bluuebunny/crossref_metadata_2025 huggingface dataset:
Density Functional Calculations on the Heats of Formation of Certain Aromatic Nitro Compounds
Authors: Chen P. C. , Chieh Y. C.
Published: May 2015

In order to select suitable isodesmic reactions, heats of formation at 298 K of seven aromatic nitro compounds were calculated by various density functional theories, together with different basis sets. The calculated heats of formation for nitrobenzene, 1,2‐dinitrobenzene, 1,3‐dinitrobenzene, 1,4‐dinitrobenzene, 1,3,5‐trinitrobenzene, 1,2,3‐trinitrobenzene, and 1,2,4‐trinitrobenzene by various DFT methods were averaged to be 14.84, 23.23, 12.84, 12.89, 14.71, 30.61, and 25.73 kcal/mol, respectively. These values are very close to the experimental or multivariable linear regression results.
Theory of the Stark Effect on Single Molecular Spectroscopy
Authors: Hayashi M. , Chiang C. H. , Liang K. K. , Shiu Y. J. , Chang C. H. , Wu D. Y. , Li F. Y. , Chang T.‐C. , Wild U. , Latychevskaia T. Y. , Lin S. H.
Published: May 2015

In this work, we study a mechanism of the Stark effect on single molecular spectroscopy using the perturbation method. In particular, mechanisms of the induced dipole moment of a molecule imbedded in polar and non‐polar host molecules are theoretically investigated by applying LCAO MO to a guest molecule. Ab initio calculations are performed to study how the distance between a guest and a host molecule affects the induced dipole and quadrapole moments. We have found that the induced dipole moment is very sensitive to short range configurations while the induced quadrapole moment can be affected by longer range configurations.
Zinc(II) and Ruthenium(II) Complexes of Novel Fluorene Substituted Terpyridine Ligands: Synthesis, Spectroscopy and Electrochemistry
Authors: Thomas K. R. Justin , Lin J. T. , Chang Chen‐Pin , Chuen Chang‐Hao , Cheng Chung‐Chin
Published: May 2015

Terpyridine ligands substituted with fluorene, fluorenylethynylthiophene and fluorenylethynylbenzene were obtained by applying Kröhnke synthesis and Sonogashira coupling reactions. [ZnL2]2+ and [Ru(L)‐(tpy)]2+ complexes were obtained by standard methods and characterized by spectroscopic and electrochemical methods. Zinc complexes are bright luminophores emitting blue to yellow colors depending on the nature of the conjugation in the ligand, while the ruthenium complexes do not emit at room temperature. The high quantum yields and short lifetimes indicate that the emission in the zinc complexes is mainly ligand centered.
Kinetics of Acid‐Catalyzed Dissociation of Copper(II) N‐Alkyl‐Substituted Diamino Diamide Complexes
Authors: Chao Min‐Shiun , Huang Shih‐Liang
Published: May 2015

The dissociation kinetics of the copper(II) complexes of 4‐methyl‐4,7‐diazadecanediamide (4‐Me‐L‐2,2,2), 4,7‐dimethyl‐4,7‐diazadecanediamide (4,7‐N,N′‐Me2‐L‐2,2,2), 4‐ethyl‐4,7‐diazadecanediamide (4‐Et‐L‐2,2,2), and 4‐methyl‐4,8‐diazaundecanediamide (4‐Me‐L‐2,3,2) have been studied at 25.0 °C and μ = 4.0 M (NaClO4 + HClO4) by the stopped‐flow method. These reactions are specific‐acid catalyzed; however, the rate constants of these reactions do not depend on the concentrations of acetic, chloroacetic, and dichloroacetic acids. At pH values below 1.4, both the proton‐assisted and the direct protonation pathways make contributions to the rates. The ratios of the rate constant of dissociation by the direct protonation pathway to the rate constant by the proton‐assisted pathway for the complexes in aqueous solution were measured and discussed.
Stereoselectivity in the Diels‐Alder Cycloadditions of a Facially Dissymmetric Bicyclo[2.2.2]octadiene‐Grafted Maleic Anhydride with Exocyclic Butadienes. Unexpected Facial Selectivity in the Cycloaddition with 2,3,5,6‐tetramethylidenebicyclo[2.2.2]octene
Authors: Chou Teh‐Chang , Kuo Liang‐Hsuan , Liu Kun‐Fa
Published: May 2015

The Diels‐Alder cycloadditions of facially dissymmetric maleic anhydride 1 with facially nonequivalent exocyclic 1,3‐butadienes(dimethylidenebicyclo[2.2.2]octene 3 and 2,3,5,6‐tetramethylidenebicyclo[2.2.2]‐octene (4)) were investigated. In each cycloaddition, the reaction occurred via the course in which 1 added exclusively by its syn‐face (same face as the etheno‐bridge) onto either π‐face of the exocyclic 1,3‐butadiene systems to produce only two of the four possible stereoisomeric monocycloadducts (8a/8b and 9a/9b). In the Diels‐Alder cycloaddition of 1 with bis‐exocyclic butadiene 4, however, both monocycloadducts 9a and 9b underwent subsequent cycloaddition with distinctive facial selectivity to produce the Cs‐symmetric bis‐cyclohexanobarrelene 10a as only bis‐cycloadduct.
Interaction of Trypan Blue with Protein and Application
Authors: Gao Hong‐Wen , Zhao Jian‐Fu
Published: May 2015

The microphase adsorption ‐ spectral correction (MPASC) technique has been described and applied to the aggregation of trypan blue (TB) in proteins. The formation of the microelectrostatic field in protein causes the Langmuir monolayer aggregation of TB. The adsorption ratio of TB to bovine serum albumin (BSA), ovalbumin (OVA), hemoglobin (Hb) and human γ‐globulin (γ‐G) was determined to be 14.8, 8.4, 2.8 and 27.6, respectively, and the adsorption constant of the aggregates to be 7.17 × 105, 4.88 × 106, 4.85 × 106 and 2.99 × 106. The adsorption ratio of TB to proteins interestingly indicates almost no relation to the array sequence of amino acid residues. The interaction of TB with proteins is sensitive at pH 3.29, and the reaction was applied to the determination of protein trace with satisfactory results.
Application of the Generalized Kinetic Ising Model to the Kinetics of Protein Folding
Authors: Liang Kuo Kan , Hayashi Michitoshi , Shiu Ying Jen , Mo Yan , Shao Jiushu , Yan Yijing , Lin Sheng Hsien
Published: May 2015

The kinetic Ising model in the mean field approximation has been applied to study the equilibrium and kinetic behaviors of protein folding‐unfolding. Thermodynamics and kinetics of protein folding‐unfolding are related by an elementary process of folding ↔ unfolding of peptide bonds. As a demonstration, we analyze, using the presented theory, the equilibrium and kinetics properties of Leu94Val mutant of horse cyt. c (Biochemistry 35, 5538 (1996).) and several characteristic properties are deduced using our theoretical model.
Thermodynamic Study of Complexation Phenomena of Some Alkaline Earth Metal (II) Complexes in Propanol‐1‐Water Mixtures at Various Temperatures
Authors: Bakr Moustafa F.
Published: May 2015

The stability constants of Mg2+, Ca2+, Sr2+ and Ba2+ perchlorates with 2,4‐diamino‐3,5‐dicyanothiophene (DADCT) have been determined at 15, 25, 35, 45 and 55 °C in 10, 20 and 30% (w/w) propanol‐1‐water mixtures using the conductometric technique.

The conductometric data were analysed using a model 1:1 stoichiometry by which the stability constants, Ks, and the limiting molar conductance were obtained. The plots of specific conductance versus the molar ratio [A]o/[Cn+]o suggest that the stoichiometry of metal ion complexes is of a 1:1 complex.

The stability constants tend to decrease with the atomic number as well as the ionic radii in the order Mg > Ca > Sr > Ba in 10% > 20% > 30% (w/w) propanol‐1‐water solvents. This trend was found to agree exactly with the Irving‐Williams series for all the systems under investigation.

The thermodynamic parameters, ΔGo, ΔHo and ΔSo, for the complexation processes of all the complexes were evaluated and their significances were discussed.
Formation of Organometallic Heterocycles by S‐alkylated and N‐alkylated Ruthenium Vinylidene Complexes
Authors: Chang Chao‐Wan , Lin Ying‐Chih
Published: May 2015

Treatment of [Ru]C=CPh (1, [Ru] = (η5‐C5H5)(dppe)Ru, dppe = Ph2PCH2CH2PPh2) with PhN=C=S at room temperature affords the [2 + 2] cycloaddition product (2) which contains a four‐membered‐ring heterocycle. A series of cationic S‐alkylated ruthenium vinylidene complexes [Ru]=C=C(Ph)C(=NPh)SCH2R+ (3a, R = CONH2; 3b, R = CH=CH2; 3c, R = p‐C6H4CF3) and N‐alkylated ruthenium vinylidene complexes [Ru]=C=C(Ph)C(=S)N(Ph)CH2R+ (4b, R = CH=CH2; 4c, R = p‐C6H4CF3) are prepared from 2 with organic halides at room temperature with high yields. Deprotonation of 3a and 3c by n‐Bu4NOH in acetone induces novel cyclization reactions via C‐C bond formation and yields neutral five‐membered‐ring heterocyclic complexes (5a, R = CONH2; 5c, R = p‐C6H4CF3). In a similar manner, deprotonation of 4b and 4c by NaOMe in CH2Cl2 also induces another cyclization to yield the pyrrole‐2‐thione complexes (6b, R = CH=CH2; 6c, R = p‐C6H4CF3). At room temperature, 5c isomerizes to the 2‐aminothiophene complex (7c) in solution.
Impedance Description of the Effect of the Polar Potential on a Schiff Base Self‐Assembled Monolayer
Authors: Ding Keqiang , Wang Qingfei , Jia Zhenbin , Tong Ruting , Wang Xinkui , Shao Huibo
Published: May 2015

In this paper, the effect of polar potentials on Schiff base self‐assembled monolayers was mainly investigated by the Electrochemical Impedance Spectroscopy (EIS) method. Different polar potentials and polarizing times were applied to this newly created monolayer, with an intention to reveal the relationship between the polar potential and the structure of this monolayer. The result showed that different polar potentials correspond to different complex resistance (Nyquist) plots, and the effect of polarizing time on this monolayer is regular and could be detected and reflected by the EIS plots conveniently. The results also demonstrated that the content of a C=N group related with the packing degree of this monolayer intimately, and the lower content of a C=N group corresponds to a denser structure of the monolayer, which could be presented by the value of electron transfer resistance (Rct). The main meaning of our work is to have developed one novel way that could reflect the relationship between the structure of the monolayer and the polar potential, which surely will encourage further experiments not only on Schiff bases but on other self‐assembled monolayer containing active groups.
A Preliminary Study on the Synthesis of Nano‐Sized Quartz
Authors: Li Li‐Jun , Fang Jiann‐Neng , Lo Huann‐Jih , Song Sheng‐Rong , Chen Yaw‐Lin , Chen Huei‐Fen , Lin I‐Chieh
Published: May 2015

Silica gel was used as the starting material to synthesize nano‐sized quartz in the presence of alkaline solution. The experiments were carried out in autoclaves under the conditions of 0.25 M NaOH solution, 210 °C, and vapor pressure.

SiO2‐X2 and α‐cristobalite appear as the intermediate unstable phases during the synthesis of quartz which occurs as a single stable phase in the synthetic product after 26 hour experiments. The growth of quartz can be separated into a fast linear growth with the rate of 75.3 nm/hr and a slow one with the rate of 1.4 nm/hr. It is shown that quartz begins to grow at 16.1 hours and the fast growth changes abruptly to the slow one at about 26.7 hours after the start of the experiments. On the other hand, nucleation occurs from 20 to 28 hours.

For the synthetic quartz, an amount of about 32% of the population is nano‐sized, but most of the population (about 78%) lies between 50 nm and 300 nm, and the geometric mean size is about 182 nm.

From the results of this preliminary study, it is encouraging that a high percentage of nano‐sized quartz could possibly be produced if suitable experimental conditions are chosen.
Separation of Herbicides from Aqueous Solutions by Paper Adsorption
Authors: Wang Wan‐Kung
Published: May 2015

Separation of the herbicides 2,4‐D methyl ester and pentachlorophenol from aqueous solutions by paper capillary permeation adsorption method was studied using paper. Nearly 43% and 99% of the investigated herbicides 2,4‐D methyl ester and pentachlorophenol, respectively, could be separated under optimum conditions. The effect of pH on the separation efficiency was studied in particular. At pH1–11 and 1, the maximum separation was achieved for 2,4‐D methyl ester and pentachlorophenol, respectively. The effects of herbicide concentration and some salts on the separatability were examined. Desorption techniques by elution with water to remove the herbicides from paper were developed. Moreover, the selective separation of the herbicides from the dispersion dyes methylene blue and congo red was attempted.
A Molecular Dynamics Simulation Study on Ion‐Conducting Polymer sPBI‐PS(Li+)
Authors: Yang Hsiao‐Ching , Huang Qiang , Hua Chih‐Yu , Lan Yi‐Kang , Chen Cheng‐Lung
Published: May 2015

To understand the mechanism of ionic migration in the amorphous matrixes of polymer electrolytes is crucial for their applications in modern technologies. Here, molecular dynamics (MD) simulation was carried out to investigate the ionic conduction mechanism of a particular conjugated rigid‐rod polymer, sPBI‐PS(Li+). The backbone of this polymer is poly[(1,7‐dihydrobenzo[1,2‐d:4,5‐d']diimidazole‐2,6‐diyl)‐2‐(2‐sulfo)‐p‐phenylene]. The polymer has pendants of propane sulfonate Li+ ionomer. The MD simulations showed that the main chains of sPBI‐PS(Li+) are in a layer‐like structure. The further detailed structure analysis suggested that the π‐electron of this polymer is not delocalized among aromatic rings. This agrees with the experimental result that sPBI‐PS(Li+) shows no electronic conductivity, and the conductivity of this polymer is mainly ionic. The calculated migration channels of lithium ions and electrostatic potential distributions indicated clearly that the polymer matrix is anisotropic for the migrations of ions. The migration of lithium ions along the longitudinal direction is more preferable than that along the transverse direction. The relaxations of the polymer host were found to play important roles in the transfer process of lithium ions. The hopping of lithium ions from one ‐SO3−1 group to another correlated strongly with characteristic motions of ‐SO3−1 group on a time scale of about 10−13 s.
A Theoretical Study of Face Selectivity in the Michael Addition of a Grignard Reagent with 5‐Substituted‐2‐dicyanomethyleneadamantanes
Authors: Wu Pei‐Fang , Wang I‐Ting , Lu Hsiu‐Feng , Yao Ching‐Fa , Sun Ying‐Chieh
Published: May 2015

Face selectivity for the reactions of 5‐substituted (X)‐2‐dicyanomethyleneadamantanes with a Grignard reagent was examined using ab initio calculation for the substituents (X=F, Cl, Br, OH, NH2, and CH3). The calculated syn/anti product ratio based on the results of transition state energies for the halide substituents are in good agreement with the available experimental results. In addition, the results of the natural bond orbital calculation suggest that the through‐bond Cieplak hyperconjugation effect, instead of the through‐space interaction suggested by the experimental results in a prior study, is the main factor in determining face selectivity for the halide substituents in the present study, while for (X=OH, NH2, and CH3) substituents, other interactions may have unnegligible effects as well.
An Alternate Mathematical Model for the TAP Technique for Numerical Integration
Authors: Wang Dezheng
Published: May 2015

The mathematical modeling of the reactor in the TAP technique describes it as composed of zones of different diffusivity, and it makes the model linear by imposing boundary conditions of the continuity of concentration and flux at zone boundaries so as to be able to use a Fourier transformation technique to solve the equations. An alternative description of the reactor that uses a spatially non‐constant diffusivity to obviate the need to impose auxiliary boundary conditions in the regions where diffusivities change is proposed. The reactor equation is the mass balance equation without the simplification to the case of constant diffusivity, that is, without the diffusivity taken out of the differential operator. Computations based on it are compared with those of the linear model. The computed response curves of both models are similar, which indicates that the alternate model is equally good as a description of the reaction system. The alternate model is useful for modeling reactor systems with a variable cross‐sectional area or with temperature non‐uniformity.
Density Functional Study of the Effect of SiH4/GeH4 and Si(001)/Ge(001) on Gas‐Surface Reactivity during Initial Dissociative Adsorption
Authors: Lin Jyh Shing , Lee Lien‐Feng , Chou Wen‐Chi
Published: May 2015

Ultrasoft pseudopotential total energy calculation based on density functional theory (DFT) with generalized gradient approximation (GGA) has been used to investigate 1) the energetic profile for the initial dissociative adsorption of XH4 (X = Si and Ge) onto Si(001) and Ge(001) surfaces to evaluate their gas‐surface reactivity in comparison with relevant measured gas‐surface reactivity using supersonic molecular beam techniques, and 2) the effect of different gaseous molecular precursors, i.e. XH4 (X = Si and Ge), and different surfaces, i.e. Si(001) and Ge(001), on their gas‐surface reactivity during initial dissociative adsorption. Our evaluated gas‐surface reactivity for GeH4 is approximately a factor of 18.45 better than that for SiH4 on Si(001)‐(2×2) surface. This calculated result is about three to four times higher than observed gas‐surface reactivity (as much as a factor of 5 depending on the incident kinetic energy) derived from measured gas‐surface reactivity using supersonic molecular beam techniques. We believe that the better evaluated gas‐surface reactivity for GeH4 than SiH4 is due to 1) the forming of a stronger bond of Si‐H between H within GeH4 and buckled‐down Si atom on the Si(001)‐(2×2) surface and 2) the smaller distortion of Ge‐H bond within GeH4 at the transition state. Additionally, our evaluated gas‐surface reactivity for SiH4 on Si(001)‐(2×2) surface is approximately a factor of 21.69 better than SiH4 on Ge(001)‐(2×2) surface. This calculated result is about two times higher than observed gas‐surface reactivity. We attributed this better evaluated gas‐surface reactivity for SiH4 on Si(001)‐(2×2) surface to 1) the smaller distortion of Si‐H bond within SiH4 and 2) the nature of weaker bond of Ge‐H between H within SiH4 and buckled‐down Ge atom on Ge(001)‐(2×2) surface in comparison with that of stronger bond of Si‐H between H within SiH4 and buckled‐down Si atom on Si(001)‐(2×2) surface even though there is the slightly shorter bond length of Ge‐H between H within SiH4 and buckled‐down Ge atom on Ge(001)‐(2×2) surface at the transition state.
New Basis Sets for Lanthanide and Actinide Energy‐consistent Small‐core Pseudopotentials
Authors: Cao Xiaoyan
Published: May 2015

The optimization of generalized contracted Gaussian (14s13p10d8f6g)/[6s6p5d4f3g] atomic natural orbital valence basis sets for relativistic energy‐consistent small‐core lanthanide and actinide pseudopotentials of the Stuttgart‐Bonn variety is described. Corresponding Gaussian valence basis sets using a segmented contraction scheme (14s13p10d8f6g)/[10s8p5d4f3g] for lanthanides and (14s13p10d8f6g)/[10s9p5d4f3g] for actinides are also discussed. The basis sets have been proven to be stable and reliable by atomic and molecular calibration studies. Application to the electronic ground states of some selected homonuclear lanthanide dimers shows that the derived molecular constants are the best theoretical estimates available at present and have a satisfactory agreement with experimental data. Remaining discrepancies in the vibrational constants of La2, Ce2 and Pr2 are shown to be probably related to quite large Ar‐matrix shifts.
The Valence Bond Calculations on Conjugated Hydrocarbons of Medium to Infinite Sizes
Authors: Ma Jing , Li Shuhua , Liu Chungen , Jiang Yuansheng
Published: May 2015

In the past decade, we devoted time to the valence bond (VB) study of huge conjugated hydrocarbons by employing the Heisenberg model. Due to the dimension of the covalent space exponentially increasing with the size of molecule, the exact solution of the VB model for large molecules encounters a fundamental difficulty. Before 1990, Alexander and Schmalz published ground‐state energy results on a set of benzenoids of up to 24 π‐electrons using the graphical unitary group approach. Around 1995, we employed Lanczos technique to diagonalize the VB Hamiltonian and presented the low‐lying state energies and wave functions of benzenoids with up to 22 π‐centers. In terms of wave functions, the physical and chemical behaviors of these conjugated species have been discussed in detail. In succession, we generalized the VB calculation to larger systems by proposing an algorithm in coding all Slater determinants of the covalent space with conserved spin quantum number. The exact solutions of the VB model have been obtained for conjugated species with up to 30 π‐electrons. Recently, we broke through this limitation by extending the density‐matrix renormalization group (DMRG) method of White to the quasi‐one‐dimensional system. The VB energies of the ground states for two series of polycyclic aromatic hydrocarbons, polyacene and polyphenanthrene, of arbitrary lengths defined by the number of constituent hexagons have been obtained. The effective conjugated length for these infinite long‐chain polymers could be estimated.
Solid Phase Synthesis of 3‐Toluenesulfonylglutarimides
Authors: Chang Meng‐Yang , Lin Kuo‐Ging , Chen Shui‐Tein , Chang Nein‐Chen
Published: May 2015

A novel route for the synthesis of 3‐toluenesulfonylglutarimides on a solid support is described. The cyclization step involves stepwise [3+3] strategy of Rink Amide resin bound onto an α‐toluenesulfonyl group with various α,β‐unsaturated esters.
A Generalized Unpaired Electron Spin Density Equation and Organic Hyperconjugation Mechanism
Authors: Shih Shawn
Published: May 2015

A large class of stereochemcial and related interactions in organic chemistry are repulsive and others are attractive, but the relative orientation of two methyl groups and the amount of energy required to twist one relative to the other (the hindered rotation energy barriers), or the alignment of such a group with respect to a conjugated ring to which it is attached (widely attributed to a mechanism called “hyperconjugation”) are estimated to be small in compared with the total energy of the molecule.

We used theories of both isotropic and anisotropic proton hyperfine interactions in the π‐electron systems developed in the early sixties. They are approximated by the magnetic dipole nteractions between each proton and an electron spin magnetization that is distributed in 2s and 2p Slater atomic orbitals center on carbon atoms. We have extended these theories to the non‐planar olefinic cation radicals, which are very important in biochemistry as well as in petroleum catalysis. A three dimensional electron spin density equation has been developed in this paper to handle some Jahn‐Teller vibronic molecules. The new electron spin density equation related the observed proton hyperfine splittings to the non‐planar structures of the open‐chain alkene cation radicals generated by radiolysis and various chemical oxidation methods. The spin densities and the conformational calculations based on valence bond theory and symmetry principles are compared with some more elaborated molecular orbital calculations in the literature. The localized valence bond approaches are better in accord with our experimental results. The anomalous line‐width effect of the four methyl groups observed in the 2,3‐dimethyl‐2‐butene cation radicals also confirmed the positive sign of the electron‐proton hyperfine constant of hyper‐conjugation mechanism.

A methyl substituent attached to a conjugated molecule often behaves as if it formed part of the region of conjugation; the charge appears to flow from the methyl group into the π electron system and it may also give rise to an appreciable dipole moment. Methylation also gives rise to an appreciable dipole moment, and the resultant red shift of electronic absorption bands is of some importance in the design of dye molecules.
Oxidative Coupling of Thiols to Disulfides with Ti(IV) in the Presence of NaI under Air Atmosphere
Authors: Zeynizadeh Behzad , Iranpoor Nasser
Published: May 2015

Ti(IV) as TiCl3(O3SCF3) and TiO(O2CCF3)2 are used as efficient catalysts for oxidative coupling of aliphatic, aromatic and heteroaromatic thiols to their disulfides in the presence of NaI under air atmosphere.
Separation of Mercury with an Ammonium Sulfate‐Ammonium Thiocyanate‐Ethyl Violet Flotation System
Authors: Chen Bingyi , Bai Haixin , Li Quanmin , Liu Guoguang
Published: May 2015

The separation behavior of mercury by a flotation system consisting of ammonium sulfate, ammonium thiocyanate and ethyl violet, and the conditions for the separation of Hg(II) with other common metal ions have been studied. The studies show that in aqueous solutions, Hg(II) combines with NH4SCN and ethyl violet(EV) into dissoluble ternary ion‐association complex [Hg(SCN)42−]•(EV)2. In the presence of ammonium sulfate, the precipitate is floats well on the surface of the water phase and separates from water thoroughly. It shows that Hg(II) can be separated completely from Cd(II), Fe(II), Co(II), Ni(II), Mn(II) and Al(III) by flotation at pH1.0. The flotation mechanism of Hg(II) is described in this paper.
An Improved Method for the Addition Reactions of 1,3‐Dichloroacetone with Combined Organolithium‐Cerium Trichloride Reagents
Authors: Chen Same‐Ting , Fang Jim‐Min
Published: May 2015

Alkyl‐, phenyl‐ and alkynyllithium reagents in combination with anhydrous cerium(III) chloride underwent addition reactions with 1,3‐dichloroacetone in a very efficient manner. The addition products are versatile precursors for 2‐substituted epichlorohydrins and glycidols. Fluconazole, a potent antifungal agent, was thus synthesized in 67% yield by addition of 1,3‐dichloroacetone to 2,4‐difluorophenyllithium in the presence of cerium(III) chloride, followed by substitution of the chlorine atoms with 1,2,4‐triazole.
A Semiempirical Study of Carbon Nanotubes with Finite Tubular Length and Various Tubular Diameters
Authors: Wang Bo‐Cheng , Wang Houng‐Wei , Lin I‐Chun , Lin Yun‐Shan , Chou Yu‐Ma , Chiu Houn‐Lin
Published: May 2015

A semiempirical PM3 quantum computational method has been used to generate the electronic and optimized geometrical structure of SWNT of zigzag and armchair types. We shed light on the electronic structures of SWNT with various diameters and lengths of the tube. Particularly, the calculated HOMO, LUMO and band‐gap of SWNT are not monotonic but exhibit a well‐defined oscillation, which depends on the tubular diameter and the tubular length. Calculated HOMO, LUMO and band‐gap of the zigzag SWNTs have oscillated with tubular diameter as they contain an odd or even number of benzenoids in the circular plane of the carbon nanotube. The zigzag SWNTs with an odd number of benzenoids have a higher band‐gap than those of SWNTs with an even number of benzenoids in the circular plane of the carbon nanotube. Calculated results also reveal that the tubular length in the zigzag SWNTs influences the band‐gaps very little. For the armchair SWNT, calculated HOMO, LUMO and band‐gap contained the oscillate depending on the number of carbon sections in the tubular length axis. Their repeat sections are 3n‐1, 3n and 3n+1. The armchair SWNT with 3n+1 sections has a high band‐gap while the SWNTs with 3n‐1 sections have a low band‐gap. The tubular diameters of armchair SWNT influence the HOMO, LUMO and band gap very little.
Volumetric Properties and Volumetric Interaction Parameters of the CsCl‐saccharides (D‐glucose, D‐fructose)‐water Solutions at 298.15 K
Authors: Jiang Yucheng , Gao Shiyang , Xia Shuping , Wang Jianji , Zhuo Kelei , Hu Mancheng
Published: May 2015

Densities have been measured for the CsCl‐saccharide (D‐glucose, D‐fructose)‐water systems at 298.15 K. These data were used to calculate the apparent molar volume of CsCl (Vφ,E) and the saccharides (Vφ,S), and the infinite dilution apparent molar volume Vφ,E0 and Vφ,S0 in the studied solutions. In addition, the standard transfer volume ΔtVφ,E0 of CsCl from water to aqueous saccharides solutions, and ΔtVφ,S0 of saccharides from water to CsCl solutions have been evaluated and discussed using the structural interaction model. The volumetric interaction parameters for CsCl with saccharide in water were obtained and analyzed by the group additivity principle and the stereochemistry of the saccharide molecules.
Thin Layer Chromatography of Purines on Silica Gel G Impregnated with Transition Metal Ions; Assay of Caffeine and Theophylline in Pharmaceutical Formulations
Authors: Singh D. K. , Srivastava Bhavana , Sahu Archana
Published: May 2015

This study was undertaken to develop thin layers of silica gel G impregnated with transition metal ions for separation, identification and estimation of purines. The influence of transition metal ions and eluting solvents on chromatographic behaviour (hRf) has been studied. The method was applied for qualitative analysis of purines in the mixtures and quantitative analysis of purine bases in the mixture as well as in pharmaceutical formulations. The results were compared statistically with those obtained by official methods. The method is simple, reproducible, and accurate within 1.3 ± 0.6%.
Metal Binding and Selectivity in Zinc Proteins
Authors: Dudev Todor , Lim Carmay
Published: May 2015

Zinc is one of the most abundant metals in living organisms and is an essential co‐factor of many metabolic enzymes and transcription factors. In this review, based on a recent body of theoretical and experimental results, the physical bases are delineated for the following aspects of zinc binding and selectivity in proteins: (1) What is the most thermodynamically preferable coordination geometry of a bidentate ligand (such as carboxylate) or Zn in Zn‐binding sites? (2) What is the protonation state of the Cys side chain in Cys4 zinc‐finger cores? (3) How does a protein select Zn from the mixture of ions in the surrounding fluids? (4) What is the role of the second shell in metal binding and selectivity? The key results are summarized and the physical basis and/or implications of the findings are discussed.
Mixed Ground‐State in the Trinuclear Complex: [Mn3O(O2CCCl3)6(H2O)3]
Authors: Tsai Hui‐Lien , Jwo Tyn‐Yih , Yang Chen‐I , Wur Ching‐Shuei , Lee Gene‐Hsiang , Wang Yu
Published: May 2015

The reaction of [Mn12O12(OAc)16(H2O)4]·4H2O·2HOAc with Cl3CCO2H in dichloromethane leads to formation of mixed‐valence trinuclear oxo‐centered [Mn3O(O2CCCl3)6(H2O)3]·2H2O (1). Complex 1 crystallizes in two forms; the monoclinic and hexagonal systems. [Mn3O(O2CCCl3)6(H2O)3]·3H2O (1a) crystallizes in hexagonal, space group P63/m (295 K) with a = 10.0741(1) Å, c = 22.8668(4) Å, and z = 2. [Mn3O(O2CCCl3)6(H2O)3]·0.5C6H14 (1b) crystallizes in monoclinic, space group P21/n (150 K) with a = 11.8258(2) Å, b = 41.9370(5) Å, c = 25.9619(4) Å, β = 95.297(1)°, and z = 12. Complex 1 possesses an oxo‐centered Mn3O unit with peripheral ligands provided by bridging trichloroacetate and terminal H2O groups. Each manganese ion is distorted octahedral, and consideration of overall charge of the trinuclear unit necessitates a mixed‐valence MnIIMnIII2 description. Magnetization measurement at 2.0 K up to 70 kG indicates the mixed ground state S = 3/2 and S = 1/2 for complex 1. X‐band EPR spectra measured at 4.0–100.0 K on polycrystalline sample of complex 1. There is a transition centered at g ≈︁ 4, which decreases in intensity with increasing temperature. Also, there is a transition centered at g ≈︁ 2, which does not disappear with increasing temperature.
The Ionic Conductivity of Ultrafine Solid Electrolytes for Li4.4Al0.4Si0.6O4‐xY2O3 Systems
Authors: Chen Rufen , Liu Huating , Song Xiuqin
Published: May 2015

The Li4.4Al0.4Si0.6O4‐xY2O3 (x = 0 to 0.5) ion conductors were prepared by the Sol‐Gel method and examined in detail. The powder and sintered samples were characterized by DTA‐TG, XRD, SEM, and AC impedance techniques. The experimental results show that the conductivity and sinterability increased with the amount of excess Y2O3 in the silicate. The particle size of the powder samples is about 0.12 μm. The maximum conductivity at 16 °C is 2.925 × 10−5s·cm−1 for Li4.4Al0.4Si0.6O4‐0.3 Y2O3.
The HPLC Enantioresolution of Phenyl Isothiocyanated Amino Acids on Vancomycin Bonded Phase Using the Acetonitrile‐Based Mobile Phase: A Comparison to the Teicoplanin Phase
Authors: Chen Shushi
Published: May 2015

The phenyl isothiocyanate, an electrophilic reagent for peptide chain sequencing, is used to pre‐column derivatize a variety of α‐amino acids in alkaline medium before their enantioresolution on a vancomycin bonded chiral phase using the acetonitrile‐based mobile phase. The observed resolution is believed to be due to the re‐location of the hydrogen receptor site from sulfur to nitrogen on the isothiocyanyl fragment of derivatizing reagent, which in turn changes the enantioselectivity. Under the same chromatographic conditions, the resolution for N‐benzoylated, 3,5‐dinitrobenzoylated and N‐carbobenzyloxylated amino acids is either not found or unsatisfactory. Also, no resolution is obtained in the reversed‐ or normal phase mode for all phenyl isothiocyanated amino acids examined in this study.
The Effects of Various Alcohols on the Stability of Melittin: A Molecular Dynamics Study
Authors: Liu Hsuan‐Liang , Hsu Chia‐Ming
Published: May 2015

In this study, 200 ps molecular dynamics simulations were conducted to investigate the effects of various alcohols on the structural stability of melittin. The averaged helicity of melittin remained 80% in pure butanol, whereas it was below 60% both in pure water and in pure methanol. The α‐helix propensity of melittin increased with the aliphatic chain length of the alcohol. Charge‐charge interaction between Lys21 and Arg24 and polar‐nonpolar interaction between Trp19 and Arg22 are probably responsible for the higher structural integrity of the C‐terminal α‐helix over the N‐terminal one. The weaker dielectric constant of longer aliphatic chain length of alcohol possibly reduces the hydrogen bonding between amide protons and surrounding solvent molecules and simultaneously promotes the intramolecular hydrogen bonding in melittin and therefore stabilizes the secondary structure of melittin. The effect of various alcohols on stabilizing melittin is most likely due to their ability to form clusters on the surface of melittin effectively, favoring the formation of intramolecular hydrogen bonds instead of intermolecular hydrogen bonds and promoting the formation of stable α‐helices.
Photooxidation of Methane over TiO2
Authors: Lien Chen‐Fu , Chen Meng‐Tso , Lin Yu‐Feng , Lin Jong‐Liang
Published: May 2015

Fourier‐transform infrared spectroscopy has been employed to investigate the adsorption and photo‐oxidation of CH4 over powdered TiO2. The interaction between the CH4 and TiO2 surface is weak. It is found that no CH4 molecules are adsorbed on the surface at 35 °C in a vacuum. Under UV irradiation, CH4 decomposes to form CO(a), CO2(g), H20(a), and HCOO(a) in the presence of O2. The photoreaction rate is retarded and only small amounts of CO(a) and HCOO(a) are formed in the absence of O2. It is observed that the oxygen atoms of O2 are incorporated into these photoproducts as 18O2 is used. The major 18O‐containing products are C18O(a), C18O2(g), H2 18O(a), HC16O18O(a), and HC18O18O(a) after 180 min UV irradiation. However, the extent of 18O incorporating into the adsorbed formate is dependent on UV irradiation time. In the early stage of UV irradiation HC16O16O(a) is the major formate form indicating the involvement of TiO2 lattice oxygens for its formation, but HC18O18O(a) becomes the major one after 180 min indicating the involvement of 18O2. Formate on TiO2 further photodecomposes to CO2(g), but not to CO(a). CO(a) formation is directly from CH4 photodecomposition with the participation of TiO2 lattice oxygens and O2.
Neolignans from the Parasitic Plants. Part 2. Cassytha Filiformis
Authors: Ho Jiau‐Ching , Chen Chiu‐Ming , Row Lie‐Ching
Published: May 2015

From the whole plant of Cassytha filiformis Linn. (Lauraceae), two new neolignans, named 4‐O‐methylbalanophonin and cassyformin together with three known compounds have been isolated. Their structures were established by spectroscopic and chemical methods.
Synthesis and Second‐Order Nonlinearities of Chiral Prolinol‐Substituted Chromophores
Authors: Chou Shang‐Shing P. , Yu Chiung‐Yi , Lin Hong‐Cheu , Yang Pao‐Keng
Published: May 2015

A new series of thiophene‐ and furan‐containing chromophores with a chiral prolinol donor and a sulfone acceptor has been synthesized. The UV‐vis absorptions, second‐order nonlinear optical properties, and X‐ray crystal structures are described.
Sulfur‐Assisted Intermolecular Triphenylphosphine Dissociation of Thiocarbamoyl Ligand in Platinum(II). X‐ray Structure of Complex [Pt(PPh3)2(η1‐SCNMe2)(Cl)]
Authors: Yih Kuang‐Hway , Lee Gene‐Hsiang , Huang Shou‐Ling , Wang Yu
Published: May 2015

Treatment of Pt(PPh3)4 with N,N‐dimethylthiocarbamoyl chloride, Me2NC(=S)Cl, in dichloromethane at −20 °C processes the oxidative addition reaction to produce platinum complex [Pt(PPh3)2(η1‐SCNMe2)(Cl)], 2 with releasing two triphenylphosphine molecules. The 31P{1H} NMR spectra of complex 2 shows the dissociation of the triphenylphosphine ligand to form diplatinum complex [Pt(PPh3)Cl]2(μ,η2‐SCNMe2)2, 3 in which the two SCNMe2 ligands coordinated through carbon to one metal center and bridging the other metal through sulfur. Complex 2 is characterized by X‐ray diffraction analysis.
Determination of Sulfide in Spring and Wastewater by a New Kinetic Spectrophotometric Method
Authors: Emami Marjan , Mousavi Mir Fazlollah , Barzegar Mohsen
Published: May 2015

A simple, rapid, and sensitive method has been developed for the determination of trace amounts of sulfide based on its reaction with thionine. The reaction is monitored spectrophotometrically by measuring the decreasing absorbance of the dyestuff at 600 nm by the fixed time method. After optimization of the measuring conditions the calibration curves were found linear up to 38.0 ppm (four regions), and the theoretical limit of detection was 0.076 ppm and the relative standard deviation for determination of 1.0 ppm sulfide (n = 10) was found to be 2.7%. The proposed method was applied successfully to the determination of sulfide in spring water and wastewater samples.
Studies on Benzothiazolo‐asycyanino‐colorants Synthesis, Structural Correlation with UV Absorption Maxima and Bactericidal Potentiality
Authors: Ansari Abdus Samad , Kumar Arvind
Published: May 2015

Fifteen new chromophoric chain β‐aryl substituted butadienyl‐benzothiazole asy‐cyanine colorants are synthesized by condensing substituted 3‐isopropylbenzothiazolium iodides and 4‐dimethylaminostyrylphenyl ketones using alkaline ethanolic DMF solution. The colorants show bathochromic shifts in comparison with unsubstituted analogues and styryl analogues but hypsochromic shifts when compared to 3‐methylbenzothiazolium analogues. The highly purified samples are screened in vitro against gram positive and gram negative microbes using Disc diffusion technique and found to be mildly active against some of them.
Synthesis of Asymmetric Triarylbenzenes by Using SOCl2‐C2H5OH Reagent
Authors: Hu Zhiguo , Liu Jun , Li Gongan , Dong Zhibing , Li Wei
Published: May 2015

A simple and efficient method for synthesis of asymmetric branched functionalized triarylbenzenes is presented. The dypnone reacting with different substituted acetophenones, corresponding asymmetric 1,3,5‐triarylbenzenes were obtained in the presence of catalytic amounts of sulfurous oxychloride in anhydrous ethanol.
Modulation of Substrate Specificity upon Modification of Cholesterol Oxidase from Brevibacterium Sterolicum by Hydrogen Peroxide: Evidence for a Peripheral Site
Authors: Tritsch Denis , Loubat‐Hugel Claire , Biellmann Jean‐François
Published: May 2015

Evidence for a peripheral site that recognizes micelles where cholesterol is inserted, is presented for cholesterol oxidase from Brevibacterium sterolicum (CHOD). The Ω loop part of this site contains methionine residues. Their oxidation is reflected in a different selectivity to the micelles. When CHOD is oxidized with hydrogen peroxide, preferential introduction of two oxygen atoms by hydrogen peroxide to the enzyme is observed by the electrospray mass spectrometry. The modified enzyme does not oxidize cholesterol inserted in H‐Triton X‐100/sodium cholate mixed micelles. However, cholesterol solubilized in microemulsions, in biphasic media or inserted in hydroxypropyl‐β‐cyclodextrin is oxidized by the modified enzyme. This modified enzyme oxidizes pregn‐5‐en‐3β‐ol solubilized in mixed micelles, and soluble steroids, such as 3β‐hydroxyandrost‐5‐en‐17β‐carboxylic acid or 3β‐hydroxyandrost‐5‐en‐17‐one. So the modification does not occur at the active site, but at the peripheral site (methionine 81), abolishing the recognition of the micelles and thus inactivating the enzyme specifically towards cholesterol inserted in the micelles.
Direct Formylation of Enol Ethers Using Cyanuric Chloride and N,N‐Dimethylformamide
Authors: Hou Duen‐Ren , Sun Chong‐Si , Sie Wu‐Sian , Jian Jing‐Yu , Hsu Yun
Published: May 2015

A new method to prepare α,β‐unsaturated enol aldehydes is described. 3‐Ethoxymethacrolein (1) and 5‐formyl‐3,4‐dihydro‐2H‐pyran (5) were effectively prepared from enol ethers and the Vilsmeier‐Haack type complex, derived from cyanuric chloride and DMF. One byproduct, amidine 4, was also characterized.
2‐Cyanoacetamide in the Synthesis of Heterocyclic Compounds: Synthesis of New Polysubstituted Pyrazole, Pyridine and Pyrimidine Derivatives
Authors: El‐Rady Eman A. , Khalil Mohamed A.
Published: May 2015

Phenylmethylenecyanoacetamide (1) was successfully transferred into polysubstituted pyrazole, pyridine and pyrimidine derivatives in a one‐pot reaction step. Hydrazine hydrate (2a,b), cyanoacetamide (6a), cyanothioacetamide (6b), cyanoacetic acid hydrazide (6c), thiosemicarbazide (10), urea (14a), thiourea (14b) and 2‐phenylenediamine (24) were selected as amine nucleophile reagents.
Catalytic Para‐Xylene Maximization. V. Toluene Methylation with Methanol and Disproportionation of Toluene Using Pt/ZSM‐5 and Pt/Mordenite Catalysts
Authors: Aboul‐Gheit Ahmed K. , Aboul‐Fotouh Sameh M. , Emam Eman A. , Ahmed Sahar M.
Published: May 2015

Toluene was methylated with methanol and disproportionated using catalysts containing different Pt contents (0.2, 0.4 and 0.6%) supported on H‐ZSM‐5 or H‐mordenite (H‐M) zeolites in a fixed‐bed flow‐reactor operated atmospherically at temperatures of 300–500 °C in a flow of hydrogen. Platinum dispersion in the zeolite supports and acid sites strength distribution were evaluated using hydrogen chemisorption (1:1 stoichiometry) and ammonia temperature programmed desorption (TPD) in a differential scanning calorimeter (DSC). Toluene methylation was much faster on all catalysts than toluene disproportionation (DISP). Both reactions were more accelerated using H‐ZSM‐5 containing catalysts than H‐M containing catalysts. The yield of xylenes, and in particular para‐xylene, was significantly influenced by the yield of trimethylbenzenes (TMBs) in product. The selectivities for para‐, ortho‐ and meta‐xylenes production were found largely dependent on the Pt content in the catalysts, particularly when supported on H‐ZSM5‐zeolite. However, using Pt/H‐M catalysts, these selectivities were not strictly controlled by Pt content in the catalysts.
Homology Models and Molecular Dynamics Simulations of Main Proteinase from Coronavirus Associated with Severe Acute Respiratory Syndrome (SARS)
Authors: Liu Hsuan‐Liang , Lin Jin‐Chung , Ho Yih , Hsieh Wei‐Chan , Chen Chin‐Wen , Su Yuan‐Chen
Published: May 2015

In this study, two structural models (denoted as MproST and MproSH) of the main proteinase (Mpro) from the novel coronavirus associated with severe acute respiratory syndrome (SARS‐CoV) were constructed based on the crystallographic structures of Mpro from transmissible gastroenteritis coronavirus (TGEV) (MproT) and human coronavirus HcoV‐229E (MproH), respectively. Various 200 ps molecular dynamics simulations were subsequently performed to investigate the dynamics behaviors of several structural features. Both MproST and MproSH exhibit similar folds as their respective template proteins. These structural models reveal three distinct functional domains as well as an intervening loop connecting domains II and III as found in both template proteins. In addition, domain III of these structures exhibits the least secondary structural conservation. A catalytic cleft containing the substrate binding subsites S1 and the S2 between domains I and II are also observed in these structural models. Although these structures share many common features, the most significant difference occurs at the S2 subsite, where the amino acid residues lining up this subsite are least conserved. It may be a critical challenge for designing anti‐SARS drugs by simply screening the known database of proteinase inhibitors.
Preparation of Nanostructural ZrO2‐Coated SiO2 Particles by Layer‐by‐Layer Assembly Technique
Authors: Chen Rufen , Song Xiuqin
Published: May 2015

We describe a method for controlled preparation of nanostructural ZrO2‐coated SiO2 particles by layer‐by‐layer assembly technique. ZrO2 colloids were synthesized by the sol‐gel method. The samples were characterized by FIIR, DTA‐TG, SEM, EDS, XPS and XRD techniques. The experimental results show that ZrO2 nanopowders on the surface of SiO2 particles are well distributed and compact; the amount of ZrO2 is increased with adding coating layers; the structure of this coating is tetragonal phase.
Cyanoacetanilides Intermediates in Heterocyclic Synthesis. Part 1: A Facile Synthesis of Polysubstituted and Condensed Pyridones
Authors: Ammar Y. A. , El‐Sharief A. M. Sh. , Mohamed Y. A. , Salem M. A. , Al‐Sehemi A. G. , El‐Gaby M. S. A.
Published: May 2015

Polysubstituted pyridone derivatives were obtained through interaction of cyanoacetanilides with different reagents such as chalcones, 1,1,3‐tricyano‐2‐aminopropene, and arylidenemalononitrile and acetyl‐acetone.
A Convenient Synthesis of Some Pyrazolinone and Pyrazole Derivatives
Authors: Aly El‐Saied A. , Abdo Mohamed A. , El‐Gharably Atif A.
Published: May 2015

A convenient synthesis of some novel 6‐amino‐4‐aryl‐1‐phenyl‐3‐pyridin‐4‐yl‐1,4‐dihydropyrano[2,3‐c]pyrazole‐5‐carbonitriles (3a,b) and 5‐chloro‐1‐phenyl‐3‐pyridin‐4‐yl‐1H‐pyrazole‐4‐carbaldehyde (4) is described. Compound 4 was obtained by the reaction of 2‐phenyl‐5‐pyridin‐4‐yl‐2,4‐dihydropyrazol‐3‐one (1) with dimethylformamide and phosphorus oxychloride under Vilsmeier‐Haack reaction conditions. Compound 4 was subjected to react with different reagents such as hippuric acid, sodium azide and aromatic ketones to afford 4‐(5‐chloro‐1‐phenyl‐3‐pyridin‐4‐yl‐1H‐pyrazolo‐4‐ylmethylene)‐2‐phenyl‐4H‐oxazol‐5‐one (5), 5‐azido‐1‐phenyl‐3‐pyridin‐4‐yl‐1H‐pyrazol‐4‐carbaldehyde (8) and 1‐aryl‐3‐(5‐chloro‐1‐phenyl‐3‐pyridin‐4‐yl‐1H‐pyrazol‐4‐yl)propenones (12a,b), respectively. The latter compounds were also prepared via Michael reaction by treatment of compound 1 with some different chalcones.
A New and Efficient Solid State Synthesis of N‐Aryl‐2‐Phenyldiazenecarboxamides
Authors: Xue Wan‐Xin , Li Jian‐Ping , Wei‐Li  , Wang Yu‐Lu
Published: May 2015

An efficient and convenient solid state reaction using Fe(NO3)3·9H2O/NaHSO4·H2O to oxidize aryl‐substituted semicarbazides for preparing azo compounds has been reported. Eight N‐aryl‐2‐phenyldiazenecarboxamides have been synthesized in excellent yields at room temperature. The method is efficient and rapid.