bluuebunny/crossref_metadata_2025_split huggingface dataset:
Spectroscopic and MO Study of Peptide Models for the M412 Intermediate of Bacteriorhodopsin. Nε-Retinylidenelysyl Peptides Containing Aromatic Amino Acids
Authors: Sakurai Minoru , Tomomasa Satoshi , Seiya Yûji , Inoue Yoshio , Chûjô Riichirô 
Published: July 2006

Abstract
N ε-Retinylidenelysyl peptides containing Tyr and Phe were prepared in order to investigate the effect of the surrounding microenvironment on the absorption maximum of the chromophore of bacteriorhodopsin. The absorption maximum of the retinylidene Schiff base of the lysyl peptide, Boc–Lys–Phe(or –Gly)–Tyr–OMe, was shifted to the red relative to the peptides lacking Tyr, Boc–Lys–Phe–Phe–OMe and Boc–Lys–Phe–OMe. UV and 13C NMR studies on the Tyr-containing lysyl-peptide have confirmed an intramolecular interaction between Tyr and the retinylidene portion in low dielectric media. A hydrogen-bond formation of the Schiff base with a Tyr side chain is supported by a theoretical estimation of the transition energy and the shielding constants for some models of Tyr-Schiff base complexes. The side-chain conformation of the Tyr-contaning lysyl-peptide is discussed in terms of the 1H NMR data. The hydrogen-bonding shift induced by Tyr was estimated as being no less than 10 nm.
Synthesis of Amides and Amidines by Reaction of Carboxylic Acids and Amines in the Presence of Polyphophoric Acid Trimethylsilyl Ester (PPSE)
Authors: Ogata Shin-ichi , Mochizuki Amane , Kakimoto Masa-aki , Imai Yoshio 
Published: July 2006

Abstract
The reaction between amines and carboxylic aicds in the presence of polyphosphoric acid trimethylsilyl ester (PPSE) has been investigated from the view point of the synthesis of amides and amidines. Benzanilide was selectively prepared from benzoic acid and aniline in the presence of PPSE and pyridine at 100 °C, whereas a mixture of benzanilide and N,N′-diphenylbenzamidine was obtained without the use of pyridine. The reaction at 160 °C almost exclusively gave N,N′-diphenylbenzamidine. Various symmetrical amidines were obtained from combinations of carboxylic acids and aromatic amines in high yields by simply heating at 160 °C with four molar amounts of PPSE. The reactions of aliphatic and aromatic amines with N-monosubstituted and N,N-disubstituted amides also afforded corresponding unsymmetrical amidines under the same conditions. The reaction mechanism is discussed in some detail.
Photochemical Reaction of 2-Aryl-1,2-benzisoselenazol-3(2H)-ones
Authors: Kamigata Nobumasa , Iizuka Hirokazu , Izuoka Akira , Kobayashi Michio 
Published: July 2006

Abstract
The photochemical reaction of 2-aryl-1,2-benzisoselenazol-3(2H)-ones (1) in benzene was found to give dibenzo[b,f][1,4]selenazepin-11(10H)-ones (2). On the other hand, the photochemical reaction of 1 in t-butyl alcohol afforded 2-(2-hydroxy-2-methylpropylseleno)benzanilide, 2-(methylseleno)benzanilide, and 2-aryl-1,2-benzisoselenazol-3(2H)-one 1-oxides together with the photoisomer 2. Mechanisms for these reactions are proposed.
Synthesis and Conformation of Aromatic Cyclic Dipeptides. Cyclo(phenylalanyl)2, Cyclo(1-naphthylalanyl)2, and Cyclo(2-naphthylalanyl)2
Authors: Egusa Syun , Takagi Jun , Sisido Masahiko , Imanishi Yukio 
Published: July 2006

Abstract
Cyclic dipeptides of aromatic amino acids, cyclo(l-phenylalanyl)2, cyclo(l-1-naphthylalanyl)2, and cyclo(l-2-naphthylalanyl)2 were synthesized and subjected to spectroscopic analyses using 1H NMR, absorption, circular dichroism (CD), fluorescence, and fluorescence-detected circular dichroism (FDCD). The 1H NMR data suggested that the 2,5-piperazinedione rings of the three cyclic dipeptides are in planar or nearly planar bowsplit boat-type conformation. The aromatic side groups of cyclo(1- and 2-naphthylalanyl)2’s were found to take asymmetric configurations, one naphthyl group being folded onto the 2,5-piperazinedione ring, the other being unfolded. Strong exciton couplet was observed in CD spectra of the three compounds. The signs of the exciton splitting were opposite in the two naphthyl cyclic dipeptides. Fluorescence spectra of the two naphthyl cyclic dipeptides showed no excimer emission. The absence of strong interchromophoric interaction in the lowest excited state was also suggested by the virtual coincidence of CD spectrum with FDCD spectrum. From the above spectroscopic data, probable conformations were proposed for the naphthyl cyclic dipeptides.
Stereochemistry of Hydroxymethylations of N-Salicylideneglycyl Dipeptide Copper(II) Complexes. A Kinetically and Also Thermodynamically Controlled Reaction
Authors: Harada Kaoru , Suzuki Shinnichiro , Narita Hideyuki , Watanabe Hiroshi 
Published: July 2006

Abstract
(N-Salicylideneglycyl-l-valinato)copper(II) or (N-salicylideneglycyl-l-isoleucinato)copper(II) was treated with formaldehyde in an aqueous solution under relatively mild conditions. It was found that the resulting seryl residue was d-configuration in the early stage of the reaction. However, the configuration was inverted from d- to l-form after prolonged reaction. The epimerization reactions of authentic (N-salicylideneglycyl-d- or l-seryl-l-isoleucinato)copper(II) were carried out under similar conditions. These results indicate that the reaction as a whole is controlled kinetically as well as thermodynamically.
Recovery of Highly-Purified Rare Earth Elements Using Newly-Synthesized Chelating Resins
Authors: Takeda Kunihiko , Akiyama Minoru , Kawakami Fumiaki , Sasaki Mitsunaga 
Published: July 2006

Abstract
The chromatographic separation of rare earth elements was studied using newly-synthesized chelating resins which have EDTA (ethylenediaminetetraacetic acid) and DTTA (diethylenetriaminetetraacetic acid) pendant groups. The chromatography using EDTA- and DTTA-chelating resins gave excellent separation results, while the IDA-chelating resin was not satisfactory. The DTTA-type resin was especially effective, allowing highly purified rare earth elements to be recovered. The separation efficiency of each resin was attributed mainly to the difference in its complexing capability among rare earth ions. Prior to experimentation, the chromatographic conditions were assessed and optimized by computer simulation based on newly introduced equations. The simulation results were effective in the case of Pr3+/Nd3+ for determining the experimental conditions. An analysis of the experimental results helped to elucidate the mechanism of the chromatographic separation while using the simulation results.
Conformation of Condensed Polycyclic Aromatic Hydrocarbons. II. The Molecular and Crystal Structure of Violanthrene B (Dibenzo[a, rst]naphtho[8,1,2-cde]pentaphene)
Authors: Oonishi Isao , Fujisawa Shoji , Aoki Junji , Ohashi Yuji , Sasada Yoshio 
Published: July 2006

Abstract
The title compound, C34H18, has been obtained by reducing violanthrone B, a byproduct in the synthesis of violanthrone. Its structure has been determined by on X-ray analysis. The space group is P21/c, with unit-cell dimensions a=25.78(1), b=3.807(5), c=19.975(8) Å, β=96.55(3)°, and Z=4. The structure was solved by the direct method and refined by a block-diagonal least-squares method to an R value of 0.076 on the basis of 1242 independent reflections. The molecules are largely distorted from a planar structure owing to a steric repulsion between the intramolecular overcrowded hydrogen atoms. Also, they are stacked face-to-face to form a column structure along the b-axis.
Infrared Multiple-Photon Decomposition of β-Propiolactone
Authors: Yamamoto Shunzo , Ishikawa Yo-ichi , Arai Shigeyoshi 
Published: July 2006

Abstract
The infrared multiple-photon decomposition of β-propiolactone was found to give only ethylene and carbon dioxide with the same yield as the products, where the material balance was above 90%. This result suggests that the unimolecular decomposition into ethylene and carbon dioxide is a unique reaction channel of the compound at highly vibrationally excited states. It was shown that the decomposition probability was strongly dependent on the fluence but slightly dependent on the pressure.
Ion/Molecule Reactions in Gaseous Acetone
Authors: Hiraoka Kenzo , Takimoto Hajime , Morise Kazuya , Shoda Takashi , Nakamura Shizuo 
Published: July 2006

Abstract
The ion/molecule reactions in acetone were investigated which were induced by the electron impact. It was found that the protonated acetone reacts with an acetone molecule to produce the protonated diacetone alcohol (4-hydroxy-4-methyl-2-pentanone) and the protonated mesityl oxide (4-methyl-3-penten-2-one) through the aldol condensation reaction. It was also found that the acetone molecule isomerizes from keto to enol form in the interaction with the chloride ion. The thermochemical data for the higher-order clustering reactions of the proton and chloride ion with acetone molecules were obtained.
An Important Metal Complex in the Asymmetric Synthesis of α-Amino Acids. The Crystal and Molecular Structure of (−)546-((R)-Alaninato)((6R,8R)-6,8-dimethyl-2,5,9,12-tetraazatridecane)cobalt(III) Bromide Trihydrate, (−)546-[Co(R-ala)(1,5R,7R,11-Me4-2,3,2-tet)]Br2·3H2O
Authors: Yashiro Morio , Ajioka Masanobu , Yano Shigenobu , Toriumi Koshiro , Ito Tasuku , Yoshikawa Sadao 
Published: July 2006

Abstract
The crystal and molecular structures of (−)546-((R)-alaninato)((6R,8R)-6,8-dimethyl-2,5,9,12-tetraazatridecane)cobalt(III) bromide trihydrate ((−)546-[Co(R-ala)(1,5R,7R,11-Me4-2,3,2-tet)]Br2·3H2O) (1), derived from (−)546-[Co(AMM)(1,5R,7R,11-Me4-2,3,2-tet)]+ on decarboxylation, have been determined from three-dimensional X-ray counter data. In the above, AMM is an α-amino-α-methylmalonate ion. The compound crystallizes in an orthorhombic space group P212121 with a=11.713 (1) Å, b=20.301 (2) Å, c=10.113 (2) Å, and Z=4. The structure was solved by the heavy-atom method followed by full-matrix least-squares and Fourier techniques. A refinement using 2168 reflections with |Fo|&gt;3[σ(Fo)] gave R=0.052. The absolute configuration of the complex cation is Λ in the β2 form. The gauche conformations of two five-membered chelate rings for the tetramine are both δ, and the central six-membered chelate ring adopts a chair conformation with one methyl group axial and the other equatorial. All the secondary nitrogen atoms have S configurations except one of the terminal nitrogen atoms whose absolute configuration is R. The N-methyl group in an “out-of-plane” five-membered chelate ring is equatorial; however, the other in an “in-plane” five-membered chelate ring has an axial disposition. The alaninate ion coordinates to the cobalt via N and O atoms. The absolute configuration around the carbon center of the alanine was found to be R.
Measurements of Association Constants of Iodine with Cyclodextrins and with Iodide or Bromide Ion in Aqueous Medium, Based on Volatilization Rate of Iodine from Aqueous into Gaseous Phase
Authors: Sanemasa Isao , Nishimoto Yuko , Tanaka Akira , Deguchi Toshio 
Published: July 2006

Abstract
Iodine molecules, which are volatile, are expelled from an aqueous medium into the gaseous phase by introducing an inert gas at a constant flow rate into the aqueous phase, and the amount of the released iodine is measured as a function of aeration time. In the presence of a nonvolatile solute which associates with molecular iodine, the releasing rate of the volatile solute is reduced with increasing degree of the association between both the solutes in the aqueous medium. The method was applied to the case of association of iodine with α-, β-, or γ-cyclodextrin; the formation constants of the three 1:1 complexes are (1.5±0.1)×104, (1.5±0.2)×102, and 24±3 dm3 mol−1, respectively, at 25.0 °C and low ionic strengths. The complexation of iodine with iodide or bromide ion was also studied; the I3− and I2Br− formation constants are (6.5±0.1)×102 and 16±1 dm3 mol−1, respectively, at 25.0 °C and I=0.1(NaClO4).
The Effect of Tetraalkylammonium Ions on the Distribution of the Silicate Anions in Aqueous Solutions
Authors: Hasegawa Isao , Kuroda Kazuyuki , Kato Chuzo 
Published: July 2006

Abstract
The effect of the addition of tetramethylammonium, (2-hydroxyethyl)trimethylammonium and benzyltrimethylammonium ions on the distribution of the silicate anions arising from the hydrolysis of tetraethoxysilane was studied by using the trimethylsilylation method. The selective formation of the octameric silicate anion with a double four-membered cage was confirmed in these solutions. It was found that tetraalkylammonium ions with three methyl groups, whether or not the other group was a methyl group, contributed to the formation of a double four-membered cage octamer.
Kinetics of Ligand-Exchange Reactions in Tetrakis(acetylacetonato)uranium(IV) in Organic Solvents
Authors: Fukutomi Hiroshi , Ohno Hideki , Tomiyasu Hiroshi 
Published: July 2006

Abstract
The kinetics of ligand-exchange reactions between tetrakis(acetylacetonato)uranium(IV) [U(acac)4] (acac=acetylacetonate) and free acetylacetone Hacac in various organic solvents, CDCl3, C6D6, and CD3CN has been studied by 1H NMR. The rate laws were found to change remarkably with these solvents used. The observed first-order rate constant kobsd in CDCl3 depended linearly on the concentration of free Hacac in the enol form as kobsd=ks[Hacac]enol, while the plots of kobsd vs. [Hacac]enol in C6D6 deviated from straight lines in higher concentrations of Hacacenol. The exchange rate was much slower in CD3CN than in CDCl3 and C6D6, and kobsd increased only slightly with [Hacac]enol. Addition of dimethyl sulfoxide (DMSO) in C6D6 yielded the retardation of exchange rate giving a rate law kobsd−1=p+q[DMSO], where p and q are constants. From the results obtained in these solvents, a mechanism passing through nine-coordinate intermediates was proposed.
Preparation and Thermal Square Planar–Octahedral Transformation of Nickel(II) Complexes Containing 1,2-Butanediamine or 3,3-Dimethyl-1,2-butanediamine in Solid Phase
Authors: Ihara Yoshinori , Wada Akiko , Fukuda Yutaka , Sone Kozo 
Published: July 2006

Abstract
Nickel(II) complexes of 1,2-butanediamine(1,2-bn) and 3,3-dimethyl-1,2-butanediamine(dmbn), were prepared, and their thermal behavior was investigated in solid phase. The original complexes were all violet, octahedral diaquabis(diamine) complexes([Ni(H2O)2(1,2-bn/dmbn)2]X2; X=Cl, Br, NO3, or ClO4). The 1,2-bn complexes with Cl− or Br− and the dmbn complex with NO3− showed a two-step thermochromism, violet→yellow→violet blue, upon heating. These steps correspond to structural changes to a square planar anhydride, and then to an octahedral dianiono complex. The complexes of both ligands with ClO4− underwent only thermal deaquation, changing into orange square planar anhydride. Other salts, the 1,2-bn complex with NO3− and the dmbn complexes with Cl− or Br−, were converted into octahedral dianiono complexes by thermal deaquation-anation which occurs in one step. The differences among the thermal reactivities of the complexes with different diamines can be understood on the basis of steric hindrance caused by the substituent groups on the diamine.
Synthesis of the 3H-Azepines Utilizing the Thermolysis of Substituted Aryl Azides
Authors: Ohba Yoshihiro , Kubo Shinji , Nakai Masaaki , Nagai Atsunori , Yoshimoto Masayo 
Published: July 2006

Abstract
Thermolysis of several p-substituted aryl azides (p-R-C6H4N3; R=COCH3, CO2CH3, COPh) in methanol gave 5-substituted 2-methoxy-3H-azepines in moderate yields. Thermolysis of m-substituted aryl azides (m-R-C6H4N3; R=COCH3, CO2CH3, COPh, NO2) gave 4-substituted 2-methoxy-3H-azepines and 6-substituted 2-methoxy-3H-azepines in good yields. In contrast, thermolysis of p-azidoacetophenone in piperidine gave 5-acetyl-2-piperidino-3H-azepine and an unusual product, 6-acetyl-2-piperidino-3H-azepine, and p-aminoacetophenone.
The Synthesis of Dihydro-2(3H)-thiophenone Derivatives
Authors: Taguchi Yoichi , Suhara Yasuo 
Published: July 2006

Abstract
The reaction of 2,2-dimethylthiirane (4) with diethyl malonate (5) in the presence of sodium ethoxide gave 3-ethoxycarbonyl-5,5-dimethyl-dihydro-2(3H)-thiophenone (6) and a polymer. The yield of 6 could be increased to 65%. The reaction of thiirane, 2-methylthiirane, 2-butylthiirane, 2-hexylthiirane, 1,2-epithiocyclohexane, and 2-phenylthiirane with 5 also gave corresponding dihydro-2(3H)-thiophenone derivatives. Although the reaction of an alkyl-substituted thiirane with 5 selectively gave a product formed by an attack of a carbanion at the less-hindered carbon of the thiirane ring, the major product of the reaction of 2-phenylthiirane with 5 was an isomer formed by an attack at the more hindered carbon of the thiirane ring. The reaction of 4 with ethyl acetoacetate gave 3-acetyl-5,5-dimethyl-dihydro-2(3H)-thiophenone selectively. A product 6 was also obtained by a reaction of 4 with 5 by using sodium hydride instead of sodium ethoxide.
A Study of the Color of Coal Liquids. II. Involvement of Light, Oxygen, Phenols, and Aromatic Amines in Formation of Colored Materials from Wandoan-Coal-Derived Liquids
Authors: Futamura Shigeru , Kamiya Yoshio 
Published: July 2006

Abstract
Triggering materials responsible for coloring of coal liquids have been searched by comparing the structures of the colored materials derived from the neutrals, acids, and bases of the coal liquid and the nitrogenous model compounds. Basic constituents of the coal liquid are most prone to photooxidation and afford colored materials of higher molecular weight and stronger absorption in the visible region. Model compound studies suggest that they are predominantly formed in the photoinduced oxidative coupling of aromatic amines.
Temperature Effect on the Rhodium-Catalyzed Direct Synthesis of Ethylene Glycol from Carbon Monoxide and Hydrogen in Several Solvents
Authors: Masuda Takashi , Murata Kazuhisa , Kobayashi Toshiaki , Matsuda Akio 
Published: July 2006

Abstract
The Rh4(CO)12/N-methyl-2-pyrrolidone system is featured in that the rate of ethylene glycol (EG) formation is significantly accelerated with increasing reaction temperature. The turnover frequency of EG at 300 °C and 2000 kg/cm2 (H2/CO=1) is about 2000 h−1. The Rh4(CO)12/tributylamine system also has a high catalytic activity at a high temperature.
The Direct Preparation of Flavones from 2′-Hydroxychalcones Using Disulfides
Authors: Hoshino Yukio , Oohinata Toshinori , Takeno Noboru 
Published: July 2006

Abstract
Flavone was obtained by a reaction of 2′-hydroxychalcone with disulfides in good yield. Among several disulfides, diphenyl disulfide gave the best result. Under the same conditions, some flavones were obtained from the corresponding 2′-hydroxychalcones in satisfactory yields.
New Piperidinic Synthons via Ring Contraction. Formal Synthesis of (±)-Perhydrohistrionicotoxin
Authors: Duhamel Pierre , Kotera Mitsuharu , Monteil Thierry 
Published: July 2006

Abstract
The 2,2-bifunctionalized piperidines 6 and 10 were obtained via ring contraction of the seven-membered heterocyclic enamino aldehyde 5 in nearly quantitative yield. The synthesis of 1-benzyl-1-azaspiro[5.5]undec-7-en-9-one 9 (a formal precursor of perhydrohistrionicotoxin 1b) in 3 steps from the piperidinedialdehyde monoacetal 6, is reported.
Electron-Transfer Reactions between Cobalt(III) Complexes and Polymer-Bound Ferrous Chelate
Authors: Kurimura Yoshimi , Takato Kiyomi , Suzuki Norihisa 
Published: July 2006

Abstract
The reductions of some cobalt(III) complexes having overall charges of −1 to +3 by the polymer-bound ferrous chelate, Fe(II)–PBDA (PBDA=vinylbenzylamine-N,N-diacetate-co-4-styrenesulfonate), and the effect of sodium chloride on the reduction rate have been investigated. The specific rate increases sharply with the positive charge on the Co(III) complexes by electrostatic interactions between reactant species.
Photochemical Reaction of Tricarbonyl(η-methylcyclopentadienyl)manganese(I), [Mn(CO)3(MeCp)], with 1,1′-Bis(diphenylphosphino)ferrocene, (dppfe), and X-Ray Molecular Structure Analysis of [Mn(CO)(MeCp)(dppfe)]
Authors: Onaka Satoru 
Published: July 2006

Abstract
Photochemical reaction of MeCpMn(CO)3 with (Ph2PC5H4)2Fe, (dppfe), was conducted in benzene. From the reaction mixture, the title compound [Mn(CO)(MeCp)(dppfe)] was isolated and its molecular structure was solved by X-ray analysis. ν(CO) peak at 1810 cm−1 of the title compound was clarified to be originated from the terminal carbonyl. Temperature-dependent 1H NMR spectra were also measured for the title compound.
NMR Spectra of Dimethyl 1-Acetyl-1,2-dihydro-2-quinolyl-phosphonate and Related Compounds
Authors: Suezawa Hiroko , Hirota Minoru , Shibata Yasuhiro , Takeuchi Isao , Hamada Yoshiki 
Published: July 2006

Abstract
1H, 13C, and 31P NMR spectra of the products from the Reissert type reactions using acyl halides and trimethyl phosphite were measured and correlated with their structures. 31P Chemical shift of dimethoxyphosphinyl group and 13C chemical shift of the α-carbon atom, as well as 1JCP and 2JPH, can be criteria to differentiate the 1,2- and the 1,4-adducts from each other. Thus, there NMR parameters can be a clue to elucidate the regioselectivity of the reactions.
Metal Carbonyl-Induced N–O Bond Cleavage of the Oxime Group
Authors: Nitta Makoto , Iino Yukio 
Published: July 2006

Abstract
The reaction of [Mo(CO)6] or [Fe2(CO)9] with oxime O-acetate of 1,3-diphenyl-2-propen-1-one undergoes a reductive N–O bond cleavage to give an imine which dimerises and/or is hydrolyzed to ketones. The dimer, so formed, undergoes fragmentations to give pyridine and pyrimidine derivatives. Similarly, the reaction of [Mo(CO)6] with several oxime O-acetates, oximes, and an oxime ether were shown to give the corresponding ketones. A reaction of oxime O-acetates with [Cr(CO)6] or with [W(CO)6] to give the corresponding ketones was also shown to proceed very slowly.
A New Phase-Transfer Porphyrin Catalyst for the Olefin Epoxidation
Authors: Takagi Shigeru , Miyamoto T Ken , Sasaki Yukiyoshi 
Published: July 2006

Abstract
A new type of amphiphilic porphyrin has been synthesized and its manganese(III) complex has been used as a catalyst for the epoxidation of olefin. Catalytic oxygenation in a two-phase (CH2Cl2/H2O) system has been undertaken in the absence of a phase-transfer reagent, such as benzyldimethyltetradecylammonium chloride.
Solvent Effects on the nπ* and ππ* Absorption Intensities of Some Organic Molecules
Authors: Abe Takehiro , Iweibo Idowu 
Published: July 2006

Abstract
Recently proposed experimental and theoretical expressions for the molecular electronic oscillator strength in a solution (J. Chem. Phys., 83, 1546 (1985)) have been succesfully applied to the spectral data of some nonpolar and polar organic molecules (benzoquinones, ketones, nitroalkanes, β-carotene, and substituted benzenes). In an application of the theoretical expression, the transition moment of a nonpolar solute molecule in various solvents was assumed to be approximately constant, while that of a polar solute molecule was developed on the assumptions of a first-order perturbation of the wave function and a Block–Walker reaction field. The ratio of the oscillator strength in a solution to that either in a vapor or a specified solvent was computed from both experimental data and theoretically from the transition moments. The results of the two computational modes are, generally, in good agreement for the range of compounds studied.
Photochemical Reactions of Pentakis(N,N-dimethylformamide)dioxouranium(VI) Ions in Nonaqueous Solutions
Authors: Fukutomi Hiroshi , Harazono Toshie , Kojima Takashi 
Published: July 2006

Abstract
Photochemical reactions of [UO2(dmf)5]2+ (dmf=N,N-dimethylformamide) ions were investigated in DMF and acetone solutions. The photolysis product of [UO2(dmf)5]2+ at the initial stage was U(V), which was so stable in acid-free organic solvents in the dark that the absorption spectrum of U(V) was easily obtained in DMF. The molar extinction coefficient of U(V) was determined to be 45.5±1.5 M−1 cm−1 (M=mol dm−3) at 755 nm. The formation of U(V) seems to proceed through the intramolecular reaction (ki) and the lower limit of ki was determined to be about 107 s−1 from the lifetime of excited uranyl ions by using a laser flash photolysis.