bluuebunny/crossref_metadata_2025 huggingface dataset:
Thermodynamic Studies on Amino Acid Solvation in some Aqueous Alcohols
Authors: Das Pravakar , Chatterjee S. , Basumallick I.
Published: May 2015

Present paper discusses the behaviour of transfer free energy of some amino acids from water to aqueous solution of Ethanol, 2‐PrOH ad t‐BuOH at different compositions. Dissection of transfer free energy into cavity term, interaction term and electrical term reveals that cavity forming free energy of transfer ΔGt0 (Cav.) plays an important role in dictating actual interaction of amino acids in these mixed solvents. Cavity forming free energy of transfer has been estimated by using Scaled Particle Theory (SPT).
Study on Determination of Six Transition Metal Ions in Biological Samples by SPE and RP‐HPLC
Authors: Yang Ya‐Ling , Miao Ming‐Ming , Lin Qiang , Yang Guang‐Yu
Published: May 2015

This paper reports the utilization of solid phase extraction and the reversed‐phase high‐performance liquid chromatography (RP‐HPLC) for the determination of six transition metal ions (iron, cobalt, nickel, copper, zinc and manganese) in biological samples. The samples were digested by microwave digestion. The iron, cobalt, nickel, copper, zinc and manganese ions in the digested samples can react with 2‐(2‐quinolinylazo)‐5‐diethylaminophenol (QADEAP) to form colored chelates in pH 4.0 acetic acid‐sodium acetic buffer solutions and cetyl trimethylammonium bromide (CTMAB) medium. These chelates were enriched by solid phase extraction with C18 cartridge. Then the chelates were separated on a Waters Nova‐Pak‐C18 column (3.9 × 150 mm, 5 μm) by gradient elution with methanol (containing 0.5% of acetic acid and 0.1% of CTMAB) and 0.05 mol/L pH 4.0 acetic acid‐sodium acetic buffer solution (containing 0.1% of CTMAB) as mobile phase at a flow rate of 0.5 mL/min. The detection limits of iron, cobalt, nickel, copper, zinc and manganese are 3 ng/L, 4 ng/L, 2 ng/L, 4 ng/L, 8 ng/L, 10 ng/L, respectively. This method was applied to the determination of iron, cobalt, nickel, copper, zinc and manganese in biological samples with good results.
Novel Hydrogen‐bond Three Dimensional Networks Generated from the Reaction of Metal Nitrate Hydrate (M = Co, Ni) with Ammonium Thiocynate and Bidentate Ligand Piperazine
Authors: Suen Maw‐Cherng , Wang Yuen‐Hua , Wang Ju‐Chun
Published: May 2015

The reaction of Co(NO3)2·6H2O with two equivalents of PPz (PPz = piperazine hexahydrate) and two equivalents of NH4SCN in CH3OH afforded the complex [Co(NCS)2(PPz)2(CH3OH)2]. The reaction of Ni(NO3)2·6H2O with two equivalents of PPz and four equivalents of NH4SCN in CH3OH afforded the complex [Ni(NCS)4(PPz)2]. Their IR spectra have been recorded and the structures have been determined. Crystal data for 1: space group P&1bar;, a = 6.7208(6) Å, b = 8.4310(8) Å, c = 8.5923(8) Å, a = 77.881(2)°, β = 76.342(2)°, γ = 83.936(2)°, V = 461.75(1) Å3, Z = 1 with final residuals R1 = 0.0650 and wR2 = 0.1725. Crystal data for 2: space group P2(1)/n, a = 7.4209(6) Å, b = 11.0231(9) Å, c = 12.317(1) Å, β = 96.642(9)°, V = 1000.9(2) Å3, Z = 2 with final residuals R1 = 0.0378 and wR2 = 0.0809. Important NCS—H‐N and O‐H—N(PPz) hydrogen‐bonding interactions in compound 1 and NCS···H‐N hydrogen‐bonding interactions and NCS—SCN interactions in compound 2 play a significant role in aligning the polymer strands in crystalline solids.
Direct Electrochemistry with Nitrate Reductase in Chitosan Films
Authors: Song Yaru , Chen Xiaoxia , Wu Hong , Shao Huibo
Published: May 2015

Stable films made from chitosan (CS) on pyrolytic graphite (PG) electrode gave direct electrochemistry for incorporated enzyme nitrate reductase (NR). Cyclic voltammetry (CV) of NR‐CS films showed a pair of well‐defined and nearly reversible redox peaks at about −0.430 V vs. SCE at pH 7.0 phosphate buffers, which was considered as the redox of FAD and heme‐ion. The electron transfer between NR and PG electrode was greatly facilitated in CS films. Integration of reduction peaks at different scan rates from 0.01 to 0.5 V s−;1 gave nearly constant charge values, which is characteristic of thin‐larger‐electrochemical behavior. The pH of the solution strongly affected the direct electron transfer of NR‐CS films. EDTA accelerated the electron transfer, and it was proposed as a stimulant for the system. Reflectance absorption infrared spectra demonstrated that NR retained a nearly native conformation in CS films.
Synthesis and Nucleophilic Addition Reactions of Tricarbonyl[η5‐2‐(phenylthio)hexadienyl]iron Hexafluorophosphate
Authors: Chou Shang‐Shing P. , Chen Ting‐Wan
Published: May 2015

3‐Phenylthio‐3‐sulfolene (1) was readily converted to a C‐5 substituted product 2, which upon thermolysis and complexation with Fe2(CO)9 gave (η4‐diene)iron complexes 3a and 3b. Treatment of 3a and 3b with aq. HPF6 and Ac2O provided the title compound 5, which reacted regio‐ and stereospecifically with some nucleophiles to give the addition products 3b and 7.
Synthesis and Characterization of Poly(Methyl Methacrylate) Grafted from Acacia Gum
Authors: Chowdhury P. , Samui S. , Kundu T. , Saha B.
Published: May 2015

Graft polymerization of methyl methacrylate onto acacia gum has been studied in detail. The grafting was found to be optimal under the following reaction conditions: gum at 0.4 g/dL, monomer at 7.52 × 10−;2 mol/dL, ceric ammonium sulfate at 15.81 × 10−;4 mol/dL, H2SO4 at 0.037 mol/dL, temperature at 50 °C and time at 3.0 h. Fourier transform infrared spectroscopy was sed for the confirmation of grafting. Thermal and physical properties of the copolymer were studied. A probable mechanism of polymerization has been suggested based on reaction kinetics.
Effect of Bacteria‐Virus Interaction on Mechanism of Virus Removal Using Microfiltration Membranes
Authors: Madaeni S. S. , Khodadadi B.
Published: May 2015

In this study, 0.22 μm hydrophobic GVHP membrane was challenged with host bacteria, Escherichia coli (ED 8656) and bacteriophage (λ wild type).

For investigation of filtration mechanism, we employed blocking laws, which are based on the profiles of t/v versus time (t) and t/v versus volume (v). For prominent demonstrating the linearity, the profiles were reconstructed.

When feed contained bacteriophage or a mixture of bacteriophages and host bacteria, the profiles indicated that at the beginning of the filtration, standard blocking (pore plugging) was the dominant mechanism. Over time the bacteriophages filled the pores and formed a cake layer on the membrane surface. The presence of bacteria facilitated the cake layer build up. Nevertheless the filtration mechanism started with pore blockage and ended with cake formation.

The comparison of the present study with another research project carried out by the authors indicates that the removal mechanisms do not rely upon the interactions between microorganisms. However the details of cake layer specifications depend on the nature of the microorganisms and operating conditions.
Reduction of Aromatic Nitro Compounds under Solvent‐Free Conditions Using Alumina‐Supported Hydrazine/FeNH4(SO4)2·12H2O
Authors: Zhang Chang‐Rui , Wang Yu‐Lu , Wang Jin‐Ye
Published: May 2015

Aromatic nitro compounds were easily reduced to the corresponding amino compounds with hydrazine hydrate supported on alumina in the presence of FeNH4(SO)2·12H2O.
Experiments and Calculations on Photoionization and Dissociative Photoionization of CH2CO
Authors: Chiang Su‐Yu , Fang Yung‐Sheng , Bahou Mohammed , Sankaran K.
Published: May 2015

The dissociative photoionization of molecular‐beam cooled CH2CO in a region of ˜10–20 eV was investigated with photoionization mass spectrometry using a synchrotron radiation as the light source. Photoionization efficiency curves of CH2CO+ and of observed fragment ions CH2+, CHCO+, HCO+, C2O+, CO+, and C2H2+ were measured to determine their appearance energies. Relative branching ratios as a function of photon energy were determined. Energies for formation of these observed fragment ions and their neutral counterparts upon ionization of CH2CO are computed with the Gaussian‐3 method. Dissociative photoionization channels associated with six observed fragment ions are proposed based on comparison of determined appearance energies and predicted energies. The principal dissociative processes are direct breaking of C=C and C‐H bonds to form CH2+ + CO and CHCO+ + H, respectively; at greater energies, dissociation involving H migration takes place.
Geometry Optimization of Ba2+(H2O)n Clusters Using a Fast Hybrid Global Optimization Algorithm
Authors: Cao Yi‐Lin , Wang Yan‐Song
Published: May 2015

A global optimization called fast hybrid global optimization algorithm was proposed based on genetic algorithm, fast simulated algorithm and conjugated gradient algorithm. We employ it to search the global minimum energy structures of Ba2+(H2O)n clusters for n = 1–30 within the TIP4P model. The results show that Ba2+(H2O)n clusters have the n+0 structure while n = 1–8. When n is in the range 9 ≤ n ≤ 18, the number of water molecules in the first shell around the barium ion is 8 and the other water molecules arrange in the outer shell. In the global minimum structure of Ba2+(H2O)19, the number of the first shell water molecules adds up to 9, and the value is kept until n = 30. According to the computational results, a conclusion that hydration numbers for Ba2+ is 9 can be drawn, which is in agreement with the result by a Monte Carlo simulation.
Assembly and Photophysics of Ternary Luminescent Lanthanide Molecular Complex Systems
Authors: Yan B. , Xie Q. Y.
Published: May 2015

In this paper, according to the molecular fragment principle, a series of eight ternary luminescent lanthanide complex systems were assembled, and whose compositions were determined with elemental analysis and infrared spectrum: Ln(MA)3(L)·H2O, where Ln = Sm, Eu, Tb, Dy; HMA = α‐methylacrylic acid; L = 1,10‐phenanthroline (phen), 2,2′‐bipyridine (bipy). The photophysical properties of these functional molecular systems were studied with ultraviolet‐visible absorption spectrum, and fluorescence excitation and emission spectrum. It was found that the heterocylic compounds (phen and bipy) act as the main energy donor and luminescence sensitizer for their suitable energy match and effective energy transfer to the emission energy level of Ln3+ ions. MMA ligand was only used as the terminal structural ligand to influence the luminescence. Especially terbium complex systems show the strongest luminescence for the optimum energy match and transfer between phen (bipy) and Tb3+ ion.
Separation of Iron(III) with Ammonium Thiocyanate‐H2O‐n‐Propyl Alcohol Extraction System in the Presence of Sodium Chloride
Authors: Wang Shaomei , Li Quanmin , Bai Haixin , Liu Guoguang
Published: May 2015

The behavior and conditions of liquid‐liquid extraction‐separation of Fe(III) by ammonium thiocyanate‐H2O‐n‐propyl alcohol system in the presence of NaCl were studied, and the possible reactive mechanism of extraction of Fe(III) was deduced. The study showed that, in the presence of a given amount of NaCl, phases were separated thoroughly between n‐propyl alcohol and water. In the process of phase separation, the complex [Fe(SCN)n](3‐n) formed by NH4SCN and Fe(III) was quantitatively extracted into the n‐propyl alcohol phase. The extracted Fe(III) exists in the n‐propyl alcohol phase mainly as the forms of Fe(SCN)2+ and Fe(SCN)3. Also, the relationship between extraction yield of Fe(III) and the amount of NH4SCN agreed well with the quadratic equation E = 0.54 + 58.14x − 8.39x2 (E and x represent the recovery rate of Fe(III) and the volume (mL) of 0.1 M NH4SCN respectively). The quadratic R‐Square is 0.9990. With this method, Fe(III) can be completely separated from Co(II), Ni(II), Mn(II), Al(III), Bi(III) and Cd(II) at pH 1.0˜2.0. The present method was applied in determining Fe(III) in samples with satisfactory results such as relative standard deviation from 2.06% to 2.89% and recovery rate in the range of 98.4˜101.4%.
Synthesis and Characterizations of Ti(O‐i‐Pr)Cl3(THF)(PhCOR) (R = H, Me, Ph) and Ti(O‐i‐Pr)Cl3(PhCOR)2 (R = Me, Ph). The Molecular Structure of Ti(O‐i‐Pr)Cl3(PhCOPh)2
Authors: Sheen Wen‐Shoei , Kuo Chun‐Nan , Hsieh Sheng‐Hsiang , Gau Han‐Mou
Published: May 2015

A series of titanium(IV) complexes Ti(O‐i‐Pr)Cl3(THF)(PhCOR) (R = H (1), CH3 (2), or Ph (3)) is prepared quantitatively from reactions of [Ti(O‐i‐Pr)Cl2(THF)(μ‐Cl)]2 with 2 molar equiv. PhCOR. Treatment of Ti(O‐i‐Pr)Cl3 with 2 molar equiv. of PhCOR affords the disubstituted complexes Ti(O‐i‐Pr)Cl3(PhCOR)2 (R = CH3 (4) or Ph (5)). The 13C NMR study of these complexes shows that the relative bonding abilities are in the order of PhCOCH3 > PhCHO > PhCOPh. The molecular structure of 5 reveals that one of the benzophenone ligands is trans to the strongest 2‐propoxide ligand with a long Ti‐O(carbonyl) distance of 2.193(5) Å which is much longer than the other Ti‐O(carbonyl) distance of 2.097(4) Å by ˜0.1 Å. All ligands cis to the alkoxide ligand are bending away from the alkoxide ligand with the RO‐Ti‐L angles ranging from 93.6(2) to 99.0(2)°.
Depolymerization Study of Pakistani Coal in a Hydrogen Atmosphere. Effect of Operating Conditions
Authors: Ahmad Imtiaz , Khan Mohammad Arsala , Shakirullah Mohammad , Ishaq Mohammad , Ahmad Rashid , Habib‐ur‐Rehman
Published: May 2015

A Pakistani coal was de‐polymerized/liquefied in toluene in a 1000 mL micro autoclave. Experiments have been performed in a pool of hydrogen under varying operating conditions of temperature, residence time, hydrogen pressure (cold), coal/solvent ratio and coal particle size. A pronounced effect of all these process variables has been noted on the yields of liquefied products, i.e., THF solubles, n‐pentane solubles, and n‐pentane insolubles. Extraction temperature of 450 °C, residence time of 1 hour, hydrogen pressure of 30 kgf/cm2, coal/solvent ratio of 1:2 and coal particle size of 53–45 μm were found optimum for maximum conversion of Pakistani coal into liquefied products.
Depolymerization Study of Pakistani Lignite Coal Influence of Pre‐treatments on Product Slate
Authors: Ahmad Imtiaz , Khan M. Arsala , Shakirullah M. , Ishaq M. , Iqbal Yousaf , ur Rehman Saeed
Published: May 2015

Influence of pretreatments, i.e., demineralization and pre‐soaking in some solvents on the yields of liquefied products obtained from hydro‐depolymerization of Pakistani coal in a pool of hydrogen has been discussed. Results of hydrogenation experiments demonstrated that demineralizing the coal sample prior to liquefaction caused the yields to decrease compared with the virgin coal samples. The contribution of mineral matter of coal has been evaluated by comparing the yields of liquid products of virgin and leached samples. Increase in the yields obtained from the hydrogenation experiments of swollen coal samples was not satisfactorily significant.
Separation and Kinetic‐Spectrophotometric Determination of Ketoconazole from Formulations Using SDS‐Coated Al2O3and KMnO4 in Alkaline‐SDS Micellar Medium
Authors: Farhadi Khalil , Bonab Hossein Sheikhloei
Published: May 2015

A kinetic method for the accurate and sensitive determination of Ketoconazole (KC) has been described. The method is based on the alkaline oxidation of KC with KMnO4 in micellar SDS medium. At a fixed time of 8 min, the formed manganate ion is spectrophotometrically measured at 610 nm. The determination of KC by the fixed‐concentration and rate constant methods is feasible with the calibration equation obtained, but the fixed time method proves to be more applicable. The proposed method was successfully used for the quantitative determination of KC in formulations after the complete separation of KC using SDS‐coated Al2O3 as a suitable solid‐phase extraction system in comparison to liquid‐liquid extraction using poisonous organic solvents. Beer's law was obeyed from 0.4 to 28 μg mL−1 and the RSD% values for tablet, cream and shampoo samples were 1.8, 1.4 and 2.3, respectively. The results obtained agreed with those obtained by the USP method.
Synthesis and Characterization of Base‐catalyzed Phenyl Modified PDMS/PHMS Copolymers
Authors: Yang Mei‐Hui , Liu Hsin‐Wang , Lin Hsin‐Tso
Published: May 2015

A series of phenyl modified polydimethylsiloxane (PDMS) / polyhydrogenmethylsiloxane (PHMS) random copolymers containing both internal Si‐H and terminal SiH2 and T (MeSiO3/2) units was synthesized in one step through n‐BuLi‐catalyzed ring‐opening polymerization of cyclic comonomers and characterized by GPC, IR and 1H and 29Si NMR. Sequential microstructures of these copolymers were determined by 29Si‐NMR spectroscopy. Epoxy‐modified polysiloxanes were prepared and used as comparable standards for the assignment of the NMR spectra. A hydride‐transfer mechanism has been proposed to account for the formation of terminal Si‐H and T group. Detailed sequential analyses and chemical shifts of 29Si‐NMR for various siloxane units are reported for the first time.
Solvent Effect of Dimethyl Sulfoxide on the Chemical Shifts of Phenyl Vinyl Ketones
Authors: Lien Jin‐Cherng , Chen Sheng‐Chih , Huang Li‐Jiau , Kuo Sheng‐Chu
Published: May 2015

In our study on the 1D and 2D NMR spectra of synthetic chalcones in DMSO‐d6, we found that, contrary to our expectation, the signals of α‐carbon correlated to the olefinic protons resonating at lower field whereas the signals of β‐carbon correlated to the olefinic protons resonating at higher field in the spectra of chalcones. To further investigate such solvent effect, four α,β‐unsaturated ketones were prepared and studied separately in CDCl3 and DMSO‐d6. The result indicated that the α,β‐unsaturated ketones that possess benzoyl moiety experienced solvent effect in DMSO‐d6 to result in an anomalous chemical shift. The shift arose from the complexation of solute molecule with DMSO that fixed the steric conformation of solute molecule so that Hβ was kept apart from its benzene ring whereas its Hα became more accessible by its benzene ring. Thus, these two olefinic protons would experience a different extent of anisotropic effect exerted by the neighboring benzene ring.
A Facile Access to Polysubstituted Bipyrazoles and Pyrazolylpyrimidines
Authors: Dawood Kamal M. , Farag Ahmad M. , Ragab Eman A.
Published: May 2015

3‐(Pyrazol‐3‐yl)‐3‐oxo‐propanenitrile derivative reacts with several nitrogen nucleophiles to give bipyrazole, pyrazolyloxazole, and pyrazolylpyrimidine derivatives. The structures of the products were confirmed on the basis of their elemental and spectral analyses.
Phenylpropanoid Glycosides from the Parasitic Plant, Aeginetia Indica
Authors: Ho Jiau‐Ching , Chen Chiu‐Ming , Li Zhi‐Qiang , Row Lie‐Ching
Published: May 2015

Two new phenylpropanoid glycosides, α‐L‐rhamnopyranosyl‐(1→3)‐1‐O‐caffeoyl‐β‐D‐glucopyrano‐side and 2″,3″′‐diacetyl acteoside, together with seven known compounds have been isolated from the parasitic plant, Aeginetia indica Linn. Their structures were established by spectroscopic and chemical methods.
Discovery of Recurrent Structural Motifs for Approximating Three‐Dimensional Protein Structures
Authors: Soong Ta‐Tsen , Hwang Ming‐Jing , Chen Chung‐Ming
Published: May 2015

The scope of conformation space that protein molecules can adopt is a problem of significant interest. Previous studies by other groups have shown that there are stereochemical constraints that confine local protein structures to a limited range of conformations. Furthermore, the results of many groups have demonstrated that the sequence‐to‐structure relationship remains detectable to some extent on a local level. By studying the conformational space of local protein structures, we may obtain more information concerning the constraints on local structural space and the sequence‐to‐structure mapping, hence facilitate ab initio structure prediction. In this study, we propose a novel algorithm that automatically discovers recurrent pentamer structures in proteins.

The algorithm starts by applying Expectation‐Maximization (EM) clustering to the distances between non‐adjacent backbone Cα atoms in a large set of pentamer fragments. A rough partition of the conformation space can thus be derived. In the second stage, by applying a split‐and‐merge algorithm, we can obtain a finite number of clusters and guarantee the homogeneity and distinctiveness of each one. Each cluster of protein structures is represented by a centroid structure. The results show that, with 40 major representative structures, we can approximate most of the protein fragments with an error of 0.378 Å. With only 20 types of structures, the fragment structures can still be modeled at 0.44 Å, which is comparable to or better than the performance of previous methods. We term the representatives “building blocks.” On the global level, we demonstrate that by concatenating different combinations of building blocks, we can model whole protein structures at high resolution: a resolution of 2.54 Å can be achieved simply by using 10 types of building blocks. This finding suggests that the study of molecular structures can be hugely simplified using this reduced representation.
Ligand Binding Subsequent to NO Photolyses of Partially Unfolded Cytochrome c
Authors: Mikšovská Jaroslava , Larsen Randy W.
Published: May 2015

Here we report folding studies of horse heart ferricytochrome c in the presence of NO (NO‐cyt c). The midpoint concentration of guanidine hydrochloride (GuHCl) for unfolding was measured to be 2.8 M in the presence of NO and is only moderately altered relative to native cyt c under similar conditions (i.e., 2.6 M GuHCl). Recombination of NO to cyt c in the presence of 2.8 M GuHCl subsequent to photolysis is biphasic with rate constants of (4.24 ± 0.15) × 103 s−1 and 197.7 ± 3.3 s−1 with the fast and slow phase representing ˜60% and 40% relative amplitudes, respectively. NO rebinding to unfolded cyt c (in the presence of 4 M GuHCl) exhibits two phases with rate constants similar to those observed in the presence of 2.8 M GuHCl with the relative amplitude of the fast phase increasing to roughly 90%. These data suggest that NO rebinds to two populations of cyt c with one population containing a five coordinate heme and the other having a six‐coordinate heme with bis‐His axial ligation. These results suggest that the mis‐ligated bis‐His conformation forms rapidly during the refolding of cyt. c3+, although a population exists that can refold down a native pathway.
Competition Between Transcription Factors and Histones, and the Role of the Histone H3 Amino Terminus, During Gene Regulation in Budding Yeast
Authors: Yu Liuning , Yu Cailin , Stafford Grace , Morse Randall H.
Published: May 2015

DNA in eukaryotes is packaged into chromatin by association with the four histone proteins, H2A, H2B, H3, and H4, to form nucleosomes. Transcription factors must recognize particular DNA sequences to activate genes and so must compete with the histones for occupancy of their cognate binding sites. Beyond this repressive role, the histones have also adopted regulatory roles, both positive and negative, which are largely mediated by amino terminal “tails” that do not contribute to the basic structure of the nucleosome. Here, we describe some of our recent progress in understanding how transcription factors compete with histones for binding site occupancy and also discuss recent results on the global role of the histone H3 amino terminus in regulating gene expression in the budding yeast Saccharomyces cerevisiae.
Experimental and Computational Studies of the Isomerization between Z and E Isomers of Benzaldoximes
Authors: Xu Weiren , Wang Jianwu , Liu Chengbu , Chen Cheng‐Lung
Published: May 2015

The isomerization between Z and E isomers of benzaldoximes in different solvents were measured by TLC method. The experimental results show that acid solvents catalyze this inter‐conversion process dramatically. Solution state NMR measurements also show very different spectra for Z and E isomers of benzaldoximes in different solvents. All this suggests that the acidity of solvent is a very important factor to affect the inter‐conversion process.

Theoretical investigations of Z to E inter‐conversion of benzaldoximes in different solvents were carried out by DFT calculations at B3LYP/6–3 11+G** level. The calculations show that the barrier from Z to E in the presence of acid is much lower than that without acid. This agrees with the experimental data very well. The calculated structure in the transition state is helpful for the understanding of the inter‐conversion mechanism.
A New Synthesis of Benzofurans from Phenols via Claisen Rearrangement and Ring‐Closing Metathesis
Authors: Tsai Tzu‐Wei , Wang Eng‐Chi , Li Sie‐Rong , Chen Yung‐Hua , Lin Yu‐Li , Wang You‐Feng , Huang Keng‐Shiang
Published: May 2015

Based on Claisen rearrangement, the double bond isomerization of O‐allyl function together with the formation of O‐vinyl function in one pot, and ring‐closing metathesis (RCM), various phenols were transformed into various benzofurans in good yields.
A Convenient Synthesis and Pharmacological Activity of Novel Annelated Pyrimidine Derivatives
Authors: Aly A. A.
Published: May 2015

Simple and convenient synthesis for a series of 2,3‐diglycosylpyrimidine 4, pyrazolo[3,4‐d]pyrimidine 8, ditetrazolo[1,5‐a;1′,5′‐c]pyrimidine 9, 2,9a,10‐triazaanthracene 12, thieno[2,3‐d]pyrimidine 14, 1,3,5,7‐tetraazafluorene‐8‐one 15, 1,3,5‐triazafluorene‐8‐one 16, 1,3‐diazafluorene 21a,b derivatives have been synthesized via a sequence of heterocyclization reactions of suitably functionalized 6‐[5‐(4‐bromophenyl)ox‐azol‐4‐yl]‐4‐oxo‐2‐thioxo‐1,2,3,4‐tetrahydropyrimidine‐5‐carbonitrile (2) with different electrophiles and nucleophiles. The new compounds were prepared with the objective to study their pharmacological properties.
Clavulazols A and B, Two New Pyrazine Derivatives from Clavularia Viridis
Authors: Shen Ya‐Ching , Wang Li‐Tang , Cheng Yuan‐Bin , Khalil Ashraf Taha , Chen Meng‐Hsien , Lin Yu‐Chi
Published: May 2015

Two new marine pyrazine derivatives, clavulazols A (4) and B (5), were isolated from ethyl acetate extract of the soft coral Clavularia viridis collected in Taiwan. The structures were determined on the basis of spectral analysis, especially 2D NMR as well as chemical conversion.
Cerebrosides from the Rhizomes of Gynura Japonica
Authors: Lin Wei‐Yu , Yen Ming‐Hong , Teng Che‐Ming , Tsai Ian‐Lih , Chen Ih‐Sheng
Published: May 2015

Four new cerebrosides, gynuramides I˜IV (1‐4), together with 37 known compounds were isolated from the rhizome of Gynura japonica. The structures of cerebrosides 1‐4 were determined by chemical and spectroscopic examination to be: (2S,3S,4R,8E)‐2‐[(R)‐2‐hydroxypentacosanoylamino]‐8‐en‐1,3,4‐octadecanetriol, (2S,3S,4R,8E)‐2‐[(R)‐2‐hydroxytetracosanoylamino]‐8‐en‐1,3,4‐octadecanetriol, (2S,3S,4R,8E)‐2‐[(R)‐2‐hydroxytricosanoylamino]‐8‐en‐1,3,4‐octadecanetriol, and (2S,3S,4R,8E)‐2‐[(R)‐2‐hydroxydocosanoylamino]‐8‐en‐1,3,4‐octadecanetriol.
External Electric Field Effects on Emission of a Mixture of Tetraphenylporphyrin and Fullerene Doped in a Polymer Film
Authors: Wahadoszamen MD. , Nakabayashi Takakazu , Ohta Nobuhiro
Published: May 2015

In a mixture of tetraphenylporphyrin (TPP) and fullerene (C60) doped in a PMMA film, fluorescence of TPP is enhanced and de‐enhanced by an electric field in zinc and free‐base compounds, respectively, indicating that the electron transfer from the excited state of TPP to C60 is decelerated in zinc compounds and accelerated in free‐base compounds by an electric field. TPP was found to form complex upon mixing with C60 which exhibits a broad emission in the wavelength region longer than that of the TPP emission. The complex emission is significantly quenched by an external electric field in both zinc and free base compounds, suggesting that the nonradiative decay of the excited complex is accelerated by an electric field in both cases.
Femtosecond Time‐Resolved Photoelectron Imaging Study of Photoinduced Molecular Dynamics
Authors: Suzuki Toshinori
Published: May 2015

Time‐resolved photoelectron imaging (TR‐PEI) allows accurate measurements of photoelectron angular distribution as a function of the pump‐probe time delay, providing a new powerful tool to study photon‐induced dynamics.
Theoretical Treatments of Radiationless Transitions
Authors: Chin C. H. , Shiu H.Y.‐J. , Wang H.‐W. , Chen Y.‐L. , Wang C.‐C. , Lin S. H. , Hayashi M.
Published: May 2015

In this review, we present a microscopic theory for describing photo‐induced radiationless transitions. For this purpose, we state that introducing the density matrix method can not only treat the dynamics due to the radiationless transitions but also deal with the population and coherence dynamics. We briefly review several rate constants of the radiationless transitions and the analytic estimation methods of those rate constants. Finally, we present the applications of the theoretical treatment to the rapid electron transfer and energy transfer taking place in the photosynthetic reaction centers.
Aggregation‐Induced Emission of 4‐Dicyanomethylene‐2,6‐Distyryl‐4H‐pyran
Authors: Tong Hui , Häußler Matthias , Dong Yong‐Qiang , Li Zhen , Mi Bao‐Xiu , Kwok Hoi‐Sing , Tang Ben‐Zhong
Published: May 2015

A new pyran (1) is synthesized. When molecularly dissolved in acetone, 1 is practically nonemissive. Addition of water induces it to cluster into nanoaggregates, which turns its emission “on” and boosts its luminescence efficiency dramatically. The color of its emission changes from green to red upon aggregation.
Multi‐Channel Surface Acoustic Wave Sensors Based on Principal Component Analysis (PCA) and Linear Discriminate Analysis (LDA) for Organic Vapors
Authors: Hsu Hui‐Ping , Shih Jeng‐Shong
Published: May 2015

A multi‐channel surface acoustic wave (SAW) detection system which is employed to detect various organic molecules in a static system was prepared using 315 MHz one‐port quartz resonators and a home‐made computer interface for signal acquisition and data process. The oscillating frequency of the quartz crystal decreases on adsorption of organic molecules on the coating materials. The principal component analysis (PCA) method with SAS software was applied to select the appropriate coating materials onto the SAW crystals for organic vapors, e.g. hexane, 1‐hexene, 1‐hexyne, 1‐propanol, propionaldehyde, propionic acid, and 1‐propylamine. A dataset for a multi‐channel sensor with 19 SAW crystals for 7 analyses was collected after comparing the correlation between the 19 coating materials and the first six principal component (PC) factor. Furthermore, linear discriminate analysis (LDA) with SPSS software and a profile discrimination map were also applied and discussed for the discrimination of these organic vapors. These organic molecules could be clearly distinguished by the six‐channel SAW static sensor. The effect of concentration for various organic vapors was investigated and discussed.
Solar Photocatalytic Degradation of 4‐Chlorophenol in Kaolinite Catalysts
Authors: Kuo Shu‐Lung , Liao Chiu‐Jung
Published: May 2015

This research applies semiconductor photocatalysts, which are formed by metal ion exchange on the surface of kaolinite catalyst with cations, to the study of photocatalytic degradation of 4‐chlorophenol.

The analysis results of catalyst properties shows that, after sintering at 400 °C, kaolinite catalyst has a particle size of between 10–100 nm indicating the nano level of synthesized catalysts. Under the same condition, kaolinite‐Ag/Zn catalyst works better in degradation efficiency than single kaolinite‐Ag and kaolinite‐Zn catalysts. Kaolinite‐Zn catalyst declines in degradation efficacy after 150 minutes and performs poorer than the other three types of kaolinite catalysts. In the experiments of different amounts of catalysts, when the concentration exceeds 0.1 wt%, utilization of light energy and degradation efficiency will be reduced due to shielding effect. When at different pH values, the higher the pH value, the more OH‐will be released and that is beneficial for reaction with substances and the increase of reaction rate. Finally multivariate analysis proves that there is one determining factor that influences the photocatalytic degradation of 4‐chlorophenol in kaolinite catalysts, named as “the factor with intermediates competition degree,” the one affecting the 4‐CP degradation at different weight percentages that is referred to as the “shielding effect factor.”
Solid Phase Extraction and Determination of Trace Amounts of Lead(II) Using Octadecyl Membrane Disks Modified by a New Schiff's Base and Flame Atomic Absorption Spectrometry
Authors: Mohammadhosseini Majid , Tehrani Mohammad Saber
Published: May 2015

A highly selective, facile and reliable method for separation and preconcentration of the trace amounts of lead present in aqueous samples is introduced. By passing the solutions through an octadecyl silica membrane disk modified by a novel Schiff's base, Pb2+ ions are adsorbed quantitatively while almost all interfering ions pass through the disk. The retained lead(II) ions are then eluted from the disk surface by a minimal amount of organic eluents. The influences of pH, sample flow‐rates and interfering ions are also investigated. The proposed method permits an enrichment factor of about 500 or higher and a detection limit of 0.0065 ng mL−;1.
Triiodide Ion‐Selective Electrode Based on Charge‐Transfer Complex of 4,7,13,16,21,24‐Hexaoxa‐1,10‐diazabicyclo‐[8.8.8]hexacosane
Authors: Khayatian Golamreza , Rezatabar Hadi , Karonian Fatemeh Salehy , Salimi Abdollah
Published: May 2015

Two new highly selective triiodide electrodes have been prepared using charge‐transfer complex of iodine with cryptand 222 as an electroactive ionophore and nitrophenyl octyl ether as a plasticizing agent. The electrodes showed Nernstian response to triiodide ions over a concentration range from 1.0 × 10−;2 — 7.9 × 10−;7 M and from 1.0 × 10−;2 — 1 × 10−;6 M with detection limits of 6.3 × 10−;7 and 7.9 × 10−;7 M for cryptand and its charge‐transfer complex with iodine, respectively. The response times (t95%) of the sensors were 10 and 5 s. The membrane could be used for more than 1 month without any divergence in potentials. The proposed sensors exhibited very high selectivity for triiodide ion over other anions, and could be used in a wide pH range ˜2–10. These electrodes were successfully applied as an indicator electrode in potentiometric titration of copper in ore samples.
Emission from Charge Recombination between Radical Cations and Radical Anions of 9‐Cyano‐10‐(p‐Substituted Phenyl)Anthracene Generated during Pulse Radiolysis
Authors: Samori Shingo , Tojo Sachiko , Fujitsuka Mamoru , Lin Jui‐Hsien , Ho Tong‐Ing , Yang Jye‐Shane , Majima Tetsuro
Published: May 2015

Emission from charge recombination between radical cations and anions of 9‐cyano‐10‐(p‐substituted phenyl)anthracenes (RA, where R is 10‐p‐substituted phenyl: R = Phenyl (PA), anisyl (OA), p‐N,N‐dimethylaminophenyl (NA), N, N‐di‐p‐anisylaminophenyl (DA)), as donor‐acceptor type molecules, generated during the pulse radiolysis in benzene was measured together with the transient absorption of RA radical cations (RA•+) and anions (RA•−). Based on the transient absorption and density functional theory (DFT‐B3LYP/6‐31G*) calculation, a twisted geometry is assumed for all RA in the ground state, RA•+, and RA•−. It is suggested that the positive charge of PA•+, OA•+, and NA•+ is delocalized on two moieties, and that of DA•+ is localized on the donor N,N‐di‐p‐anisylaminophenyl moiety, while the negative charge of all RA•− is mainly on the acceptor 9‐(10‐cyano)anthracenyl moiety. When both RA•+ and RA•− are generated with sufficiently high concentrations during the pulse radiolysis in benzene, the charge recombination between RA•+ and RA•− occurred to give RA in the singlet excited state (1RA*) as the emissive species, but not the excimers because of the twisted geometries of RA•+ and RA•− with the large torsional angles between the 9‐(10‐cyano)anthracenyl and p‐substituted phenyl moieties. Not only the fluorescence quantum yield of 1RA* but also the energy differences between the annihilation enthalpy change and the excitation energy of 1RA* are important factors for the radiolysis induced emission intensity of RA in benzene.
A Novel Three‐Dimensional Coordination Polymer, [Cd(bpym)0.5(μ1,1‐N3)(μ1,3‐N3)]n (Bpym = 2,2′‐Bipyrimidine), Containing Both End‐on and End‐to‐End Azide Bridges
Authors: Wang Chih‐Chieh , Kuo Chen‐Tsung , Lee Gene‐Hsiang
Published: May 2015

A new polymeric complex, [Cd(bpym)0.5(N3)2]n (bpym = 2,2′‐bipyrimidine) has been synthesized and characterized by spectroscopic, elemental analyses and single crystal X‐ray diffraction. The title compound crystallizes in the monoclinic system, space group P21/c, with chemical formula C4H3CdN8, a = 7.6763(5), b = 13.1539(9), c = 7.9693(5) Å, β = 109.988(1)°, and Z = 4. Structural determination reveals that the coordination environment of the cadmium atoms is distorted octahedral, consisting of two nitrogen donors of one bpym and four nitrogen donors of four azide ligands. The azide ligand acts as a bridging ligand with two different bridging modes, an end‐on (μ1,1‐) and an end‐to‐end (μ1,3‐) coordination mode, linking the CdII ions to form a two‐dimensional layer metal‐organic framework (MOF), which get cross‐linked by the bridges of bis‐bidentate bpym ligands to form a novel 3D network.
Fluorescence Dynamics of Zinc Protoporphyrin in Solution and inside Anodized Aluminum Oxide (AAO) Nano‐channel Arrays
Authors: Lin Jin‐Shyong , Chen Yu‐Chying , Chen Chien‐Chon , Luo Li‐Yang , Diau Eric Wei‐Guang , Liu Tzeng‐Feng
Published: May 2015

The excited‐state relaxation dynamics of zinc protoporphyrin (ZnPP) in THF solution and inside nano‐channel arrays of anodized aluminum oxide (AAO) have been investigated with time‐correlated single‐photon‐counting (TCSPC) fluorescence spectra with S2 excitation (λex = 435 nm). We used three initial concentrations of immersion‐4.8 × 10−;6, 4.8 × 10−;5 and 4.8 × 10−;4 M‐to examine the extent of aggregation of ZnPP inside the AAO nano‐channel arrays of two pore sizes — 15 and 70 nm. Only one decay component corresponds to the aggregation of ZnPP in THF solution, whereas at least two decay components are required to describe the transient behavior of ZnPP inside AAO. The observed systematic variation of the decay coefficients and the corresponding amplitudes of the ZnPP/AAO samples are consistent with the observation of steady‐state spectra of the system reported previously (JCCS 2006, 53, 201), but through fluorescence lifetime measurements we further highlight the significance of aggregation of ZnPP in the specific nanoporous environment that is not achievable in ZnPP/THF solutions in large concentrations.
Synthesis of Singly and Doubly Cage‐Annulated Bicyclo[2.2.2]octenes Derived from Triptycene Skeleton
Authors: Chou Teh‐Chang , Liu Nen‐Yor
Published: May 2015

Triptycene‐diquinone 5 was synthesized from 1,4‐dimethoxyanthraene (6b) and found to undergo Diels‐Alder reaction with 5,5‐dimethoxy‐1,2,3,4‐tetrachlorocyclopentadiene (DTCp) to afford exclusively the least symmetric (Cs) bis‐adduct 4b. The double Diels‐Alder reaction exhibited π‐facial selectivity, in which the initial cycloaddition occurred preferentially on the π‐face of the benzoquinone moiety of 5 that is syn to the other benzoquinone unit (about 6:1), thereby producing the corresponding mono‐adducts 13b and 13a. Both stereoisomeric 13a and 13b underwent the second cycloaddition via exclusively the π‐face that is opposite to the orientation of previous DTCp addition 5, thus leading to the formation of bis‐adduct 4b as sole product. The structure of 4b was unequivocally established by X‐ray structural determination.
Synthesis and Cytotoxic Activity of Novel Pyrazoline Derivatives against Human Lung Tumor Cell Line (A549)
Authors: Yar Mohammad Shahar , Siddiqui Anees Ahmad , Ali Mohamed Ashraf , Murugan Vedigounder , Chandrashekhar Raghu
Published: May 2015

In the present investigation, a series of 5‐(‐4‐(substituted)phenyl)‐3‐(4‐hydroxy‐3‐methylphenyl)‐4,5‐dihydro‐1H‐1‐pyrazolyl‐2‐toluidino methane thione and 5‐(substituted)phenyl‐3‐(4‐hydroxy‐3‐methylphenyl)‐4,5‐dihydro‐1H‐1‐pyrazolyl‐2‐methoxy anilino methane thiones were synthesized and were examined against human lung tumor cell line (A549) in vitro using the MTT assay system. Among those tested, 5‐(4‐flurophenyl)‐3‐(4‐hydroxy‐3‐methylphenyl)‐4,5‐dihydro‐1H‐1‐pyrazolyl‐2‐toluidino methane thione & 5‐(4‐chlorophenyl)‐3‐(4‐hydroxy‐3‐methylphenyl)‐4,5‐dihydro‐1H‐1‐pyrazolyl‐2‐methoxy anilino methane thione showed more potent cytotoxicity against human lung tumor cell line (A549) than the other synthesized compounds.
Synthetic Studies on the Synthesis of Some New Fused Heterocyclic Compounds Derived from 3,5‐Pyrazolidinedione
Authors: Khodairy A.
Published: May 2015

Condensation of 1‐phenylpyrazolidine‐3,5‐dione 1 with 3‐formylchromone afforded 4‐(chromenylmethylene)pyrazolidinedione 2, which was reacted with hydrazine or hydroxylamine in different molar ratios and conditions to give the corresponding pyrazole and isoxazole derivatives 3‐8, respectively. Compound 2 was subject to react with ammonia, N,S‐ or S,S‐acetals, mercaptoacetic acid, cyanoacetamide or cyanothioacetamide to give the corresponding pyridine, dithiine, thiazine and thiophene, 9‐14, respectively. The reaction of compound 2 with thiourea, guanidine, cystamine, o‐aminothiophenol, ethylenediamine, o‐phenelenediamine or barbituric acid afforded the corresponding thiazine, pyrimidine, thiazepine, diazepine, and pyran derivatives 17‐23, respectively. The study of the reaction of compound 2 with nucleophiles via chromene ring opening was investigated.
Synthesis of Pentafluorophenyl‐ and Pyridinyl‐3 Allenes
Authors: Erenler Ramazan , Biellmann Jean‐François
Published: May 2015

The allenes 1,2,3,4,5‐pentafluoro‐6‐(3‐phenylpropa‐1,2‐dienyl)benzene 4, 3‐(3‐phenylpropa‐1,2‐dienyl)pyridine 11 and 3‐(3‐(pyridine‐3‐yl)propa‐1,2‐dienyl)pyridine 17 and the acetylenes 5, 12 and 16 were obtained by reduction of the corresponding propargylic acetates 3, 10 and 15 by Samarium(II) iodide in the presence of Pd(0). Base‐promoted isomerisation of acetylene 12 provided allene 11 in a yield of 80%. 1‐(Pentafluorophenyl)‐3‐phenylprop‐2‐yn‐1‐ol 2 was prepared from phenylacetylene and pentafluorobenzaldehyde. The condensation of nicotinaldehyde with trimethylsilylacetylene gave the 3‐(trimethylsilyl)‐1‐(pyridine‐3‐yl)prop‐2‐yn‐1‐ol 7. The removal of the silyl group of 7 to acetylene 8 was done in basic conditions. The Pd catalysed condensation of the acetylene 8 with iodobenzene gave 3‐phenyl‐1‐(pyridine‐3‐yl)prop‐2‐yn‐1‐ol 9. The Pd catalysed condensation of 8 with 3‐bromopyridine gave the 1,3‐dipyridin‐3‐yl‐prop‐2‐yn‐1‐ol 14. The propargylic alcohols 2, 9 and 14 were converted to the acetates 3, 10 and 15 with acetic anhydride‐pyridine.
Determination of Labetalol Hydrochloride in Drug Formulations by Spectrophotometry
Authors: Rahman Nafisur , Rahman Habibur , Azmi Syed Najmul Hejaz
Published: May 2015

A validated, selective and sensitive spectrophotometric method has been developed for the determination of labetalol hydrochloride in commercial dosage forms. The method is based on the coupling reaction of positive diazonium ion of 4‐aminobenzenesulfonic acid with phenolate ion of labetalol to form a colored azo compound which absorbs maximally at 395 nm. Under the optimized experimental conditions, the color is stable up to 2 h and Beer's law is obeyed in the concentration range of 0.8–17.6 μg mL−1 with a linear regression equation of A = 4.84 × 10−4 + 7.864 × 10−2 C and coefficient of correlation, r = 0.9999. The molar absorptivity and Sandell's sensitivity are found to be 2.874 × 104 L mol−1 cm−1 and 0.013 μg cm−2 per 0.001‐absorbance unit, respectively. The limits of detection and quantitation of the proposed method are 0.08 and 0.23 μg mL−1, respectively. The intra‐day and inter‐day precision variation and accuracy of the proposed method is acceptable with low values of standard analytical error. The recovery results obtained by the proposed method in drug formulations are acceptable with mean percent recovery ± RSD of 99.97 ± 0.52 ‐ 100.03 ± 0.63%. The results of the proposed method compared with those of Bilal's spectrophotometric method indicated excellent agreement with acceptable true bias of all samples within ± 2.0%.
Synthesis and Structural Study of Copper(I) or Silver(I) Complexes of 2,11‐Dithia‐4,5,6,7,8,9‐Hexahydro[3.3]paracyclophanes
Authors: Yang Ya‐Chen , Lin Shaw‐Tao , Cao Cha‐Chi
Published: May 2015

The complexes of 2,11‐dithia‐4,5,6,7,8,9‐hexahydro[3.3]paracyclophane (dthhpcp) with Cu(I), i.e. [Cu2I2(dthhpcp)2]·2H2O 1, or with Ag(I), i.e. [Ag(dthhpcp)(NO3)]thf 2 and [Ag(dthpcp)(CF3COO)] 3, were prepared for structural study by single‐crystal X‐ray diffraction analysis. For these three complexes, dthhpcp serves as a bridging group in the polymeric structure through bridging sulfur atoms via metal, while the bonding of anion with the second metal atom forms the multi‐diminished structures. Complex 1 is a novel two‐dimensional coordination polymer composed of Cu6 motifs, in which Cu2I2 formed a square planar unit to link the dthhpcp molecule. The two oxygen atoms of the nitrate anion as a bridge for two Ag atoms in complex 2 provides a three‐dimensional channel framework of silver(I) with a tetrahydrofuran molecule as a guest inside the open cavities. In contrast, the analogous reaction with silver triflouroacetate gave a complex 3, which is composed of infinite linear chains of‐Ag‐dthhpcp‐Ag‐dthhpcp‐ along the a axis. Unit cell data: complex 1, orthorhombic system, space group P2(1)2(1)2(1), a = 19.2982(11) Å b = 16.5661(10) Å, c = 25.3006(15) Å, β = 90°, Z = 8; complex 2, orthorhombic system, space group Pna2(1), a = 8.8595(6) Å, b = 12.6901(9) Å, c = 19.8449(14) Å, β = 90°, Z = 4; complex 3, monoclinic system, space group P2(1)/n, a = 8.845(3) Å, b = 20.841(6) Å, c = 11.061(3) Å, β = 107.832(6)°, Z = 4.
Modification of Rhodium Catalyst with Stibines for Hydroformylation of 1‐Pentene
Authors: Sharma Pankaj , Arias Jose Luis , Vasquez Jaime , Gomez Valente , Guiterrez Rene
Published: May 2015

Homogeneous hydroformylation of 1‐pentene under synthesis gas experimental conditions was studied using RhClCO(PPh3)2 complex with different triarylstibines. Three different stibine ligands SbR3 [where R = 2,4,6‐mesityl (TMS), 2‐furyl (TFS), 2‐N,N‐dimethylbenzylamine (TDMBAS)], have been tested. It is interesting to note that 2:1 addition of these stibine ligands to the RhClCO(PPh3)2 complex catalyst increases the aldehydes yields with an appreciable n:iso ratio. The catalytic activity of the system shows a TDMBAS > TMS > TFS pattern which indicates that not only basicity of the ligand alone is playing a role in the activity but the steric effect is also very important, and it is combination of these two factors that contributes to the resulting catalytical activity. The maximum yield of aldehydes obtained were 98.7% with n/iso = 1.4 when RhClCO(PPh3)2 + TFS system was used and 93.7% with n/iso = 2.43 when TDMBAS ligand was studied.