bluuebunny/crossref_metadata_2025_split huggingface dataset:
Long-Lived Triplet Radical Ion Pair State of Porphyrin-Methylviologen Combined Systems as Revealed by a Large Magnetic Field Effect on Its Lifetime
Authors: Saito Toshiro , Hirata Yoshinori , Sato Hisashi , Yoshida Toshikatsu , Mataga Noboru 
Published: July 2006

Abstract
The external magnetic field effect on the lifetime of the ion pair state has been examined for the porphyrinmethylviologen combined systems in polar solvents by using nanosecond laser flash photolysis techniques. Applying the external magnetic field, a drastic increase in the lifetime has been observed. For PllMV2+ in DMSO under the magnetic field of 50 mT, the ion pair lifetime was almost three times longer than the zero field value, which can be deemed the ideal case of the external magnetic field effect due to the hyperfine interaction mechanism. The results clearly showed that the long-lived ion pair was formed by the intramolecular electron transfer from the triplet state of porphyrin.
The Micellar Properties of Dodecyltrimethylammonium Chloride as Studied by Ion-Selective Electrodes and Fluorescence Probe Technique
Authors: Maeda Tamaki , Satake Iwao 
Published: July 2006

Abstract
The activities of the surfactant ion, counter ion, and co-ion in micellar solutions of dodecyltrimethylammonium chloride (DTAC) in the presence of NaCl were determined by using ion-selective electrodes. An application of the charged phase separation model gave an apparent degree of counter ion association to the micelle of 0.68 regardless of the salt concentration. A tentative estimation of the intermicellar concentrations of surfactant ion and counter ion was made on the basis of an assumption that the activity coefficients of the monomeric surfactant ion and co-ion were identical with each other. In the concentration range above the critical micelle concentration (cmc), the intermicellar concentration of the surfactant ion decreased gradually with increasing surfactant concentration, whereas the reverse was found for that of counter ion. Similar behaviors were also found for the activity coefficients of these ions. However, an increase in salt concentration caused a successive decrease in the concentration dependences of intermicellar concentrations as well as activity coefficients. Measurements were also made with the fluorescence decay curves of micelle-solubilized pyrene. An analysis based on the knowledge of the intermicellar concentration of surfactant ion estimated above revealed that the micelle aggregation number of DTAC remained virtually constant over wide concentration range above the cmc.
Photoacoustic Study of 280 nm Band of Acetone Vapor
Authors: Oka Takefumi , Kobayashi Humiyo , Oguma Naoki , Morohashi Makoto 
Published: July 2006

Abstract
Relaxation of the energy absorbed by acetone vapor (200 Torr) on excitation with UV (230–340 nm) was investigated by the photoacoustic technique. The presence of two relaxation paths was found by their difference in heat production rates: The faster path is S0→S1→T1→S0 and the slower path is S0→radicals→recombination products. The PA spectra corresponding to these paths were determined separately. The spectrum for the T1 path has a peak around 295 nm and extends to longer wavelengths beyond 310 nm. The spectrum for the decomposition path has a peak around 275 nm and overlaps with the spectrum for the T1 path in the region of λ&lt;310 nm. The study of frequency dependences of PA signals showed the presence of faster and slower heat releasing steps in each path. In the T1 path, the faster and the slower steps are due to vibrational deactivation of hot T1 formed from S1 and of hot S0 formed from T1 respectively. In the radical path, the faster and slower steps are the deactivation of the hot radicals and the recombination of the thermalized radicals respectively. The addition of O2 to the system accelerated the heat release process via the relaxed T1 and also converted the slow heat release process of recombination into a fast process of addition reactions of O2 to the radicals.
Dichalcogen-Bridged Acenaphthenes as New Electron Donors
Authors: Aso Yoshio , Yui Koji , Miyoshi Takanori , Otsubo Tetsuo , Ogura Fumio , Tanaka Jiro 
Published: July 2006

Abstract
Three new electron donors, 5,6-dihydroacenaphtho[5,6-cd]-1,2-dithiole (1a), -diselenole (1b), and -ditellurole (1c) have been prepared with a view to developing new electron donors for low-dimensional molecular complexes. Their donor characters are markedly enhanced as compared with the corresponding dichalcogen-bridged naphthalenes. They formed charge-transfer complexes with tetracyanoquinodimethane (TCNQ). Their electrical conductivities increase in the order of polarizable chalcogen. The crystal structures of 1a–TCNQ complex and neutral 1c were determined by X-ray analyses. In the crystal, 1a and TCNQ form a unique mixed stack, that is, a pair of donors and a pair of acceptors make an alternately stacking column. Neutral 1c takes an almost planar conformation and molecules are connected to each other with strong Te–Te interactions.
Reinvestigation on Thermal Cycloaddition of 1-Aryl-2-(9-fluorenylidene)-1-haloethylenes
Authors: Minabe Masahiro , Yoshida Masaaki , Saito Seiji , Tobita Keisuke , Toda Takashi 
Published: July 2006

Abstract
The thermal treatment of 1-bromo-2-(9-fluorenylidene)-1-phenylethylene afforded three different types of [2+2]cycloaddition products. The 1-tolyl homolog showed similar trends, but the chloro analog gave only two types. These results suggest that reactions of the rigid and bulky allenes take place through a 2,2′-biradical giving head-to-head, head-to-tail, and tail-to-tail adducts through the expected processes.
Diastereomers of Methionine S-Oxide in the Hinge-Ligament Proteins of Molluscan Bivalve Species
Authors: Kikuchi Yasuo , Higashi Kiyoshi , Tamiya Nobuo 
Published: July 2006

Abstract
The diastereomer ratio was analyzed on methionine S-oxide residues formed by in vivo posttranslational oxidation of methionine residues in a protein. The hinge-ligament protein of molluscan bivalves is distinct from usual proteins in containing a large amount of methionine S-oxide. The methionine S-oxide was released from the protein by proteolytic digestions and was found to be a mixture of approximately equall amounts of two diastereomers, (5S)- and (5R)-l-methionine S-oxide.
Conductance of Electrolytes in Dipolar Aprotic Solvent Mixtures. II. Conductance of Lithium Perchlorate in Mixtures of Ethyl Methyl Ketone and Acetone with N,N-Dimethylformamide at 25 °C
Authors: Niazi M S K 
Published: July 2006

Abstract
The electrolytic conductance of LiClO4 has been determined in N,N-dimethylformamide (DMF) and its binary mixtures with acetone (Ac) and ethyl methyl ketone (MEK) at 25 °C. Ion association constants (KA) and limiting molar conductance (Λ0) were calculated from these data using Fuoss equation with modifications. The KA values of LiClO4 in these binary mixtures are interpreted in terms of solvent separated ion pairs while in pure Ac and MEK almost contact ion pairs are expected. A comparison is made for Λ0 and KA values of this salt in Ac and Ac–DMF mixtures with those obtained by Gill et al. Further, a comparison is made between these results and spectroscopically derived results by others in analogous media. LiClO4 has been found more associated in Ac–DMF solvent system than in the MEK–DMF mixed solvent system.
Electrophoresis of Progesterone Particles Dispersed in Aqueous Solutions of d-Glucose and Urea
Authors: Srivastava M L , Ram Bali 
Published: July 2006

Abstract
Electrophoretic mobilities of progesterone particles dispersed in aqueous solutions of d-glucose and urea, in the concentration range 10−3–104 mol l−1 have been measured to investigate electrical properties of the interface. Zeta potentials have been determined for this purpose. The dependence of zeta potentials on concentration has also been examined. Theory of the electrical double layer has been used to explain the results.
The Preparation and the Crystal Structure of 1,3,5,7-Tetramethyltetrahydro-1,3,5,7-tetrazocine-2,6(1H,3H)-dione
Authors: Ebisuno Toichi , Takimoto Michiaki , Takahashi Miyuki , Shiba Ryuichi 
Published: July 2006

Abstract
1,3,5,7-Tetramethyltetrahydro-1,3,5,7-tetrazocine-2,6-(1H,3H)-dione was prepared in a good yield, and its crystal structure was determined by means of X-ray analysis. The molecule is centrometric. It has practically a planar structure except for four methyl groups and two methylene linkages and a hole of 0.5–1.6 Å in the interior of the ring structure.
A Convenient Synthesis of 3-Cyano-2-methylpyridines under Ultrasonic Irradiation
Authors: Shibata Katsuyoshi , Urano Katsuyoshi , Matsui Masaki 
Published: July 2006

Abstract
Ultrasonic irradiation of α,β-unsaturated carbonyl compounds 1a–i with acetonitrile in the presence of potassium t-butoxide gave 3-cyano-2-methylpyridines 2a–i in moderate to good yields. The pyridines are produced by a Michael reaction of 3-iminobutanonitrile, an acetonitrile dimer, to the substrates 1a–i.
Volume of Mixing in the Liquid Bismuth–Lead System
Authors: Badawi Walid Ahmad 
Published: July 2006

Abstract
The results obtained in determining the volume of mixing vm in the liquid Bi–Pb system at 660 K using the pycnometer method indicate the compound Pb3Bi2 at the composition 0.6. The shifting of the slight positive vmaxm to the composition 0.4 is attributed to a nonlinear Wagner effect.
Raman Spectral Characteristics of Cobalt(III) Complexes with Quadridentate Ligands
Authors: Kawamoto Tatsuya , Hidaka Jinsai , Einaga Hisahiko 
Published: July 2006

Abstract
The Raman spectra of cobalt(III) complexes with quadridentate ligands such as triethylenetetramine (trien), ethylenediamine-N,N′-diacetate (edda), tris(2-aminoethyl)amine (tren), and N-(2-aminoethyl)iminodiacetate (aeida), were measured for the skeletal vibration region of 200–700 cm−1 in order to obtain general information on the relation between the spectra and the structures of these complexes. The Raman bands can be classified into four vibration modes; a totally symmetric stretching vibration mode in the 420–670 cm−1 region, a stretching vibration mode excluding the totally symmetric one in the 390–450 cm−1 region, a metal-ligand skeletal bending deformation mode in the 300–420 cm−1 region, and the chelate ring deformation mode in the 240–290 cm−1 region. The skeletal vibrations of cis-α and cis-β isomers of the cobalt(III) complexes with linear quadridentate ligands correspond to those of the tris(bidentate)cobalt(III) and the mer isomers of bis(terdentate)cobalt(III) complexes, respectively. In addition, the skeletal vibrations of the cobalt(III) complexes with tripodlike quadridentate ligands also correspond to those of the mer isomers of bis(terdentate)cobalt(III) complexes. The Raman spectra of the present complexes depend primarily on the configuration of the quadridentate ligands and the effect due to the bidentate ligands is of secondary importance.
Syntheses and Properties of Dipyridylnorbornadienes
Authors: Yamashita Yoshiro , Hanaoka Takaaki , Takeda Yasuyuki , Mukai Toshio , Miyashi Tsutomu 
Published: July 2006

Abstract
2,3-Dipyridylnorbornadienes were prepared using the Diels–Alder reaction of the HBF4 salts of dipyridylacetylenes with cyclopentadiene. Their absorptions extend to 380 nm and are red-shifted in an acidic media. They underwent photocyclization to give quadricyclanes which reverted to norbornadienes upon heating or encountering a Co(II)–TPP catalyst. 2,3-Bis(1-methylpyridinio)norbornadienes were also prepared by a Diels–Alder reaction of bis(1-methylpyridinio)acetylenes with cyclopentadiene. Irradiation of 1-methyl-2-pyridinio and 1-methyl-3-pyridinio derivatives led to the photostationary state between them and the corresponding quadricyclanes, while a 1-methyl-4-pyridinio derivative gave a water or methanol adduct in the presence of water or methanol. Electron-transfer reactions of bis(1-methylpyridinio)norbornadienes were investigated by cyclic voltammetry. The radical cations formed by their reduction were unstable compared with those of the corresponding trans-bis(1-methylpyridinio)ethylenes. Steric factors were shown to strongly affect the reactivities.
The Preparation of Photoresponsive Cyclobutanocrown Ethers by Means of Intramolecular [2+2]Photocycloaddition
Authors: Akabori Sadatoshi , Kumagai Takeshi , Habata Yoichi , Sato Sadao 
Published: July 2006

Abstract
The reaction of o-bis(3-hydroxy-1-oxapropyl)benzene (7b) with 3,3′-(trimethylenedi-4,1-phenylene)bis[2-propenoyl chloride] gave 8,9-benzo-4,7,10,13-tetraoxa[16.3]paracyclopha-1,8,15-triene-3,14-dione (8b) in a 6.5% yield, together with its dimer in a 12.3% yield. Also, 5,6-benzo-4,7-dioxa[10.3]paracyclopha-1,5,9-triene-3,8-dione (8a) and 11,12-benzo-4,7,10,13,16,19-hexaoxa[22.3]paracyclopha-1,11,21-triene-3,20-dione (8c) were obtained by the same method in 7.0 and 8.0% yields, together with their respective dimers (9a: 6.0%, 9c: 10.8%). X-Ray analysis of 8b revealed the two double bonds to be trans and the distances between the two olefinic carbon atoms (C17–C35) and (C18–C34) to be 5.341(11) and 5.906(9) Å respectively. These distances are too long for intramolecular [2+2]photocycloaddition to occur in the crystalline state. However, the irradiation of the solutions of the crown ethers 8a and 8b in acetonitrile by Pyrex-filtered UV light (&gt;300nm) gave two intramolecular [2+2]photocycloadducts, cyclobutanocrown ethers 10a and 10b, in 95.7 and 91.8% yields respectively. Subsequently, 10a and 10b were transformed to 8a and 8b in 37 and 29% yields respectively upon irradiation with 220 nm UV light. The structures of 10a and 10b were confirmed to be the β-form.
Water-Soluble Acylating Agents: Preparation of 2-Acylthio-1-alkylpyridinium Salts and Acylation of Phenols, Acids, and/or Amines with These Salts in an Aqueous Phase
Authors: Sakakibara Tohru , Watabe Yukie , Yamada Masahide , Sudoh Rokuro 
Published: July 2006

Abstract
Reaction of phenols, amines, and acids with 2-benzoylthio-1-methylpyridinium chloride prepared in situ from benzoyl chloride and 1-methyl-2(1H)-pyridinethione, afforded the corresponding benzoyl derivatives in good yields. In the reaction of p-nitrophenol, even a catalytic amount of 1-methyl-2(1H)-pyridinethione proved to be effective. Similar reactions of p-nitrophenol with isobutyryl chloride and acetyl chloride in the presence of 1-methyl-2(1H)-pyridinethione afforded p-nitrophenyl isobutyrate and p-nitrophenyl acetate in 63 and 44% yields, respectively. 2-Benzoylthio-, 2-acetylthio-, and 2-isobutyrylthio-1-ethylpyridinium tetrafluoroborates were prepared by treatment of the corresponding 2-acylthiopyridines with triethyloxonium tetrafluoroborate. These pyridinium salts also acted as acylating agents in an aqueous phase. Some competitive reactions of 2-aminoethanol and phenols with 2-benzoylthio-1-methylpyridinium chloride were also investigated.
The Knoevenagel Reactions of Aldehydes with Carboxy Compounds. I. Reactions of p-Nitrobenzaldehyde with Active Methine Compounds
Authors: Tanaka Mayumi , Oota Osamu , Hiramatsu Hideo , Fujiwara Kazuyoshi 
Published: July 2006

Abstract
The Knoevenagel reactions of p-nitrobenzaldehyde (1) with β-keto acids, methylmalonic (2a) and α-methylacetoacetic acids (2b) were carried out in the presence of a tertiary amine such as pyridine. We have isolated the corresponding β-hydroxy intermediate (3a) by the reaction of 2a which positively suggested the reaction proceeded by the Hann and Lapworth mechanism. A kinetic study using 1H NMR revealed the existence of the reversibility between the starting materials and the β-hydroxy intermediate and that the rate determining step was decarboxylattion. But, when using the secondary amine, both the β-hydroxy acid and the corresponding condensation product were obtained via this reaction. These findings led to the conclusion that the reaction proceeded according to the two competing mechanisms, i.e., the Hann and Lapworth and Knoevenagel mechanisms. It was further clarified that either the decarboxylation step or the formation of the bis(dialkylamino) derivative was the rate determining step. The stereoselectivity of the β-hydroxy saturated compound has been closely related to the fact that the conformation of the intermediate possesses an intramolecular hydrogen bond to a hydroxyl group.
Thermal and Ferroelectric Properties of Novel Ferroelectric Liquid Crystals Containing α-Methylcinnamoyl Moiety in the Core Structure
Authors: Nakauchi Jun , Kageyama Yoshitaka 
Published: July 2006

Abstract
Six homologous series of novel ferroelectric liquid crystals containing α-methylcinnamoyl moiety in the core structure:
(Remark: Graphics omitted.)
(IA: k=1, l=1, (Remark: Graphics omitted.), n=8–16; IB: k=1, l=1, (Remark: Graphics omitted.), n=8–16; IIA: k=1, l=2, (Remark: Graphics omitted.), n=9–16; IIB: k=1, l=2, (Remark: Graphics omitted.), n=8–14, IIIA: k=2, l=1, (Remark: Graphics omitted.), n=9–16; IIIB: k=2, l=1, (Remark: Graphics omitted.), n=9–16) have been synthesized and their thermal and ferroelectric properties have been investigated. The mesomorphic transition temperatures and the spontaneous polarization for the homologous series (IA, IB, IIA, IIB, IIIA, and IIIB) depend on the core structure, the chiral group, and the terminal alkoxyl chain length. These homologous series show the chiral smectic C phase over wide temperature ranges including room temperature and the values of their maximum spontaneous polarization are in the range of 30 to 800 μCm−2. The thermal stability of the mesophase and the magnitude of the spontaneous polarization have been discussed from the view point of the molecular structure and the local molecular interactions.
A New Method for Determining Cyclodextrin Complex Formation Constants with Electrolytes in Aqueous Medium
Authors: Sanemasa Isao , Fujiki Motohisa , Deguchi Toshio 
Published: July 2006

Abstract
By making use of the volatilization rate of iodine from aqueous into gaseous phase, association constants of α-cyclodextrin with electrolytes (chlorides, nitrates, and perchlorates) have been determined at 25 °C; the counter cations are found to be largely responsible for the association.
Electrochemical Oxidation of Ruthenium and Iron Complexes at Rotating Disk Electrode in Acetonitrile Solution
Authors: Morita Masayuki , Tanaka Yoshinori , Tanaka Keisuke , Matsuda Yoshiharu , Matsumura-Inoue Takeko 
Published: July 2006

Abstract
The diffusion coefficient and the apparent rate of charge-transfer have been determined for various ruthenium and iron complexes in an acetonitrile solution by using a rotating disk electrode (RDE) method. The diffusion coefficients of [Ru(bpy)3]2+, [Ru(acac)3], and [Fe(bpy)3]2+ (bpy: 2,2′-bipyridine, acac: acetylacetone), being similar to each other, were about 2×10−10 m2 s−1 in acetonitrile containing 0.1 mol dm−3 (C2H5)4NBF4. The apparent rate of electrochemical oxidation increased in the order [Ru(bpy)3]2+&lt;[Ru(acac)3]&lt;[Fe(bpy)3]2+. The order of the rates was reciprocal to the order of their oxidation potentials in the same electrolyte.
Permeability Control of Polyelectrolyte Complex Membrane Including Chitosan Derivative as a Component
Authors: Kikuchi Yasuo , Kubota Naoji 
Published: July 2006

Abstract
The properties of polyelectrolyte complexes (PEC) and PEC membranes were investigated in the systems of glycol chitosan (GC)–poly(vinyl sulfate) (PVSK) and methyl glycol chitosan (MGC)–(carboxymethyl)dextran (CMD). The degree of dissociation and the conformation of GC and CMD depend upon pH, because GC and CMD are weak polybase and weak polyacid, respectively. On the basis of this knowledge, a research into the pH dependence of dissociation and viscosity of GC and CMD was carried out. PEC including chitosan derivative as a constituent was synthesized at the adequate pH, pH 3.0 in the GC–PVSK system and pH 7.0 in the MGC–CMD system. PEC membranes were prepared, and the permeability of KCl, urea, and sucrose through the GC–PVSK membrane was determined under various pH. It was revealed that the permeability of KCl, urea, and sucrose varies with the solution pH. The permeability in the neutral region was 2–10 times as high as that in acidic region. The increase of permeability in neutral region was considered from IR spectra of membranes to be due to swelling caused by a conformational change.
Terplex Formation in the Excited Triplet State. The Chloranil and Mesitylene System
Authors: Kobashi Harumichi , Hiratsuka Ken-ichi , Motegi Kazuaki 
Published: July 2006

Abstract
The enthalpy and entropy changes have been estimated for the formation of a triplet-state (1:2) terplex as well as an ordinary (1:1) exciplex between triplet chloranil (3CA) and mesitylene (M) in carbon tetrachloride. Results indicate that the terplex is energetically less stable than the bimolecular exciplex, while the stabilization of the terplex is compensated by the positive entropy change associated with transformation from the exciplex to the terplex.
Development and Applications for the Simulater of Intermolecular Potentials. II. Hydration Effects on the Conformation of Tyramine
Authors: Takagi Tatsuya , Tanaka Akito , Tani Mika , Maezaki Hironobu , Fujiwara Hideaki , Sasaki Yoshio 
Published: July 2006

Abstract
Conformational energy maps of the tyramine monocation and its hydrated species were calculated using the SIMP system. The populations of the trans conformer were calculated to be 18% and 53% for the isolated monocation and the hydrated one respectively. The computational results was supported by the results of conformational analysis based on 1H NMR spectroscopy.
Specific Binding of Substrates Containing Nitrogen and Oxygen Donor Groups to Copper(II)–Gadolinium(III) Hetero-Metal Center
Authors: Sakamoto Masatomi , Ishimori Tomitaro , Okawa Hisashi 
Published: July 2006

Abstract
Substrate binding to the Cu(II)–Gd(III) heterometal complex of N,N′-bis(3-carboxysalicylidene)ethylenediamine was studied in N,N-dimethylformamide. It was suggested that substrates with a nitrogenous and an oxygenous groups (amino alcohols, 8-quinolinol, amino acids, and amino acid esters) were specifically bound to the Cu(II)–Gd(III) center, with the nitrogen to the copper and with the oxygen to the gadolinium.
Relationship between Solubility and Micellization of Surfactants; Micelle Temperature Range (MTR) Instead of Krafft Point
Authors: Moroi Yoshikiyo , Matuura Ryohei 
Published: July 2006

Abstract
In order to clarify the relation between the solubility and micellization of surfactants, the micellar temperature range (MTR) is proposed instead of the usually used Krafft point. The physicochemical meaning of cmc defined by Phillips was examined from a mathematical point of view. As a result, it became clear that the temperature range for MTR is based on the concentration range for cmc, which in turn results from the polydispersity of micelles. The mass-action model of multiple association can be used to explain these facts. The MTR, thus determined by solubility and by cmc, was found to be able to explain a leveling of the MTR for homologous surfactants with an increase of the alkyl chain length and its increase of sodium dodecyl sulfate with increasing concentration of added sodium chloride.