionic liquid indicates that the ionic liquid may have a highly polar nature. The ionic liquid used was recyclable in one case, but was not in the other case.
Flame-Induced Addition of Urea to Unsaturated Carboxylic Acids
Authors: Terasaki Masanori , Nomoto Shinya , Mita Hajime , Shimoyama Akira
Published: September 2002

When a hydrogen-oxygen flame was blown against an aqueous solution of urea and maleic acid, N-carbamoylaspartic acid was generated. This compound seemed to be formed by the addition of an amidinoxyl radical to a C–C double bond of the acid, followed by a thermal rearrangement of an amidinoxy to a ureido group.
The Facile Oxidative Coupling of a Hindered Phenol, 2,6-Di-t-butylphenol, Driven by N,N′-Bis(ethoxycarbonyl)-1,4-benzoquinone Diimine; The Reaction Pattern Traced by 1H NMR Spectroscopy
Authors: Miyagi Yo , Banjyo Noriko , Yamamura Emiko
Published: September 2002

Good yields of 3,3′,5,5′-tetra-t-butyl-4,4′-diphenoquinone were obtained by the reaction of 2,6-di-t-butylphenol with N,N′-bis(ethoxycarbonyl)-1,4-benzoquinone diimine, which had been shown to undergo addition with aniline derivatives and phenols. The reaction was followed with 1H NMR spectroscopy to deduce the reaction intermediates.
Organization of Amphiphiles, Part 1: Evidence in Favor of Pre-micellar Aggregates through Fluorescence Spectroscopy
Authors: Sahoo Lingaraj , Sarangi Jitendra , Misra Pramila K
Published: September 2002

The advantage of a change in the vibrational structure of the emission spectra of pyrene as a function of the concentration of a series of polyoxyethylated alkyl ethers and alkylsulfonates has been utilized to explore the co-operative association of ionic and nonionic amphiphiles into micelles, the micropolarity of these micelles and the solubilization site of pyrene in micelles. The results indicate that the micropolarity of the environment experienced by pyrene is alcohol-like. Pyrene preferably resides in the palisade layer of a nonionic micelle, while in the interior of an anionic micelle. A multiple equilibrium model for micelle formation has been suggested and the existence of pre-micellar aggregates has been evidenced from the excimer characteristics of pyrene.
LB Deposition of a Stearic Acid Multilayer without Heavy Metals
Authors: Hayashi Shujiro , Yokogawa Yoshiyuki , Kinoshita Takatoshi
Published: September 2002

LB films consisting of stearic acid (SA) multilayers and silicon substrates without heavy metal were prepared using a computer-controlled LB film deposition apparatus. Using dimethyldioctadecylammonium bromide as the first (or first and second) monolayer(s), up to 70 layers were deposited, and the interference color was expressed. This indicated that the surface charge of the substrate needed to be canceled in order to successfully deposit a multilayer. Moreover, it was demonstrated that LB multilayers of fatty acid could be prepared using a computer-controlled apparatus even without using a heavy metal salt.
Degradation of Mixed Char of Poly(vinyl chloride) with Polyethylene Glycol to Give Hydrocarbons by the Reaction with Potassium Carbonate in Supercritical Water: Formation of Hydrocarbons Containing Lower Amounts of Benzene Accompanied by Formation of Water Soluble Potassium Salts of Carbon Oxides
Authors: Akiyama Fuminori
Published: September 2002

Degradation of char from poly(vinyl chloride) (PVC) or chars from mixtures of PVC and polyethylene glycol (PEG) with potassium carbonate in supercritical water was performed. Degradation of chars from a mixture of PVC and PEG prepared by heating at 250 °C in nitrogen atmosphere with potassium carbonate at 500 °C for 3 h in supercritical water gave a mixture of hydrocarbons in the yield of 11 wt%, in which the content of benzene was only 5%, accompanied by formation of oil in the yield of 16 wt%. The main reaction products in this degradation reaction were water soluble products. The facts that these water-soluble products did not any absorption in 1H NMR and 13C NMR spectra and that these water-soluble products show FT-IR absorptions at 1378 and 1622 cm-1 suggest that these water soluble products are potassium salts of carbon oxides.
Accelerated Corrosion of Stainless Steels with the Presence of Molten Carbonates below 923 K
Authors: Ota Ken-ichiro , Toda Katsuya , Mitsushima Shigenori , Kamiya Nobuyuki
Published: September 2002

The high-temperature corrosion of stainless steels (SUS316L and SUS310S) in the presence of lithium-potassium eutectic carbonate and lithium-sodium eutectic carbonate has been studied by thermogravimetry and the metal consumption method under a carbon dioxide–oxygen atmosphere in the temperature range of 773–1123 K. Although the corrosion of SUS310S obeyed the parabolic rate law for all reaction conditions, the corrosion of SUS316L significantly depended on the reaction conditions. At or above 923 K, the corrosion of SUS316L obeyed the parabolic rate law, even with a carbonate coating. The corrosion rates were accelerated during the initial period of corrosion tests below 923 K, especially around 823 K with a lithium-sodium carbonates coating. The initial accelerated corrosion was a local corrosion, which produced through holes in the metal specimens, and occurred more clearly at higher carbon dioxide partial pressures with the lithium-sodium carbonate coating than with the lithium-potassium carbonate coating.
Physical Chemistry of the Lowest Excited Singlet State of trans-Stilbene in Solution as Studied by Time-Resolved Raman Spectroscopy
Authors: Hamaguchi Hiro-o , Iwata Koichi
Published: September 2002

Structure and dynamics of the lowest excited singlet state of trans-stilbene (the S1 state of tSB) in solution are discussed with an emphasis placed on the elucidation of the mechanism of the trans–cis photoisomerization. Structure of S1  tSB in solution is first discussed based on the time-resolved Raman spectral data and their isotope substitution effects. Original data for an asymmetrically deuteriated tSB, tSB-d5, are presented to confirm the ethylene-like structure of the central C–C linkage of S1  tSB. Next, the time-, temperature-, and solvent-dependent band shape changes of the olefinic C=C stretch band are discussed in terms of the solvent induced dynamic polarization. It is shown that the dynamic polarization model accounts very well, not only for the observed band shape changes, but also for their relevance to the isomerization mechanism. A new microscopic view on the photoisomerization of tSB is thus presented. Picosecond energy dissipation process of S1  tSB is then discussed in relation to the microscopic solvation structure in chloroform. Finally, the mechanism of a new bimolecular reaction between S1  tSB and carbon tetrachloride is discussed on the basis of the diffusion-controlled reaction model.
A Novel Tyrosine Derivative to Study Non-Covalent Assembly Involving C–H···O Hydrogen Bonding
Authors: Satheeshkumar K S , Padma Malar E J , Jayakumar R
Published: September 2002

A novel tyrosine derivative, 3-N-tosyl-4-p-tosyloxybenzyl oxazolidin-4-one (TTBO), C24H23NO7S2, was synthesized. It shows high affinity to chloroform in a ratio of 1 : 1 as evidenced by spectroscopic studies. Ab initio 3-21G*//PM3 calculations indicate that the C–H···O hydrogen bond with a strength of up to 5.9 kcal/mol may be responsible for the non-covalent assembly.
Applications of Ultrafast Transient Infrared Spectroscopies
Authors: Heimer Todd A , Heilweil Edwin J
Published: September 2002

Broadband femtosecond and longer timescale mid-infrared and far-infrared (THz) probing techniques being explored at NIST using multi-element, mid-infrared focal plane arrays and solid-state THz generators/detectors are presented. Ultrafast infrared pulse generation, detection and pump-probe spectroscopy schemes are first reviewed in detail. These methods are used to examine transitory vibrational, chemical and electron transfer phenomena amenable to time-resolved infrared spectroscopy. Direct monitoring of electron transfer rates (> 5×1012 s) from dye sensitizers ([Ru(dceb)(bpy)2]+2 and Ru(dcb)2(NCS)2 derivatives) anchored to semiconductor solar-cell substrates (nanoparticle TiO2, ZrO2 and SnO2 films) is accomplished by measuring increased mid-IR absorption originating from C=O groups and injected electrons in the substrate. Coherent control of CO-stretching vibrational overtone population distributions in liquid-phase metal-hexacarbonyl systems using deliberately chirped mid-IR excitation pulses has also been explored. Identification of molecular steric and diffusional properties involved in internal ring-closing reaction dynamics of ultraviolet (UV) photo-dissociated (RCp)Mn(CO)3 systems in n-hexane will be presented. Terahertz spectroscopic methods and pulsed THz spectra of calf-thymus DNA, proteins and model dipeptides are also presented and their potential use for extracting bio-molecular functional dynamics discussed.
Femtosecond Mid-Infrared Pump–Probe Study of Wave Packet Motion in a Medium-Strong Intramolecular Hydrogen Bond
Authors: Madsen Dorte , Stenger Jens , Dreyer Jens , Hamm Peter , Nibbering Erik T J , Elsaesser Thomas
Published: September 2002

We inspect the O–H stretching vibration of the medium-strong hydrogen bond in phthalic acid monomethyl ester in nonpolar solution by use of single-colour spectrally integrated femtosecond mid-infrared spectroscopy. We derive amplitude and phase characteristics of the coherent modulations of the pump-probe signals as a function of excitation wavelength. We exclude the role of Fermi resonances in the oscillatory contribution to the pump–probe signals. The observed periodic feature is due to wave packet motion of an underdamped out-of-plane 100 cm-1 mode that modulates the hydrogen bond distance. This low-frequency mode anharmonically coupled to the O–H stretching vibration is impulsively excited by the ultrashort mid-infrared pump pulse.
Thiolato-Ligand Substitution Reaction with Halide Ions of Five-Coordinate Trigonal-Bipyramidal Palladium(II) Complexes with Tris(2-(diphenylphosphino)ethyl)phosphine. Electronic and Steric Effects on the Reaction Mechanism
Authors: Aizawa Sen-ichi , Iida Takashi , Sone Yasushi , Kawamoto Tatsuya , Funahashi Shigenobu , Yamada Shinkichi , Nakamura Motoshi
Published: September 2002

Mononuclear and dinuclear thiolato complexes with five-coordinate trigonal-bipyramidal palladium(II), [Pd(pt or tt)(pp3)](BF4) and [Pd2(pdt)(pp3)2](BF4)2 (pp3 = tris(2-(diphenylphosphino)ethyl)phosphine, pt = 1-propanethiolate, tt = α-toluenethiolate, pdt = 1,3-propanedithiolate) have been synthesized. The solid-state structure of the dinuclear pdt complex was confirmed by an X-ray crystal structure analysis and the structures of the pt, tt, and pdt complexes in solution were characterized by 31P NMR spectroscopy. It is indicated from the 31P NMR chemical shifts of the bound pp3 ligand that the axially coordinated thiolato ligands are strong σ and π donors compared with the halo ligands in the axial position of the corresponding trigonal-bipyramidal palladium(II) complexes, [PdX(pp3)]+ (X- = Cl-, Br-, I-). The kinetic parameters for the one-step and successive two-step thiolato-ligand substitution reactions with halide ions in chloroform were obtained for the mononuclear and dinuclear complexes, respectively. These results have revealed that the reaction mechanism of the present thiolato-ligand substitutions is much more dissociative than that of the corresponding halo-ligand substitutions using trimethyl phosphite as the entering ligand, and that the reaction mechanism of the two-step substitution of the dinuclear thiolato complex is more dissociative than that of the mononuclear complexes. It has been concluded that the reaction mechanism of the five-coordinate trigonal-bipyramidal palladium(II) complexes with the 18-electron ground state is quite sensitive to the electronic properties of the entering and leaving ligands and the steric environment of the reaction site compared with that of four-coordinate square-planar palladium(II) complexes with the 16-electron ground state, which is generally associatively activated.
Slowing Down of Vibrational and Structural Relaxation of Water Molecules in Concentrated Aqueous NaCl Solutions
Authors: Laenen Robert , Thaller Andy
Published: September 2002

Sub-picosecond IR-spectroscopy is applied to aqueous NaCl solutions with low concentrated HDO–molecules acting as local probes for the strength of the H-bonds. We find a notable lengthening of the OH-lifetime by the presence of the dissolved ions by a factor of almost 3 up to 2.7 ps at 273 K in comparison to neat water. Simultaneously the average reorientation of the OH–dipoles slows down to 11 ps (273 K) and 4 ps (343 K) while also structural relaxation is found to proceed slower as compared to the case of neat water.
Time Resolved Spectroscopy of Water in the Infrared: New Data and Discussion
Authors: Laenen Robert , Simeonidis Konstantinos , Laubereau Alfred
Published: September 2002

We demonstrate sub-picosecond spectroscopy of an isotopic water mixture presenting strong evidence for four major spectral components within the OH-band of HDO in the solvent D2O peaked at approximately 3330 cm-1 (I), 3390 cm-1 (II), 3460 cm-1 (III), and 3520 cm-1 (IV). Species I and IV are. proposed to give rise for discrete components with local hexagone and weakly bound structures, respectively. The remaining species are most probably related to combination tones with hydrogen bridge bond vibrations. Furthermore we summarise the findings on the vibrational and spectral dynamics of water as determined by time-resolved IR-spectroscopy of HDO molecules dissolved at low concentration in D2O.
Vibrational Spectra of Dipyrido[3,2-a:2′,3′-c]phenazine and Its Radical Anion Analyzed by Ab Initio Calculations and Deuteration Studies
Authors: Matthewson Benjamin James , Flood Amar , Polson Matthew Ian James , Armstrong Christopher , Phillips David Lee , Gordon Keith Christopher
Published: September 2002

The ligand dipyrido[3,2-a:2′,3′-c]phenazine (dppz) and its deuterated analogues, d4-dppz, d6-dppz, d10-dppz, and [ReCl(CO)3] complexes with these ligands have been synthesized. Using DFT calculations it is possible to calculate a geometry of the ligand such that it matches the crystallographic data for a variety of dppz complexes. B3LYP/6-31G(d) frequency calculations correspond closely to the experimental IR and Raman data. Analysis of the calculated normal modes of vibration reveals the presence of a number of modes that are localized to the ring sections of the dppz-framework. Modes 79, 78, 77, 50, and 49, which lie at 1602, 1586, 1576, 1071, and 1034 cm-1, respectively, in the experimental spectra of dppz correspond to phenanthroline-based modes. Modes 68 and 67, lying at 1414 and 1402 cm-1 in dppz are phenazine-based vibrations. These provide an insight into the nature of the MLCT transitions for metal complexes with dppz. The preferential enhancement of phenanthroline-based modes in the resonance Raman spectra of these complexes strongly suggests the π* accepting MO is of phenanthroline character. DFT calculations (B3LYP/6-31G(d)) on the radical anion reveal the elongation of bonds about the pyrimidine ring. The frequency calculations also reveal significant changes in the vibrational spectra for dppz•- from the neutral ligand. Experimental resonance Raman data for the electrochemically reduced [ReCl(CO)3(dppz)]- and the deuterated analogues show distinct isotope shifts that may be correlated to results obtained from the calculations. The characteristic bands observed in these spectra are phenanthroline-based. They may be correlated with time-resolved resonance Raman spectra of Ru(II) and Re(I) complexes.
Transient Resonance Raman Spectroscopy and Density Functional Theory Investigation of Iso-Dibromoacetic Acid Photoproduct Produced From Ultraviolet Photolysis of Dibromoacetic Acid in the Solution Phase
Authors: Li Yun-Liang , Wang Dongqi , Phillips David Lee
Published: September 2002

We present transient resonance Raman spectra and density functional theory calculations that indicate the iso-dibromoacetic acid (Br–BrCHCOOH) species can be produced in noticeable amounts following ultraviolet photolysis of dibromoacetic acid in cyclohexane solution. We compare the properties of the iso-dibromoacetic acid species to those previously found for the related iso-dibromomethane species. We briefly discuss the potential utility of using iso-dibromoacetic acid in cyclopropanation reactions to make substituted cyclopropane products.
Femtosecond Time-Resolved Raman Signals on Ultrafast Dynamics in All-trans-β-Carotene
Authors: Yoshizawa Masayuki , Aoki Hirokazu , Hashimoto Hideki
Published: September 2002

Raman signals of excited states in all-trans-β-carotene have been investigated using recently developed femtosecond time-resolved Raman spectroscopy. The Raman signals are distinguished from other absorbance changes due to highly excited states using temporal and spectral dependence on the Raman pump pulse. The negatively stimulated Raman signals due to the 2Ag- excited state are explained by the Raman transition from the vibrational excited levels. The vibrational relaxation of the 2Ag- state has fast and slow kinetics. The fast one has a time constant of 0.6 ps, but the other is slower than the internal conversion to the ground state. Since the molecule exists in the vibrationally excited levels through the relaxation kinetics, the vibrational features in β-carotene are quite important with relation to energy transfer in photosynthesis.
Picosecond Infrared Spectra and Structure of Locally Excited and Charge Transfer Excited States of Isotope-Labeled 4-(Dimethylamino)benzonitriles
Authors: Okamoto Hiromi , Kinoshita Mariko , Kohtani Shigeru , Nakagaki Ryoichi , Zachariasse Klaas A
Published: September 2002

Infrared spectra of the ground, charge transfer (CT), and locally excited (LE) states of isotope-labeled 4-(dimethylamino)benzonitriles (DMABNs) in the region between 1700 and 900 cm-1 are reported. The isotopomers measured are normal DMABN, NC–C6H4–15NMe2 (dimethylamino nitrogen labeled DMABN), and NC–C6H2D2–NMe2 (3,5-dideuterated DMABN). The infrared spectrum of the excited CT state of DMABN-d2 is consistent with the previous band assignments for normal DMABN and DMABNs isotopically labeled on dimethylamino group. For the LE state of normal DMABN, three bands are observed at 1481, 1415, and 1399 cm-1. This is in contrast with a previously reported transient infrared spectrum, where positions of bands due to the transient do not shift from the ground state ones. The band at ca. 1481 cm-1 is observed for normal and 15N labeled DMABN, but not for DMABN-d2. Except for this point, the band positions are almost identical for the three isotope-labeled species. The vibrational transitions observed at ca. 1415 and 1398 cm-1 are hence attributed to modes with atomic displacements localized on methyl groups and/or the part of the benzonitrile moiety adjacent to the cyano group or the cyano group itself. Quantum chemical calculations of the vibrational spectra for the CT and LE states of DMABN at present do not correctly reproduce the experimental spectra, which means that more accurate calculations are needed for a reliable analysis of these spectra.
Mode Dependence of Vibrational Energy Redistribution in Nickel Tetraphenylporphyrin Probed by Picosecond Time-Resolved Resonance Raman Spectroscopy: Slow IVR to Phenyl Peripherals
Authors: Mizutani Yasuhisa , Kitagawa Teizo
Published: September 2002

The formation of the (d, d) excited state of (meso-tetraphenylporphyrinato)nickel(II) ([Ni(tpp)]) upon (π, π*) excitation, and its vibrational energy relaxation were monitored by picosecond time-resolved resonance Raman spectroscopy. Stokes resonance Raman bands due the (d, d) excited state instantaneously appeared upon the photoexcitation into the (π, π*) excited state. Their intensities decayed with a time constant of about 250 ps, which corresponds to electronic relaxation from the (d, d) excited state to the electronic ground state. This is consistent with the results of ultrafast absorption measurements reported by Eom et al. [H. S. Eom, S. C. Jeoung, D. Kim, J. H. Ha, and Y. R. Kim, J. Phys. Chem. A, 101, 3661 (1997)]. Anti-Stokes ν4 (macrocycle in-plane mode) intensities of [Ni(tpp)] in the (d, d) excited state appeared promptly and decayed with a time constant of 3.6 ± 0.6 ps. The rise and decay of anti-Stokes intensity are interpreted as vibrational excitation due to the excess energy and intermolecular vibrational energy transfer to the surrounding solvent molecules, respectively. The φ4 mode, which is mainly ν(CC) of the peripheral phenyl groups, gave no detectable anti-Stokes intensity although the mode gave appreciable Stokes intensity. This means that the φ4 mode is left vibrationally less excited than the ν4 mode in the process of vibrational energy relaxation and that intramolecular vibrational energy redistribution is not completed in a subpicosecond time regime. These results for [Ni(tpp)] demonstrate that the vibrational modes of peripheral groups are vibrationally less excited shortly after the formation of the (d, d) excited state and that energy redistribution in the peripheral groups takes place in picoseconds, such a short time is competitive with vibrational energy transfer to the surrounding solvent molecules.
Time-Dependent Vibration Stokes Shift during Solvation: Experiment and Theory
Authors: Asbury John B , Wang Yongqiang , Lian Tianquan
Published: September 2002

Peak shift dynamics of CO stretching modes of [Re(R2-bpy)(CO)3Cl] [R = COOH and COOEt] complexes in their MLCT excited state were studied in polar solvents using femtosecond visible pump and IR probe spectroscopy. For Re complex in dimethyl formamide, peak shift magnitudes for the three CO stretching modes are different but their dynamics are identical. Comparison in different alcohols showed that peak shift magnitude increases with solvent dielectric constant and peak shift time follows the trend of solvation time. The observed peak shift is attributed to solvation-induced time-dependent vibrational Stokes shift. A general theory based on the Onsager dielectric continuum model of solute solvent interaction and time-dependent reaction field was developed to qualitatively describe time-dependent vibrational Stokes shift. The theory predicts that the peak shift correlation function is determined by solvent dielectric relaxation at the vibration frequency, and the peak shift magnitudes are solvent and normal mode dependent. Although the observed trend of solvation-induced vibrational Stokes shift is consistent with the theoretical predictions, other contributions such as solute polarizability should also be included in more complete models. Solvation induced vibrational Stokes shift may be a general phenomenon in time-resolved vibrational spectroscopy of molecules undergoing significant change in charge or charge distribution.
Coupling of the Amide I Modes of the Glycine Dipeptide
Authors: Hamm Peter , Woutersen Sander
Published: September 2002

Several approaches to calculate the coupling between the two amide I modes of the glycine dipeptide are compared. The full (φ,  ψ) conformational space of the molecule is explored, and conditions for the validity of the different approaches are discussed.
Magnetic Resonance Analogies in Multidimensional Vibrational Spectroscopy
Authors: Scheurer Christoph , Mukamel Shaul
Published: September 2002

We survey the principles for the design of multidimensional vibrational spectroscopies that draw upon the analogy with liquid or solid state NMR and EPR spectroscopy. The much faster time-scales and the different energy regime in laser spectroscopy provide additional possibilities that lack magnetic spectroscopy counterparts. We also discuss the notion of through-bond vs through-space couplings between localized vibrations, which are of different nature than in NMR.
Heterodinuclear MIINiII (M = Co, Ni, Cu, Zn) Complexes of a Macrocyclic Compartmental Ligand. Anomalous EPR of CuIINiII Complex by Coordination of 1-Methylimidazole
Authors: Inoue Ko-ji , Ohba Masaaki , Okawa Hisashi
Published: September 2002

A phenol-based macrocyclic compartmental ligand, (L2;2)2-, having N(amine)2O2 and N(imine)2O2 metal binding sites sharing two phenolic oxygen atoms, has formed the following heterodinuclear MIINiII complexes: [CoNi(L2;2)(AcO)]PF6·CH3CN (1), [NiNi(L2;2)(AcO)]PF6 (2), [CuNi(L2;2)(AcO)]PF6 (3) and [ZnNi(L2;2)(AcO)]PF6·CH3CN (4). Furthermore, [CuNi(L2;2)(CH3CN)](PF6)2·CH3CN (3′) was obtained when 3 was recrystallized from acetonitrile. X-ray crystallographic studies for 1, 2, 3′ and 4 demonstrate that the MII resides in the N(amine)2O2 site and the NiII in the N(imine)2O2 site. The NiII in the N(imine)2O2 site has a planar geometry and is diamagnetic in all the complexes. The CoII of 1 and the NiII of 2 in the N(amine)2O2 site have a six-coordinate geometry together with a bidentate acetate group. The CuII in 3′ has a five-coordinate geometry together with one acetonitrile molecule, and the ZnII in 4 has a square-pyramidal geometry together with a unidentate acetate group. Complex 3′ in DMF combines 1-methylimidazole (MeIm) at the axial site of the NiII and the MeIm adduct in frozen DMF solution at 77.4 K shows EPR signals of g|| = 2.06 and g⊥ = 2.26 with a multi-line structure superimposed on the g|| component (A|| = 15.8 × 10-4 cm-1). The EPR signals are ascribed to the spin-doublet ground state (ST = 1/2) of antiferromagnetically coupled CuII(S = 1/2) - NiII(S = 1), and the multi-line structure is explained by considering hyperfine interaction with Cu nucleus (ACu = 50.0 × 10-4 cm-1) and superhyperfine interaction with N nucleus of MeIm (AN = 15.0 × 10-4 cm-1).
Selective Formation of Acetic Acid from Syngas in the Presence of H2O over Zirconium Hydroxide
Authors: Maruya Ken-ichi , Okumura Koichiro , Komiya Teruaki
Published: September 2002

Acetic acid was selectively synthesized from syngas using zirconium hydroxide catalysts without precious metals.
A Highly Selective Calix[4]arene-Based Chromoionophore for Ni2+
Authors: Ma Quanli , Ma Huimin , Wang Zhihua , Su Meihong , Xiao Hongzhan , Liang Shuchuan
Published: September 2002

A novel chromoionophore 5,17-bis(quinolyl-8-azo)-25,26,27,28-tetrahydroxycalix[4]arene has been synthesized as a highly selective reagent for Ni2+ in the presence of excess alkali, alkaline earth and other transition metal ions.
Useful Synthesis of the Main Dehydrohexapeptide Segment of a Macrocyclic Antibiotic, Berninamycin B
Authors: Yamada Takahiro , Okumura Kazuo , Yonezawa Yasuchika , Shin Chung-gi
Published: September 2002

The useful synthesis of tetradehydrohexapeptide segment 2, which is the main skeleton of a macrocyclic antibiotic, berninamycin B, was first achieved. The skeleton 2 is constructed, in turn, of 2-[(Z)-1-amino-1-propenyl]-5-methyl-oxazole-4-carboxylic acid, α-dehydroalanine (ΔAla), l-Val, 2-[1-amino-1-ethenyl]-5-methyloxazole-4-carboxylic acid residues, besides l-Thr and ΔAla at the N- and C-termini, respectively.