bluuebunny/crossref_metadata_2025 huggingface dataset:
A Molecular Orbital Study of Cyclodextrin Inclusion Complexes. I. The Calculation of the Dipole Moments of α-Cyclodextrin Aromatic Guest Complexes
Authors: Kitagawa Masaki , Hoshi Hajime , Sakurai Minoru , Inoue Yoshio , Chûjô Riichirô
Published: July 2006

The dipole moments of α-cyclodextrin(α-CD)-aromatic guest systems have been calculated by means of the CNDO/2 molecular orbital (MO) method in order to investigate the role of electrostatic interaction in the stabilization of the inclusion complexes. It is found that α-CD has a remarkably large dipole moment which amounts to 13.5 D and is directed from its secondary hydroxyl side (the wider rim) towards the primary hydroxyl side (the narrower rim). The dipole moments of the guests, benzene derivatives, run antiparallel to that of α-CD in the complexed state. The MO total energy of the α-CD-guest supermolecular complexes shows that these antiparallel-orientations are energitically more favorable than the reversed one. It is concluded that the electrostatic interaction, mainly dipole–dipole interaction, between the α-CD and the guest molecules plays an essential role in determining the guest orientation. On the basis of these results, it is deduced that during complexation the CD molecule undergoes appreciable amount of conformational change, suggesting that the “induced-fit” mechanism is operating when the guest molecule is admitted into the host cavity.
The Model Compounds and Conformational Analysis of Poly(thiotrimethylene) Using Molecular Mechanics Method
Authors: Miyasaka Taira , Yoshida Takaichi
Published: July 2006

Several model compounds of poly(thiotrimethylene), including one to four thiotrimethylene units, were studied by means of a molecular mechanics method. The geometric and statistical weight parameters were directly derived from the results of molecular mechanics calculations concerning several conformers of these model compounds. Although the first-order interactions of poly(thiotrimethylene) were significantly larger than those of poly(oxyalkylenes), the second-order interactions of this polymer were much smaller. The “gauche effect” by sulfur atoms seemed to be mainly caused by small second-order interactions. By means of the model, compounds including more than three repeating units, the calculated configuration-dependent properties were in better agreement with the experimental ones than that calculated earlier. The better agreement was obtained by varying some of the geometric parameters. Compounds including more than three repeating units of the polymer were available as model compounds. Since this was also true in poly(oxyalkylenes), it was found that a combination of the methods of molecular and statistical mechanics was sufficiently effective to investigate the configurational properties of poly(thiotrimethylene).
ESR Studies of Solvent and Pressure Effects on Spin Exchange of Nitroxide Radicals in Solution
Authors: Sueishi Yoshimi , Nishimura Norio , Hirata Koichi , Kuwata Keiji
Published: July 2006

The rate constants of spin exchange for 2,2,6,6-tetramethyl-4-oxo-1-piperidinyloxyl (Tanone) in various solvents at high pressures were estimated from the line-broadening in ESR spectra. The rate constants of the spin exchange were in the range of 109–1010 M−1 s−1 and were compared with the calculated ones on the basis of the Smoluchowski–Stokes–Einstein equation. A significant disagreement between them was observed as the solvent viscosity decreased. The activation volumes estimated from the pressure dependence of the rate constant for the spin exchange were slightly smaller than those for diffusive processes. These findings suggest that the rate process for the spin exchange is virtually a diffusion-controlled one. An interpretation of activation volumes for diffusive process of spin exchange is given.
Rotamer Populations and Molecular Structure of 9-Isobutyl-1,4-dimethoxytriptycene: Further Evidence for the Presence of CH3···O Hydrogen Bond
Authors: Oki Michinori , Takiguchi Naoyoshi , Toyota Shinji , Yamamoto Gaku , Murata Shigeru
Published: July 2006

1H NMR spectra of the title compound at low temperatures show the presence of the sc conformer as a major constituent: ΔH°=0.9±0.3 kcal mol−1, ΔS°=5±2 cal mol−1 for the sc\ightleftarrowsap equilibrium. The line shape analysis of the spectra at various temperatures afforded the following activation parameters for the internal rotation about the C9–Ci-Bu bond: ΔH\eweq=8.8±0.3 kcal mol−1, ΔS\eweq=−5.0±1.2 cal mol−1 K−1 for the ap→sc process. X-Ray crystallography of the compound revealed that the molecule exists as sc conformers in the crystal. One of the methyl groups of the isobutyl group that directs inward relative to the triptycene skeleton, is placed very closely to the 1-methoxy-oxygen to indicate the presence of the CH3···O hydrogen bond. Implications of other structural parameters are also discussed.
Oxidation of Coals in Liquid Phases. IX. Kinetics of the Base-Catalyzed Oxidation of Acetate Ion by Oxygen at Elevated Temperatures
Authors: Wakabayashi Takayoshi , Okuwaki Akitsugu
Published: July 2006

The kinetics of the oxidation of the acetate ion by oxygen have been studied to clarify the mechanism of the formation of oxalate from coal in concentrated alkaline solutions at elevated temperatures. The rate for the oxidation in a nickel reactor in the presence of 3 g of iron powder was expressed as −dmAc⁄dt=k′ mAcmOH2Po2, where k′ is the apparent rate constant, mAc is the molality of acetate ion, mOH is molality of the hydroxide ion, and Po2 is the partial pressure of oxygen. This result indicates that the oxidation of the acetate ion proceeds according to a base-catalyzed mechanism. The activation energy was 160 kJ mol−1. In addition, the rate of oxidation was affected by the coexistence of the metal powder and the oxidation activity in the order Cu> Ni> Co> Mn \fallingdotseq Fe>Cr. The catalytic effect of metal oxides on the rate is discussed.
Regioselective 6-Amination and 6-Arylation of 5,8-Quinolinedione Promoted by Metal Ions
Authors: Yoshida Katsuhira , Ishiguro Miwa , Honda Hiroyuki , Yamamoto Mayumi , Kubo Yuji
Published: July 2006

The effects of some metal ions on the amination and arylation of 5,8-quinolinedione (1) and on the amine displacement of 6-piperidino-5,8-quinolinedione have been investigated. The reaction of 1 with various amines in chloroform or ethanol was specifically promoted by Ni(II) ions to give selectively the corresponding 6(substituted amino)-5,8-quinolinediones. With N,N-dialkylanilines in acetic acid the reaction was strongly promoted by Cu(II) ions to give exclusively 6-arylated products, 6-[p-(dialkylamino)phenyl]-5,8-quinolinediones. The metal chelate complex was proposed as an activated intermediate.
Mechanism of the Carboxylation of Cyclohexanone with Carbon Dioxide Catalyzed by 1,8-Diazabicyclo[5.4.0]undec-7-ene
Authors: Mori Hisakazu
Published: July 2006

The dependence of the rate of carboxylation upon the concentration of the reactant was investigated in dimethyl sulfoxide. The reaction rate depended upon the concentration of cyclohexanone and 1,8-diazabicyclo[5.4.0]undec-7-ene(DBU) in the first order, respectively. The reaction also followed first-order kinetics regarding the CO2 pressure in the range 50–400 Torr. From these reaction characteristics, it is suggested that carboxylation proceeds via a reaction between CO2 dissolved in dimethyl sulfoxide and the anion of cyclohexanone, rather than between the CO2 adduct with DBU and cyclohexanone. The results of carboxylation by the CO2 adduct with DBU and by CO2 dissolved in dimethyl sulfoxide also support the above conclusion. The formation of the cyclohexanone anion by a reaction of cyclohexanone with DBU was verified by the UV spectrum of a solution of concentrated DBU and cyclohexanone.
Carbonylation of Enynes under Hydroformylation Conditions Catalyzed by Rhodium Carbonyl. A New Method for Synthesis of Cyclic Enones
Authors: Doyama Kazuo , Joh Takashi , Shiohara Tomoo , Takahashi Shigetoshi
Published: July 2006

The reactivities of 1-buten-3-yne derivatives toward hydroformylation were studied using a rhodium catalyst. Unexpectedly, cyclopentenone derivatives were obtained in moderate yields together with formylsubstituted dienes and unsaturated lactones. This reaction offers a new method for the catalytic synthesis of cyclopentenones. A mechanism for the cyclic carbonylation of enynes is also discussed.
The Chlorination of Vinyl Compounds in Alcohols
Authors: Shinoda Kiyonori , Yasuda Kensei
Published: July 2006

Upon the chlorination of vinyl compounds in alcohols, the reaction products were composed of 2-alkoxy-1-chloro compound (A), 1-alkoxy-2-chloro compound (B) and vicinal dichloride (C). Various vinyl compounds were chlorinated in alcohols at 40 °C in order to elucidate the effect of their molecular structure on the product distribution. The A/(A+B) was inversely proportional to the relative rate of ordinary chlorination in carbon tetrachloride. The A/(A+B) for the chlorination of allyl chloride in methanol was little affected by the reaction conditions: (1) reaction temperature, (2) mole ratio, and (3) elapse of time. However, the A/(A+B) increased with increasing Es value of the alkyl group of alcohol.
Kinetics of the Oxidation of [N-(2-Hydroxyethyl)ethylenediamine-N,N′,N′-triacetato]chromium(III) by Periodate
Authors: Abdel-Khalek Ahmed A , Elsemongy Mahmoud M
Published: July 2006

The kinetics of oxidation of [CrIII(H2O)(TOH)], (TOH=N-(2-hydroxyethyl)ethylenediamine-N,N′,N′-triacetate) by periodate in aqueous solutions has been found to obey the following equation

Rate=\frack2K6[CrIII]T[IVII]T1+[H+]⁄K5+K6[IVII]T

where k2 is the rate constant for the electron-transfer process, K5 is the equilibrium constant for dissociation of [CrIII(H2O)(TOH)] to [CrIII(OH)(TOH)]−+H+ and K6 is the pre-equilibrium formation constant. The activation parameters are reported. It is proposed that electron transfer proceeds via an innersphere mechanism with the hydroxo ligand of the chromium(III) complex bridging the two reactants.
Studies of the Selective O-Alkylation and Dealkylation of Flavonoids. XI. A New Convenient Method for Synthesizing 3,5,7-Trihydroxy-8-methoxyflavones from 7-Hydroxy-3,5,8-trimethoxyflavones
Authors: Horie Tokunaru , Tsukayama Masao , Kawamura Yasuhiko , Seno Masamichi , Yamamoto Shigeo
Published: July 2006

The 3- or 5-methoxyl group in the ditosylates of 5,7-dihydroxy-3,4′,8-trimethoxy- and 3,7-dihydroxy-4′,5,8-trimethoxyflavones was quantitatively demethylated with anhydrous aluminum bromide in acetonitrile to give the corresponding monohydroxyflavones, which were easily hydrolyzed into 3,5,7-trihydroxy-4′,8-dimethoxyflavone. On the basis of the results, the following convenient method for synthesizing 3,5,7-trihydroxy-8-methoxyflavones from 7-hydroxy-3,5,8-trimethoxyflavones was established. 7-Hydroxy-3,5,8-trimethoxyflavones or their tosylates were demethylated with 5% w/v anhydrous aluminum bromide in acetonitrile to give a mixture of the corresponding 3- and 5-hydroxyflavones. The mixture was tosylated and the resultant mixture was demethylated under the same conditions. The demethylated products were hydrolyzed with anhydrous potassium carbonate in methanol to give the desired 3,5,7-trihydroxy-8-methoxyflavones in high yields.
Synthesis and Structure of the Diterpenoid Peucelinendiol
Authors: Moran Joaquín R , Alcazar Victoria , Grande Manuel
Published: July 2006

The synthesis of peucelinendiol has been carried out starting from geraniol, and using as a key intermediates the anion of phenylthiogeraniol and (−)-geraniol epoxide obtained by the Sharpless procedure. Its structure was stablished as (6S,7R)-7-hydroxymethyl-2,6,10,14-tetramethylpentadeca-2,9,13-trien-6-ol. Isopeucelinendiol, epipeucelinendiol, and epiisopeucelinendiol were also synthesized.
The Magnetic Properties of Copper(II) Alkanoate Adducts with Pyridine and Quinoline Analogues
Authors: Emori Shuji , Ohishi Katsuko , Kurihara Hikari , Muto Yoneichiro
Published: July 2006

Various copper(II) alkanoate adducts with pyridine and quinoline analogues have been prepared, and characterized by means of magnetic susceptibility and IR measurements. The effects of axial ligands on the magnetic moments are discussed on the basis of their basicities and steric requirements.
The Preparation and the Structure of Bis(1,3-dimethylureido)methane
Authors: Ebisuno Toichi , Takimoto Michiaki , Takahashi Miyuki , Shiba Ryuichi
Published: July 2006

A new 1,3-dimethylurea–formaldehyde condensate, bis(1,3-dimethylureido)methane, was prepared and the molecular structure, as determined by X-ray analysis, and possible specific interaction to alkaline metal ions were compared with those of 1,3,5,7-tetramethyltetrahydro-1,3,5,7-tetrazocine-2,6(1H,3H)-dione. Although both structures are different from each other, their UV spectra in aqueous solution show that alkaline metal ions, Li+ and Na+, are caught by both of them.
Resolution of Hosoya’s Mystery?
Authors: Cyvin Sven J
Published: July 2006

Three classes of polynomials for conjugated hydrocarbons are studied: characteristic polynomials (Hückel determinants) for cyclic polyenes, and combinatorial formulas for Kekulé structure counts of two classes of circulenes.
A Theoretical Study on Bromochlorination
Authors: Yamabe Shinichi , Minato Tsutomu
Published: July 2006

The bromochlorination to ethylene is studied by ab initio MO calculations. The presence of the bridge ion is verified by a transition state (TS) search. The TS geometry is represented as an ion pair. Two mechanistic questions, orientation of Br–Cl and the anti Cl− addition, are discussed in terms of the frontier-orbital theory.
The Baeyer–Villiger Reaction of Polycyclic Aromatic Aldehydes: Preparation of Polycyclic Phenols
Authors: Fujishiro Koichi , Mitamura Shuichi
Published: July 2006

Baeyer–Villiger reactions of such polycyclic aromatic aldehydes as 2-dibenzofurancarbaldehyde with various peroxy compounds have been studied in detail, giving predominantly the corresponding phenols.
New Synthetic Methods and Reagents for Complex Carbohydrates. II. Synthesis of 2-Acylamino-2-deoxy-d-glucopyranose Derivatives by Dimethylphosphinothioic Mixed Anhydride Method
Authors: Inazu Toshiyuki , Hosokawa Hideaki , Amemiya Masahide
Published: July 2006

Dimethylphosphinothioic (Mpt) mixed anhydrides of carboxylic acids were found to be useful for N-acylation of 2-amino-2-deoxy-d-glucopyranose derivatives without protecting the hydroxyl functions. By this method, N-acylation of 2-amino-2-deoxy-d-glucopyranose hydrochloride in methanol was also found to be possible.
Carbonyl Fluoride of Molybdenum (Synthesis and Structural Investigation)
Authors: Misra Sudhindra N , Venkatasubramaniant K
Published: July 2006

Difluorotricarbonylmolybdenum MoF2(CO)3 has been synthesized by selective fluorination of molybdenum carbonyl by xenon difluoride in perfluoro solvents as well as in anhydrous hydrogen fluoride. The titled compound was isolated as an orange yellow solid and its composition was established by elemental analysis. It decomposes very slowly at room temperature, but on heating at 100 °C it decomposes completely to yield molybdenum carbonyl, molybdenum fluoride oxide and molybdenum fluoride. The compound was structurally characterized using IR, mass spectral, and X-ray powder diffraction analysis.
Synthesis, Characterization, and the Thermal Decomposition of Copper(II) Bis(oxalato)cuprate(II) Dihydrate
Authors: Deb Nidhuban , Gogoi Pradip K , Dass Narendra N
Published: July 2006

Copper(II) bis(oxalato)cuprate(II) dihydrate, Cu[Cu(C2O4)2]·2H2O, has been synthesized and characterized by elemental analysis, magnetic moment measurement, and IR, electronic and ESR spectral studies. The low value of magnetic moment (1.57 B.M.) from spin-only value is indicative of the antiferromagnetic spin pairing between two paramagnetic copper(II) ions. The ESR spectrum of the powder showed a single signal with a g value of 2.1. The thermal decomposition in air and nitrogen media was investigated by TG, DTG, and DSC. Some of the decomposition products were identified by spectral, analytical and X-ray powder diffraction studies.
Organophosphorus Analogues and Derivatives of the Natural l-Amino Carboxylic Acids and Peptides. V. Synthesis of Analogues of Plumbemycin A
Authors: Natchev Ivan A
Published: July 2006

Analogues of antibiotic Plumbemycin A were synthesized by an exchange of d-norvaline residue with 1,2,3,6-tetrahydro-1,2-azaphosphorine and by coupling of alanylaspartic acid with N-terminal norvaline. The protecting groups were released by highly selective enzyme hydrolysis.
Reaction of Benzeneseleninyl Chloride with Olefins in the Presence of a Lewis Acid. A Novel One Step Vinylic Chlorination
Authors: Kamigata Nobumasa , Satoh Takeshi , Yoshida Masato
Published: July 2006

In the presence of aluminum chloride benzeneseleninyl chloride was found to be an excellent vinylic chlorinating reagent of olefins under mild conditions. However, such olefins as styrene, trans-stilbene, and trans-1-phenylpropene afforded dichloro adducts under similar conditions. A plausible reaction mechanism involving positive chlorine intermediate is proposed.
Spectral and Biological Studies on Organotin(IV) Complexes of Heterocyclic Benzothiazolines
Authors: Singh Kiran , Singh Ranvir , Tandon Jagdish Prasad
Published: July 2006

The monobasic bidentate benzothiazolines, which were produced by the reaction of 2-mercaptoaniline and the heterocyclic aldehydes e.g., 2-furaldehyde, 2-thiophenecarbaldehyde, 2-pyridinecarbaldehyde, and 3-indolecarbaldehyde, have reacted with dialkyltin dichloride to give colored compounds. These compounds were characterized on the basis of elemental analyses, molar conductance, molecular weight determination, electronic and infrared spectral studies. Multinuclear NMR(1H, 13C, and 119Sn) data suggest trigonal bipyramidal and octahedral geometries for the resulting Me2SnCl(\ {NS}) and Me2Sn(\ {NS})2 type complexes where \ {NS} indicates benzothiazoline ligand, respectively. The fungitoxicity of 2-(2-thienyl)benzothiazoline and its complexes has been evaluated on pathogenic fungi.
Studies in the Extraction of Metals with 3-Phenyl-4-acetyl-5-isoxazolone
Authors: Jyothi A , Rao G N
Published: July 2006

Extraction of manganese(II), iron(II), cobalt(II), nickel(II), copper(II), zinc(II), and cadmium(II) from aqueous solution with 3-phenyl-4-acetyl-5-isoxazolone (HPAI) in 4-methyl-2-pentanone (MIBK) has been studied and the extraction constants have been calculated for all the systems except cadmium(II). Separation factors have been calculated for the separation of metals.
The Asymmetric Diels–Alder Cycloaddition Using Ethyl (−)-(Z)-(R)S-2-Methyl-3-(p-tolylsulfinyl)propenoate: Application to an Enantioselective Synthesis of (+)-epi-β-Santalene
Authors: Arai Yoshitsugu , Yamamoto Masatoshi , Koizumi Toru
Published: July 2006

The Diels–Alder reaction of ethyl (−)-(Z)-(R)S-2-methyl-3-(p-tolylsulfinyl)propenoate (6) with cyclopentadiene gave the cycloadducts 7, 8, and 9 in a high diastereoselective manner. The cycloadduct 7 was transformed into the acetal (−)-25. The racemic 25 was used as an intermediate in the synthesis of (±)-β-santalol. Thus, the chiral acetal (−)-25 should provide a route to (−)-β-santalol. The cycloadduct 8 was converted into (+)-epi-β-santalene in 11 steps.
On the Characterization of Fibonacci Numbers as Maximal Independent Sets of Vertices of Certain Trees
Authors: El-Basil Sherif
Published: July 2006

Fibonacci numbers are identified for the first time as maximal independent sets of vertices of certain caterpillar trees. Their relation to king patterns of certain classes of polyomino graphs as well as polyhex graphs is illustrated.
Molecular Motion in Some Hydrogen-Bonded Complexes of Trichloroacetic Acid as Studied by 35Cl-NQR
Authors: Nogaj Boleslaw
Published: July 2006

The paper presents the results of 35Cl-NQR frequency and spin-lattice relaxation time measurements as a function of the temperature in some solid hydrogen-bonded complexes: Trichloroacetic acid (TCA)–3-cyanopyridine, TCA–4-methylpyridine and [CCl3COO···H···OOCCCl3]−[K]+. The activation energies, Ea, for hindered rotation of CCl3 group of the TCA molecule were determined. Employing the available Ea data for the other complexes of this type a linear dependence between the activation energy and 35Cl–NQR frequency shift was obtained. This dependence allowed us to find Ea=f(ΔpKa) as well as Ea=f′(P) where P is the proton transfer degree. The influence of hydrogen bond on the potential barrier of the rotating CCl3 groups of TCA in the complexes studied is also discussed.
A Conformational Study on Some Thiobenzophenones. Molecular Orbital Calculations
Authors: Abu-Eittah Rafie Hassan , El-Kourashy Abdel-Ghany
Published: July 2006

MO calculations were performed on the different conformers of thiobenzophenone and on the planar conformer of a number of its derivatives using the INDO-CI procedures. A nonplanar conformer with an angle of 15° between the planes of benzene rings was predicted for thiobenzophenone. Dipole moment and charge density were calculated and correlated to the reactivity of the studied molecules. A Gaussian analysis was performed on the spectra of the studied compounds, results compared satisfactorily with the results of MO calculations.
Different Acyl Specificity between Mold and Kidney Acylases: Correlation of Hydrolytic Rate to Molecular Size and Electronegative Property of Acyl Group in Acyl-l-phenylalanine Hydrolysis
Authors: Kang Shinwon , Minematsu Yoshihiro , Shimohigashi Yasuyuki , Waki Michinori , Izumiya Nobuo
Published: July 2006

A series of acyl-l-phenylalanines were hydrolyzed by mold and hog kidney acylases. The formyl was found to be the most susceptible for mold acylase, and the butyryl for kidney acylase, indicating the different preferences of these acylases in molecular size and electronegative property of acyl group of substrates.
The Crystal Structure of a Charge-Transfer Complex of Tetrakis(methylthio)tetrathiafulvalenium Dibromoiodate, TMT-TTF·IBr2
Authors: Honda Kazumasa , Goto Midori , Kurahashi Masayasu , Anzai Hiroyuki , Tokumoto Madoka , Ishiguro Takehiko
Published: July 2006

The crystal structure of the title complex, a semiconductor, has been determined. The space group is P21⁄n, with a=8.207(3), b=11.537(4), and c=21.804(12) Å, β=91.88(5)°, and Z=4. The donor cations assume dimer structures with short intermolecular S···S contacts of 3.43, 3.53, and 3.60 Å.
Pentaamminechromium(III) t2g3 Level Properties as Determined from Vibronic Spectra and Crystal Field Calculations
Authors: Schmidtke Hans-Herbert , Adamsky Heribert , Schönherr Thomas
Published: July 2006

Low temperature (∼5 K) absorption and emission spectra of various halogenopentaamminechromium(III) salts have been recorded at high sensitivity in the intercombination region from pure microcrystalline powders and doped into corresponding rhodium complexes. Zero phonon and vibrational side bands are better resolved than reported in earlier investigations. They depend on the crystal lattice and allow a more detailed analysis of the vibrational fine structure. For carrying out reliable assignments to vibronic energy levels, the influence of the crystalline environment in different salts is found to be of major importance. Ligand field and angular overlap calculations are very helpful for solving the assignment problem, they can reproduce the proposed energy level scheme if symmetry adapted π-orbital expansion coefficients are introduced into the electron repulsion terms.
Halogenation Using Quaternary Ammonium Polyhalides. VII. Iodination of Aromatic Amines by Use of Benzyltrimethylammonium Dichloroiodate(1—)
Authors: Kajigaeshi Shoji , Kakinami Takaaki , Yamasaki Hiromichi , Fujisaki Shizuo , Okamoto Tsuyoshi
Published: July 2006

The reaction of aromatic amines with benzyltrimethylammonium dichloroiodate(1—) in dichloromethane–methanol in the presence of calcium carbonate powder for several hours at room temperature gave selectively iodosubstituted aromatic amines in good yields.
An Improvement of the Anderson Test by the Use of High Performance Liquid Chromatography
Authors: Miyazawa Toshifumi , Yamada Takashi , Kuwata Shigeru
Published: July 2006

The replacement of the N-benzyloxycarbonyl (Z) group in the Anderson peptide (Z–Gly–l/d–Phe–Gly–OEt) by Z–l-Ala and the subsequent separation of the diastereomers of the resulting tetrapeptide by reversed-phase HPLC offer a more convenient version with higher accuracy to the original Anderson test for studying racemization in peptide synthesis.
Atom Trapping Atomic Absorption Spectrometric Determination of Some Trace Elements in Soils, Natural Waters, Seawater, and Bovine Liver
Authors: Lau C M , Ure A M , West T S
Published: July 2006

The operational conditions for the determination of Ag, As, Au, Bi, Cd, Cu, Mn, Pb, Sb, Se, Tl, and Zn by atom trapping atomic absorption spectrometry are summarised. With this technique some of these trace elements can be determined in soils, natural waters, seawater and bovine liver at concentrations that are not possible by the conventional technique of flame AAS. For example, seawater is diluted ten-fold with distilled water to overcome nebulisation problems due to salt concentrations and the trace elements are collected for 2 min in situ in the air-acetylene flame before release and measurement. The attack of sodium on the hot silica atom trap tube in the flame gases is prevented by pre-aspiration of aluminium chloride into the flame, thus depositing a protective film of Al2O3. X-Ray diffraction, infrared spectroscopy, scanning electron microscopy, and spark source mass spectrometry are used to show that the protective alumina film consists of mainly σ alumina with a small amount of θ alumina spheroids of varying sizes <1 μm diameter and is highly pure. The nature of a similarly deposited Fe2O3 film is shown to be a more closely packed and irregular form of hematite with a small content of metallic iron. The results obtained by this simple new technique compare well with those obtained by spark source mass spectrometry and electrothermal AAS with a graphite furnace.
Photochemical Reactions of Phthalazine in 2-Propanol
Authors: Inoue Hiroyasu , Sakurai Tadamitsu , Tomiyama Koichi , Sano Ryo , Oshio Masahiro , Hoshi Toshihiko , Okubo Jun
Published: July 2006

Phthalazine undergoes dual photoreactions to simultaneously give two photoproducts, 1,2-dihydrophthalazine (1) and 1,1′,2,2′-tetrahydro-1,1′-biphthalazine (2), upon ultraviolet light irradiation in 2-propanol under nitrogen. There occurs neither photochemical nor thermal interconversion between 1 and 2; these compounds are formed independently from a common intermediate through different reaction pathways. The results of quenching and sensitization experiments for both the reactions and the phosphorescence emission show that the lowest excited singlet and triplet states of phthalazine participate in the formation of 1 and 2, respectively. The observed photochemical behaviors under various conditions lead us to propose a reaction mechanism: Phthalazine is photoreduced in the S1 state to form 1,2-dihydro-1-phthalazinyl radical. The resulting radical in a solvent cage undergoes a subsequent hydrogen abstraction to form 1. On the other hand, the same radical produced in the T1 state escapes from the solvent cage to cause a dimerization which affords 2.
Photocatalytic Decomposition of 2-Ethoxyethanol on Titanium Dioxide
Authors: Yamagata Sadamu , Baba Ryo , Fujishima Akira
Published: July 2006

The reaction mechanism of the photocatalytic oxidation of 2-ethoxyethanol (Ethyl Cellosolve, EtOCH2CH2OH) on TiO2 powder was investigated by gas chromatography-mass spectrometry (GC-MS), infrared (IR) spectroscopy, and electron spin resonance (ESR) with spin trapping technique. Irradiation of TiO2 powder with UV light in the presence of EtOCH2CH2OH under air led to the formation of ethyl formate, ethanol, acetaldehyde and carbon dioxide. The main product, ethyl formate was different from the product through the reaction pathway proposed before for primary alcohols. It was also different from the product of electrolysis on Pt. Reaction mechanism is proposed based on IR and ESR studies.
The Preparation of Monodispersed α-Iron(III) Oxide Particles from 2,2′-Bipyridineiron(II) Complex
Authors: Hamada Shuichi , Kudo Yoshiyuki , Matsumoto Takanobu
Published: July 2006

Monodispersed α-iron(III) oxide (hematite) particles were produced from an iron(II) chloride/2,2′-bipyridine system in the presence of potassium nitrate at elevated temperatures, 90–100 °C. An aqueous solution of 2,2′-bipyridineiron(II) complex directly gave spherical hematite particles (0.35 μm in size with a relative standard deviation of 0.09) under the conditions of 1.0×10−3 mol dm−3 FeCl2, 3.0×10−3 mol dm−3 2.2′-bipyridine, 6.0×10−3 mol dm−3 HCl, and 5.0×10−2 mol dm−3 KNO3 at 100 °C for 8 h. The oxidation of iron(II) ions would be slower than the dissociation of the complex and precipitation during the course of aging. The hematite particles grew through the polynuclear layers mechanism. Iron(II) sulfate/2,2′-bipyridine mixed solutions were also capable of yielding monodispersed particles, though they were a mixture of hematite and α-iron(III) hydroxide oxide (goethite). The points of zero charge (PZC) of these particles were estimated as pH 7.7 and 7.5 for those obtained from the iron(II) chloride and sulfate/2,2′-bipyridine systems, respectively.
Interaction between Disodium 1,14-Tetradecanediyl Disulfate and Sodium Dodecyl Sulfate or Poly(oxyethylene) Nonyl Phenyl Ether on Alumina
Authors: Esumi Kunio , Asano Yuki , Sakamoto Yuichi , Meguro Kenjiro
Published: July 2006

The interactions between disodium 1,14-tetradecanediyl disulfate (α,ωC14) and sodium dodecyl sulfate (SDS) or poly(oxyethylene) nonyl phenyl ether (NP 7.5) on α-alumina have been studied by measuring the zeta potential, the mean particle size, the amounts of surfactants adsorbed, and the fluorescence spectra of pyrene. When α,ωC14, SDS, or NP 7.5 as a second additive is added to alumina previously flocculated by the addition of SDS or α,ωC14, as a first additive, the flocculated alumina redisperses in the α,ωC14–SDS and α,ωC14–NP 7.5 systems. For the α,ωC14–SDS and α,ωC14–NP 7.5 systems, the redispersion of alumina proceeds in such a manner that the hydrophobic parts of SDS or NP 7.5 are in contact with the α,ωC14-coated alumina and the hydrophilic polar groups direct out to aqueous solution, resulting in the formation of mixed bilayers on the alumina, while for the α,ωC14–SDS system the adsorption of SDS on the α,ωC14-coated alumina is not enough to attain the redispersion of alumina. The measurement of the ratio I1⁄I3 of intensities of the first and third vibrionic bands of the pyrene monomer fluorescence spectra indicates that pyrene is solubilized in a much lower polar site for the α,ωC14–SDS mixed bilayer than for the mixed bilayer of α,ωC14–NP 7.5.
Thermodynamic Study on the Extraction of Cobalt Complex with 8-Quinolinol into 1,1,2,2-Tetrachloroethane
Authors: Yamada Etsu , Nakayama Eiichiro , Sato Masanori
Published: July 2006

The extraction behavior of cobalt(II) into 1,1,2,2-tetrachloroethane (TCE) with 8-quinolinol (HQ) from an aqueous solution in the presence of various inorganic anions (X−) such as perchlorate, nitrate, and chloride ions was studied themodynamically. The extraction equation can be written as

2Co2++6HQ(o)+X−\ightleftarrowsCo2Q3(HQ)3+(o)+X(o)−+3H+

The ion-pair of the binuclear complex (complex ion-pair) dissociates to a complex cation and an inorganic anion in the organic phase. The extraction constant increases in proportion to the radius of the counter anion. Changes in the enthalpy and entropy are negative for the overall extraction of cobalt with 8-quinolinol. These thermodynamic parameters were compared with those of zinc and cadmium. The temperature effect on the extraction behavior of cobalt with 8-quinolinol was also investigated in a chloroform system for comparison.
The Solubility of (Biphenyl, Naphthalene)–(Benzene, Cyclohexane, 1-Octanol) Binary Mixtures in Water
Authors: Sanemasa Isao , Kumamaru Masaya , Ishibashi Kazunari , Deguchi Toshio
Published: July 2006

The solubility in water at 25 °C of binary mixed solutes, combinations of biphenyl and naphthalene with benzene, cyclohexane, and 1-octanol, was measured using a shake-flask method. As a function of biphenyl or naphthalene mole fraction, activity coefficients of biphenyl and naphthalene in benzene, cyclohexane, and 1-octanol, and those of benzene in biphenyl–benzene and naphthalene–benzene binary systems have been determined.
Structures of Three Diastereomers of trans(N-Ph, N-Ph)-2,4-Pentanedionatobis(N-phenylethylenediamine)cobalt(III) and of One Diastereomer of trans(N-Ph, N-Ph)-Oxalatobis(N-phenylethylenediamine)cobalt(III) Complex Cations
Authors: Akagawa Toshiaki , Ma Guilin , Suzuki Nahomi , Ohba Shigeru , Ouyang Yue , Kojima Masaaki , Fujita Junnosuke , Saito Yoshihiko
Published: July 2006

The molecular structures of three racemic pairs of diastereomers, ΔRR(ΛSS)-, ΔSR(ΛRS)-, and ΔSS(ΛRR)-trans(N-Ph, N-Ph)-[Co(pd)(Ph-en)2]2+ and of one racemic pair of diastereomers, ΔSS(ΛRR)-trans(N-Ph, N-Ph)-[Co(ox) (Ph-en)2]+ (pd=2,4-pentanedionate ion, ox=oxalate ion, Ph-en=N-phenylethylenediamine) were determined by the single-crystal X-ray diffraction method in order to study the intramolecular interactions between π-systems in the ligands. For the ΔSS(ΛRR)-isomer of [Co(pd)(Ph-en)2]2+, three kinds of crystal structures 3a, 3b, and 3c were investigated. The crystal data and final R values are: ΔRR(ΛSS)-[Co(pd)(Ph-en)2](ClO4)2·H2O (1), orthorhombic, Pbca, a=32.472(9), b=11.120(3), c=15.303(4) Å, V=5526(3) Å3, Z=8, R=0.065 for 2113 observed unique reflections. ΔSR(ΛRS)-[Co(pd)(Ph-en)2](ClO4)2 (2), orthorhombic, P212121, a=19.440(8), b=16.406(8), c=8.407(3) Å, V=2681(2) Å3, Z=4, R=0.038 for 2205 reflections. ΔSS(ΛRR)-[Co(pd)(Ph-en)2]Cl2·H2O (3a), monoclinic, P21⁄c, a=12.475(3), b=11.590(2), c=19.054(4) Å, β=117.18(2)°, V=2450.6(9) Å3, Z=4, R=0.035 for 2164 reflections. ΔSS(ΛRR)-[Co(pd)(Ph-en)2](ClO4)Cl·H2O (3b), triclinic, P\bar1, a=11.847(5), b=13.584(4), c=8.367(2) Å, α=103.57(2), β=91.85(3), γ=84.25(3)°, V=1302.1(8) Å3, Z=2, R=0.087 for 1374 reflections. ΔSS(ΛRR)-[Co(pd)(Ph-en)2](ClO4)Cl (3c), triclinic, P\bar1, a=11.660(5), b=14.028(3), c=8.308(7) Å, α=108.00(8), β=101.57(9), γ=92.47(13)°, V=1258(3) Å3, Z=2, R=0.052 for 1118 reflections. ΔSS(ΛRR)-[Co(ox)(Ph-en)2] Br·6H2O (4), orthorhombic, Pna21, a=15.804(1), b=15.646(1), c=10.428(2) Å, V=2578.5(4) Å3, Z=4, R=0.065 for 1496 reflectios. The numbers of phenyl rings of the Ph-en ligands that overlap with the pd π system in the complex cation are 0, 1, and 2 for 1, 2, and 3 respectively. The ox ligand of 4 is ill-sandwiched by the two phenyl rings, whereas the pd ligand is well-sandwiched in 3a. The arrangements of the phenyl groups relative to the pd differ slightly from one another in the crystals of 3a, 3b, and 3c. The dihedral angles between the pd (or ox) and phenyl rings range from 25 to 35°.
Reaction of 1,4,2-Dithiazolium and 1,3-Dithiolium Salts with Malononitrile
Authors: Yonemoto Katsumi , Shibuya Isao , Honda Kazumasa
Published: July 2006

The reaction of 5-substituted 3-phenyl-1,4,2-dithiazolium salts with malononitrile gave not only 5-dicyanomethylene-3-phenyl-1,4,2-dithiazole and an isothiazole derivative, but 4-amino-5-cyano-2-(1-cyano-2-dialkylamino-2-mercaptovinyl)-6-phenylpyrimidines (6) and a butadiene derivative, depending on substituents at C-5 and bases used. The structure of 6 was confirmed by X-ray crystallographic analysis of its methylated derivative. These results are well explained by assuming three possible fission modes of the initial adduct: liberation of substituents at C-5 (Path A), ring opening-ring closure reaction (Path B), and fragmentation of dithiazole ring (Path C). On the other hand, 2-dialkylamino-4,5-diphenyl-1,3-dithiolium salts were allowed to react with malononitrile to afford 2-amino-3-cyano-5,6-diphenyl-1,4-dithiin (13) and 4-amino-3-cyano-2-dicyanomethylene-5,6-diphenyl-2H-thiin (14) as well as 2-dicyanomethylene-4,5-diphenyl-1,3-dithiole (12). In a separate experiment, both 13 and 14 were formed by the reaction of 12 with malononitrile. This pathway can be interpreted in terms of considerable contribution of polar structure of 12 due to the push–pull effect of sulfur atoms and cyano groups. Furthermore, the reaction of 2-substituted 4-phenyl-1,3-dithiolium salts with malononitrile also gave 2-dicyanomethylene-4-phenyl-1,3-dithiole and thiophene derivatives.
Studies on Synthetic Ionophores. VIII. Transport of Alkaline Earth Metal Ions by Polyether Carboxylic Acids through Liquid Membrane
Authors: Yamaguchi Kazuo , Kuboniwa Hitoshi , Murakami Nobuya , Hirao Akira , Nakahama Seiichi , Yamazaki Noboru
Published: July 2006

Seven ω-hydroxy carboxylic acids bearing 2–5 ether oxygens with or without aromatic rings and five ω-alkoxy carboxylic acids bearing 2–6 ether oxygens with aromatic rings were employed as carriers for the active transport of alkaline earth metal ions as well as alkali metal ions through 1,2-dichloroethane or 1-hexanol as an organic liquid membrane. The relatively hydrophobic ω-hydroxy and ω-alkoxy carboxylic acids (logP>7) exhibited a high M2+ transport ability and selectivity over M+ through 1,2-dichloroethane, regardless of the number of ether oxygen. However, a marked selectivity among alkaline earth metal ions (Mg2+, Ca2+, Ba2+) was not observed. The less hydrophobic carboxylic acids (logP<6) did not transport Ba2+ through 1,2-dichloroethane. Ba2+ transport ability of the hydrophobic acids through 1-hexanol was lower than that through 1,2-dichloroethane. Linoleic acid in the presence of oligo- and polyethylene glycols showed efficient Ba2+ transport through 1,2-dichloroethane, although a long-chain fatty acid was not able to transport Ba2+ by itself.
Effect of Additives on Selective Formation of Isobutene from the CO–H2 Reaction over ZrO2
Authors: Maruya Ken-ichi , Fujisawa Takeshi , Takasawa Akihiro , Domen Kazunari , Onishi Takaharu
Published: July 2006

The CO–H2 reaction over ZrO2 was carried out in the presence of various organic additives. The addition of dimethyl ether, methylal, acetaldehyde, and dimethyl acetal showed the marked enhancement effects on the hydrocarbon formation keeping the high selectivity for isobutene. Ethylene was little effective. The addition of acetone, propanal, and propylene resulted in the decrease in the formation of isobutene and the increase in that of n-butenes. The presence of CO and H2 was essential to the selective formation of isobutene. The formation pathways of isobutene and the other hydrocarbons are discussed.
Reduction of 2-Carboxy-4′-dimethylaminoazobenzene by Bacillus Diaphorase
Authors: Yatome Chizuko , Ogawa Toshihiko , Ogawa Toshihiko , Hayashi Hideki
Published: July 2006

2-Carboxy-4′-dimethylaminoazobenzene (CDMAB) was reductively cleaved into its two component primary arylamines by Bacillus diaphorase together with NADH (pH 6.1, 25 °C). The reductive cleavage was found to proceed stoichiometrically by a spectrofluorometric assay of fluorescent o-aminobenzoic acid and a fluorescent product formed between N,N-dimethyl-p-phenylenediamine and fluorescamine. Parallel lines were obtained in Lineweaver–Burk plots of initial rate vs. CDMAB concentration for the reduction. This experimentally observed kinetic behavior is consistent with a reaction scheme in favor of the Ping Pong mechanism in which CDMAB is reduced by a reduced form of diaphorase. From a kinetic formula, the apparent Km(CDMAB), Km(NADH), and Vmax values are 2.14×10−5 mol dm−3, 7.35×10−5 mol dm−3, and 1.8×10−7 mol dm−3 min−1 per mg of protein, respectively.
The Effect of Pressure on Sigmatropic Rearrangements of Seven-Membered Conjugated Systems. [3,3] and [1,9] Sigmatropies
Authors: Sugiyama Shigeru , Mori Akira , Kato Nobuo , Takeshita Hitoshi
Published: July 2006

The kinetic features of the [1,9] sigmatropy (with 2-benzyloxy-3-bromotropone) and the [3,3] sigmatropy (with 2-allyloxytropone and 2-[(3-methyl-2-butenyl)oxy]tropone) were investigated under various pressures (1 to 1600 bar). The activation volume of [1,9] sigmatropy was of the same order as those of [1,5] sigmatropy of cyclopentadienes. The activation volume of [3,3] sigmatropy of more sterically-hindered substrate was more negative than that of the unhindered one.
An Efficient Route to Both Enantiomers of N-(p-Tolylsulfonyl)benzenesulfonimidamide and Their Use for Asymmetric Allylic Amination of Olefins
Authors: Tsushima Susumu , Yamada Yasuhiro , Onami Tetsuo , Oshima Koichiro , Chaney Michael O , Jones Noel D , Swartzendruber John K
Published: July 2006

The chiral compounds (R)- and (S)-N-(p-tolylsulfonyl)benzenesulfonimidamide have been prepared efficiently from N-(p-tolylsulfonyl)benzenesulfonimidoyl chloride and both enantiomers were transformed into chiral selenium diimide reagents, (S)- and (R)-N,N′-bis[N-(p-tolylsulfonyl)benzenesulfonimidoyl]selenium diimide, respectively, for the asymmetric allylic amination of olefins. Asymmetric allylic amination of methylenecyclohexane with the S-configured selenium diimide reagent afforded allylic amide, (1S)-N-[(R)-N-(p-tolylsulfonyl)benzenesulfonimidoyl]-2-methylenecyclohexylamine as a major diastereomer (42% diastereomeric excess). Similarly, cyclohexene, 1-heptene, and cyclooctene gave chiral allylic amides with 34%, 32%, and 20% diastereomeric excess, respectively. It is apparent that the S-configured diimido selenium reagent gives S-configured allylic amides, and that the R-configured reagent affords R-configured allylic amides as the major diastereomers in all of the cases investigated.
Monosubstituted Tetramethoxynaphthalenes
Authors: Tanoue Yasuhiro , Terada Akira , Torisu Kazuhiko , Taniguchi Hiroshige
Published: July 2006

As new intermediates for the syntheses of monosubstituted naphthazarins and anthracyclines, several tetramethoxynaphthalenes having a substituent such as CH3, COOH, CN, Br, OAc, OH, and OMe groups were prepared from 1,4,5,8-tetramethoxynaphthalene and 2-formyl-1,4,5,8-tetramethoxynaphthalene.
Nonacidic and Highly Chemoselective Protection of the Carbonyl Function. 3-Methylbenzothiazolines as a Base- and Acid-Resistant Protected Form for the Carbonyl Groups
Authors: Chikashita Hidenori , Komazawa Shun-ichiro , Ishimoto Nishiki , Inoue Koji , Itoh Kazuyoshi
Published: July 2006

A simple and useful new type of protection method for carbonyl groups by conversion into 3-methylbenzothiazoline derivatives with o-(methylamino)benzenethiol was described. With this method, 3-methylbenzothiazolines were conveniently obtained in excellent yields from various aldehydes and ketones. This method allows efficient protection and deprotection under mild and neutral conditions and affords protection of the carbonyl group against both basic and acidic conditions. The difference in reactivity between different carbonyl groups was successfully utilized for the chemoselective benzothiazolination of the formyl group of 4-oxopentanal and also for the chemoselective conversion of 4-androstene-3,17-dione and progesteron into the corresponding benzothiazolines with the nonconjugated keto groups remaining intact. 2-Substituted benzothiazolines derived from aldehydes were efficiently converted into 2,2-disubstituted benzothiazolines via alkylation, with a variety of Grignard or organolithium reagents, of 2-substituted 3-methylbenzothiazolium salts which were readily obtained by the treatment of the former thiazolines with trityl perchlorate in acetonitrile. These salts were also obtained in good yields from aldehydes in one-pot syntheses by the treatment with o-(methylamino)benzenethiol in acetonitrile followed by addition of trityl perchlorate. 3-Methylbenzothiazolium iodide was found to be also effective as a formyl cation equivalent and the reactions with Grignard or organolithium reagents produced the corresponding 2-substituted benzothiazolines in good yields. With this reaction, 2-deuterio-3-methylbenzothiazolium iodide was effectively applied as a deuterated formyl cation equivalent for the synthesis of aldehyde-d.
Viscosity B-Coefficients of Tetraalkylammonium Bromides in 2-Methoxyethanol at 25 °C
Authors: Dasgupta Debasis , Das Susanta , Hazra Dilip K
Published: July 2006

The relative viscosities of solutions of tetraalkylammonium bromides, R4NBr, (R=C2H5 to C7H15) have been measured in 2-methoxyethanol (ME) at 25 °C. The data have been analyzed in the form of associated electrolytes and the B-coefficients have been evaluated. The ionic B-values have been determined using the “reference electrolytes” viz. Bu4NBBu4 and Bu4NBPh4. The results have been discussed on the basis of Einstein’s equation and in terms of a transition state treatment.
Conductometric Determination of Thermodynamics Dissociation Constants of Benzoic and Nitrobenzoic Acid in Methanol–Water Mixtures at 298 K
Authors: Niazi MSK
Published: July 2006

The thermodynamic dissociation constants and the limiting molar conductivities of 2-, 3-, 4-nitrobenzoic and benzoic acids have been determined in water–methanol mixtures at 298 K. The experimental data are analyzed with the Lee and Wheaton conductance equation incorporating modifications. The derived results are compared with the ones in literature, pertaining to analogous media. The findings are interpreted in terms of solute–solvent interactions, intramolecular hydrogen bonding, resonance and inductive effect and the substituent position. The study showed that the dissociation order decreases as 2-nitrobenzoic acid> 3-nitrobenzoic acid≈ 4-nitro benzoic acid> benzoic acid.
The Effect of Cadmium Ions on the Polarographic Reduction of Poly[(p-methylbenzyl)viologen] Dibromide in Water
Authors: Prasad Bhim Bali
Published: July 2006

The d.c. polarographic reduction of a redox polyelectrolyte, poly[(p-methylbenzyl)viologen] dibromide, in the presence of cadmium sulfate salt demonstrated two well-defined, irreversible diffusion-controlled cathodic waves corresponding to the reduction of protonated form as well as the cadmium complex of the polyelectrolyte in aqueous buffers (pH 2.00–6.00). No wave was observed due to the reduction of the unprotonated form of the polymer in the present instance, however, another ill-defined wave of irreversible nature was emerged at relatively higher negative potential presumably because of the catalytic evolution of hydrogen, at the dropping mercury electrode. An attempt has been made to correlate these results in terms of cadmium ion interaction with the polyelectrolyte during the course of electrode processes.
Preparation and Crystal Structure of Diaquabis(1,8-naphthyridine 1-oxide)cobalt(II) Nitrate
Authors: Yin Zhu , Xinmin Gan , Ning Tang , Minyu Tan
Published: July 2006

The complex [Co(napyo)2(H2O)2](NO3)2 was formed by the reaction of cobalt(II) nitrate with 1,8-naphthyridine 1-oxide (napyo) in methanol medium. The complex crystallizes in the monoclinic system, space group P21⁄n with Z=2. Lattice parameters are: a=7.165(2), b=11.797(2), c=11.830(3) Å, β=95.14(3)°, V=995.9(4) Å3, Dc=1.705 g cm−3, DO=1.714 g cm−3, λ(Mo Kα)=0.71069 Å, μ=9.26 cm−1, F(000)=522. The final R=0.036 for 1433 unique observed reflections. Co2+ ion is coordinated by two nitrogen atoms and four oxygen atoms to form a distorted octahedron.
Electronic Spectra of 9,10-Phenanthrenediamine: Effects of Solvents and Acid Concentrations
Authors: Manoharan R , Dogra Sneh K
Published: July 2006

Dual fluorescence is observed from 9,10-phenanthrenediamine (PDA) in defferent solvents. Normal Stokes shifted fluorescence band is a structured one with vibrational frequency of ca. 750 cm−1 and is polarized along the longer axis (1Lb state). Large Stokes shifted fluorescence is a broad band and is polarized along the shorter axis of phenanthrene (1Lb state). Fluorescence intensities of both the bands decrease with the increase of polarity and hydrogen-bond formation tendency of the solvents, but the preferential decrease in the fluorescence intensity of latter band system is more than that of the former band system under the above environments. Equilibrium for the prototropic reaction of monocation-free base is not established in the S1 state within the lifetimes of the conjugate acid–base pair. Proton-induced fluorescence quenching constant for monocation is found to be 2×107 dm3 mol−1 s−1 and this low value, as compared to that for neutral aromatic amines, is because of the presence of positive charge on the monocation.