bluuebunny/crossref_metadata_2025_split huggingface dataset:
Nanocrystalline Tin‐Oxide Modified Electrodes and their Electrochemical Characterization
Authors: Wang Wen‐Ying , Wang Chong Mou 
Published: May 2015

AbstractNanocrystalline tin‐oxide particles were prepared as electrodes on the bases of ITO glass and AT‐cut quartz crystals (sputtered gold), respectively, and characterized for their electrochemical behavior. Experiments suggested that the SnO2 particles could induce an energy barrier to the redox reactions taking place on the electrode surface. When the amount of SnO2 exceeded ca. 10−7 mol cm−2, electrochemical activity demonstrated by the solution redox couples was entirely suppressed. Nevertheless, electrochemical impedance spectroscopic (EIS) measurements suggested that mutual communication between redox couples would still take place on the surface of SnO2. For instance, although the CV curves of Fe(CN)63‐/4‐ were completely blocked, the exchange current of Fe(CN)63‐/4‐ could still flow through the tin‐oxide modified electrode, increasing with its concentration up to 40 mM. The propagation of electrons in the SnO2 film was likely via a hopping mechanism. Electrochemical quartz microbalance (EQCM) measurements, in addition, suggested that a charge‐compensating cation (K+ or H+) uptake reaction may be induced as electrons were pumped to the Sn02 electrode, while, if electrons were removed, that could cause water desorption. Analysis based on the Frumkin adsorption isotherm showed the driving force behind the adsorption of water on SnO2 is about −2 kcal/mol. Nonetheless, the adsorbed water might face a competitive repulsion from acetonitrile when acetonitrile was used as the electrolyte medium.
Analysis of Synthetic Drugs in Chinese Medicine by High Performance Liquid Chromatography/Mass Spectrometry with In‐Source Collision Induced Dissociation
Authors: Song Yi , Cheng Hsing‐Ling , Her Guor‐Rong , Wen Kuo‐Ching 
Published: May 2015

AbstractSixteen chemical drugs, often found in adulterated Chinese medicine, were studied by high performance liquid chromatography/atmospheric ionization mass spectrometry. Under optimal conditions, three pairs of compounds were either coeluted or unresolved. The lack of chromatographic resolution and the lack of specificity in UV detection were overcome by a method based on high performance liquid chromatography/electrospray mass spectrometry. This method was capable of detecting the adulterants based on their retention times, molecular ions, and characteristic fragments resulting from in‐source collision induced dissociation.
Synthesis and Reactivity of 2‐(2,2‐Dicyano‐1‐methylvinyl)benzothiazole in Heterocyclic Synthesis: Convenient Route to Some Pyridazinone, Hydrazonoethyl, Thiophene, Phathalic Anhydride and Benzene Derivatives Incorporating a Benzothiazole Moiety
Authors: Selim Maghraby A. , Raslan Mohamed A. , Khalil Mohamed A. , Sayed Samia M. 
Published: May 2015

AbstractA facile route to some pyridazinone, hydrazonoethyl, thiophene, phathalic anhydride and benzene derivatives incorporating a benzothiazole moiety is reported.
Bishordeninyl Terpene Alkaloids from Zanthoxylum Integrifoliolum
Authors: Liu Sian‐Ling , Tsai Ian‐Lih , Ishikawa Tsutomu , Harayama Takashi , Chen Ih‐Sheng 
Published: May 2015

AbstractExamination of the leaves of Zanthoxylum integrifoliolum led to the isolation of a new bishordeninyl alkaloid, integramine, along with alfileramine, α‐allocryptopine, pseudoprotopine and (+)‐sesamin from the tertiary non‐phenolic base fraction. The structures of these compounds were elucidated by spectral evidence.
Optical Absorption of Long Range Electron Transfer Systems in Intense Fields
Authors: Okada Akira , Chernyak Vladimir , Mukamel Shaul 
Published: May 2015

AbstractEffects of strong radiation field on long range electron transfer reactions and the crossover between the nonadiabatic and adiabatic limits are investigated. Dramatic variations of the absorption spectrum as a function of laser intensity were predicted in the nonadiabatic limit by Dakhnovskii, Lubchenko, and Coalson (Phys. Rev. Lett. 1996, 77, 2917). These results are extended by utilizing the interaction picture and Green function technique to calculate the spectrum in the crossover and the adiabatic regions. As the solvation timescale becomes slower, the multiphoton absorption is enhanced, and the dependence of the absorption spectrum on field intensity is supressed, eventually vanishing in the adiabatic limit.
Femtosecond Investigation of Photophysics of Intersystem Crossing in Terthiophene
Authors: Yang Ji‐Ping , Paa Wolfgang , Hotzel Mario , Rentsch Sabine 
Published: May 2015

AbstractPhotophysics of ultrafast intersystem crossing and triplet yield in 2,2′:5′,2″ ‐terthiophene (3T) was investigated in dependence of excitation wavelength by means of femtosecond time‐resolved absorption/emission spectroscopy. Triplet generation yield was monitored by using the product of maximum and width of the photoinduced triplet absorption band near 460 nm. We found that triplets were generated by two different processes: (i) the well‐known intersystem crossing from the lowest vibrational S1 state and (ii) ultrafast intersystem crossing from an intermediate state generated by photoexcitation. We discuss the probable formation mechanism and the lifetime of an intermediate state. The results suggest that this intermediate state is a nonplanar conformer within the S1 manifold; it seems to be responsible for the high effective triplet generation.
Excitation Energy‐Transfer in the LH2 Antenna of Photosynthetic Purple Bacteria via Excitonic B800 and B850 States
Authors: Linnanto Juha M. , Korppi‐Tommola Jouko E. I. 
Published: May 2015

AbstractA newly developed CIEM method that uses a combination of semi‐empirical or ab‐initio configuration interaction methods and exciton theory to predict electronic energies, eigenstates, absorption and CD spectra of aggregated chromophoric systems with environmental interactions included is extended and used for estimation of excitation energy transfer rates. Excitonic energy levels of the two ring systems the B800 and the B850 of the light harvesting antenna LH2 of Rhodopseudomonas acidophila and the corresponding absorption spectrum were calculated by assuming inter‐ring interactions to be zero. Excitation energy transfer rates were calculated by using the Fermi Golden rule with the dipole ‐ dipole operator, the excitonic basis sets created by the CIEM method of the non‐interacting ring systems and a statistical variation of the elements of the exciton Hamiltonian to account for the inhomogenous broadening of the experimental spectrum. Energy transfer rates of from 300 fs to 450 fs within the B800 ring, from 450 fs to 800 fs from the B800 ring to the B850 ring, that are in good agreement with the experimentally observed rates, were obtained. The model predicts wavelength dependent energy transfer rates within the B800 band, with slower rates in the red end of the absorption. Energy transfer between two excitonic systems imply that observed rates depend on the spectral/temporal widths of the excitation and probe pulses. The model also predicts decreasing rates for low temperatures, as homogenous line widths become narrower at lower temperatures.
Spectral Holography and Spectral Nonlinear Optics of Ultrashort Pulses
Authors: Mazurenko Yuri T. 
Published: May 2015

AbstractThis paper reviews the principles of recording, reconstruction and nonlinear transformations of ultrashort light pulses, based on spatial spectral decomposition of light. Some applications of these methods for processing time‐dependent signals in the femtosecond to nanosecond range are also considered.
Generalised Master Equation for the Spin‐Boson Hamiltonian by the Projection Operator Technique
Authors: Cheche T. O. , Hayashi M. , Lin S. H. 
Published: May 2015

AbstractStarting from the von Neuman equation of quantum theoretical dynamics, by using the projection operator technique, we write the generalised master equation (GME) of the reduced statistical operator. By using this technique we find a series expansion of the memory kernel which allows, in principle, a treatment of the higher orders of approximation. By keeping only the first term of this expansion, which corresponds to the second order of the perturbation treatment, GME is applied, in the Markov approximation, to the spin boson Hamiltonian to describe the dynamics of the relevant pseudo‐spin subsystem. In the secular and rotating wave approximations this dynamics is found to be described by the Bloch equations.
The Adsorbate Electron Affinity Dependence of Femtosecond Electron Dynamics at Dielectric/Metal Interfaces
Authors: Gaffney Kelly J. , Liu Simon H. , Miller Andre D. , Szymanski Paul , Harris Charles B. 
Published: May 2015

AbstractThe two photon photoemission technique has been utilized to investigate the adsorbate electron affinity dependence of interfacial electron transfer dynamics. The comparison of calculated and experimental results highlight a brief discussion of a dielectric continuum model. For the n‐heptane/Ag(111) and the benzene/Ag(111) interfaces, the model effectively reproduces experimental image potential state properties. The model fails to adequately describe the influence of anthracene adsorbates on image potential state lifetimes, as demonstrated by the experimental and theoretical results. The experimental n = 1 lifetime of 1200 femtoseconds and binding energy of −0.53 eV for the anthracene bilayer differ greatly from the calculated values of 40 femtoseconds and −1.4 eV.
Anharmonic Oscillator Approach to the Exciton‐Exciton Annihilation Dynamics in Molecular Aggregates
Authors: Renger T. , May V. , Sundström V. , Kühn O. 
Published: May 2015

AbstractThe dynamics of Frenkel excitons in aggregates of coupled electronic three‐level molecules in the presence of strong external fields is investigated. Particular emphasis is paid to the microscopic inclusion of exciton‐exciton annihilation. It appears as a combination of exciton fusion and internal conversion processes which are taken into account within perturbation theory. The influence of an environment on the exciton dynamics is treated by means of stochastic fluctuations of the electronic transition energies. A closed set of equations of motion is derived and it is shown how nonlinear optical spectra can be calculated nonperturbatively.
Importance of Acoustic Solvent Mode and Solute‐Solvent Radial Distribution Functions in Solvation Dynamics: Studied by RISM Theory
Authors: Nishiyama Katsura , Hirata Fumio , Okada Tadashi 
Published: May 2015

AbstractWe have applied the reference interaction‐site model (RISM) theory to explain our experiments on solvation dynamics of laser dyes in polar organic solvents by means of the transient hole‐burning and time‐resolved fluorescence spectroscopy [K. Nishiyama and T. Okada, J. Phys. Chem. A, 101 (1997)5729; 102 (1998) 9729]. The experiments show that the dynamic response function of the relaxation derived from the inhomogeneous spectral band‐width of the solute‐solvent system relaxes about an order of magnitude slower than that of average energy of the system. On the basis of our present theoretical prediction, we suggest that the relaxation dynamics of the spectral width might be mainly characterized by the solvent acoustic mode (translational motion) as well as the rearrangement of second plus further solvent shells.
Time‐Resolved Fluorescence Spectroscopy of Porphyrin J‐Aggregates Using Optical Kerr Gate Methods
Authors: Kano Hideaki , Kobayashi Takayoshi 
Published: May 2015

AbstractWe observed for the first time ultra‐fast relaxation process due to internal conversion from S2‐exciton to S1‐exciton in porphyrin J‐aggregates using the optical Kerr gate method. The S2 fluorescence shows sharp spectra with almost zero Stokes shift. The decay time is less than the instrumental function and cannot be time‐resolved by the Kerr gate method. The relaxation time of the S2‐exciton was also measured by pump‐probe spectroscopy with about 10 fs resolution, and the decay time, 130 ± 10 fs, was consistently obtained with that of the S2 fluorescence.
The Decomposition Reaction of 4‐Acetylsydnones Arylhydrazones
Authors: Kuo Wen‐Fa , Chiu Chun‐Yen , Lin I‐Tzu , Sheu Shu‐Ya , Lm Kao‐Hung , Yeh Mou‐Yung 
Published: May 2015

AbstractThe acidic decomposition of 4‐acetylsydnones arylhydrazones 2 results in the formation of 4‐arylhydrazo‐1,2‐pyrazolin‐5‐ones 3 and 4‐arylamino‐1,2,3‐triazoles 4, respectively. The reactions of 4‐acetylsydnones 1 with arylhydrazines 5 afford compounds 3 as the only products in the absence of solvent.
Synthesis and Structure Characterization of 2‐(Dimethylaminomethyl)pyrrolate and 2,5‐Bis(dimethylaminomethyl)pyrrolate Zirconium Complexes
Authors: Huang Jui‐Hsien , Kuo Pei‐Cheng , Lee Gene‐Hsiang , Peng Shie‐Ming 
Published: May 2015

AbstractTetrakis(diethylamido)zirconium reacts with 2‐(dimethylamino)methyl pyrrole (DMAMP) and 2,5‐[bis(dimethylamino)methyl]pyrrole (BDMAMP) to give Zr(NEt)2(DMAMP)2 1 and Zr(NEt)3(BDMAMP) 2, respectively. Both 1 and 2 have been characterized by 1H and 13C NMR spectroscopies and 1 has also been characterized by X‐ray crystallography. Complex 1 shows an agostic interaction between Zr and H(21A) in solid state that is not sustained in solution. Reacting 1 with 2 equivalents of trimethylsilyl chloride in toluene yields ZrCl2(DMAMP)2 3 in 75% yield which was characterized by 1H and 13C NMR spectroscopies.
Kinetics of 2‐Propanol Dehydration over Montmorillonite Clays and Pillared Montmorillonites
Authors: Cho Youg‐Gou , Ko An‐Nan 
Published: May 2015

AbstractMetal ion exchanged montmorillonites (AlM & CrM) and metal oxide pillared montmorillonite (AlPM & CrPM) were prepared and characterized with XRD, FT‐IR, nitrogen adsorption and TPD of ammonia. The pillaring process results in a remarkable increase of interlayer distance, surface area and acid amount of the catalyst. However, increasing the calcined temperature causes reverse effects for the CrPM catalyst. The acid amount decreases in the order of CrPM200 < CrPM300 < AlPM500 < CrM < CrPM400 ≥ CrPM500 ≥ AlM. In the dehydration of 2‐propanol to propene, the reaction follows first order kinetics and the apparent rate constant is related to the catalyst acid amount. Compensation effect occurs in this reaction over the series of catalysts.
The Separation of Alanine Enatiomer Derivatives by the Proton‐Inhibition Method
Authors: Lee Sheau‐Long , Yang Chung‐Min , Shieh Kuan‐Jiunn , Liang Xinmiao , Li Hai‐Yan 
Published: May 2015

AbstractBetter peak shapes and complete separation of amino‐3,5‐dinitro derivatives by (S)‐N‐(2‐naphthyl)alanine derived chiral stationary phase (CSP) is achieved by adding a trace amount of acetic acid in the mobile phase. This method provides an indication of its broad applicability on direct separation of a series of amino‐containing enantiomers on CSP. In addition, the reversed elution order was obtained on its enatiomeric CSP.
Synthesis of ϵ‐Caprolactam from Cyclohexanone Oxime Using Zeolites Hβ, HZSM‐5, and Alumina Pillared Montmorillonite
Authors: Ouyang Kuang‐Hao , Chen Chih‐Wei , Ko An‐Nan 
Published: May 2015

AbstractThe Beckmann rearrangement of cyclohexanone oxime (CHO) to ϵ‐caprolactam (ϵ‐C) was studied in a plug flow reactor at 300–400°C under atmospheric pressure by using Hβ, ZSM‐5, and alumina pillared montmorillonite. With Hβ(X) Y zeolites, raising the SiO2/Al2O3 molar ratio (X) results in the enhancement of catalyst acid strength with concomitant decrease of the total acid amount. In creasing the calcination temperature (Y) causes remarkable diminution of catalyst surface area, acid strength, and acid amount. A similar trend was found for AlPMY catalysts. In there action of CHO, the initial catalytic activity correlates well with the total acid amount of various catalysts except for Hβ(10) Y (Y > 600°C). The reaction proceeds on both Brönsted and Lewis acid sites and the catalyst deactivation most likely occurs at the strong Brönsted acid sites. The effect of solvents in the feed on the catalytic results was also investigated; it was found that polar solvents such as ethanol or n‐butanol give high ϵ‐C yield and longer catalyst life time. In the reaction of CHO/C2H5OH over Hβ(10)800 at 400°C and W/F 74.6 gh/mol, the CHO conversion and ϵ‐C yield remain 100% and 92%, respectively, for at least 20 h time‐on‐stream. The reaction paths and the mechanism for ϵ‐C formation are proposed.
A Conformational Study of Cyclohexane‐1,3,5‐tricarbonitrile Derivatives
Authors: Chuang Tsung‐Hsun , Fang Jim‐Min 
Published: May 2015

AbstractCyclohexane‐1,3,5‐tricarbonitrile reached equilibrium having 1,3‐cis‐1,5‐cis and 1,3‐cis‐1,5‐trans isomers in a ratio of 3:7. The cis, cis‐isomer preferred the conformation with three equatorial cyano groups, where as the cis, trans‐isomer displayed two cyano groups on equatorial positions and another cyano group on axial position. Condensation of cis, cis‐cyclohexane‐1,3,5‐tricarbonitrile with L‐(S)‐valinol by the catalysis of ZnCl2 in refluxing 1,2‐dichlorobenzene afforded two isomeric cyclohexane‐1,3,5‐trioxazolines in favor of the 1,3‐cis‐1,5‐trans isomer. Metalation of cis, cis‐cyclohexane‐1,3,5‐tricarbonitrile, followed by alkylations with dimethyl sulfate, benzyl bromide or allyl bromide, gave the cor responding trialkylation products with predominance of 1,3‐cis‐1,5‐trans isomers. The cis, trans‐isomer showed two cyano groups on axial positions and another cyano group on equatorial position, where as the cis, cis‐isomer exhibited three axial cyano groups. Treatment of trimethyl cis, cis‐cyclohexane‐1,3,5‐tricarboxylate with lithium diisopropylamide and dimethyl sulfate afforded mainly the trimethyl ester of Kemp's triacid, which showed three axial carboxylate groups. Two competitive factors, i.e. the steric effect of in coming electrophiles and the dipole‐dipole inter actions of the cyano or carboxylate groups, might inter play to give different stereoselectivities in these reaction systems.
Exploration of an Efficient Method for Optical Resolution of Etodolac
Authors: Chou Shan‐Yen , Tseng Chin‐Lu , Chang Lien‐Shange 
Published: May 2015

AbstractThe exploration of an efficient method for resolving etodolac using either L‐cinchonidinium salt or chiral isopinocamphenol diastereomeric esters is described herein. Furthermore, racemization mechanism of chiral etodolac is rationalized in terms of an isotope labeling experiment.
Chemical Constituents from Strychnos Cathayensis
Authors: Cheng Ming‐Jen , Tsai Ian‐Lih , Chen Ih‐Sheng 
Published: May 2015

AbstractSecostrychnosin (1), a new secoiridoid, as well as seven compounds never before isolated from nature: 4‐tert‐butyl‐2‐oxazolidinone (2), 3‐acetoxyindole (3), indole‐2‐carboxylic acid (4), benzocaine (5), 3‐acetylindole (6), butylparaben (7) and 2‐hydroxy‐3‐methoxybenzaldehyde (8), together with fifty other known compounds, have been isolated from the stem of Strychnos cathayensis. These compounds include twenty‐three alkaloids, twelve benzenoids, four steroids, three flavonoids, three iridoids, two triterpenoids, two secoiridoids, two fatty acids, one lignan, one acetophenone, one coumarin, one chromane, one tetraterpenoid, one tannin, and one organic acid. The structures of these compounds were determined by means of spectralanalyses.
An Efficient Synthetic Strategy for Introduction of C3‐C4 Double Bond into Eudesmane Skeleton: First Total Synthesis of (+)‐Chrysanthemol
Authors: Chen Yonggang , Zhou Gang , Xiong Zhaoming , Liu Lijun , Li Yulin 
Published: May 2015

AbstractThe first enantioselective synthesis of (+)‐chrysanthemol 1 was carried out starting from (+)‐dihydrocarvone in ten steps. In our studies, a facile synthetic strategy has been developed for introduction of C3‐C4 double bond into a eudesmane skeleton.
Product Imaging Studies of Photodissociation and Bimolecular Reaction Dynamics
Authors: Houston Paul L. , Cosofret Bogdan R. , Dixit Amitaviram , Dylewski Scott M. , Geiser Joseph D. , Mueller Julie A. , Wilson Ruth J. , Pisano Patrick J. , Westley Michael S. , Lorenz K. Thomas , Chandler David W. 
Published: May 2015

AbstractThis paper briefly reviews recent progress in product imaging studies of photodissociation and bimolecularreaction dynamics.The SO2 + hv → SO(3Σ−) + O(3P2) channel in the ultraviolet photodissociation of sulfur dioxide at photolysis wave lengths between 202 and 207 nm has been studied using resonance‐enhanced multiphoton ionization with time‐of‐flight product imaging. These imaging experiments allowed the determination of the vibrational populations of the SO(3Σ−) fragment at several wave lengths. A change in the vibrational populations occurs from a distribution where most of the population is inv = 0 for wave lengths shorter than 203.0 nm to one where the population is more evenly distributed for longer wavelength dissociation. The changes in the internal energy distribution are attributed to participation of two different predissociation mechanisms. Our data suggest that the predissociation mechanism below 203.0 nm involves an avoided crossing with the repulsive singlet state.1A1.The O3(X 1A1) +hv → 0(2p3PJ) + O2(X3Σg−) product channel in the UV photodissociation of ozone has been investigated at photolysis wave lengths of 226, 230, 233, 234, 240, and 266 nm. At 226, 230, 233, 234, and 240 nm, the yield of the O2 product in vibrational states greater than or equal to 26 was 11.8 ± 1.9%, 11.5 ± 1.2%, 8.2 ± 2.0, 4.7 ± 1.8, and 0.6 ± 0.1%, respectively.Two‐dimensional ion counting product imaging has also been used to determine the bond energy for the dissociation of jet‐cooled O3 into O(1D) + O2(1Δ). The bond dissociation energy into O(1D) + O2(1Δ) was found to be 386.59 ± 0.04 kJ/mol. The standard heat of formation of O3 is calculated to be −144.31 ± 0.14 kJ/mol.State‐selective differential cross sections for rotationally in elastic scattering of NO (Ji = 0.5, 1.5, F1 → Jf = 2.5–12.5, F1 and Jf=1.5–9.5, F2) from He and D2 measured by crossed molecular beam ion imaging are reported. The images typically exhibit a single broad rotational rain bow maximum that shifts from the forward to the back ward scattering direction with in creasing ΔJ. The angle of the rain bow maximum was lower at a given ΔJ for D2 than for He as a collision partner. At a collision energy of ∼500 cm−1, primarily the repulsive part of the potential surface is probed, which can be modeled with a 2‐D hard ellipse potential. This model for rotationally in elastic scattering is shown to qualitatively match the experimental differential cross sections. A more advanced CEPAPES for NO + He does not give substantially better agreement with the experiment.
Control of Photodissociation by Alignment, Bleaching and Optical Phase
Authors: Kawasaki Masahiro 
Published: May 2015

AbstractWe have demonstrated alignment of neutral molecules by nonresonant IR laser pulse, bleaching of electronically excited states by resonant IR laser pulse and photoabsorption control of ground state molecules by phase of incident light. The electric field of a pulsed laser is used for alignment that is demonstrated by measurement of the control of the anisotropy of photo fragments generated by polarized light. The angular distribution of I(2P3/2) atoms from the photodissociation of CH3I at 304 nm was measured with alignment by the 1.06 μm laser pulse excitation:

By the alignment, the photodissociation branching ratio of Cl(2P3/2) and Cl*(2P1/2) was controlled in the photodissociation of Cl2 at 404 nm. The 1.06 μm laser pulse excitation of the photoprepared OCS at 230 nm bleaches the formation of CO(X1Σ+, J) + S(1D) and induces a new excitation pathway by an upconversion process:

The phenomenon of interference of the amplitude for absorption of one photon of frequency 3 ω (201 nm) and the amplitude for absorption of three photons of frequency ω (603 nm) was successfully applied to ammonia, alkylamines, cyclooctatetraene and 1,1‐dimethylhydrazine.