bluuebunny/crossref_metadata_2025_split huggingface dataset:
A New Type of Cyclic Alkylacrylamide Polymer Langmuir-Blodgett Film
Authors: Feng Fei , Aoki Atsushi , Miyashita Tokuji 
Published: March 2003

Abstract
A high quality polymer LB film was newly prepared from adamantylacrylamide polymer without usual long alkyl chain. The measurements with XRD and cyclic voltammetry suggest that the polymer LB film with a thickness of 1.1nm and well defined molecular orientation is fabricated.
Sorption of CO2 in the Photocrosslinked PVCA Film
Authors: Matsuguchi Masanobu , Miura Jun-Ichi , Sakai Yoshiro 
Published: March 2003

Abstract
Sorption behavior of CO2 in the photocrosslinked poly(vinyl cinnamate) film was examined. The amount of sorbed CO2 was enhanced with the degree of crosslinking, while the amount decreased beyond ca.95% crosslinking.
Synthesis and Structural Characterization of Octanuclear Indium-Tungsten Mixed-metal Carboxylate Cluster, Na2[W3InO4(O2CEt)8]2
Authors: Xu Li , Cui Yong , Huang Jinshun 
Published: March 2003

Abstract
The insoluble indium-tungsten chain cluster, Na2[W3InO4(O2CEt)8]2, has been prepared from the self-assembly reaction of W(CO)6, Na2WO4·2H2O and InCl3 in propionic anhydride at 120 °C. The octametallic dianion, [W3InO4(O2CEt)8]22−, consists of the two incomplete cuboidal units [W3O4(O2CEt)8]4− which are centro-symmetrically bridged by two In3+. The In3+ ions dissociate from the trinuclear units in aqueous acidic solution.
Effects of the π and π* Orbitals of the 5-Unsaturated Substituents on the π-Facial Selectivities in the Diels-Alder Reactions of Cyclopentadienes
Authors: Ishida Masaru , Kobayashi Hiroki , Tomohiro Shingo , Wasada Hiroaki , Inagaki Satoshi 
Published: March 2003

Abstract
The exclusive anti-π-facial selectivity in the Diels-Alder reaction of 5-formylpentamethylcyclopentadine, Cp*-CHO, was proposed to come from the π-HOMO distortion of the diene due to the perturbation by low-lying π*orbital on the substituent. The role of the π* orbital was experimentally substantiated by a considerable amount of syn-attack products in the reactions of Cp*-CH=NOH and Cp*-CH=CH2 having high-lying substituent π* orbitals.
Reaction of Aromatic Aldehydes with (Dialkylamino)magnesium Reagents. Formation of 1,2-Diaryl-1,2-ethenediamines
Authors: Kobayashi Kazuhiro , Uneda Tomokazu , Uchida Masaharu , Furuta Yoshihisa , Tanmatsu Miyuki 
Published: March 2003

Abstract
(Dialkylamino)magnesium reagents, derived from secondary amines and ethylmagnesium bromide, have been found to react with aromatic aldehydes to give 1,2-diaryl-1,2-bis(dialkylamino)ethenes in moderate to good isolated yields.
New Route for Preparation of Layered Manganese Oxides with Multivalent Metals in the Interlayer
Authors: Yang Xiaojing , Kanoh Hirofumi , Tang Weiping , Liu Zong-huai , Ooi Kenta 
Published: March 2003

Abstract
Fe(III)-, Cr(III)-, Al(III)- and La(III)-buserite type manganese oxides were synthesized from a hydrothermally treated, well-crystallized Na+-birnessite through a two-step ion-exchange route, M/Mg2+ ion exchange subsequent to Mg2+/Na+exchange. The ion-exchange reactions progressed smoothly and the layered manganese oxides with multivalent metal ions in the interlayer could be obtained at room temperature.
Extraordinarily Low Cycloreversion Quantum Yields of Photochromic Diarylethenes with Methoxy Substituents
Authors: Shibata Katsunori , Kobatake Seiya , Irie Masahiro 
Published: March 2003

Abstract
Diarylperfluorocyclopentenes having 2-methoxy-5-phenylthiophene as the aryl groups were synthesized. Introduction of two methoxy substituents instead of methyl groups at the reactive carbons of 1,2-bis(5-phenyl-3-thienyl)perfluorocyclopentene decreased the photocycloreversion quantum yield by a factor of 103, while the cyclization quantum yield was similar.
MMA Modified Inorganic/Organic Hybrid Membranes by Sol–Gel Technology
Authors: Zhang Guochang , Chen Yunfa , Wu Zhenjiang , Xie Yusheng 
Published: March 2003

Abstract
The inorganic/organic hybrid membranes modified by MMA were deposited on the porous α-Al2O3 substrates (pore size, 2 µm) by the sol–gel technology. It was found that the introduction of MMA can not only improve the membrane formation properties, but also increase the selectivity of O2/N2 and O2/CO2. On the other hand, the modified hybrid membranes have more dense structure.
New Synthesis of Pinacols By Oxidative Coupling Mediated by 1,2-Disulfides as Dehydrogenating Reagents under Irradiation
Authors: Fujisawa Hidehiko , Hayakawa Yuichiro , Sasaki Yasuhiro , Mukaiyama Teruaki 
Published: March 2003

Abstract
A new procedure for the synthesis of pinacols is established by way of oxidative coupling reaction of benzylethers with a thiyl radical, a hydrogen acceptor, generated from disulfide under UV irradiation.
Improvement of the Hydrothermal Stability of Siliceous MCM-48 by Fluorination
Authors: Xia Q-H , Hidajat K , Kawi S 
Published: March 2003

Abstract
The siliceous MCM-48 molecular sieve, a member of the M41s family, is prepared for the first time in the presence of fluoride ions, and the hydrothermal stability of fluorinated MCM-48 framework is found to be remarkably improved as compared with those synthesized in other media.
Reaction of 1-Disilagermirene with Benzaldehyde: An Unexpected Combination of Cycloaddition and Insertion Pathways
Authors: Lee Vladimir Ya , Ichinohe Masaaki , Sekiguchi Akira 
Published: March 2003

Abstract
New strained bicyclic compounds were formed by the reaction of tetrakis[di-tert-butyl(methyl)silyl]-1-disilagermirene 1 with benzaldehyde, involving cycloaddition following the rearrangement and insertion pathways. Reaction of 1 with PhCHO gave three different products: two mono-adducts 2, 3 and one bis-adduct 4, depending on the ratio of the reagents and the reaction conditions.
Asymmetric Aldol Polymerization of Bis(trimethylsilylketene thioacetal) and Dialdehyde
Authors: Komura Kenichi , Itsuno Shinichi 
Published: March 2003

Abstract
Asymmetric repetitive Mukaiyama aldol reaction between bis(trimethylsilylketene thioacetal) and dialdehydes proceeded in the presence of chiral oxazaborolidinone to afford optically active poly(β-hydroxy thioester)s. Degree of asymmetric induction during polymerization was evaluated both by a model reaction and chiral HPLC analysis of degradation products of the chiral polymers.
Formation of an Optically Active Helical Polyisocyanide Langmuir–Blodgett Film
Authors: Feng Fei , Miyashita Tokuji , Takei Fumie , Onitsuka Kiyotaka , Takahashi Shigetoshi 
Published: March 2003

Abstract
An optically active helical polyisocyanide synthesized with a screw-sense-selective living polymerization formed a condensed monolayer on the water surface and was transferred onto a solid support as Y-type LB film with an ordered orientation.
Photocyanation of Pyrene in an Oil-in-Water Emulsion System
Authors: Kitagawa Fumihiko , Murase Masato , Kitamura Noboru 
Published: March 2003

Abstract
Photoirradiation of pyrene in the presence of 1,4-dicyanobenzene and NaCN in a benzonitrile/water mixture (1/100, vol/vol%) under vigorous stirring gave 1-cyanopyrene (PyCN) in an 83% yield, while an analogous reaction in acetonitrile/water (9/1, vol/vol%) yielded PyCN in a 61% yield.
Synthesis Conditions and Catalytic Properties of Highly Acidic Zeolite, UTM-1
Authors: Yamamoto Katsutoshi , Uneme Motonori , Plévert Jacque , Tatsumi Takashi 
Published: March 2003

Abstract
Preferable synthesis conditions for zeolite UTM-1 are studied; UTM-1 is crystallized under similar conditions to those of MCM-22, although it prefers high SiO2/Al2O3 ratio in mother gel. UTM-1, composed of the same basic building unit as ZSM-5, shows strong acidity comparable to that of ZSM-5. Although small aperture of UTM-1 actually restricts the catalytic activities, its large outer surface area enables the high catalytic activity in reactions occurring at the outer surface of catalyst.
A Novel Lithium Salt with a Chelate Compound of Phosphorus for Lithium Battery Electrolytes
Authors: Nanbu Noritoshi , Shibazaki Takatsugu , Sasaki Yukio 
Published: March 2003

Abstract
We have synthesized a novel Li salt with a chelate compound of phosphorus, lithium tris[4-methyl-1,2-benzenediolato(2–)-O,O′]phosphate (4-MLTBP). The thermal stability and electrolytic properties of 4-MLTBP, and the charge–discharge characteristics of a lithium electrode are investigated. The thermal decomposition temperature of 4-MLTBB is higher than those of a common lithium salt with phosphorus, LiPF6, and lithium tris[1,2-benzenediolato(2–)-O,O′]phosphate, which we previously synthesized. The specific conductivities and the cycling efficiencies become higher in an ethylene carbonate– and a propylene carbonate–dimethyl carbonate equimolar binary solutions containing a mixture of 4-MLTPB with LiPF6.
Photocatalytic Activity for Water Decomposition of RuO2-Loaded SrIn2O4 with d10 Configuration
Authors: Sato Junya , Saito Nobuo , Nishiyama Hiroshi , Inoue Yasunobu 
Published: March 2003

Abstract
A p-block metal oxide of SrIn2O4 with d10 configuration was found to be a new photocatalyst for the overall splitting of water when combined with RuO2.
Synthesis, Structure, and Optical Characterization of Sandwich-type (2,3-Naphthalocyaninato)(octaethylporphyrinato)europium(III)
Authors: Furuya Fumio , Kobayashi Nagao , Bian Yongzhong , Jiang Jianzhuang 
Published: March 2003

Abstract
The heteroleptic sandwich dimer of the title {Eu(OEP)(2,3-Nc)} has been synthesized, and its crystal structure, electronic absorption, and magnetic circular dichroism are discussed.
Crystallographic report: Bis[bis(N,N‐diethyldithiocarbamato)zinc(II)] (trans‐1,2‐bis(4‐pyridyl)ethylene)trans‐1, 2‐bis(4‐pyridyl)ethylene lattice adduct
Authors: Lai Chian Sing , Tiekink Edward R. T. 
Published: March 2003

AbstractThe dimeric and centrosymmetric structure of [Zn(S2CNEt2)2(trans‐NC5H4C(H)C(H)C5H4N)]2 shows bidentate coordination by the dithiocarbamate ligands and a distorted square pyramidal geometry for zinc, defined by a NS4 donor set with the N atom in the apical position. The compound co‐crystallises with a centrosymmetric molecule of trans‐NC5H4C(H)C(H)C5H4N that does not form a significant interaction to the Zn atom. Copyright © 2003 John Wiley & Sons, Ltd.
Crystallographic report: (4,4′‐Bipyridine)bis[bis(N,N‐diethyldithiocarbamato)zinc(II)]
Authors: Lai Chian Sing , Tiekink Edward R. T. 
Published: March 2003

AbstractThe structure of [Zn(S2CNEt2)2]2(4,4′‐bipy) shows two independent dimeric molecules, one located about a centre of inversion, the other lying on a two fold axis containing the zinc atoms. Bidentate coordination by the dithiocarbamate ligands and a distorted square pyramidal geometry are found for two of zinc atoms whereas for the third zinc atom, the geometry is intermediate between square pyramidal and trigonal bipyramidal, a result that underscores the flexibility of coordination in these systems. Copyright © 2003 John Wiley & Sons, Ltd.
Synthesis, structure characterization and insecticidal activity of some triorganotin dithiocarbamates
Authors: Eng George , Song Xueqing , Duong Quyen , Strickman Daniel , Glass Jacqulin , May Leopold 
Published: March 2003

AbstractA series of triorganotin dithiocarbamates

has been synthesized using a low‐temperature method. Their structures have been characterized by IR, Mössbauer and NMR spectroscopies. In the solid state, an unsymmetrical chelation of the dithiocarbamate ligand was found in all the compounds synthesized. The observation of two SnS distances in the compounds was confirmed in the crystal structure of tricyclohexyltin N‐n‐butyldithiocarbamate. In solution, the compounds were found to exhibit distorted tetrahedral structures. The insecticidal activities of the title compounds were screened against the second larval instar of the Anopheles stephensi Liston and Aedes aegypti (L.) mosquitoes. Results from the screening studies indicated that the triorganotin dithiocarbamates were effective larvicides against both species of larvae. However, there were no significant activity differences between the triphenyltin and tricyclohexyltin derivatives. A quantitative structure–activity relationship was also developed for the An. stephensi. Copyright © 2003 John Wiley & Sons, Ltd.
Multisite Catalysis: A Mechanistic Study of β‐Lactone Synthesis from Epoxides and CO—Insights into a Difficult Case of Homogeneous Catalysis
Authors: Molnar Ferenc , Luinstra Gerrit A. , Allmendinger Markus , Rieger Bernhard 
Published: March 2003

AbstractCarbonylation of epoxides with a combination of Lewis acids and cobalt carbonyls was studied by both theoretical and experimental methods. Only multisite catalysis opens a low‐energy pathway for trans opening of oxirane rings. This ring‐opening reaction is not easily achieved with a single‐site metal catalyst due to structural and thermodynamic constraints. The overall reaction pathway includes epoxide ring opening, which requires both a Lewis acid and a tetracarbonylcobaltate nucleophile, yielding a cobalt alkyl—alkoxy–Lewis acid moiety. After CO insertion into the CoCalkyl bond, lactone formation results from a nucleophilic attack of the alkoxy Lewis acid entity on the acylium carbon atom. A theoretical study indicates a marked influence of the Lewis acid on both ring‐opening and lactone‐formation steps, but not on carbonylation. Strong Lewis acids induce fast ring opening, but slow lactone formation, and visa versa: a good balance of Lewis acidity would give the fastest catalytic cycle as all steps have low barriers. Experimentally, carbonylation of propylene oxide to β‐butyrolactone was monitored by online ATR‐IR techniques with a mixture of tetracarbonylcobaltate and Lewis acids, namely BF3, Me3Al, Et2Al+⋅diglyme, and a combination of Me3Al/dicobaltoctacarbonyl. We found that the last two mixtures are extremely active in lactone formation.
Tetra‐ and Octalactam Macrocycles and Catenanes with Exocyclic Metal Coordination Sites: Versatile Building Blocks for Supramolecular Chemistry
Authors: Li Xi‐you , Illigen Jens , Nieger Martin , Michel Steffen , Schalley Christoph A. 
Published: March 2003

AbstractThe synthesis of a new tetralactam macrocycle and the simultaneous formation of catenanes and larger octalactam macrocycles is reported. These species bear 2,2′‐biquinoline moieties suitably positioned to bind a metal center at the outer periphery of the macrocycles. 1H NMR chemical shifts permit the unambiguous distinction of transoid and cisoid conformations of the biquinoline moiety, thereby allowing an unequivocal identification of the catenane and octalactam structures, despite the fact that both have the same elemental composition and bear identical structural subunits. With the aid of an anion template effect, rotaxanes can be prepared from the smaller tetralactam macrocycle. These reveal significantly altered requirements in terms of the stopper size as compared to previously reported tetralactam wheels. Several copper(I)‐mediated dimers and a (bpy)2RuII complex (bpy=2,2′‐bipyridine) have been synthesized from the tetralactam macrocycle and the rotaxanes. The anion binding abilities of the tetralactam macrocycle and its (bpy)2RuII complex in DMSO have been compared by 1H NMR titration experiments, which revealed significantly enhanced binding by the metal complex. Mass spectrometry has been used to study the potential formation of larger assemblies of copper(I) and the catenane built‐up from two tetralactam macrocycles. Indeed, a 2:2 complex was identified. In contrast, the octalactam macrocycle of the same elemental composition yields only 1:1 complexes, with the CuI ion connecting its two biquinoline moieties in the center of a figure‐eight‐shaped molecule. Molecular modeling studies support the structural assignments made.
Structural Investigation of High‐Valent Manganese–Salen Complexes by UV/Vis, Raman, XANES, and EXAFS Spectroscopy
Authors: Feth Martin P. , Bolm Carsten , Hildebrand Jens P. , Köhler Manuela , Beckmann Oliver , Bauer Matthias , Ramamonjisoa Rivo , Bertagnolli Helmut 
Published: March 2003

AbstractXANES and EXAFS spectroscopic studies at the Mn–K‐ and Br–K‐edge of reaction products of (S,S)‐(+)‐N,N′‐bis(3,5‐di‐tert‐butylsalicylidene)‐1,2‐cyclohexanediaminomanganese(III) chloride ([(salen)MnIIICl], 1) and (S,S)‐(+)‐N,N′‐bis(3,5‐di‐tert‐butylsalicylidene)‐1,2‐cyclohexanediaminomanganese(III) bromide ([(salen)MnIIIBr], 2) with 4‐phenylpyridine N‐oxide (4‐PPNO) and 3‐chloroperoxybenzoic acid (MCPBA) are reported. The reaction of the MnIII complexes with two equivalents of 4‐PPNO leads to a hexacoordinated compound, in which the manganese atom is octahedrally coordinated by four oxygen/nitrogen atoms of the salen ligand at an average distance of ≈1.90 Å and two additional, axially bonded oxygen atoms of the 4‐PPNO at 2.25 Å. The oxidation state of this complex was determined as ≈+IV by a comparative study of MnIII and MnV reference compounds. The green intermediate obtained in reactions of MCPBA and solutions of 1 or 2 in acetonitrile was investigated with XANES, EXAFS, UV/Vis, and Raman spectroscopy, and an increase of the coordination number of the manganese atoms from 4 to 5 and the complete abstraction of the halide was observed. A formal oxidation state of IV was deduced from the relative position of the pre‐edge 1s→3d feature of the X‐ray absorption spectrum of the complex. The broad UV/Vis band of this complex in acetonitrile with λmax=648 nm was consistent with a radical cation structure, in which a MCPBA molecule was bound to the MnIV central atom. An oxomanganese(V) or a dimeric manganese(IV) species was not detected.
Time‐Resolved Resonance Raman and Density Functional Study of an Azirine Intermediate in the 2‐Fluorenylnitrene Ring‐Expansion Reaction To Form a Dehydroazepine Product
Authors: Ong Shing Yau , Zhu Peizhi , Leung King Hung , Phillips David Lee 
Published: March 2003

AbstractWe report time‐resolved resonance Raman spectra for the azirine intermediate produced in the 2‐fluorenylnitrene ring‐expansion reaction to form a dehydroazepine product. The Raman bands obtained with a 252.7 nm probe wavelength and 500 ns delay time exhibit reasonable agreement with predicted vibrational frequencies from density functional calculations for two isomers of azirine intermediates that may be formed from a 2‐fluorenylnitrene precursor. The Raman bands observed for delay times of 15 ns and 10 μs were consistent with predicted vibrational frequencies from density functional calculations for the 2‐fluorenylnitrene and dehydroazepine product species as well as previously reported 416 nm time‐resolved Raman spectra obtained on the ns and μs time scales. Our results demonstrate that the 2‐fluorenylnitrene ring‐expansion reaction to produce dehydroazepine products proceeds via relatively long‐lived 2‐fluorenylnitrene and azirine intermediates. Substitution of a phenyl ring para to the nitrene group of phenylnitrene appears to lead to significant changes in the ring‐expansion reaction so that longer lived arylnitrene and azirine intermediates can be observed. This should enable the chemical reactivity of azirine intermediates formed from arylnitrenes to be examined more readily.
Asymmetric Synthesis with 6‐tert‐Butyl‐5‐methoxy‐6‐methyl‐3,6‐dihydro‐2H‐1,4‐oxazin‐2‐one as a New Chiral Glycine Equivalent: Preparation of Enantiomerically Pure α‐Tertiary and α‐Quaternary α‐Amino Acids
Authors: Koch Claus‐Jürgen , Šimonyiová Soňa , Pabel Jörg , Kärtner Annerose , Polborn Kurt , Wanner Klaus Theodor 
Published: March 2003

AbstractThe chiral oxazinone 2 has been developed as a new chiral glycine equivalent for the asymmetric synthesis of mono‐ and disubstituted α‐amino acids. It is derived from the α‐hydroxycarboxylic acid 1, which serves as a chiral auxiliary, and is easily accessible in enantiomerically pure form by optical resolution of the racemic compound (RS)‐1. For alkylation reactions, 2 was deprotonated with sBuLi or phosphazenic base. Subsequent treatment with alkyl halides yielded the monosubstituted compounds 13/14a−c, e, f, (ent)‐13d, (ent)‐14d, while a second alkylation step, via the corresponding enolates, provided the disubstituted compounds 17/18a−d. Both alkylation steps proceeded with good yields and excellent diastereoselectivities (up to 99% de) and even less reactive electrophiles such as isopropyl iodide could be used. The results obtained in this reaction supported the assumption that the enolate of 2, as well as those of the monosubstituted derivatives of 2, have less tendency to form the aggregates that hamper alkylation reactions with other systems with higher oxygen content. From the major diastereomers of both the mono‐ and the disubstituted derivatives of 2 the corresponding α‐amino acids 33a−c and 34a−d were obtained in high enantiomeric purity by hydrolytic cleavage of the oxazinone ring, accomplished either in two steps with aqueous TFA and aqueous NaOH or in one with either aqueous NaOH or 3 N HBr. Alkylation of the enolate ions of (S)‐2 or (R)‐2 with epichlorohydrins as bifunctional electrophiles provided the hydroxymethylenecyclopropyl derivatives 21 and 22. Hydrolysis of 21 and 22 afforded the free amino acids 35 and (ent)‐35. Reductive amination with aniline after oxidation of 21 and 22 to the corresponding aldehydes 24 and 26 provided the compounds 25 and 27, whereas Mitsunobu treatment of 21 and 22 with 1‐phenyl‐3‐(trifluoroacetyl)urea (28) afforded the urea derivatives 29 and 31. Hydrolysis of these compounds yielded the corresponding 1‐aminocylopropanecarboxylic acid derivatives 36/(ent)‐36 and (ent)‐37. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Mono and double polar [4 + 2+] Diels–Alder cycloaddition of acylium ions with O‐heterodienes
Authors: Meurer Eduardo C. , Eberlin Marcos N. 
Published: March 2003

AbstractGas‐phase reactions of acylium ions with α,β‐unsaturated carbonyl compounds were investigated using pentaquadrupole multiple‐stage mass spectrometry. With acrolein and metacrolein, CH3—C+O, CH2CH—C+O, C6H5—C+O, and (CH3)2N—C+O react to variable extents by mono and double polar [4 + 2+] Diels–Alder cycloaddition. With ethyl vinyl ketone, CH3—C+O reacts exclusively by proton transfer and C6H5—C+O forms only the mono cycloadduct whereas CH2CH—C+O and (CH3)2N—C+O reacts to great extents by mono and double cycloaddition. The positively charged acylium ions are activated O‐heterodienophiles, and mono cycloaddition occurs readily across their C+O bonds to form resonance‐stabilized 1,3‐dioxinylium ions which, upon collisional activation, dissociate predominantly by retro‐addition. The mono cycloadducts are also dienophiles activated by resonance‐stabilized and chemically inert 1,3‐dioxonium ion groups, hence they undergo a second cycloaddition across their polarized CC ring double bonds. 18O labeling and characteristic dissociations displayed by the double cycloadducts indicate the site and regioselectivity of double cycloaddition, which are corroborated by Becke3LYP/6–311++G(d,p) calculations. Most double cycloadducts dissociate by the loss of a RCO2COR1 molecule and by a pathway that reforms the acylium ion directly. The double cycloadduct of the thioacylium ion (CH3)2N—C+S with acrolein dissociates to (CH3)2N—C+O in a sulfur‐by‐oxygen replacement process intermediated by the cyclic monoadduct. The double cycloaddition can be viewed as a charge‐remote type of polar [4 + 2+] Diels–Alder cycloaddition reaction. Copyright © 2001 John Wiley & Sons, Ltd.