bluuebunny/crossref_metadata_2025 huggingface dataset:
Reaction of (η5‐C5H4R)Fe(CO)2l (R = H, Me) with 1,1′‐Bis(diphenylphosphino)ferrocene (Dppf); Crystal Structure of {[(η5‐C5H5)Fe(CO)(η2‐dppf)]+l−}
Authors: Hsu Ming‐Ann , Yen Wen‐Yann , Chiang Michael Y.
Published: May 2015

Treatment of (η5‐RC5H4)Fe(CO)2I (R=H, Me) with 1, 1′‐bis(diphenylphosphino)ferrocene (dppf) in refluxing benzene afforded {[(η5‐RC5H4)Fe(CO)(η2‐dppf)+I} (R = H, 1a; R = Me, 1b), (η5‐RC5H4)‐Fe(CO)1(η2‐dppf) (2a, 2b), and [(η5‐RC5H4)Fe(CO)I]2(μ,η2‐dppf) (3a, 3b). The same reaction catalyzed by [CpFe(CO)2]2 produced only 1a and 1b. Compound 1a crystallizes in space group P1 with a = 11.201(4) Å, b = 13.597(4) Å, c = 14.692(5)Å, α = 78.36(3)° β = 83.58(3)°, γ = 75.00(3)°, V = 2112(1) Å3, Z = 2 and RF = 0.055.
Syntheses and X‐ray Crystal Structures of Dichlorobis(tert‐butylimido) Complexes of Molybdenum(VI); Potential Precursors to Molybdenum Nitride and Molybdenum Carbonitride
Authors: Chiu Hsin‐Tien , Chang Gau‐Banng , Ho Wen‐Yu , Chuang Shiow‐Huey , Lee Gene‐Hsiang , Peng Shie‐Ming
Published: May 2015

The bistertbutylimido complexes [MoCl(μ‐Cl)(NBu1)2(NH2Bu1)]2, 1, and MoCl2(NBu1)2(py)2, 2 (py = pyridine), were prepared by reacting MoCl2(NBu1)2(dme) (dme = dimethoxyethane) with excess Bu1NH2 and pyridine, respectively. Their structures were determined by X‐ray crystallography. 1 has a pseudo edge‐shared bioctahedral geometry with two Cl ligands bridging the Mo centers unequally. Pertinent bond distances and angles for 1, Mo = NBu1beut = 1.737(3) Å, ∠Mo = N‐CMe3 = 154.0(2)°; Mo = NBu1linear = 1.725(3) Å, ∠Mo = N‐CMe3 = 172.4(2)°; Mo‐Bu1NH2 = 2.233(2) Å; Mo‐Clbridging = 2.575(1) and 2.835(1) Å, and Mo‐Clterminal = 2.428(1) Å. Crystal data for 1: triclinic, space group P1, a = 8.897(4) Å, b = 10.518(3) Å, c = 10.663(3) Å, α = 107.68(2)° β = 98.03(3)° γ = 99.26(3)°, V = 919.3(5) Å3, Z = 1, Dc = 1.381 g/mL. 2 is mononuclear with a distorted octahedral geometry with two trans Cl ligands, two cis‐oriented Bu1N = ligands, and two py ligands trans to the imido groups. Pertinent averaged bond distances and angles for 2, Mo = NButbent = 1.736(4) Å, ∠Mo = N‐CMe3 = 163.8(4)°; Mo = NButlinear.= 1.705(5) Å, ∠Mo = N‐CMe3 = 173.4(4)° Mo‐N(py) = 2.44(1), Mo‐Cl = 2.421(3) Å. Crystal data for 2: orthorhombic, space group Pna21 a = 16.860(2) Å, b = 8.920(3) Å, c = 15.120(3) Å, V = 2274.1(9) Å3, Z = 4, Dc = 1.362 g/mL. A potential application of 2 as a single‐source precursor to grow molybdenum nitride and molybdenum carbonitride thin films by low pressure chemical vapor deposition (LPCVD) was explored. Cubic phase thin films (athin film = 4.16–4.20 Å) were grown at temperatures between 450 °C and 650 °C with hydrogen as carrier gas. At 450 °C, thin films of molybdenum nitride were obtained. With temperature of deposition increased from 450 °C to 650 °C, the ratio C/Mo increased from 0.03 to 0.5 whereas me ratio N/Mo decreased from 0.7 to 0.3. Thus, thin films of molybdenum carbonitride were deposited at 650 °C.
Chemistry of Cage‐shaped Hydrocarbons. The Oxidation of Heptacyclo[6.6.0.02,6.03,13.0 4,11.05,9.010,14]tetradecane
Authors: Chow Tahsin J. , Wei Chin‐Chuan , Wu Tung‐Kung
Published: May 2015

Oxidative ring opening reactions enabled disassembly of the cage structure of the title compound. Stepwise oxidations were achieved through radical intermediates using lead tetracetate and iodine. The regioselectivity of bond fission is rationalized by comparing the relative strains of each bond. Multiple cleavages of C‐C bond were accomplished by photolysis with HgO and iodine under UV. The oxidative effect of Ce(IV) ion on a cage‐shaped diketone is examined. New skeletons of polyquinanes are obtained from these reactions.
Capillary Electrophoresis Separation Techniques and Mechanisms in Dilute Polymer Matrices
Authors: Navin Michael J. , Morris Michael D.
Published: May 2015

Capillary electrophoresis in ultradilute derivatized solutions is used to separate nucleic acid fragment mixtures. Pulsed field techniques are used to improve resolution. Protocols in which pulse parameters are varied during the course of the separation are used to increase the range of fragment sizes separated. Fluorescence microscopy is used to study the separation mechanism in ultradilute solution.
Fluorescence Spectra of S2CI Excited with Laser Radiation at 488 nm
Authors: Chiu Chi Lian , Chang Hua
Published: May 2015

Fluorescence from S2C1 induced by radiation at 488 nm was observed when the parent molecule S2C12 was heated. The dependence of the intensity of fluorescence is third order on laser power. The mechanism of excitation is proposed to be dissociation of hot S2C12 after two‐photon absorption to yield hot S2CI and one‐photon absorption of the latter to reach the fluoresing states. The fluorescence spectrum consists of two systems, called α and β here. The lower state of the a system is the ground state χ and that of the β system is assumed to be the Ã state. The upper states of both systems are unknown but may be related to previously observed slates lying about 460 nm and 330 nm. The vibrational structure of the β system was partially analyzed. The vibrational quantum numbers of the v2 and the v3 modes in the upper state are assessed to be 26 and 0, respectively, from a count of the number of nodes of the curves of the fluorescence intensity distribution. From the abrupt termination of the intensity curve of v2″ progressions, the absolute v2″ quantum numbers were determined. The excitation was in this way assigned to be (p,q + 6,0)′ ← (m,4,n + 3)″, in which p, q, m and n are non‐negative integers.
Effect of the Phase of Titanium Oxide on Metal‐Support Interaction
Authors: Chang Chun‐Show , Jong Sung‐Jeng , Cheng Soofin
Published: May 2015

The metal‐support interaction in the system of platinum supported on titanium oxides of different crystalline structures was investigated. Titanium oxide powders used as supports were prepared by neutralization of TiOCl2‐analogue solution with either NaOH or NH3 base at varied pH. Pt was introduced onto the supports by impregnation. The phenomenon of strong metal‐support interaction (SMSI) was determined by the suppression of chemisorption of H2 over samples reduced at 773 K, in comparison with the behavior of samples reduced at 473 K. The loss of adsorption capacity was proved not due to metal sintering by examining the recovery of adsorption capacity after reduction, reoxidation and reduction cycle, accompanied with examination of the size of Pt particle with an x‐ray diffractiometer and a transmission‐electron microscope. The results showed that SMSI phenomenon was common to Pt supported on titanium oxides of all the varied crystalline structures. However, the chemisorption capacity of Pt reduced at 473 K varied greatly with the sodium content in the supports, which in turns affects the crystalline structure of titanium oxide. These results are attributed mainly to electronic effect endowed by the support.
Kinetics of 2,2′‐Bipyridyl‐Catalyzed Oxidation of Isopropyl Alcohol with Chromic Acid
Authors: Lin Tzucn‐Yeuan , Zeng Han‐Wei , Chuo Chin‐Ming
Published: May 2015

2,2′‐Bipyridyl and some substituted compounds catalyze effectively the oxidation of isopropyl alcohol by chromic acid. The reaction is first order in chromium(VI), alcohol and 2,2′‐bipyridyl; it is first order in hydrogen ions at high acidity and slightly alters to second order at low acidity. The proposed mechanism shows that the rate‐limiting step is mainly the decomposition of a termolecular complex to products. However, at low acidity, the formation step of this complex is a little less reversible and hence somewhat rate‐limiting. Electron‐donating substituents at the 4‐position enhance the catalytic activity. Electron‐withdrawing substituents at the 4‐ and 2‐positions diminish the reaction rates by electronic and steric factors.
Intercalation Compounds of Cu2+ and Nl2+ — Exchanged Montmorillonite Clay with 8‐Hydroxyquinoline
Authors: Labhasetwar Nitin K. , Shrivastava O. P.
Published: May 2015

Montmorillonite clay mineral shows remarkable ion exchange, intercalation and swelling properties. It can act as a good host for large organic molecules. Intercalated coordination compounds can be prepared in the interlayer spaces of montmorillonite structure. Cu(II)‐ and Ni(II)‐ exchanged montmorillonite sorb 8‐hydroxyquinoline (oxine) to form corresponding coordination compounds of the exchanged metal ions. Such compounds have been characterised by means of elemental analysts, infrared spectroscopy, magnetic susceptibility data and X‐ray diffraction. These compound show good thermal stability.
Chemical Constltuents from the Roots of Zizyphus jujuba Mill. var. spinosa (I)
Authors: Lee Shoei‐Sheng , Wang Jeng‐Shu , Chen Karin Chiung‐Sheue
Published: May 2015

The chemical constituents of the roots of Zizyphus jujuba Mill. var. spinosa were investigated with a combination of Sephadex LH‐20 column, centrifugal partition chromatography and RP‐18 low pressure liquid chromatography. We isolated seven flavonoids‐quercetin (1), (+)‐dihydroquercetin (2), (+)‐dihydrokaempferol (7), quercetin‐3‐0‐β‐glucoside (8), 2‐hydroxynaringenin (11), rutin (12), and quercetin 3‐0‐(2G‐β‐D‐xylopyranosylrutinoside) (13); four catechins‐(‐)‐gallocatechin (3), (‐)‐epigallocatechin (4), (‐)‐catechin (5), and (‐)‐epicatechin (6); and two phenolic carboxylic acids‐p‐hydroxybenzoic acid (9) and protocatechuic acid (10) from the water soluble fraction of the ethanolic extract NMR date of 13 were assigned by 2D NMR techniques.
Structure and Synthesis of Evofolin‐C from Tetradium glabrifolium
Authors: Wu Tian‐Shung , Yeh Jyh‐Her , Wu Pei‐Lin
Published: May 2015

A new benzenoid compound evofolin‐C was isolated from the heartwood of Tetradium glabrifolium (Evodia meliaefolia). The structure was elucidated by spectral analysis. The synthesis of evofolin‐C is described.
Femtosecond‐Picosecond Laser Photolysis Studies on Photoinduced Electron Transfer Phenomena in Solutions
Authors: Mataga Noboru
Published: May 2015

Results of our femtosecond‐picosecond laser photolysis studies on photoinduced electron transfer phenomena in solutions including exciplex dynamics and its solvent dependences, energy gap dependences of photoinduced charge separation and charge recombination of various geminate ion pairs, mechanisms of chemical reactions via exciplexes and ion pairs, dynamics of photoinduced election transfer in hydrogen bonding complexes, dynamics and mechanisms of photoinduced electron transfer in fixed distance donor acceptor dyads and photosynthetic reaction center models, and mechanisms of electron ejection from solute fluorescent state in polar solutions are summarized and discussed.
Dependence of the Interaction Potentials of Ar‐HF and N2‐HF on HF Bond Length
Authors: Chang Huan‐Cheng , Tao Fu‐Ming , Tsang Susy N. , Klmpcrer William
Published: May 2015

We explore in detail the nature of the intermolecular interactions in two HF containing complexes, ArHF and N2 HF, at vibrationally excited HF stretching states using both high overtone spectroscopic and ab initio computational methods. By using an infrared intracavity laser‐induced fluorescence technique, second overtone spectra of the two HF complexes have been obtained for the HF stretches and their combination modes with low‐frequency van der Waals vibrations. The two complexes show the same trend that both van der Waals bond strength and rotational constant increase smoothly with v of the HF stretch. The investigation of the intermolecular potential above minimum provides a rigorous test of ab initio calculations. In particular for the ab initio calculations using an efficient basis set incorporating bond functions, the technique reproduces reasonably well the anisotropy of the interaction potential of Ar and HF. It is found that the intermolecular potential depends strongly upon the HF bond length only at the linear Ar‐H‐F geometry.
Computed Potential Energy Surfaces and Minimum Energy Pathways for Chemical Reactions
Authors: Walch Stephen P.
Published: May 2015

Computed potential energy surfaces are often required for computation of such observables as rate constants as a function of temperature, product branching ratios, and other detailed properties. We have found that computation of the stationary points/reaction pathways using CASSCF/derivative methods, followed by use of the internally contracted CI method with the Dunning correlation consistent basis sets to obtain accurate energetics, gives useful results for a number of chemically important systems. Applications to complex reactions leading to NOx and soot formation in hydrocarbon combustion are discussed.
Photon Energy Dependence of the Vibrational Fine Structure in Core Level Photoemission Spectra Near Threshold
Authors: Köppe H. M. , Kilcoyne A. L. D. , Feldhaus J. , Bradshaw A. M.
Published: May 2015

The C 1s and N 1s main lines in the photoelectron spectra of CO, CO2, CH4, C2H2, C2H4, C2H6, N2, and N2O have been measured with high resolution in the threshold region, revealing in each case the extent of the rich vibrational fine structure. Using a simple line shape analysis which allows for the effect of post‐collision interaction, the vibrational energies and approximate lifetimes of the core‐excited ions are determined. The relative intensities of the vibrational lines change dramatically with photon energy due to the influence of shape resonances and double excitations.
The Adsorption and Thermal Decomposition of CH2CO (CD2CO) on Si(111)‐7 × 7
Authors: Bu Y. , Lin M. C.
Published: May 2015

The adsorption and thermal decomposition of ketene on Si(l 11)‐7 × 7 were investigated using various surface analysis techniques. When the surface was exposed to ketene at 120 K, two CO stretching modes at 220 and 273 meV appeared in HREELS, corresponding to two adsorbed ketene states. After the sample was annealed at −250 K, the 273 and the 80 meV peaks vanished, indicating the disappearance of one of the adsorption states by partial desorption of the adsorbate. In a corresponding TPD measurement, a desorption peak for ketene species was noted at 220 K. Annealing the sample at 450 K caused the decomposition of the adsorbate, producing CHx and O adspecies. Further annealing of the surface at higher temperatures resulted in the breaking of the CH bond, the desorption of H and O species and the formation of Si carbide. The desorption of H at 800 K was confirmed by the appearance of the D2 (m/e = 4) TPD peak at that temperature when CD2CO was used instead of CH2CO.
Laser‐Induced Stabilization in Atomic and Molecular Systems
Authors: Chu Shih‐I
Published: May 2015

We present a short account of the recent progress in the study of a novel strong‐field phenomenon recently uncovered: atoms and molecules may be stabilized by intense laser fields. The laser‐induced atomic and molecular stabilization arises from quite different origins. We present a complex‐scaling Fourier‐grid Hamiltonian method for the discretization and solutior of the Schrödinger equation within the non‐Hermitian Floquet Hamiltonian formalism. The method provides a simple, yet accurate and highly efficient, new technique for the determination of the complex quasienergies (ERT −Γ/2) of atoms and molecules. The real parts, ERT provide the a.c. Stark shifts, and the imaginary parts, Γ, give rise to multiphoton ionization rates of atoms or multiphoton dissociation rates of molecules. The method is applied to the studies of (i) stabilization and ionization suppression of negative ions in high‐frequency superintense laser fields; (ii) laser‐induced molecular stabilization and chemical bond hardening in strong laser fields.
Magnetic Field and Magnetic Isotope Effects upon Reactions of Heavy Atom‐Centered Radicals
Authors: Hayashi Hisaharu , Wakasa Masanobu , Sakaguchi Yoshio
Published: May 2015

We present our recent studies on magnetic field effects (MFEs) observed in reactions of heavy atom‐centered radicals such as Si‐,P‐, Ge‐, and Sn‐radicals with a ns‐laser photolysis technique under magnetic fields of 0–10 T. Although the MFES of heavy atom‐centered radicals are much smaller than those of C‐radicals due to the spin‐orbit interaction of heavy atoms, we have found appreciable MFEs in many reactions of such heavy atom‐centered radicals. Comparing the MFES of C‐radicals with those of heavy atom‐centered ones, we have explained the MFEs of heavy atom‐centered radicals in terms of the Δg and relaxation mechanisms. We have found that the separation between the MFES due to the Δg mechanism and those due to the relaxation one is possible with the enhancement of spin relaxation by the addition of a paramagnetic ion.

We have also tried to enrich magnetic isotopes of heavy atoms with the magnetic isotope effect (MIE), using the reactions which show fairly large MFES. Recently, we have succeeded in enriching 73Ge. This is the heaviest isotope which has so far been enriched with the MIE from samples of natural abundance.
Overlapping Resonances, Multiple Time Regime Evolution Laws and the Sampling of Phase Space in Unimolecular Processes
Authors: Remacle F. , Levine R. D.
Published: May 2015

Unimolecular processes can be described as the decay of an ensemble of N excited resonances coupled to K decay channels. Resonances are metastable states characterized by a complex energy whose real part is the position of the state along the energy axis while the imaginary part gives the individual decay rate of the state. Resonances usually overlap in the RRKM regime. The degree of overlap is measured by the parameter R = /dE where  is the average of the individual decay rates of the excited resonances and dE is the average spacing between their position. In the exact degeneracy limit, that is, for an infinite value of R, (N‐K) resonances have a zero width, so that a fraction of the initial excitation remains permanently trapped in the bound subspace. This trapping effect subsists in the non degenerate case but is not complete. We use a random coupling effective Hamiltonian model to discuss the effect of the degree of overlapping R, and of the number of resonances N and decay channels K, on the temporal evolution laws of the bound subspace and of the fragments. The decay law of the bound subspace and the temporal evolution of the yields in fragments exhibit several time regimes. This is due to the fact that after the diagonalization of the effective Hamiltonian, the decay widths of the resonances cluster into one group of K large widths and one group of (N‐K) small ones. The trapping effect is due to the (N‐K) small widths. The amount of trapping depends on the value of the degree of overlapping R, and for a given value of R, on the ratio N/K: large values of R and of N/K correspond to a large amount of trapping in the bound subspace for times long when compared to ħ/. The temporal evolution laws of the yields in fragment are also strongly affected by the degree of overlapping and the value of the ratio N/K. Due to the reorganization of the partial widths which follows the diagonalization of the effective Hamiltonian, we show that the nature of the dominant product can change while increasing the value of R and N/K. We also discuss the time evolution of the sampling of phase space for a specific preparation in terms of these two parameters. The volume sampled is computed using an entropic measure. When the resonances overlap, there is not enough time to completely sample phase space prior to dissociation. The fraction sampled decreases as the amount of trapping in the bound phase space increases.
Low Pressure Chemical Vapor Deposition of III/V‐Nitrides Using Organometallics and Hydrazoic Acid Precursors
Authors: Bu Y. , Lin M. C.
Published: May 2015

In and Ga nitride films have been deposited on various substrates using organometallics and hydrazoic acid (HN3) as nitrogen precursor. The film deposition was carried out under low pressure (10−510 −6 Torr) and low V/III ratios (1‐10). XPS analysis indicated that the ln(Ga):N atomic ratio of unity can be easily achieved by adjusting the experimental conditions. For the growth of InN on Si(100) substrate, 308‐nm photon beam is needed to speed up the film deposition rate. He(II) UPS spectra of InN films are in good agreement with the result of a pseudo‐potential calculation for InN valence band, while the spectra of GaN compare favorably with a recent semi‐ab‐initio calculation and with the UPS results of GaN single crystal films. The bandgap of our GaN films is ∼ 3.3 cV as determined by photoluminescence and UV‐VIS absorption spectra. Raman spectra taken from GaN Films showed peaks at 66 and 88 meV for TO and LO phonons, respectively, indicating a wurtzite structure of the GaN. In a corresponding X‐ray diffraction spectrum, the (002) peak is about 400 times more intense than that of the (101) peak, suggesting that the GaN layers are highly oriented with the c‐axis normal or nearly so to the Al2O3 substrate.
Probing Structure, Spectroscopy, Kinetics, and Dynamics on Metal Surfaces by Optical Second Harmonic Generation
Authors: Dai Hai‐Lung
Published: May 2015

With the intrinsic surface sensitivity, superior frequency and time resolution, and adaptability to all pressure conditions, optical second harmonic generation has proven a versatile and powerful diagnostic tool for surface science studies. Examples are provided in the use of surface second harmonic generation in elucidating the adsorption kinetics and structural transitions of molecular adlayers, detecting surface electronic transitions, and determining transient temperature changes on metal surfaces.
Graphical Determination of Monomer Shift, Dimer Shift and Dimerization Constant for Self‐Association: 2‐Isopropyl Phenol in C6D12 as an Example
Authors: Chen Jehn‐Shing , Shiau Jiin‐Chyuan , Fang Cheng‐Yu
Published: May 2015

We propose a graphical method to treat dilution shift in NMR spectra to determine the monomer shift, dimer shift and dimerization constant simultaneously and consistently for the system of monomer/dimer equilibrium. The salient features include avoiding error‐prone manual extrapolation to zero concentration to obtain a monomer shift, and providing consistent assessment and error estimation for the determination. The dilution shifts of 2‐isopropyl phenol in C6D12 serve to demonstrate this graphical method. The enthalpy and entropy of dimerization are determined via a van't Hoff plot from the temperature variation of the dimerization constant.
Chelation Properties of Highly Selective and Affinity Polymeric Complexing Agents
Authors: Lee N‐Ming , Liu Chuen‐Ying
Published: May 2015

Procedures are described to prepare γ‐aminobutyrohydroxamate resin and its N‐methyl and O‐methyl derivatives. With the aid of a chemical method, IR and electronic spectra, and potentiometry, the chelating properties of these resins are compared with each other. The selectivity of resins for various metals is expected to be comparable to complexing properties of a monomer having a structure similar to that of active groups. This correlation was made quantitatively by measurement of metal capacity, fraction of sorption, pH and period for extraction of half the metal ions, stability constants etc. Not only γ‐aminobutyrohydroxamate resin but also its N‐methyl and O‐methyl derivatives exhibit much potential for application in chelation ion chromatography.
Formation of YBa2Cu408 Thick Films via Spray Pyrolysis
Authors: Sheen Shyang Roeng , Kao Ching Haai , Wu Maw‐Kuen , Chen Dian Hau , Huang Ju‐Chun , Cheng Chien Hong , Chang Chau Ting
Published: May 2015

Thick films of YBa2Cu4O8 superconductor were prepared by a spray‐pyrolysis coating technique using silver strip as the substrate. The precursor solution consisted of metal nitrates dissolved in a mixture of ethandiol and water. The solution was nebulized onto the heated substrates to obtain films as‐deposited. The temperature of deposition had a great effect on the morphology of the film. Sintering the films in flowing oxygen at 810 °C for 60 h yielded films with Tc(onset) = 82.0 K and Tc(zero) = 74.6 K. Films were characterized by x‐ray diffraction, scanning electron microscopy, transport and magnetic measurements.
Chemical Constituents from the Root and Aerial Parts of Rosa taiwanensis
Authors: Yang Shen‐Chyun , Fang Jim‐Min , Cheng Yu‐Shia
Published: May 2015

The root and aerial parts of Rosa taiwanensis Nakai contain the chemical constituents phenols, unsaturated acids, loliolide, abscisic acid, flavones, sterols, lupeol, betulin, betulinic acid, oleanolic acid and ursolic acid derivatives. Among them, 2α,3α‐dihydroxyurs‐12,19‐dien‐28‐oic acid and its C‐3 epimer are new compounds.
Resolution of Secondary α‐Ketoalcohols Catalyzed by Lipase and Inversion of Stereochemistry
Authors: Duh Tsai‐Hui , Wang Yi‐Fong , Wu Ming‐Jung
Published: May 2015

Several α‐ketoalcohols of synthetic value were resolved using lipase as a catalyst. Lipoprotein lipase (LPL) provided the best rate of hydrolysis and kinetic differentiation. One of these optically pure α‐ketoalcohol was converted to (5)‐ibuprofen in good optical purity. The stereospecific inversion of (R)‐alcohol to (S)‐alcohol is described.
Synthesis of 2,5 ‐Bis(4‐methyl‐2‐thienyl)thiophene and 2,5‐Bis(4‐methyl‐2‐thienyl)pyrrole
Authors: Luo Thung‐Mei H. , Chen Liang‐Huei
Published: May 2015

Syntheses of 2,5‐bis(4‐methyl‐2‐thienyl)thiophene 3 and 2,5‐bis(4‐methyl‐2‐thienyl)pyrrole 4 are described. The key step involves Stetter reaction between 4‐methyl‐2‐thiophenecarboxaldehyde and divinyl sulfone. Cyclizaton of the resulting 1,4‐bis‐(4‐methyl‐2‐thienyl)‐1,4‐butanedione 2 with Lawesson's reagent gives 2,5‐bis(4‐methyl‐2‐thienyl)thiophene 3, whereas condensation with ammonium acetate provides the 2,5‐bis(4‐methyl‐2‐thienyl)pyrrole 4.
Recently Developed Concepts for Studying and Understanding the Aggregation of Organic Molecules. Aggregating Tendencies of the Culprits of Arteriosclerosis
Authors: Jiang Xi‐Kui
Published: May 2015

Recent developments in research on aggregation and self‐coiling of organic molecules are reviewed: structure and medium effects on aggregating tendencies, electrostatically stabilized aggregates (ESAg), co‐aggregating tendencies of cholesterols and the effect of chain‐folding, and neutral and effective deaggregators (deAgr).
α‐Carbonyl Radicals for Total Synthesis of Natural Products
Authors: Sha Chin‐Kang , Jean Tsong‐Shin , Yau Nei‐Tung , Huang Shih‐Jung , Chiou Ruey‐Torn , Young Jenn‐Fenn , Lih Shin‐Hong , Tseng Wei‐Hong
Published: May 2015

Intramolecular cyclization of α‐carbonyl radicals to the trimethylsilylacetylenic side chain gives bicyclic vinylsilane ketones and enones. Application of this cyclization to total synthesis of (±)‐modhephene is described.
Light Induced Electron Transfer and Charge Separation of Porphyrin Compounds for Photoelectric Conversion
Authors: Cao Yi , Zhang Bao‐Wen , Qian Wen‐Yuan , Bai Jian‐Wei , Xiao Xu‐Rui , Jia Jian‐Guang
Published: May 2015

A series of artificial photosynthesis porphyrin compounds consisting of electron donor and electron acceptor (compounds 1‐6) were synthesized. Their spectroscopic behaviors in solution were investigated and the synthetic molecular devices were prepared with these molecules by using LB technique. It was indicated that multistep electron transfer and charge separation for these compounds actually occur, which is of great advantage to their photoelectric conversion. An efficient energy transfer process takes place for compound 6. A mechanism involving photoinduced electron transfer and multistep charge separation for these compounds was suggested. With only one monolayer of tetrad 1 LB film on the surface of Sn02 conductive glass, high photo‐driven voltage and current were obtained.
Conformational Behavior of Rigid and Dancing (1,3)(1,4)Cyclophanes
Authors: Lai Yee‐Hing
Published: May 2015

Annelation or substitution of the (1,4)‐bridged ring of [22](1,3)(1,4)cyclophane 4, such as in 8 and 9, respectively, result in two different conformational ground states in each case. Each conformational ground state involves a different destabilizing factor arising from one form of non‐bonding interaction. Only the conformers 8b and 9b were isolated experimentally. Their corresponding precursors 11 and 23 were also found to be conformationally rigid. Only the conformers 11a and 23a were isolated indicating an abrupt change in conformational preference going from the dithia[32]cyclophanes to the respective [22]cyclophanes. The selectively methylated [22]cyclophanes 27, 31 and 32 were, however, found to be conformationally mobile. There is an increase of about 10–15 kJ mol−1 in conformational energy barrier going from 4 to 27 or 31. This is consistent with the fact that the presence of the methyl substituents increases the relative conformational ground‐state energy more than it would affect the transition‐state energy. The conformational barrier of 32 was unexpectedly found to be similar to those of 27 and 31. This could be explained by a decrease in the transition‐state energy due to an inward bending of the (1,4)‐bridged ring accompanied by a decrease in conformational ground‐state energy due to an outward bending of the methyl groups in 32.
Studies on the Antisense Oligonucleotide Conjugate
Authors: Wang Lai‐Xin , Yang Ding‐Cheng , Lu You‐Yong , Takaki Yasuomi , Taira Kazunari , Li Tong , Zhang Li‐He
Published: May 2015

Four oligonucleotides (15 mer) 13–16 and their conjugates 17–20 in which psoralen was covalently linked to 5′ end were synthesized. Compounds 16 and 20 contain the sequence which is complementary to the sense strand covering the first four codons and the upstream sequence close to the ribosome binding site of c‐Ha‐ras mRNA. It was found that compounds 16 and 20 inhibited the growth of cells that had been transformed by the c‐Ha‐ ras plasmid activated c‐Ha‐ ras oncogene. Compound 20 that carried psoralen was more efficient in inhibiting the growth of transformed cells than compound 16 without psoralen, suggesting that the psoralen might have increased permeability of oligodeoxynucleotides. A model experiment of duplex formation was pertinent to the idea that the inhibitory effect was caused by RNase H activity.
A Synthesis of (+)‐Oblongolide
Authors: Shing Tony K. M. , Yang Jun
Published: May 2015

The absolute configuration of natural oblongolide is reassigned as (3aS,5aR,7S,9aS,9bS)‐3a,5a,6,7,8,9,9a,9b‐octahydro‐7,9b‐dimethylnaphtho[1,2‐c]furan‐1(3H)‐one 2 by a 7‐stage synthesis of its enantiomer 1 from (+)‐citronellol involving a regioselective reduction and an intramolecular Diels‐Alder reaction (IMDA) as the key steps. (+)‐Citronellol was converted into methyl (2E,4E,10E)‐(S)‐(+)‐11‐tert‐butoxycarbonyl‐7‐methyl‐undeca‐2,4,10‐trienoate 7 by sequential Lemieux‐Johnson oxidation, Wittig reaction, pyridinium chlorochromate oxidation, and Wadsworth‐Emmons‐Homer alkenation. A regioselective reduction of the methoxycarbonyl group in 7 afforded tert‐butyl (2.E,8E,10E)‐(S)‐(+)‐2,6‐dimethyl‐12‐hydroxy‐dodeca‐2,8,10‐trienoate 8 from which (+)‐oblongolide was readily obtained via an IMDA reaction.
Receptor Mapping by Comparative Molecular Field Analysis of Phospholipase A2 Inhibitors
Authors: Deng Qiaolin , Cao Bin , Lai Luhua
Published: May 2015

In structure‐based design of phospholipase A2 inhibitors, comparative molecular field analysis is performed on known phospholipase A2 (PLA2) inhibitors to build a pseudo‐receptor map of the enzyme, which is compared to maps from probe searches with proton and methane. The pseudo‐receptor map resembled in steric properties to the map from a probe search. Hence known ligands can be used to deduce the shape and chemical properties of the binding site of a receptor. Useful information for drug design can be obtained from such receptor mapping.
Molecular Orbital Calculations on 2, 4, 6‐Trinitrotoluene
Authors: Chen P. C.
Published: May 2015

Three ab initio calculations (HF/6‐3IG, HF/6‐3IG*, and HF/6‐3IG**) on 2,4,6‐trinitrotoluene were made, The results compare well with xray data, except dihedral angles of NO2 relative to the plane of the benzene ring. The deviations are attributed to packing forces and steric effects in the crystal. The most stable structure was a torsional angle 10° of the methyl top with the benzene ring, unlike toluene. The rotational barriers of the methyl top and the 4‐nitro group are small. Hydrogen bonding, dipole moments and total atomic charges arc calculated.
Programmed‐Temperature Vaporizing (PTV) Liners to Introduce Chlorinated and Sulfur Compounds into a Capillary Gas Chromatograph
Authors: Sye Wen‐Fa , Shu Chia‐Ching
Published: May 2015

Introduction of a sample at a programmed temperature is an attractive approach both for dilute samples in large volumes and to prevent discrimination inside the syringe needle with this injection into a capillary gas Chromatograph. Quantitative data obtained with glass liners packed with trapping materials including glass wool, Tenax TA, Chromosorb 101 and Thermotrap‐TA to analyze chlorinated and sulfur compounds are compared. To eliminate the solvent, these vapors were vented through the injection port cap, which provided greater efficiency than through the split line.
Resolution of Ibuprofen Catalyzed with Free and Immobilized Lipases
Authors: Tai Dar‐Fu , Huang Chi‐Yuan , Chao Yunn‐Hsin , Luo Jih‐Mei , Lin Yi‐Tsong , Wu Shih‐Hsiung
Published: May 2015

Enzymatic hydrolyses of ibuprofen esters produced 99% optically pure S‐(+)‐ibuprofen. The ee values of two enantiomers of ibuprofen were determined on a HPLC equipped with a chiral column.
Formation of Tetraacetal Oxa‐Cages and Convex Oxa‐Cages on Ozonolysis of Bicyclo[2.2.2] Octenes
Authors: Lin Chu‐Chung , Wu Hsieii‐Jen
Published: May 2015

Tetraacetal oxa‐cage compounds 5a and 5b and convex oxa‐cage compounds 7a and 8b are synthesized in a short sequence. Ozonolysis of endo adducts 2a and 2b in dichloromethane at −78 °C followed by reduction with dimethylsulfide gave tetraacetal oxa‐cages 5a and 5b in 35% yields respectively. Ozonolysis of 2a in dichloromethane at −78 °C followed by treatment with triethylamine gave the convex oxa‐cage 7a in 34% yield. These results support an acid‐base proton transfer between the final ozonides and the base. The reasons that these oxa‐cage compounds formed in low yields are discussed. The synthesis of tetraacetal oxa‐cage 14, possessing aromatic substitutents directly on the skeleton of the oxa‐cage, is accomplished.
Formal Syntheses of (±)‐Verbenalol and (±)‐Udoteatrial
Authors: Tai Huo‐Mu , Yang Chau‐Chen , Chang Nein‐Chen
Published: May 2015

A formal total synthesis of (±)‐verbenalol 1 and (±)‐udoteatrial 2 is described. Tie key intermediate is diiodolactone 7.
Oxidation of Tricarbonyl (η1 η2‐but‐3‐en‐1‐yl)iron(0)and Tricarbonyl (η3‐allyl)iron(0) Anion Complexes with Dioxygen
Authors: Hwu Chong‐Chen , Yeh Ming‐Chang P.
Published: May 2015

The addition of reactive carbanions to tricarbonyl(η4‐1,3‐diene)iron(0) complexes proceeded at −78 °C to give putative tricarbonyl(η1,η2‐but‐3‐en‐1‐y1)iron(0) anion complexes and at 25 °C to produce postulated tricarbonyl(η3‐allyl)iron(O) anion complexes; trapping of reactive intermediates with dioxygen produced γ,δ‐unsaturated acids and allylic alcohols, respectively.
Ultrasound Promoted 1, 3‐Dipolar Cycloaddition Reactions of Nitrile Oxides with α, β‐Unsaturated Acetals
Authors: Lu Ta‐Jung , Sheu Lij‐Jyi
Published: May 2015

The 1,3‐dipolar cycloaddition reactions of nitrile oxides and α,β‐unsaturated 1,3‐dioxolanes were effectively accelerated by ultrasound irradiation to give the A2‐isoxazolines with yields and regioselectivities surpassing those of the corresponding thermal reactions.
Effect of Strong Irradiation on Raman Magnetic Resonance in an AX Spin System
Authors: Ye Chaohui , Miao Xija , Jiang Bang‐Chin , Hwangsp Lian‐Pin
Published: May 2015

In Raman magnetic resonance an initially prepared multiple quantum coherence (MQC) in a spin system introduces all the possible single quantum (SQ) and multiple quantum (MQ) NMR signals when an irradiation is applied during the detection period. If the irradiation is weak, the induced signals include those MQs up to the very order of this given MQC, while in the strong irradiation case, those MQs beyond the very order of the given MQC will also appear. An analytical approach based on the product formalism is developed to predict the intensities and frequencies of these induced signals. The analysis provides a complete treatment to cover both cases of weak and strong irradiation. It is also demonstrated with an AX spin system. Experimental results are in qualitative agreement with the analysis.
Multiple Quantum Transitions Induced by Irradiating Single Quantum Coherence in a Heteronuclear Spin System
Authors: Jiang Bang‐Chih , Miao Xijia , Hwang Lian‐Pin , Ye Chaohui
Published: May 2015

In a heteronuclear spin system, with initially prepared single quantum (SQ) coherence of X‐spin, the irradiation of the proton spins will induce all the possible transitions including those SQs and multiple quanta (MQs) available in the system to be studied. The MQs appear in a rather weak irradiation while a strong irradiation results in a complete decoupling situation. Theoretical analysis is made to explain this phenomenon and is agreed qualitatively with experiments in the CH2 group. This phenomenon of MQ induction may happen in a decoupling experiment, when the effective irradiation strength is rather weak and it may also provide a convenient approach to create and then to manipulate MQ coherences in heteronuclear spin systems.
Brønsted Acidity and Aluminum Substitution Characteristics of Si(nAi) Sites in Zeolites: A Theoretical MNDO Calculation
Authors: Prasad S. , Liu Shans‐Bin
Published: May 2015

The Brønsted acidity of the various Si(nAl) sites present in zeolites is evaluated from proton binding energy and LUMO energy calculated by the semiempirical MNDO quantum chemical method. The two calculated energy values both exhibit a linear correlation with the existing 29Si NMR chemical shift and the IR hydroxyl stretching frequency data. The inter‐convertibility between different Si(nAl) sites during an alumination or dealumination process is also evaluated based on the calculated substitution energy. The results indicate that alumination processes are less favorable to occur in zeolites than dealumination processes and the latter is more likely to occur for Si(nAl) clusters that contain the maximum number of aluminum nearest neighbors.
Dynamics of 3′‐Cytidine Monophosphate Bound to Ribonuclease A — A Molecular Dynamic Simulation Study
Authors: Lee Kuei‐Jen , Huang Tai‐Huang
Published: May 2015

Molecular dynamic simulations of the 3′‐cytidine monophosphate (3′‐CMP)/RNase A complex were carried out at three temperatures, 273 K, 300 K and 323 K. The trajectories obtained allowed us to calculate the dynamics of 3′‐CMP in protein complex. The O‐P bond was found to exert angular fluctuations with an average magnitude of 20° 26°, and 30° at 273 K, 300 K, and 323 K, respectively. These values compare quite favorably with those obtained from lineshape simulation of the 31P NMR powder patterns. The magnitude of the translational fluctuation of the center of mass of the ligand was found to be in the range of 0.17 A to 0.21 Å. On the other hand, the phosphate atom was found to fluctuate with amplitude ranging from 0.22 Å to 0.42 Å, depending on orientation. Fluctuation of the dihedral angle, defined by P‐O3‐C3‐C4′ bonds of the ligand, was more restricted in the protein complex as compared to that in free form. The average number of hydrogen bonds formed between the phosphate group and the protein moiety was 1.6 at 273 K and 1.2 at 323 K.
Product‐Specific Methods of Syntheses of Hexaphenylcyclotrisiloxane and Octaphenylcyclotetrasiloxane — Monomers of Phenylsilicones
Authors: Yane Mei‐Hui , Chou Chyuan , Lin Chih‐Hwa
Published: May 2015

Pure hexaphenylcyclotrisiloxane (P3) and octaphenylcyclotetrasiloxane (P4) were synthesized with high yields via proper choice of preparation conditions, such as catalysts, solvents and reaction temperatures, from diphenylsilanediol. Up to 98% yield of this pure starting material can be obtained from diphenyldi‐chlorosilane through modifying a known procedure on carefully adjusting the temperature of hydrolysis and washing procedure. This method produced pure P3 exclusively with high yield (approximately 90%) in ethanol in the presence of concentrated sulfuric acid as the catalyst at various reaction temperatures. P4 was produced exclusively in high yield (approximately 90%) in alcohols in the presence of sodium hydroxide. A method applying HPLC was used to analyze the reaction products quantitatively.
The Structures of Quadricyclanone and its 3‐Cyclopentadienylidene Derivative
Authors: Lee Chia‐Fu , Lin Kuan‐Jiuh , Wang Yu‐Wen , Cheng Uan‐Ling , Chow Tahsin J.
Published: May 2015

The crystal structures of quadricyclanone (2) and 3‐(cyclopentadienylidene)quadricyclane (3) are solved by X‐ray diffraction analyses. Their bonding parameters cannot be accurately estimated by semiempirical models AM1 and PM3.
Psoralen‐Derivatized Oligothymidine Methylphosphonates form Triple Helices with DNA and Crosslink to a Specific Strand
Authors: Lin Shwu‐Bin , Wu Cheng‐Wen
Published: May 2015

Oligothymidine methylphosphonates derivatized at the 5′‐end with 4′‐aminoalkyl‐4,5′,8‐trimethylpsoralen (AMT) were prepared. The interaction of these oligonucleoside methylphosphonates with double‐stranded DNA was studied. Oligothymidine tnethylphosphonates, T7 and T14, were found to form triple helix with an oligodeoxyribonucleotide 45‐mer DNA duplex which contains an A15‐T15 sequence. Upon irradiation with 365 nm (UV light, AMT crosslinked to accessible thymidine residues in the target DNA. Both AMT‐derivatized T7 and T14 crosslink to the T15 containing strand of the double‐stranded DNA target, but they do not crosslink to the A15 containing strand which also contains a potential thymidine crosslinking site. Methylphosphonate oligomer, T7, was derivatized with AMT using either an ethyl‐, butyl‐ or hexyl‐linker. The efficiency of crosslinking is affected by the length of the aminoalkyl linker arm connecting the AMT to the methylphosphonate oligomer. The relative crosslinking efficiencies of the oligomers with these three types of linkers were different. Greatest crosslinking, 45%, was obtained using an oligomer having a butyl‐or a hexyl‐linker. The interaction of oligothymidine methylphosphonates with DNA can be enhanced by using two shorter AMT‐oligomers instead of using one full‐length AMT‐derivatized oligomer. This strategy was demonstrated by the interaction of AMT‐derivatized T7 with duplex DNA 35‐mer and 45‐mer target. The extent of crosslinking to the 45‐mer target, whose binding site can accommodate two molecules of AMT‐derivatized T7, is 45% whereas that with the 35‐mer target, which can accommodate only one T7 molecule, is only 3%. The results of our experiments suggest that AMT‐derivatized oligothymidine methylphosphonates can form triple‐stranded complex and psoralen photoadduct with DNA. The formation of such complexes may be useful in probing and controlling gene expression at the DNA level.
Partition Coefficients in Octanol‐Water and Liquid Chromatographic Behavior of Eight Oxygenated Triterpenes Which are Paired Stereo‐ and Positional Isomers
Authors: Lin Lee‐Juiau , Lee Kuan Rong , Shiao Ming‐Shi
Published: May 2015

The chromatographic behavior of eight lanostanoid triterpenes, which are four pairs of C‐3 epimers and two pairs of C‐3/C‐15 positional isomers, were determined by reverse‐phase high performance liquid chromatography (RP‐HPLC). In the mobile phase systems of acetonitrile‐water‐acetic acid, methanol‐water‐acetic acid, and tetrahydrofuran‐water‐acetic acid, these triterpenes showed a very good linear relationship between capacity factors (k′) and volume fractions of organic modifiers. The partition coefficients (Poet) of these triterpenes in 1‐octanol/water and capacity factors (k′) in RP‐HPLC, when both expressed in logarithm, correlated linearly. This study showed that RP‐HPLC is an effective method to evaluate the molecular hydrophobicity of multi‐functional compounds which are stereo‐ and positional isomers.
Photocycloaddition of 2‐Cyanocycloalk‐2‐Enones to 2, 3‐Dimethylbut‐2‐Ene
Authors: Andresen Sven , Margaretha Paul
Published: May 2015

Irradiation of 5,5‐dimethyl‐6‐oxocyclohex‐ l‐ene‐ l‐carbonitrile (1) in the presence of 2,3‐dimethylbut‐2‐ene afforded 3,3,4,4,7,7‐hexamethyl‐3,4,4a,5,6,7‐hexahydroindeno[1,7‐c,d]‐],2‐oxazole (3) in nearly quantitative yield. In contrast, 4,4‐dimethyl‐5‐oxo‐cyclopent‐l‐ene‐l‐carbonitrile (2) under the same conditions reacted not to a tricyclic isoxazole but to a 2:1 mixture of 3,3,6,6,7,7‐hexamethyl‐2‐oxo‐bicyclo[3.2.0]heptane‐l‐carbonitrile (4) and trans‐3,3‐dimethyl‐2‐oxo‐5‐(2,3‐dimethylbut‐3‐en‐2‐yl)cyclopentane‐l‐carbonitrile (5), respectively.
Photodegradation of Chlorinated Organic Wastes with n‐TiO2 Promoted by P‐CuO
Authors: Chiang Hui‐Jean , Shyuu Jyh Mirng , Wang Chong Mou
Published: May 2015

A variety of chlorinated organic wastes were photodecomposed with p‐CuO‐modified TiO2 particles (denoted CuO/TiO2). Based on the photoactivity measured in oxygenated solutions containing sodium 2,2′‐dichloropropionate, the photoactivity of TiO2 is significantly enhanced with p‐CuO loading; in the case with 0.4 wt% of CuO, the activity is increased by a facor of 4. Photochemical‐TiO2‐slurry cell techniques and voltammetric characterizations suggest this CuO‐promoted enhancement is likely to result from the acceleration of oxygen reduction at TiO2 via CuIIO/CuI0. Long‐term tests showed that these CuO/TiO2 particles are photochemically robust; within 100‐hours' continuous photolysis, insignificant loss in photoactivity was detected. However, increasing loading of p‐CuO may jeopardize the photoactivity, due to the deterioration in the TiO2 absorbability of UV irradiation.
Synthesis and Applications of 3‐Phenylthio‐2‐Sulfolenes
Authors: Chou Shang‐Shing P. , Chao Mao‐Hsun
Published: May 2015

Treatment of 3‐phenylthio‐2‐sulfolene (1) with an equimolar proportion of butyllithium at −78 °C in THF followed by addition of an electrophile gave the 2‐substituted 3‐phenylthio‐2‐sulfolenes (2). The deprotonation was found to proceed only at the vinylic C‐2 position. Some of the 2‐sulfolenes 2 underwent desulfonylation upon heating with base. Of particular interest was the conversion of 3‐phenylthio‐2‐trimethylsilyl‐2‐sulfolene (2h) to its 3‐sulfolene isomer 6 by sequential addition of butyllithium and salicylic acid at low temperatures. The 3‐sulfolene 6 was desulfonylated by Kugelrohr distillation at 150° C under vacuum to give (Z)‐2‐phenylthio‐l‐trimethylsilyl‐1,3‐butadiene (8). The regiochemistry of the Diels Alder reaction of this highly reactive diene 8 was found to be controlled by the phenylthio group, and the stereochemistry is endo addition. Diene 8 was oxidized to its sulfone derivative 12 which also underwent a stereospecific Diels‐Alder reaction.
Reaction of Aromatic and Unsaturated Compounds with the Potassium Permanganate/HCl (HBr) Acetonitrile Reagent
Authors: Liu Lilian Kao , Lin Ching‐Shan
Published: May 2015

Addition of hydrochloric or hydrobromic acid to a solution of potassium permanganate in acetonitrile produced a homogeneous mixture, which is suitable for laboratory chlorination or bromination, respectively. Aromatic compounds more reactive than alkylbenzenes can be chlorinated or brominated without additional catalyst. Alkenes and alkynes give the corresponding vicinal dihaloalkanes and vinyl halides. All reactions complete within two hours under mild condition (25‐60 °C) with excellent to moderate yields.
The Syntheses of Triazole, Sulfur‐Containing Diazole and n‐Phenylthiatriazole Biphenyltetrazoles as Potential Angiotensin II Receptor Antagonists
Authors: Chou Shan‐Yen , Chen Sn‐San , Ho Chin‐Chung , Huang Shiang‐Ling , Huang Tsai‐Mien , Pan Ohm‐Guo , Wang Chia‐Lin , Chen Ying , Lu Hsiao‐Hwa , Liu Shih‐Hwa , Huang Shir‐Ly , Chiang Ren‐Shou
Published: May 2015

The syntheses of triazole, sulfur‐containing diazole and N‐phenylthiatriazole analogs of imidazole angiotensin II antagonist, DuP 753, are reported. 5‐Butyl‐3‐[(2‐trifluoromethyl)phenyl]‐2,1,3,4‐lH‐thiatriazole‐2‐one biphenyltetrazole (63) is found to have good in vitro activity.