bluuebunny/crossref_metadata_2025 huggingface dataset:
Probing the Enzyme Catalytic Mechanism by Nuclear Magnetic Resonance ‐ A Case Study of a Serine Protease
Authors: Tyukhtenko Sergiy I. , Huang Yao‐Te , Lin Ta‐Hsin , Chen Chinpan , Chang Chi‐Fon , Lee Shin‐Jye , Litvinchuk Alexandra V. , Shaw Jei‐Fu , Liaw Yen‐Chywan , Huang Tai‐Huang
Published: May 2015

Serine proteases are among the most studied enzymes for their role as model enzymes for studying the enzyme catalytic mechanism and medical interest in their inhibition. We have applied NMR methods to determine the structure, dynamics, and catalytic mechanism of a serine protease, E. coli thioesterase/protease I (TEP‐I). In this article we review the results of our efforts. We showed that TEP‐I is an / / type SNGH‐hydrolase with Ser10, Asp154 and His157 as the catalytic triad residues. In free TEP‐I, His157 was found to forma strong hydrogen bond to Asp154, but not to Ser10‐O H. Modelfree analysis of 15N‐T1, 15N‐T2 and 1H‐15N NOE data revealed that TEP‐I is a rigid protein with a flexible catalytic binding pocket. Slow motion involving segments around the catalytic site was detected. The formation of Michaelis complex (MC) between TEP‐I and a transition state analogue, diethyl p‐nitrophenyl phosphate (DENP), and its subsequent conversion to the tetrahedral complex (TC) follow a two‐step process, a fast formation of MC followed by a slow conversion to TC. In both steps residues perturbed were confined mainly to four conserved segments comprising the active site. Comparable magnitudes of chemical shift perturbations were detected in both steps. From the large chemical shift perturbation upon conversion from MC to TC we proposed that the amide protons of Ser10 and Gly44 serve as the oxyanion‐hole proton donors to stabilize the tetrahedral adduct. The pattern of residues perturbed in both steps suggests a sequential, stepwise structural change upon binding of DENP.
The Triple Layer Model: A Different Perspective on Lipid Bilayers
Authors: Lee Clarence C. , Petersen Nils O.
Published: May 2015

In this review a modified view of the Singer‐Nicholson model, termed the triple layer model, is presented. Structural and dynamic studies of lipid bilayers have demonstrated that the two interface regions of a membrane are more rigid and less dynamic than the inner hydrocarbon region. The results from these studies are gathered in this paper to support the notion of modifying the viewpoint of the fluid mosaic model. The idea of lipid bilayers consisting of three distinct and functional layers has interesting implications. We speculate on how the triple layer model pertains to both the mechanical properties of membranes and its biological relevance.
DNA Hydrolysis Catalyzed by Tris(diisopropyl‐1,4,7‐triazacyclononanes)ethane Metal Complexes
Authors: Cheng Chien‐Chung , Huang Yan‐Chen , Liu Ming‐Chan
Published: May 2015

Novel trinuclear coordinated ligands were designed using three of 1,4,7‐triazacyclononane moieties with a tribromo linker. These ligands show greater capability and potency in association with various metal ions. Tris(diisopropyl‐1,4,7‐triazacyclononanes)ethane (2) associated with Cu2+ and Ce4+ ions shows better reactivity to achieve DNA hydrolysis at 37 °C at pH 8 for 5 hr. Using high resolution of polyacrylamide gel electrophoresis, DNA cleavage reaction in Tris‐HCl buffer causes a nicking site at the single‐stranded region. Alternatively, the reaction in HEPES buffer shows a random DNA cleavage included the double‐stranded region. Hydrolysis of phosphodiester bond mediated by trinuclear metal complex is capable of performing at the physiological temperature 37 °C, but it has a lower reactivity compared to mono‐ and di‐nuclear metal complexes. The result suggests that trinuclear metal complexes have a bulky environment to prevent from going toward the phosphodiester bond. The design of an efficient chemical hydrolyase will be a challenge in order to construct a coordinate ligand with the enhancement of hydrolytic activity and the reduction of the steric environment.
Hypervalent Iodine(III) Sulfonate Mediated Synthesis of Imidazo[1,2‐a]pyridines
Authors: Huang Hsin‐Yu , Hou Rei‐Sheu , Wang Huey‐Min , Chen Ling‐Ching
Published: May 2015

A direct and efficient method for the conversion of alkyl aryl ketones to imidazo[1,2‐α]pyridines has been developed based on initial formation of α‐organosulfonyloxy ketones and their subsequent cyclocondensation by 2‐aminopyridines in one‐pot conditions.
Nucleosides XII.1 Synthesis of 5‐Modified Isoguanosines and Reinvestigation of 5′‐Deoxy‐N3,5′‐cycloisoguanosine
Authors: Chien Tun‐Cheng , Kuo Chia‐Chi , Chen Chien‐Shu , Chern Ji‐Wang
Published: May 2015

Isoguanosine (3) underwent a coupling reaction with diaryl disulfides in the presence of tri‐n‐butylphosphine when its 6‐amino group was protected by N,N‐dimethylaminomethylidene. The synthesis of 5′‐deoxy‐N3,5′‐cycloisoguanosine (6) and its 2′,3′‐O‐isopropylidene derivative (11) were accomplished in excellent yields from isoguanosines (3 & 10) in the presence of triphenylphospine and carbon tetrachloride in pyridine. Chlorination at the 5′‐position of isoguanosine (3) with thionyl chloride followed by the aqueous base‐promoted cyclization afforded the same product 6. The structures were elucidated by spectroscopic analysis including IR, UV, 1‐D and 2‐D NMR.
Formation of Caged Compounds in the Photocycloaddition of Furan to 2‐, 2,3‐, and 2,6‐Substituted Naphthalenes via Dipole‐Dipole Interaction
Authors: Mizuno Kazuhiko , Tachibana Yuko , Konishi Gen‐Ichi , Chiyonobu Kazuhiko , Maeda Hajime
Published: May 2015

Photocycloaddition of furan to naphthalene derivatives having electron‐withdrawing groups at 2‐ or 2,3‐position via exciplex afforded caged‐products in high yields. The structure‐reactivity relationship can be reasonably explained by dipole‐dipole interaction between two chromophoric molecules.
Photoinduced Electron Transfer and Electron‐Mediating Systems of [60]Fullerene and Triphenylamine Derivatives in the Presence of Viologen Dication in Polar Solvent
Authors: Sasaki Yoshiko , Araki Yasuyuki , Ito Osamu , Alam Maksudul M.
Published: May 2015

Photoinduced electron‐transfer processes between fullerenes (C60) and three triphenylamines (TPA's) including bis(tolylaminophenyl)cyclohexane in the absence and presence of hexylviologen dication (HV2+) and 1‐benzyl‐1,4‐dihydronicotinamide (BNAH) have been studied by the transient absorption method in the visible and near‐IR regions. Electron‐transfer takes place initially from TPA's to the triplet states of fullerenes (3C60*), giving the radical anions of fullerenes (C60−) and the radical cations of TPA's (TPA+). The rate constants and efficiencies of electron transfer are quite high, because of the high electron‐donor abilities of TPA's as their low oxidation potentials indicate. On addition of HV2+to the C60and TPA systems, the electron‐mediating process from C60−to HV2+occurs, yielding the viologen radical cation (HV+). In the further addition of BNAH, which acts as a sacrificial donor, steady‐state concentration of HV+was accumulated during continuous photoirradiation and persisted for a long time.
Fourth Order Derivative Spectrophotometric Determination of Benzyl Alcohol in Piroxicam Injections
Authors: Rizk M. , Ibrahim F. , Hefnawy M. , Nasr J. J.
Published: May 2015

Piroxicam is a drug with analgesic and anti‐inflammatory properties. It is present in numerous pharmaceutical preparations. Injectable forms usually contain benzyl alcohol as an excipient, which is used as a blocking anesthetic (4%) and an antiseptic (4–10%). In this work, spectrophotometric methodology was used in order to determine benzyl alcohol in piroxicam injectable formulations by applying the fourth derivative method adopting the zero‐crossing technique. The results obtained show that the method has significant advantages over other reported methods and is appropriate for routine pharmaceutical analysis. The method showed excellent linearity in the range of 2–100 μg mL−1 with limit of detection (S/N = 3) 0.07 μg mL−1 (6.47 × 10−7 M). The proposed method could be applied successfully for the determination of benzyl alcohol in injectable formulations with average % recovery of 100 ± 0.61.
Theoretical Study of Weakly Bound Dimers between Hydrogen Fluoride and Some Polar Molecules
Authors: Chen Shyh‐Jong , Chen Cheng , Hong Yaw‐Shun
Published: May 2015

Weakly bound linear and bent dimers, FH—X (where X = CO, OC, CNH, NCH, N2O and ON2), are investigated using the DFT B3LYP and ab initio MP2 methods with the same basis sets (6–311++G(3df,2pd)). The strengths of the H—C or H—N H‐bonds in dimers FH—CO, FH—CNH, and FH—N2O are compared with those of the H—O or H—N H‐bonds in dimers FH—OC, FH—NCH, and FH—ON2. The results obtained for the H‐bond distances, the elongation effect of the HF bond, the red shift of the HF stretching frequency, and the energy difference between the dimer and the charge transfer reveal that the H‐bonds of the first group of dimers are stronger than those of the second. The Gibbs energies calculated for the six dimer formations indicate that the weakly bound dimers are unstable at room temperature (T = 298 K) (FH—X's → FH + X's, ΔG < 0).
ESR Studies on a Friedel‐Crafts Alkylation Reaction in [bmim]Cl‐AlCl3 Ionic Liquid
Authors: Zhai Cui‐Ping , Song Ai‐Xin , Liu Wei‐Min , Wanga Han‐Qing
Published: May 2015

The paramagnetic complexes formed in Friedel‐Crafts alkylation reaction systems are invistigated by electron spin resonance (ESR) spectroscopy, in room temperature ionic liquids system 1‐butyl‐3‐methyl‐limidazolium chloride‐aluminium chloride ([bmim]Cl‐AlCl3). The results indicate that ESR spectra observed are due to polycyclic aromatic radical cations formed from their parent hydrocarbons. ESR spectrum of spin adduct is obtained in an ionic liquid system composed of [bmim]Cl‐AlCl3. In acidic solution the 14N hyperfine coupling constant of 4‐oxo‐TEMPO, 2.15 mT, is appreciably larger due to an adduct formed with AlCl3.
Novel Synthesis of Dihydroquinoxalinylpyridazine Derivatives
Authors: Elassar Abdel‐Zaher Abdel‐Aziz
Published: May 2015

Methylquinoxaline derivative 1 undergoes bromination to give bromomethyl quinoxaline 2, which could be transferred to cyanomethyl quinoxaline 3. The latter compound 3 readily coupled with arene diazonium salts to give hydrazone derivatives 5a‐c. Compounds 5a,b reacted with active methylene reagents to give the target ring system, quinoxalinylpyridazine derivatives 8a‐c. Compound 1 reacted with DMFDMA to give the enamine derivative 9, which coupled with arene diazonium salts to give the aldehydic hydrazone derivatives 10a‐c. Compound 10 reacted with active methylene compounds to give quinoxalinylpyridazine derivatives. UV characterization of some of the prepared compounds was reported.
Formal Synthesis of (±)‐Trachelanthamidine via Base‐Induced Formal [3+2] Annulation and Intramolecular Cyclization
Authors: Hsu Ru‐Ting , Chang Nein‐Chen , Chang Meng‐Yang
Published: May 2015

Base‐induced coupling/cyclization stepwise [3+2] annulation of α‐sulfonylacetamide with (Z)‐2‐bromoacrylates yielded polysubstituted pyroglutamates with three contiguous chiral centers with trans‐trans orientation in a one‐pot synthesis. The pyrrolizidine skeleton was obtained via an intramolecular cyclization. This facile strategy was used to synthesize (±)‐trachelanthamidine.
In Situ Generated Palladium Nanoparticles for Catalytic Dehalogenation of Aryl Halides and Deboronation of Arylboronic acids
Authors: Lai Rung‐Yi , Chen Chuan‐Lin , Liu Shiuh‐Tzung
Published: May 2015

Palladium nanoparticles in situ generated from palladacyclic complexes efficiently catalyzed the deboronation of arylboronic acids and the dehalogenation as well as homo‐coupling of aryl iodides in an alcohol medium under basic conditions. Isotope labeled studies indicated that the β‐elimination of alcohols provided the hydrogen source for the reaction.
Density Functional Theory Study on the Nitration of Halobenzene by Nitronium Ion
Authors: Chen Li‐Tao , Chen Guang‐Ju , Xiao He‐Ming
Published: May 2015

The rate determining steps of isomeric ortho, meta and para nitrations of fluorobenzene and chlorobenzene have been theoretically investigated at the B3LYP/6‐311G* level. Stationary points of the step involving reactant, transition state and intermediate complexes were successfully located and characterized without any restriction on the internal coordinates. Their molecular geometries, electronic structures, IR spectra, and the FMO symmetries of two initial aromatic compounds and the NO2+ suggest that the halogens are ortho‐para directive, and also activating substituents in the gas phase. The blue shift of the C‐N stretching vibration and the red shift of the tetrahedral C‐H stretching vibration from transition state to Wheland intermediate demonstrate that the formation of the C‐N and the cleavage of the C‐H are not concerted but stepwise at the rate determining step. This provides theoretical evidence for the experimental fact of the absence of primary kinetic isotopic effect in most aromatic nitration reactions. The fully optimized geometries of nitro‐chlorobenzene complexes show that the C‐Cl bond in nitro‐chlorobenzene complexes become much shorter than in chlorobenzene molecules and appears as a double bond. On the contrary, the C‐F bond in nitro‐fluorobenzene complexes is still a single bond, and even lengthens slightly as the NO2+ moves toward the fluorobenzene. This reveals that there is a special interaction, namely inductomeric effect, between the chlorine and nitro group in nitro‐chlorobenzene complexes. The inductomeric effect may cause a marked increase in the percentage of ortho product for the nitration of chlorobenzene.
Electrochemical Behavior of the Li+/Li Couple and Stability of Lithium Deposits in Tri‐1‐Butylmethylammonium Bis((Trifluoromethyl)Sulfonyl)Imide Room Temperature Ionic Liquid
Authors: Chen Po‐Yu
Published: May 2015

The electrochemical behavior of the Li+/Li couple was studied at polycrystalline tungsten, platinum, copper and aluminum electrodes in tri‐1‐butylmethylammonium bis((trifluoromethyl)sulfonyl)imide ionic liquid mixed with a little propylene carbonate at 30 °C. Lithium cations were introduced into the ionic liquid by dissolution of lithium bis((trifluoromethyl)sulfonyl)imide which is highly soluble in ionic liquid. Propylene carbonate was used to reduce the viscosity of this ionic liquid in order to enhance the mass transfer and to additionally improve the stability of lithium deposits. At the tungsten and copper electrodes, the cyclic voltammetric behavior of a Li+/Li couple is a quasi‐reversible reaction. At the platinum electrode, the behavior becomes very complicated because of the alloy formation. Coulombic efficiency was used to evaluate the stability of lithium deposits at each electrode. The aluminum electrode showed the best efficiency due to the formation of Li‐Al alloy. However, lowest efficiency was obtained at the platinum electrode because of the low redox reversibility of the lithium in the Li‐Pt alloy. The diffusion coefficient of lithium cation in this solution was 1.0 ± 0.1 × 10−;7 cm2 s−;1 as determined by chronopotentiometry. The best coulombic efficiency obtained at the Al electrode is 97% but dropped to about 90% after 12 hours. The self‐discharge current of the lithium deposits at the Al electrode was 0.4 μA/cm2 during the experimental period.
Spectral Analysis of Some Distillates from Asphalt Cracking and Evaluation of UTIMAC as Cracking Catalyst
Authors: Shakirullah Mohammad , Ahmad Imtiaz , Rahman Habibur , Khan M. Arsala , Ishaq M. , Shah Amjad Ali
Published: May 2015

This paper demonstrates the spectral analysis of some distillates obtained from asphalt cracking in the presence of a conventional expensive catalyst, i.e., HZSM‐5, and local cheap and readily available clay, i.e., UTIMAC. Each distillate was fractionated into pentane soluble (PI) and pentane insoluble (PI) fractions based on solubility in n, pentane. Both PS and PI obtained in the case of HZSM‐5 and UTIMAC were analyzed by 1H‐NMR spectrophotometry using CDCl3 as dissolving solvent and tetramethylsilane (TMS) as internal standard. It is evident from the profiles that both catalysts caused the generation of some peaks ascribed to methylene and methene configurations in the aliphatic region. Bands corresponding to aromatic configurations were also generated. The results indicate that the cheap local catalyst used has comparable suitability with the conventional expensive catalyst in terms of asphalt cracking.
A Low Cost LED Based Spectrometer
Authors: Yeh Tai‐Sheng , Tseng Shih‐Shin
Published: May 2015

A low cost LED based spectrometer is described. This LED based spectrometer could be operated as a standalone instrument or under PC control via serial link. A total of seven wavelength selections are available by the plug‐and‐measure LED light module. With the seven wavelength selections, the LED based spectrometer could provide qualitative visible absorption spectra that predict the absorption maximum. Based upon the qualitative visible spectra, quantitative photometric information could be obtained.
Conversion of Waste Tyres into Carbon Black and their Utilization as Adsorbent
Authors: Shah Jasmin , Jan M. Rasul , Mabood Fazal , Shahid M.
Published: May 2015

Pyrolysis has the potential of transforming used tyres into useful recyclable products. Pyrolytic carbon black is one of the most important products of tyre pyrolysis. Waste tyres were pyrolysed at 450 °C in a batch reactor under atmospheric pressure. The recovered pyrolytic carbon black residues were studied to investigate their characteristics for use as a possible adsorbent. EDX elemental analysis and surface area determinations were used to investigate the distinctive features of pyrolytic carbon black. Due to various inorganic additives of the original tyre that contaminated the carbon black obtained, it was treated with acid for demineralization. The demineralized carbon black was activated at 900 °C in a furnace. It was observed that acid treatment and activation increased the surface areas and decreased the concentration of contaminants. Furthermore, adsorption characteristics of methylene blue on acid‐treated and activated carbon black (prepared via acid treatment) were compared with those of commercial activated carbon in liquid phase adsorption. It was found that adsorption capacity of methylene blue on acid‐treated activated carbon black was greater.
The Plausible Motion's Confinement of Electrons by the Structure in YBa2Cu3O7‐x
Authors: Lee Yng‐Long
Published: May 2015

A hypothesis is proposed that tryies to correlate the observed structure transitions of YBa2Cu3O7‐x for x from 0 to 1 with measured super‐conductivity and electric properties.
Synthesis of 1,3,4‐Oxadiazole Acyclo C‐Nucleosides Bearing 5‐Methylthio{7‐substituted‐1,2,4‐triazolo[1,5‐d]tetrazol‐6‐yl}moieties
Authors: Taha Mamdouh Ahmed Mohamed , El‐Badry Susan Mohamed
Published: May 2015

Oxidative cyclization of the sugar hydrazones (3a‐f) derived from {7H‐1,2,4‐triazolo[1,5‐d]tetrazol‐6‐ylsulfanyl}acetic acid hydrazide (1) and aldopentoses 2a‐c or aldohexoses 2d‐f with bromine in acetic acid in the presence of anhydrous sodium acetate, followed by acetylation with acetic anhydride gave the corresponding 2‐(per‐O‐acetyl‐alditol‐l‐yl)‐5‐methylthio{7H‐1,2,4‐triazolo[1,5‐d]tetrazol‐6‐yl}‐1,3,4‐oxadiazoles (5a‐f). Condensative cyclization of the sugar hydrazones (3a‐f) by heating with acetic anhydride gave the corresponding 3‐acetyl‐2‐(per‐O‐acetyl‐alditol‐1‐yl)‐2,3‐dihydro‐5‐methylthio{7‐acetyl‐1,2,4‐triazolo[1,5‐d]tetrazol‐6‐yl}‐1,3,4‐oxadiazoles (11a‐f). De‐O‐acetylation of the acyclo C‐nucleoside peracetates (5 and 11) with methanolic ammonia afforded the hydrazono lactones (7) and the acyclo C‐nucleosides (12), respectively. The structures of new oxadiazole derivatives were confirmed by analytical and spectral data.
An Efficient Method of Solid‐State Synthesis of Diazenecarboxamide Azo Compounds Using Active Manganese Dioxide Supported on Acidic Silica Gel
Authors: Xue Wan‐Xin , Su Yong‐Xiang , Li Jian‐Ping
Published: May 2015

An efficient solid‐state method to oxidize aryl‐substituted semicarbazides into their corresponding N‐aryl‐2‐phenyldiazenecarboxamides with active manganese dioxide (AMD) supported on acidic silica gel is described. With this method, eleven diazenecarboxamides have been synthesized in high yields.
Novel Cesium Membrane Sensor Based on a Cavitand
Authors: Ganjali Mohammad Reza , Norouzi Parviz , Emami Mehdi , Golmohammadi Mahmoud , Mouradzadegun Arash
Published: May 2015

A PVC‐based membrane sensor was prepared for Cs+ ions, which was based on 7,11,15,28‐tetraiodo‐1,21,23,25‐tetramethyl‐2,20:3,19‐dimethano‐1H,21H,23H,25H‐bis[1,3]dioxocino[5,4‐i:5′,4′i′] benzo[1,2‐d:5,4‐d′]‐bis[1,3]benzodioxocin stereoisomer (cavitand). The proposed membrane electrode exhibits a linear dynamic range of 1.0 × 10−;1–1.0 × 10−;5M, with a Nernstian slope of 59.1 ± 0.3 mV per decade, and a detection limit of 5.0 × 10−;6 M. It has a very fast response time of <10 s and can be used for at least eight weeks without any considerable divergence in its potentials. The best sensor performance was obtained with a membrane containing 30% PVC, 62% dibutylphthalate (DBP), 6% cavitand, and 2% potassium tetrakis(p‐chlorophenyl) borate (KTpClPB). The sensor could be used in a pH range of 4.3–9.5.
QSAR Analysis of the Lipid Peroxidation Inhibitory Activity with Structure and Energetics of 36 Flavonoids Derivatives
Authors: Liao Hsien‐Ren , Chang Yeong‐Sheng , Yang Ling‐Ling , Lin Yu‐Chun , Chou Yu‐Ma , Wang Bo‐Cheng
Published: May 2015

The biological activity relationship of 36 flavonoid compounds was investigated using theoretical methods including quantitative structure activity relationships (QSAR) and quantum chemistry calculation. The results suggested that the 5 and/or 8 positions of the substituents of the hydroxyl group in the A ring and the 3′ and 4′ positions of substituents of the hydroxyl group in the B ring play an important role in flavonoid biological activity. This is probably due to the formation of an intra‐molecular hydrogen bond. In addition, the electronic energy, electrostatic energy and bond energy may have an effect on the biological activity of flavonoids. Also, our analysis has shown that the presence of the 1,4 and 1,2‐hydroquinone in the A ring and/or the Bring of flavonoids and the contribution of electronic energy, electrostatic energy and bond energy required consideration in the generation of the QSAR model and that the potential compounds will be predicted out of 36 flavonoids.
Electrocatalytic Activity of Methanol Oxidation at a Boron‐doped Diamond Electrode in Alkaline Solution
Authors: Changa Chia‐Chin , Chen Li‐Chia , Chang Hsien‐Chang , Tien Hsien‐Ju
Published: May 2015

The electrocatalytic activity of methanol oxidation at a boron‐doped diamond (BDD) electrode in alkaline solution is investigated by voltammetry and electrochemical impedance spectroscopy. Methanol oxidation in this work involves the generation of OH radicals. The intermediate, as formaldehyde, adsorbed at the BDD electrode surface is subsequently oxidized to formic acid or CO2 by OH radicals. Additionally, the reaction is influenced by the ratio of methanol and OH− concentration in the solution and is enhanced with the increased OH− concentration. Methanol adsorption at the BDD electrode surface is an important factor and difficult in this work. However, formaldehyde adsorption is more difficult than methanol. Methanol oxidation in this investigation is dominated by organic adsorption at a lower potential range. With the increased potential, it is gradually dominated by the generation of OH radicals.
Synthesis and Characterization of Donor‐Acceptor‐Substituted Fluorene Fluorophores for Non‐Doped Red Organic Light Emitting Diodes
Authors: Chiang Chih‐Long , Wen Ya‐Ju , Wen Yuh‐Sheng , Shu Ching‐Fong , Chen Chin‐Ti
Published: May 2015

A series of fluorene fluorophores bearing bis(4‐methoxyphenyl)amino electron donating substitutent as well as bisbenzothiazolylvinyl (AFDB), benzothiazolylcyanovinyl (AFCB), or dicyanovinyl (AFDC) electron accepting substituent were synthesized and characterized. A non‐doped red organic light‐emitting diode (OLED) device based on AFCB exhibited deep red (λ = 670 nm, CIE, x = 0.65, y = 0.34) electroluminescence with brightness over 2380 cd/m2 and an external quantum efficiency higher than 1.2%.
γ‐Polyglutamic Acid Produced by Bacillus Subtilis (Natto): Structural Characteristics, Chemical Properties and Biological Functionalities
Authors: Ho Guan‐Huei , Ho Tong‐Ing , Hsieh Kuo‐Huang , Su Yuan‐Chi , Lin Pi‐Yao , Yang Jeng , Yang Kun‐Hsiang , Yang Shih‐Ching
Published: May 2015

γ‐(D,L)‐Polyglutamic acid [γ‐(D,L)‐PGA, or γ‐PGA] produced by Bacillus subtilis (natto) both on laboratory and pilot scale fermenter systems has been characterized. γ‐PGA in its free acid form (H+) is insoluble in water. The salt forms of K+, Na+, NH4+, Ca2+, and Mg2+ of γ‐polyglutamates are fully soluble in water. The structural characteristics of the salts of γ‐Polyglutamates (Na+, K+, NH4+, Ca2+, and Mg2+) were determined with 1H‐ and 13C‐NMR spectroscopy and FT‐IR spectroscopy. The thermal properties were determined with thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The typical physical and chemical properties including pH‐titration curve, concentration‐dependent viscosity temperature‐dependent viscosity, and heavy metal binding properties with Pb2+, Cd2+, and Cu2+ were also determined. The biological functionalities were partially characterized with in vivo feeding studies with broilers and egg‐layers, and activation of GTF (Glucose tolerance factor) activity with rat 3T3‐L1 cell culture studies. γ‐(D,L)‐Polyglutamic acid [γ‐(D,L)‐PGA] appears to have five different conformations depending on the environmental conditions. They are the α‐helix, β‐sheet, helix‐to‐random coil transition, random‐coil and enveloped aggregate. The conformational states, hydrogen bonding and polyanionic nature make γ‐PGA a versatile multi‐functional biopolymer possessing many useful biological functionalities.
Synthesis and Liquid Crystal Properties of Chiral Compounds Containing the Core Structure of 6‐Hydroxynicotinic Acid or 4‐Hydroxyphenylacetic Acid
Authors: Tsai Wen‐Liang , Huang Kuang‐Yu , Hsueh Ching‐Yi , Wang Kuan‐Tung , Wen Chi‐Chang , Lai Hsin‐Mei , Cheng Pao‐Swu
Published: May 2015

The carboxylic acid 4‐hydroxybenzoic acid, bonded directly with (R)‐2‐octanol, is the core molecule of chiral liquid crystal (R)‐MHPOBC. This acid was substituted either by 6‐hydroxynicotinic or by 4‐hydroxyphenylacetic acid. Such a structural variation induced a remarkable influence on the liquid crystal properties of (R)‐MHPOBC. The series of compounds 1˜4 containing 6‐hydroxynicotinic acid moiety tend to exhibit a chiral smectic C (SmC*) phase, while the series of compounds 5˜8 containing 4‐hydroxyphenylacetic acid moiety tend to possess a chiral nematic (N*) phase.
Banana‐Shaped Mesogens: Odd‐even Effect in Dimeric Twins
Authors: Hsieh Chung‐Ching , Liu Kwang‐Ting , Lai Chung K.
Published: May 2015

The synthesis, characterization, and mesomorphic properties of a series of homologue compounds 1 derived from salicylaldehydes are reported. These compounds were characterized by 1H, 13C‐NMR spectroscopy and elemental analysis. The phase behavior of these mesogenic compounds was characterized and studied by differential scanning calorimeter (DSC) and polarization optical microscope. All compounds 1 were found to be mesogenic, and the mesophases were dependent of the carbon length of the spacer group. The results indicated that all compounds with an even‐carbon spacer (m = 2, 4, 6, 8) exhibited smectic C phases; however, all other compounds with an odd‐spacer (m = 3, 5, 7) formed banana phases. The difference in phase behavior was attributed to the dependence of the molecular shape and/or geometry on the parity of the central spacer when considered in the all‐trans‐conformation. The formation of the mesophases was related to the optimized conformation of the compounds. The most stable optimized geometry was also simulated by the semi‐empirical Spartan ′04 version 1.0.0/AM1 method.
Effects of Azo Bridge and Substituents on the Electrochemical and Spectral Properties of Bis(triarylamine)s
Authors: Chiu Kuo‐Yuan , Chung Yi‐Chun , Su Yuhlong Oliver
Published: May 2015

4,4′‐Azo‐bis(triarylamine) derivatives with electron‐donating groups have been synthesized. Their spectral and electrochemical characteristics have been investigated. Their first and second oxidations exhibited different degrees of overlapping, depending on the electron‐donating groups at the para‐position of the phenyl rings. The stability of the oxidation products was monitored with UV/VIS/NIR spectro‐electrochemical methods. The derivatives have much stronger IV‐CT bands in the near‐IR range. The spectral change reveals the number of electron transfer in the stepwise oxidation and the stability of the products.
The First Metal‐Carbon Bond β‐Isomer Paddlewheel Pd24+ Compounds
Authors: Yih Kuang‐Hway , Lee Gene‐Hsiang
Published: May 2015

The first metal‐carbon bond β‐form paddlewheel complexes containing a Pd24+ core, [Pd(η2‐dithio)]2(μ‐dppa)( μ‐SCNMe2) (dithio = S2P(OEt)2, 2; S2COEt, 3; S2CNC4H8, 4), were prepared by the reactions of the α‐form paddlewheel‐type Pd2+4 dipalladium complex [Pd2 (μ‐Hdppa)2(μ‐SCNMe2)2][Cl]2, 1 with various dithio‐ligands, [NH4][S2P(OEt)2], [K][S2COEt] and [NH4][S2CNC4H8], in methanol at ambient temperature (Hdppa = bis(diphenylphosphino)amine). Electronic spectra and two X‐ray structures of the Pd2+4 species have been determined.
Tocopherols and Triterpenoids from Sida acuta
Authors: Chen Chiy‐Rong , Chao Li‐Hui , Liao Yun‐Wen , Chang Chi‐I , Pan Min‐Hsiung
Published: May 2015

A new tocopherol derivative, 7a‐methoxy‐α‐tocopherol (1), and a new taraxastane triterpene, taraxast‐1,20(30)‐dien‐3‐one (5), together with four known compounds, β‐tocopherol (2), α‐tocopherol (3), α‐tocospiro B (4) and taraxasterone (6) were isolated from the whole plant of Sida acuta. Their structures were elucidated by spectral analysis including MS, 1D and 2D‐NMR spectroscopy. Among those compounds, compounds 1, 2, and 3 showed significant antioxidant effect (EC50 = 86.9, 68.2, and 70.9 μM, respectively) in the DPPH radicals scavenging activity assay.
Synthesis of 3‐(Pyridin‐4‐Ylmethyl)‐4‐Substituted‐1,2,4‐Triazoline‐5‐Thione
Authors: Pitucha Monika , Wujec Monika , Dobosz Maria
Published: May 2015

The reaction of the hydrazide of pyridine‐4‐acetic acid with isothiocyanate gave thiosemicarbazide derivatives respectively. Further cyclization with 2% NaOH led to the formation of 4‐substituted 3‐(pyridin‐4‐ylmethyl)‐1,2,4‐triazoline‐5‐thione and 3‐(pyridin‐4‐ylmethyl)‐1,2,4‐triazoline‐5‐thione. The structures of all new products were confirmed by analytical and spectroscopic methods.
Chemical Constituents from the Root Bark of Rodgersia Sambucifolia
Authors: Hu Hao‐Bin , Jian Yu‐Feng , Cao Hong , Zheng Xu‐Dong
Published: May 2015

A new demethylacetovanillochromene glycoside, 2,2‐dimethyl‐2H‐(8‐hydroxy‐6‐acetyl)‐[2,3‐b] pyran‐8‐O‐β‐D‐apiofuranosyl‐(1 →6)‐β‐D‐glucopyranoside (1), together with twenty‐three known compounds, have been isolated from the root bark of Rodgersia sambucifolia. These known compounds include two diterpenoids, three flavonoids, two catechins, four lignans, two benzenoids, two isocoumarins, two steroids and six monoterpene glycosides, which were determined by means of spectral analyses.
Studies on Chemical Constituents of Polygonum Ciliinerve Ohwi
Authors: Shen Tong , Liu Wu‐Xia , Jia Zhong‐Jian
Published: May 2015

Three new apianen lactones Maomailiaoine I (1), Maomailiaoine II (2) and Maoimaliaoine III (3), together with one known apianen lactone, five known flavonoids and three other known compounds were isolated from Polgonum ciliinerve Ohwi. Their structures were deduced from spectroscopic methods and 2D NMR techniques.
Classifying Structural Characteristics to Enhance Computation of Enthalpy of Formation of Halohydrocarbons
Authors: Liu Min Hsien
Published: May 2015

Density functional theory (DFT) calculations are made and least squares calibration performed for various halohydrocabons, which were 27 straight‐chain alkyl halides, 20 branch‐chain alkyl halides and 19 aromatic halides, to determine their enthalpies of formation (ΔHf). The mean absolute error (M. |A.E.|) in ΔHf across 66 molecular computations was only 7.8 kJ/mol (1.9 kcal/mol). Grouping the molecules by their structural characteristics improved M. |A.E.| of ΔHf by 0.2–2.2 kJ/mol over that obtained using corresponding modified data for the same 66 unclassified molecules.
Synthesis and Structures of the Novel Biferrocenamine‐Based Receptor and its Voltammetric Responses to Transition Metal Ions
Authors: Wang Fei , Xu Yan , Gao Lin , Ye Bao‐Xian
Published: May 2015

Reactions of formylferrocene and 1,2‐di‐(o‐aminophenoxy)ethane yield the novel bis(ferrocenyl) receptor (FcL). This compound has been characterized by IR, 1H NMR and elemental analysis. In addition, the electrochemical behavior of FcL was investigated in detail in 0.1 M tetra‐n‐butylammonium perchlorate (TBAP) + CH3CN by cyclic voltammetry (CV) and chronoamperometry. Its co‐ordination properties with metal ions in acetonitrile were also studied. The FcL shows a two‐wave behavior for H+, Cu2+, Zn2+ and Ni2+, but was unresponsive to Mg2+ and Ca2+. The maximum oxidation peak shift of about 250 mV was found for FcL in the presence of Cu2+, Zn2+ or Ni2+.
The Synthesis of Tetra‐α‐Phenoxyphthalocyanines and Research of their Physical and Chemical Properties
Authors: Xu Hai‐Tao , Xie Wen‐Wei , Guo Yan‐Chuan , Ci Ying , Chen Li‐Juan , Peng Bi‐Xian
Published: May 2015

A series of phthalocyanines (Pcs) substituted by phenoxy groups were synthesized through the route whose intermediates are selected to be phthalonitriles with different structures. These phthalocyanines and their intermediates are characterized by elemental analysis, IR and MS. The thermogravimetric loss and the aggregation behavior data of phthalocyanines are determined with the purpose to better understand the possible recording mechanism and to improve the dye's practical applications in the optoelectronic field.
Total Synthesis of (±)‐Boonein
Authors: Chang Meng‐Yang , Lin Chun‐Yu , Sun Pei‐Pei , Chang Nein‐Chen
Published: May 2015

A total synthesis of (±)‐boonein (8) from bicyclo[2.2.1]ketone 9 is described. Bicyclo[3.2.1]lactone 10 is the key intermediate.
A Theoretical Study of 1‐D and 2‐D Helium Lattices
Authors: Sabzyan Hassan , Zanjanchi Farzaneh
Published: May 2015

One‐ and two‐dimensional (1‐D and 2‐D) helium lattices have been studied using ab initio RHF/6–31G** computations. Structural, physical and thermochemical properties have been calculated and analyzed for the 1‐D and 2‐D HeN lattices respectively up to N = 50 and N = 36. Asymptotic properties of the 1‐D HeN lattices are obtained by extrapolating N‐dependence properties to large values of N. Analysis of the results show that the bulk per‐atom interaction (binding) energies increase while the optimized interatomic distances (bond lengths) slightly decrease with the increase in size of the 1‐D HeN lattices and both reach their asymptotic values of 0.352 cm−1 and 3.18775 Å, respectively. Between the square and hexagonal (packed) structures of the 2‐D HeN lattices, the latter is more favored. Extrapolated values of the calculated properties, including lattice parameter, binding and zero point energies, heat capacity, and entropy have also been calculated for both 1‐D and 2‐D HeN lattices. The surface densities for monolayer films of helium atoms with square and hexagonal configurations have been calculated to be respectively 9.84 × 1018 and 1.04 × 1019 helium atoms/cm2 which are comparable to the experimental value of 2.4 × 1019 helium atom/m2 well within the typical large and directional error bars of the experiments. Surface effects have been investigated by comparing the packed HeN2‐D lattices with the same value of N but with different geometries (arrangements). This comparison showed that the HeN lattices prefer arrangements with the smallest surface area.
Syntheses, and Crystal Structures of Indium Complexes with η2‐Piperidinyldithiocarbamate and η2‐Pyridine‐2‐Thionate Containing Ligands: Structures of [In(η2‐S2CNC5H10)3] and [In(η2‐pyS)3]
Authors: Chou Wei‐Lung , Chang Hao‐Han , Yih Kuang‐Hway , Lee Gene‐Hsiang
Published: May 2015

The η2‐thio‐indium complexes [In(η2‐thio)3] (thio = S2CNC5H10, 2; SNC4H4, (pyridine‐2‐thionate, pyS, 3) and [In(η2‐pyS)2(η2‐acac)], 4, (acac: acetylacetonate) are prepared by reacting the tris(η2‐acac)indium complex [In(η2‐acac)3], 1 with HS2CNC5H10, pySH, and pySH with ratios of 1:3, 1:3, and 1:2 in dichloromethane at room temperature, respectively. All of these complexes are identified by spectroscopic methods and complexes 2 and 3 are determined by single‐crystal X‐ray diffraction. Crystal data for 2: space group, C2/c with a = 13.5489(8) Å, b = 12.1821(7) Å, c = 16.0893(10) Å, β = 101.654(1)°, V = 2600.9(3) Å3, and Z = 4. The structure was refined to R = 0.033 and Rw = 0.086; Crystal data for 3: space group, P21 with a = 8.8064 (6) Å, b = 11.7047 (8) Å, c = 9.4046 (7) Å, β = 114.78 (1)°, V = 880.13(11) Å3, and Z = 2. The structure was refined to R = 0.030 and Rw = 0.061. The geometry around the metal atom of the two complexes is a trigonal prismatic coordination. The piperidinyldithiocarbamate and pyridine‐2‐thionate ligands, respectively, coordinate to the indium metal center through the two sulfur atoms and one sulfur and one nitrogen atoms, respectively. The short C‐N bond length in the range of 1.322(4)–1.381(6) Å in 2 and C‐S bond length in the range of 1.715(2)–1.753(6) Å in 2 and 3, respectively, indicate considerable partial double bond character.
Trace Spectrophotometric Determination of Dichlorvos using Diphenyl Semicarbazide (DPC) in Environmental and Agricultural Samples
Authors: Janghel E. K. , Rai M. K. , Gupta V. K. , Rai J. K.
Published: May 2015

A new and highly sensitive spectrophotometric method is developed for the determination of sub ppm levels of the widely used organophosphorus insecticide dichlorvos. The method is based on alkaline hydrolysis of dichlorvos to dichloroacetaldehyde followed by coupling with diphenyl semicarbazide (DPC) in alkaline medium. The absorption maxima of the wine red dye compound formed is measured at 490 nm. Beer's law is obeyed over the concentration range of 4.3 to 34 μg in a final solution volume of 25 mL (0.18–1.36 ppm). The molar absorptivity, Sandell's sensitivity and correlation coefficient were found to be 2.9 × 105 l mole−1 cm−1, 0.013 μg cm−2 and 0.9999, respectively. The standard deviation and relative standard deviation were found to be ± 0.007 and 1.90%, respectively. The lower limit of detection is 0.04 μg. The method is simple, sensitive and free from interferences of other pesticides and diverse ions. Other organophosphorous pesticides do not interfere with the proposed method. The method has been satisfactorily applied to the determination of dichlorvos in environmental and agricultural samples.
Effects of Neodymium on the Properties of Ni‐B/CNTs Amorphous Alloy Catalyst
Authors: Hu Chang‐Yuan , Li Feng‐Yi , Zhang Rong‐Bin , Liao Xiao‐Ning , Hua Li
Published: May 2015

Neodymium is used as a promoter of Ni‐B/CNTs amorphous alloy catalyst to modify its catalytic properties. Ni‐B/CNTs and Ni‐Nd(5wt%)‐B/CNTs catalysts were prepared by the impregnation chemical reduction method. Their catalytic performances were examined in acetylene selective hydrogenation, which is a crucial step in industrial polymerization processes, with the aim of the complete elimination of alkynes from alkene feedstocks. Experiments showed that the latter exhibited higher acetylene hydrogenation activity but lower ethylene selectivity. Catalysts were characterized by ICP, CO‐chemisorption, XPS, XRD and H2‐TPD techniques. On the basis of characterizations, the modification of Nd on Ni‐B/CNTs catalyst was related to its geometric and electronic effects.
Sensitivity in Supramolecular Architectures of Polyaromatic Salts Containing Two Singly‐Pimerized Bipyridines
Authors: Liu Shih‐An , Kuo Ting‐Shen , Lee Gene‐Hsiang , Shiu Kom‐Bei
Published: May 2015

Three novel supramolecular arrays of zigzag polyaromatic salts are reported. Both the conformation and disposition of the dications are subjected to various noncovalent interactions. Thus, the presence or absence of the π‐π interacting enclathrated molecules, the efficient packing and the involved hydrogen bonding interactions of anions, as well as the increased hydrophobic property of the dications themselves exert influence.
The Study of Indirect Determination of Tiopronin by Extraction Flotation Copper(II) with an Ammonium Sulfate‐Water‐n‐Propyl Alcohol System
Authors: Zhang Yu‐Ping , Li Quan‐Min , Zhao Xiao‐Hong , Liu Guo‐Guang
Published: May 2015

A novel method for indirect determination of tiopronin by extraction flotation of copper(II) with an ammonium sulfate‐water‐n‐propyl alcohol system was developed. The effects of different parameters, such as acidity, the amount of NH4SCN and various salts on the flotation yield of Cu(II), have been studied to optimize the experimental conditions. Under the optimum conditions, Cu(II) is reduced to Cu(I) by tiopronin, and the resulting Cu(I) can react with SCN− to form a white emulsion precipitate CuSCN. In the presence of (NH4)2SO4, the mixture consisting of n‐propyl alcohol and water can be separated into an n‐propyl alcohol phase and a water phase. In the process of phase separation of n‐propyl alcohol from water, the precipitated CuSCN is extracted and stays in the interface of n‐propyl alcohol and water. The amount of tiopronin can be determined by measuring the flotation yield of Cu(II). The detection limit is 0.32 mg L−1 and the linear range is maintained in the range of 0.40±13.0 mg L−1 with a correlation coefficient of 0.9991. This proposed method has been successfully applied to the determination of tiopronin in tablets, urine and human plasma with satisfactory results.
Synthesis and Characterization of Poly(Biphenyl‐2‐yl p‐Styrenesulphonate) as Profungicide in Controlled Release Technique
Authors: Khazaei Ardeshir , Soudbar Davood , Sadri Minoo , Hosseini Hassan
Published: May 2015

A new fungicide controlled release formulation was prepared by the reaction of p‐styrenesulphonyl chloride with biphenyl‐2‐ol (Dowicide A) as fungicide. The resulting monomer containing the fungicide was polymerized with benzoyl peroxide as initiator. The monomer and the polymer were identified by spectroscopic methods, and molecular weight of the polymer was determined by GPC. Also mp, Tg and Td of the polymer were identified by DSC. The release characteristic of the polymer was studied in neutral, alkaline, and acidic media. Also, the effect of the temperature on the release of bioactive agent (Dowicide A) was investigated. The hydrolysis data showed that the release rates are strongly dependent upon the pH of the medium and the temperature.
Synthesis and Cytotoxicity of 6‐Pyrrolidinyl‐2‐(2‐Substituted Phenyl)‐4‐Quinazolinones
Authors: Hour Mann‐Jen , Yang Jai‐Sing , Lien Jin‐Cherng , Kuo Sheng‐Chu , Huang Li‐Jiau
Published: May 2015

In our continuing search for potential anticancer candidates, 2‐(3‐methoxyphenyl)‐6‐pyrrolidinyl‐4‐quinazolinone (JJC‐1) was selected as the lead compound.

Starting 5‐pyrrolidinyl‐2‐aminobenzamide was prepared using standard methodology from 5‐chloro‐2‐nitrobenzoic acid by reaction with SOCl2, NH3, pyrrolidine, and H2. The starting benzamide then was reacted with 2‐substituted benzaldehyde or benzoyl chloride in N,N‐dimethylacetamide (DMAC) in the presence of NaHSO3 at 150 °C. Thermal cyclodehydration/dehydrogenation gave the target 6‐pyrrolidinyl‐2‐(2‐substituted phenyl)‐4‐quinazolinones (15–22).

These target compounds were assayed for their cytotoxicity in vitro against six cancer cell lines, including human monocytic leukemia cells (U937), mouse monocytic leukemia cells (WEHI‐3), human hepatoma cells (HepG2, Hep3B) and human lung carcinoma cells (A549, CH27). Most of them exhibited significant cytotoxic effect toward U937 and WEHI‐3 cells, with EC50 values ranging from 0.30 to 10.10 μM. Compound 19 was investigated further for its action mechanisms. Preliminary findings indicated that compound 19 induced G2/M arrest and apoptosis on U937 cells.
Poly(N‐Bromobenzene‐1,3‐Disulfonylamide), N,N,N′,N′‐Tetrabromobenzene‐1,3‐Disulfonylamide and DABCO‐Bromine Complex: As Novel Reagents for the Oxidative Coupling of Thiols to Disulfides
Authors: Ghorbani‐Vaghei Ramin , Zolfigol Mohammad Ali , Moshfeghifar Nasrin , Koukabi Nadiya , Chehardoli Gholamabbas
Published: May 2015

An efficient method for the oxidative coupling of thiols to their corresponding disulfides by new reagents poly(N‐bromobenzene‐1,3‐disulfonylamide) PBBS, N,N,N′,N′‐tetrabromobenzene‐1,3‐disulfonylamide TBBDA and DABCO‐bromine complex is described. The reaction was applicable to a variety of thiols with high chemoselectivity.
A Brief Catalyst Study on Direct Methane Conversion Using a Dielectric Barrier Discharge
Authors: Indarto Antonius , Choi Jae‐Wook , Lee Hwaung , Song Hyung Keun
Published: May 2015

A series of metal catalysts was used for methane conversion to higher hydrocarbons and hydrogen in a dielectric barrier discharge. The main goal of this study is to identify the metal catalyst components which can influence the reactions in room‐temperature plasma conditions. The catalysts supported by γ‐Al2O3 and zeolite (ZSM 5x) were prepared by the incipient wetness method with solutions containing the metal ions of the second component. Among the catalysts tested, only Pt and Fe catalysts showed a unique result of catalytic reaction in a reactor bed packed with glass beads.
A Computational Study of 3‐D Helium Clusters
Authors: Sabzyan Hassan , Zanjanchi Farzaneh
Published: May 2015

Physical and thermodynamic properties have been calculated and analyzed for the best and optimized geometries of the 3‐D clusters with N = 3 to N = 10 atoms and unit cells of three types of crystalline systems using ab initio RHF/6–31G** method. Dependence of the lattice binding energy on the cluster parameter, R, has been studied. Similar behavior observed for the binding energies for all clusters shows that probabilities of their existence in the condensed phase are more or less the same. In the next step, thermodynamic properties have been calculated and analyzed for He27 3‐D helium clusters with simple cubic, body centered cubic (bcc), trigonal and hexagonal (hcp) configurations. The results show that the hexagonal cluster is more favored over other clusters. It is found that these clusters are electronically stable over a limited range of the values for the lattice parameter. ΔfH is constant in this stability region and thus the ΔfG exactly follows the variations of TΔfS. Surface effects have been investigated by comparing the square and hexagonal He9 2‐D lattices with the cubic and hexagonal He27 3‐D lattices, respectively. The lattice parameters, densities and molar volumes calculated for the clusters with hcp and bcc configurations have satisfactory agreement with the available experimental values. Properties of the He13, He34 and He104 hcp clusters have also been calculated and analyzed.