bluuebunny/crossref_metadata_2025_split huggingface dataset:
Optical Properties of Host(SBA‐15)‐guest(AgI) Composite Materials
Authors: Kamalakar G. , Zhai Q.‐Z. , Hwang Dennis W. , Chien Shu‐Hua , Yang Yi‐Han , Lin Jin‐Dong , Chen Yit‐Tsong , Hwang Lian‐Pin 
Published: May 2015

AbstractNanoclusters AgI have been prepared in the channels of SBA‐15 molecular sieve host, and the host‐guest nanocomposite materials were prepared by a heat diffusion method. The (SBA‐15)‐AgI host‐guest nanocomposites were characterized by powder X‐ray diffraction analysis, nitrogen adsorption‐desorption isotherms at 77 K, and solid‐state diffuse reflectance absorption spectra. The decrease in surface area, pore diameter, and pore volume showed the existence of silver iodide clusters in the channels of SBA‐15 host. X‐ray diffraction illustrates that the framework of the SBA‐15 remained in the host‐guest composites of (SBA‐15)‐AgI. As the guest loading decreases, a blue‐shift was observed in the diffuse reflectance spectra. This shows that the guest existed in the channels of SBA‐15 and a quantum confinement effect emerged. The photoluminescence (PL) spectra show that the PL at ∼2.38 eV, associated with the hydrogen‐related species, decreases substantially after the loading of AgI in SBA‐15. The decrease of the PL indicates the reduction of the hydrogen concentration on the pore surface of SBA‐15 after the loading of AgI guest. The intensity decrease of the self‐trapped exciton (STE) band at 2.76 eV also suggests a hindrance for generating the excitons upon adding the AgI guest into the SBA‐15 host.
Evaluation of Natural Porous Crab Shell Powder Used for the Enrichment of Sulfur Compounds from Gaseous Samples
Authors: Sye Wen‐Fa , Chen Yen‐Chun , Wu Shang‐Fei 
Published: May 2015

AbstractA glass liner of a PTV injector packed with porous crab shell powder (50–100 mesh) was used to enrich the trace concentrations of sulfur components in natural gas, then the sulfur gases were thermally released according to a programmed temperature from the crab shell powder trap and re‐collected in a PLOT‐column head cooled with liquid nitrogen. The sulfur compounds were revolatilized and directly transferred to the system of PLOT‐column gas chromatography/flameless sulfur chemiluminescence detector for analysis. The characteristics of natural crab shell powder as an adsorbent have been presented. The sulfur gaseous compounds known to cause nuisance odors in natural gas were determined. The application of a porous crab shell powder trap for the analysis of sulfur compounds from gaseous samples has been proved to be useful.
Regioselective Photoamination of 2‐Styrylthiophenes with Ammonia
Authors: Ho Jinn‐Hsuan , Ho Tong‐Ing 
Published: May 2015

AbstractPhotoinduced electron transfer from the singlet excited state of 2‐styrylthiophenes (1a‐1f) to p‐DCB (p‐dicyanobenzene) has been proposed from the negative value of ΔGET (the free energy of the electron transfer) calculated by the Rehm‐Weller equation. This leads to the formation of radical cations of 1a‐1f and a radical anion of p‐DCB. The p‐nitro derivative 1g can not result in the radical cation due to the positive ΔGET value which results from the unfavorable singlet excitation energy (E0,0) and oxidation potential. Regioselective amination by ammonia to the radical cations of 1a‐1e has occurred to afford 1‐amino‐1‐aryl‐2‐(thien‐2‐yl)ethanes (2a‐2e) in reasonable yields (50–90%). The regioselectivity arises from the attack of ammonia at the localized positive charge on C‐1 of the ethene bond of the radical cations of 1a‐1e.
Preparation and Properties of 2‐(9′‐Carbazolyl)‐3‐(8″‐hydroxy‐2″‐Quinolinyl)Acrylonitrile Derivatives
Authors: Xu Peng‐Fei , Chow Tahsin J. , Lin Richard , Lu Ta‐Jung 
Published: May 2015

AbstractThe E and Z‐isomers of the titled compound were synthesized by condensation of 2‐carboxaldehyde‐8‐alkyloxyquinoline and N‐cyanomethylcarbazole, followed by hydrolysis. The alkoxy protection groups in 3b‐c can be cleaved either in acid or in base to yield 3a. All compounds exhibit blue/green luminescence, which may be used as emitting materials in the fabrication of light‐emitting diodes. Crystal diffraction analyses were performed for 3a‐E, 3d‐Z, and 4‐Z, while the results indicated the presence of a common structural feature among these molecules. The rings of quinoline are co‐planar with the double bond of acrylonitrile, forming a major conjugated chromophore. The carbazole group is twisted along the N(9″)‐C(2) bond away from the major plane with a large dihedral angle. The major conjugated chromphore was found to be responsible for the spectral properties of these compounds. Protonation of the quinoline in these compounds red‐shifted their absorption bands substantially.
The Intramolecular Diels‐Alder Reactivity of N‐Phenyl‐1,2‐Propadienyl Phosphinic Acid Amides and Related O‐Phenyl Esters
Authors: Himbert Gerhard , Ruppmich Martin , Knöringer Heinz 
Published: May 2015

AbstractThe P‐phenylpropa‐1,2‐dienyl phosphinic amides 4a‐h, the corresponding phosphinates 4i‐k and the (1‐phenylpropa‐1,2‐dienyl) phosphonic diamide 4l, whose amide N‐atoms resp. ester O‐atoms wear unsubstituted or substituted benzene nuclei, were formed by [2,3] sigmatropic rearrangement of the corresponding (2‐alkynyloxy)phosphine derivatives 3a‐l. Heating the solutions of 4a‐l led in some cases to decomposition (see 4a‐c), but in other cases to the tricycles 5d‐l, which were formed by Intramolecular Diels‐Alder (IMDA) reaction between the second allenic double bond as dienophile and the benzenic π‐system as diene.
Study of Reactions of Triiodide and Alizarin Red S with Some Important Phenothiazines. Development of an Indirect Titrimetric and a Spectrophotometric Method for the Assay of Phenothiazine Derivatives
Authors: Farhadi Khalil , Savojbolaghi Amir Karimi , Maleki Ramin 
Published: May 2015

AbstractThe reactions of a triiodide ion and alizarin red S with some N‐substituted phenothiazine drugs have been studied for the development of two simple, rapid, sensitive and accurate indirect titrimetric and extractive‐spectrophotometric methods for determining these drugs. Spectroscopic studies and chemical analysis showed that the protonated forms of phenthiazines, (PhenH2)2+, react with triiodide ions forming highly stable and insoluble ion pair products as (PhenH2)(I3)2. Formation of ion association complexes have been applied to the development of an indirect visual titrimetric method for the determination of chlorpromazine hydrochloride (CPH), trifluoperazine hydrochloride (TFPH), fluphenazine hydrocholoride (FPH) and promethazine hydrochloride (PMH) over the range 10−5–10−2 M. The extractional‐spectrophotometric method is based on the formation of (1:1) ion‐association complexes between drugs and alizarin red S as chromogenic reagents in acidic citrate buffer that are extractable into chloroform with an absorption maximum at 425 nm. The effect of different factors such as organic solvents, pH, and reagents concentration, were studied. CPH, TFPH and FPH can be determined over the range 9–57, 14–77 and 7–71 ppm, respectively. The proposed methods were applied for the analysis of the studied drugs in pure forms and their commercial preparations. Results are in good agreement with those obtained by official methods.
Oxidation of Stereo‐regular Poly(styrene‐co‐4‐methylstyrene) by Cobalt(II) Acetate Tetrahydrate/Sodium Bromide Catalyst
Authors: Chen Yu‐Pin , Hong Jin‐Long 
Published: May 2015

AbstractChemical modification on the stereo‐regular poly(styrene‐co‐4‐methylstyrene) (sPS‐PMS) was attempted in this study. Metallocene copolymerization of styrene (St) and 4‐methylstyrene (MSt) was performed by using η5‐pentamethylcyclopentadienyl‐titanium(IV)tributoxide (Cp*Ti(OBu)3)/methylaluminoxane (MAO)/tri‐iso‐butylaluminum (TIBA) catalyst in the bulk state. Cobalt(II) catalyst was then applied to oxidize the benzylic methyl group on the MSt units of the resulting sPS‐PMS copolymer. Both aldehyde and carboxylic acid in the oxidized products were resolved by the FTIR and 1H NMR. The oxidized sPS‐PMSs exhibit a low and a high‐temperature Tg and Tm corresponding to the transitions in the amorphous and the crystalline regions. Hydrogen‐bond and polar interactions between the aldehyde and carboxylic acids tend to interrupt the regular chain packing of the oxidized sPS‐PMS, resulting in the lowering of Tm with oxidation level. The oxidized sPS‐PMS showed better adhesion to glass fiber than pure sPS‐PMS copolymer as evaluated from the respective SEM fractured micrographs.
Synthesis and Photophysical Properties of Hetero‐Bischelated Complexes of Rhodium(III) Containing Phenyl‐Pyridin‐2‐Ylmethylene‐Amine
Authors: Lee Jen Rong , Lung Jin Wang , Huang Wen Liang 
Published: May 2015

AbstractThree new hetero‐bischelated rhodium (III) complexes ofcis‐[Rh(PA)(L)Cl2]Cl (where PA = phenylpyridin‐2‐ylmethylene‐amine; L = 2,2′‐bipyridine, 2,2′‐dipyridylamine and 1,10‐phenanthroline) have been successfully prepared and characterized. Each complex shows high intensity bands in the UV region, and these are assigned to spin‐allowed π‐π* transitions. The medium‐intensity absorption band profile in the lower energy region can be explained by convolution of spin‐allowed CT and d‐d* transitions. The emission spectra at low temperature (77 K) of these complexes in EtOH/MeOH (4:1 v/v) are virtually identical. They all exhibit a broad, symmetric, and structureless red emission with a microsecond lifetime and hence are assigned as the d‐d* phosphorescence.
Colorimetric Determination of Sulphur Dioxide and Sulphites in Various Environmental Samples
Authors: Chatterjee Sukumar , Pillai Ajai K. , Gupta V. K. 
Published: May 2015

AbstractRhodamine‐B has been proposed as a simple and sensitive colorimetric reagent for the estimation of sulphur dioxide in air. The air sample containing sulphur dioxide is passed through the absorbing solution of aqueous potassium iodate and N‐chlorosuccinimide to liberate iodine. The liberated iodine bleaches the pinkish red coloured rhodamine‐B dye, which measured at 555 nm. Beer's law was obeyed in the range of 0.5–5.0 μg, of sulphite per 25 mL (0.02–0.2 ppm) equivalent to 0.4–4.0 μg of sulphur dioxide (0.016–0.16 ppm). The molar absorptivity and Sandell's sensitivity were found to be 4.56 × 105 l mol−1 cm−1 and 0.00017 μg cm−2, respectively. The method has been suitably modified and successfully applied to the determination of sulphites in water after liberation of sulphur dioxide in acidic medium.
Synthesis of Some New 6,8‐Disubstituted 7,8‐Dihydropyrimido[2,3:4,3]pyrazolo[1,5‐a]pyrimidines and 6,7,8‐Trisubstituted Pyrimido[2,3:4,3]Pyrazolo[1,5‐a]Pyrimidine Derivatives
Authors: Ho Yuh‐Wen , Yao Chia‐Tseng 
Published: May 2015

AbstractCyclization of 5‐cyano‐1,6‐dihydro‐4‐methyl‐2‐phenyl‐6‐thioxopyrimidine 4 with excess of 85% hydrazine hydrate afforded the 3‐amino‐4‐methyl‐6‐phenylpyrazolo[3,4‐d]pyrimidine 5, which can react with appropriate Mannich base derivatives 13a‐c and chalcones 27a,b to yield the corresponding 6,8‐disubstituted 7,8‐dihydropyrimido[2,3:4,3]pyrazolo[1,5‐a]pyrimidines 15a‐c and 30a,b, respectively. On the other hand, the 6,7,8‐trisubstituted pyrimido[2,3:4,3]pyrazolo[1,5‐a]pyrimidine derivatives 8a‐g, 20a‐e, 36 and 38 were obtained by treatment of compound 5 with appropriate 1,3‐diketones 6a‐g, 3‐dimethylamino‐1‐(substituted)prop‐2‐enones 18a‐e, 3‐aminocrotononitrile 3, and ethoxymethylenemalononitrile 37 under acidic condition, respectively.
Spectrophotometric and Conductometric Studies of Charge Transfer Interaction of 2‐(1H)‐Pyridinethione with π‐Acceptors
Authors: Sayed N. I. Abdel 
Published: May 2015

AbstractKinetic studies on the formation of charge transfer complexes of 2‐(1H)‐pyridinethione with π‐acceptors p‐chloranil and p‐bromanil in dipolar aprotic solvent N,N‐dimethylformamide have been carried out spectrophotometrically at various temperatures. The reaction follows an overall third order rate equation, through first order with respect to π‐acceptors and second order with respect to the 2‐(1H)‐pyridinethione. The rates were found to increase with increasing temperature. Activation parameters, ΔH≠ and ΔS≠ have been calculated for the charge transfer complexes. The structure of the products was confirmed by their elemental analysis, IR, 1H NMR and mass spectrometry. Conductometric method has been used to investigate the electron donor‐acceptor complex formation. The stoichiometries of these complexes have been established and their conductance (σP−) and molar conductivity (σM−) values are reported.
Estimation of the Taurocholate to Lecithin Molar Ratio of Mixed Micelles in Taurocholate‐Lecithin Solutions by an Interaction Model and Laser Light‐Scattering Measurements
Authors: Liu Chen‐Lun , Weng Ming‐Shin 
Published: May 2015

AbstractThe taurocholate (TC) to lecithin (L) molar ratio (K) and molecular weight of mixed TC‐L micelles coexisting with simple TC micelles were determined by employing laser light‐scattering measurement and an interaction model of mixed and simple micelles. When the nonmixed micellar taurocholate (NMTC) concentration was greater than 25 mM, the K value and molecular weight of mixed TC‐L micelles were ∼ 4.3 and ∼ 20,000 daltons, respectively, at an L concentration of 6 mM, and ∼ 2.0 and ∼ 35,000 daltons at L concentrations of 12 mM and 21 mM. A quantitative model of the formation of simple TC micelles and mixed TC‐L micelles indicated that, when the NMTC concentration was greater than 25 mM, mixed TC‐L micelles were unstable at low L levels because of low concentrations of L monomers.
Sensitive Determination of Zinc(II) in Real Samples Using a Poly(4‐vinylpyridine)/Mercury Film Electrode
Authors: Zen Jyh‐Myng , Tsai Dong‐Mung , Yang Hsueh‐Hui 
Published: May 2015

AbstractA poly(4‐vinylpyridine)/mercury film electrode (PVP/MFE) was applied for the determination of trace amounts of zinc ion by square‐wave anodic stripping voltammetry. The PVP/MFE shows better mechanical stability, higher sensitivity, and enhanced resistance to common ions and surface‐active compounds than conventional mercury film electrodes. Various experimental parameters affecting the performance of the PVP/MFE in Zn(II) determination were optimized. Under the optimized conditions, the PVP/MFE shows a linear response up to 50 μg l−1 with a detection limit (S/N = 3) of 1.7 μg l−1. The practical applicability of the electrode was evaluated through the analytical estimation of Zn(II) in various real samples.
Nitrile Hydrolysis of 4‐Cyanopyridinepentaammineruthenium(III) Complex
Authors: Yeh Joyce , Liu Kwery , Lien Ming‐Huei , Yeh Andrew 
Published: May 2015

AbstractThe nitrile ligands undergo hydrolysis to amides under mild conditions when Ru(NH3)5NCR2+ (R = 4‐py, 4‐pyCH3+ and CH=CHCN) complexes are oxidized to Ru(III). The rate of hydrolysis of Ru(NH3)5NCpy3+ increases with the increase in acid concentration as a result of the protonation of the pyridyl nitrogen. The kinetic results yield the rate constant of the hydrolysis for Ru(NH3)5NCpyH4+ complex as 0.12 s−1 at μ = 1.0 M HCl/LiCl, greater than that of a deprotonated species by nearly two orders of magnitude. The enormous increase in rate for the protonated complex arises mainly from the increase in electron withdrawing power due to protonation which will decrease the electron density on the nitrile carbon and make it easier for the nucleophilic attack of the water molecule.
Total Synthesis of (±)‐Abieta‐8,11,13‐trien‐7β‐ol
Authors: Zhang Cheng‐Lu , Bie Ping‐Yan , Peng Xuan‐Jia , Pan Xin‐Fu 
Published: May 2015

AbstractThe first total synthesis of (±)‐abieta‐8,11,13‐trien‐7β‐ol (1) was accomplished, in which α‐cyclocitral was used as the A ring synthon, and triphenylphosphonium chloride (9), which was obtained from m‐bromobenzyl alcohol (4) via five steps, as the C ring synthon. The reduction of another natural organic compound (±)‐abieta‐8,11,13‐trien‐7‐one (2) with LiAlH4 gave exclusively the title compound 1.
Heterocyclic Spiro‐Compounds from Tandem Cascade Reaction of Alkyl Azides and Methyl Vinyl Ketone
Authors: Yang Chia‐Hsi , Lee Lang‐Tong , Wang Yu 
Published: May 2015

AbstractTandem cascade reaction of one molecule of alkyl azide and four molecules of methyl vinyl ketone gives a heterocyclic compound having an 1,4‐diazepine fused to a pyrazoline and spiro‐linked to a dihydropyran. The tandem cascade reaction is composed of an intermolecular [3+2] dipolar cycloaddition to give a triazoline, an isomerization to a diazo compound, another intermolecular [3+2] dipolar cycloaddition to give a pyrazoline, a Michael addition, dehydration, and a [4+2] cycloaddition.
Synthesis of Galanthamine Analogs as Acetylcholinesterase Inhibitors via Intramolecular Heck Cyclization
Authors: Liang Pi‐Hui , Hsin Ling‐Wei , Pong Sung‐Ling , Hsu Chia‐Huei , Cheng Chen‐Yu 
Published: May 2015

AbstractA novel approach towards the construction of the galanthamine skeleton was demonstrated by the Pd‐catalyzed cyclization of N‐[2‐(1,4‐dioxa‐spiro[4,5]dec‐7‐en‐8‐yl)‐ethyl]‐2‐iodo‐4‐methoxy‐N‐methyl‐benzamide (23), with formation of the benzazepine ring and creation of a quaternary carbon.
Theoretical Investigation of the Spin‐dependent Exciton Formation Rates in Polymeric Light‐emitting Diodes
Authors: Shuai Zhigang , Yin Shiwei , Chen Liping , Ye Aijun , Beljonne David , Brédas Jean‐Luc 
Published: May 2015

AbstractFirst, a brief review is given of recent experimental and theoretical progress in the determination of the spin‐dependent exciton formation rates in electroluminescent π‐conjugated polymers. We then describe our recent development of the coupled‐cluster equation of motion method and present its application to the theoretical study of singlet and triplet exciton formation rates and polymer light‐emitting diode quantum efficiency. It is found that, in general, singlet excitons can be formed with a higher yield than triplet excitons. The underlying mechanism is still a matter of debate. Here, we explore the role of inter‐chain charge‐bond correlation effects.
Theoretical Study on the Formation Mechanism of Resonance States for the Na + I2 → Na+ + I2− System
Authors: Cai Zhengting , Ma Wanyong , Sun Xiaomin , Feng Dacheng , Zhang Donghui 
Published: May 2015

AbstractAn extended LCAC‐SW (linear combination of arrangement channels‐scattering wavefunction) quantum scattering dynamic method combined with ab initio quantum chemical calculations has been used to study the formation mechanism of the resonance states for the ion‐pair formation reaction Na + I2 → Na+ + I2−. Resonance energy and resonance width or lifetime for the first resonance peak were calculated. Resonance can be identified to Feshbach resonance, and the physical interpretation has been given.
Theoretical Study on the Decomposition of NO via Dimer in the Presence of Cu
Authors: Sun Yueming , Zhang Yuan , Cao Ainian , Liu Juzheng 
Published: May 2015

AbstractThe interaction between NO molecules and copper atoms has been studied at the B3LYP/Lanl2DZ level. The results show that the NO molecules can be stably adsorbed on the adjacent Cu atoms to form the co‐adsorption configurations and the dimer‐adsorption configurations. The relative energies indicate that the structure of NO adsorbed on the Cu with N‐down is more stable than any other structure in the NO co‐adsorption models, and the NO atop adsorption is less stable than the others. On the other hand, the N‐N bond is strengthened, while the N‐O bond is weakened in the NO dimer adsorption models. It indicates that the formation of NO dimer is propitious to the NO direct decomposition on the copper surface. The intermediates of NO decomposing to N2O or N2 via dimer on the copper surface are found. The calculation results reasonably explain that the NO can be directly decomposed via the dimer configurations on the adjacent Cu atoms.
Theoretical Study of Photosynthetic Light‐Harvesting Processes: Application of Time‐Dependent Density Functional Theory
Authors: Hsu Chao‐Ping 
Published: May 2015

AbstractWe review recent progress in the area of theoretical investigations of light‐harvesting processes. The application of time‐dependent density functional theory (TDDFT) in the calculation of excitation energy transfer coupling factor will be emphasized. The effect of a dielectric environment can be obtained through a response theory based on TDDFT formalism. As an example of applicability of TDDFT, the role of a transition forbidden S1 state of carotenoid in a light‐harvesting complex LH2 is discussed in detail. The applicability of TDDFT to states with charge‐transfer character is also discussed with a few examples in the literature. Finally we briefly review works on the applications of TDDFT for excitations in chlorophylls and bacteriochlorophylls.
Unified Semiclassical Theory for the Nonadiabatic Transition
Authors: Zhu Chaoyuan 
Published: May 2015

AbstractUnified semiclassical theory for general two‐state nonadiabatic transition is discussed by demonstrating an important quantity that represents a type of nonadiabatic transition. This quantity is essentially defined by the rotation angle which determines transformation between diabatic and adiabatic representation, and it runs from unity to infinity continuously. The unified semiclassical formula is numerically demonstrated, especially in the high energy range where the transition probability is sensitive to the type of nonadiabatic transition. The present semiclassical theory can be incorporated with the framework of the Tully's fewest‐switches trajectory surface hopping method to deal with nonadiabatic transitions in multi‐dimensional systems.
Stability and Unfolding Mechanism of the N‐terminal β‐Hairpin from [2Fe‐2S] Ferredoxin I by Molecular Dynamics Simulations
Authors: Liu Hsuan‐Liang , Lin Yuan‐Ming 
Published: May 2015

AbstractThe stability and unfolding mechanism of the N‐terminal β‐hairpin of the [2Fe‐2S] ferredoxin I from the blue‐green alga Aphanothece sacrum in pure methanol, 40% (v/v) methanol‐water, and pure water systems were investigated by 10 ns molecular dynamics simulations under periodic boundary conditions. The β‐hairpin was mostly in its native‐like state in pure methanol, whereas it unfolds dramatically following the ‘zip‐up’ mechanism when it was placed in pure water. Both interstrand and inside‐turn hydrogen bonds account for the stability of the β‐hairpin in its native‐like conformation, whereas hydrophobic interactions among nonpolar side chains are responsible for maintaining its stable loop‐like intermediate structures in 40% (v/v) methanol‐water. Reducing solvent polarity seems to increase the stability of the β‐hairpin in its native‐like structure. Methanol is likely to mimic the partially hydrophobic environment around the N‐terminal β‐hairpin by the subsequent α‐helix.
Phase Chemistry Investigation on Cr(NO3)3‐Met‐H2O System
Authors: Chen San‐Ping , Gao Sheng‐Li , Hu Rong‐Zu , Shi Qi‐Zhen 
Published: May 2015

AbstractThe solubility property of the ternary of Cr(NO3)3‐Met‐H2O has been investigated in the whole concentration by the phase equilibrium method, and the phase diagram has been constructed. From the phase diagram, the congruently soluble complexes Cr(Met)(NO3)3·2H2O (D) and Cr(Met)2(NO3)3·2H2O (E) have been prepared and characterized by chemical analysis, elemental analysis, IR and TG‐DTG. Their combustion energies have been determined by a RBC‐type I precision rotating‐bomb calorimeter, and their standard enthalpies of formation, Δf, Hθm, have been calculated as (‐1842.01 ± 2.13) kJ·mol−1 and (‐1136.16 ± 4.45) kJ·mol−1, respectively.