Chlorophytoside A, a New Labdane Diterpene Glycoside from Chlorophytum laxum

A new labdane-type diterpene glycoside 1 , chlorophytoside A, had been isolated from Chlorophytum laxum R.Br. The structure had been elucidated as (10S)-6α-hydroxylabda-8,13-dien-15,16-olide 3R-O-β-D-glucopyranoside on the basis of chemical and spectroscopic data.     

A New Prenylated Isoflavone and a New Flavonol Glycoside from Flemingia philippinensis

A new prenylated isoflavonoid, flemiphilippinin G ( 1 ), and a new flavonol glycoside, flemiphilippininside ( 2 ), along with eleven known isoflavonoids were obtained from the roots of Flemingia philippinensis (Merr. et Rolfe) Li . Their structures were elucidated on the basis of spectroscopic data. The in vitro cytotoxicities of compounds 1 – 13 against MCF‐7, A549, and Hep‐G2 cell lines were determined by using the MTT (=3‐(4,5‐dimethylthazol‐2‐yl)‐2,5‐diphenyl‐2H‐tetrazolium bromide) colorimetric assay, and their antioxidant activities were evaluated by ferric‐reducing antioxidant power (FRAP) method. Compound 1 exhibited significant cytotoxicity against all the tested cell lines with IC₅₀ values of 4.8–7.3 μM , and compound 2 was found to be inactive. Both compounds 1 and 2 showed weak antioxidant activities with FRAP values of 110±15 and 124±16 μmol/g, respectively.     

Three Saponins, a Steroid, and a Flavanol Glycoside from Achyrantes aspera

Summary.  Three bisdesmosidic saponins, 20-hydroxyecdysone, and quercetin-3-O-β-D-galactoside were isolated from the methanol extract of the aerial parts of Achyranthes aspera L. (Amaranthaceae). Their structures were established on the basis of NMR spectroscopic analysis; the complete ¹H and ¹³C assignments of the compounds were achieved by means of 2D NMR studies. Received July 21, 1999. Accepted August 26, 1999     

A New Flavanone and a New Flavanone Glycoside from ScuteUaria baicalensis

A new flavanone （2S）-5, 7, 2＇, 5＇-tetrahydroxy-flavanone 1 together with a new flavanone glycoside （2S）-5, 7, 2＇, 5＇-tetrahydroxy-flavanone 7-O-13-D-glucopyranoside 2, were isolated from the dry roots of Scutellaria baicalensis. Their structures were elucidated on the basis of spectroscopic data.     

A New Iridoid Glycoside and a New Iridoid from Pedicularis kansuensis f. albiflora

A new iridoid glycoside 1 and a new iridoid 2 were isolated from the whole plant of Pedicularis kansuensis f. albiflora. Their structures were elucidated by spectroscopie methods.     

A New Iridoid Glycoside and a New Iridoid from Pedicularis kansuensis f. aibiflora

A new iridoid glycoside 1 and a new iridoid 2 were isolated from the whole plant ofPedicularis kansuensis f. albiflora. Their structures were elucidated by spectroscopic methods.     

A Sequence of Aldol Condensations and a Michael Addition Giving a Cyclohexenone Ring System

Summary.  The reaction of 1,5-diphenylpentanetrione, 4-chlorobenzaldehyde, and acetone in the presence of methylamine resulted in 2,6-dibenzoyl-5-(4-chlorphenyl)-3-methyl-cyclohex-2-en-1-one, which was formed by a sequence of a Knoevenagel reaction, an aldol condensation, and a Michael addition in a one-pot reaction. Received August 16, 2000. Accepted September 8, 2000     

Zinc-Promoted Reduction of 1,2-Diketones: A Simple, Efficient, and Mild Approach to a-Hydroxy Ketones

Summary.  1,2-Diketones were readily converted to α-hydroxy ketones in high to excellent yields using zinc in saturated ammonium chloride solution. Received June 7, 2001. Accepted (revised) August 7, 2001     

Novel Fused Heterocycles: Synthesis and Activity of 5,6-Dihydro-7-thia-1,3,3a,5-tetraazainden-4-one and 1-Thia-3,4a,9-triazafluoren-4-one Derivatives

Summary.  Thiatetraazaindenone derivatives were synthesized by reaction of 3-substituted 1,2,4-triazole-5-thiols with N-substituted N-chloromethyl carbamoyl chlorides. A series of thiatriazafluorenone derivatives were also prepared by reaction of benzimidazole derivatives with the same substrate. Some of the new compounds show fungicidal, herbicidal, and insecticidal activity. Received February 14, 2000. Accepted (revised) April 11, 2000     

A Rapid Spectrophotometric Method to Resolve Ternary Mixtures of Propyphenazone, Caffeine, and Acetaminophen in Tablets

Summary.  A simple and rapid derivative spectrophotometric assay procedure is described for the analysis of caffeine (1), acetaminophen (2), and propyphenazone (3) in tablet formulations. The concentration range of application is 5.0–25.0 μg·cm⁻³ for 2 and 3 and 1.0–5.0 μg·cm⁻³ for 1. The method involves the extraction of the drugs from tablets with 0.1 N H₂SO₄, filtration, appropriate dilution, and measurement of the fourth derivative absorbance values at zero crossing wavelengths of 230.0, 263.2, and 256.6 nm for 1, 2, and 3. As a reference method, a reversed phase HPLC procedure was developed. Commercially available tablets were analyzed; statistical comparison of the results with those obtained from the reference method showed good agreement. The derivative spectrophotometric method has the advantage of being simple, rapid, inexpensive, and easy to perform. Received April 18, 2001. Accepted (revised) June 5, 2001     

Synthesis, Characterization, and Fluxional Behaviour of Binuclear Palladium Complexes with a Half-A-Frame Structure

Summary.  Partial removal of chloride anions from the dimer [Pd(η³-2-CH₃*C₃H₄)(μ-Cl)]₂ with AgTf(Tf = CF₃SO₃) followed by addition of dppm affords [Pd₂(η³-Me*C₃H₄)₂(μ-Cl)(μ-dppm)]Tf (1). The substitution of Cl⁻ by X⁻ (X = pz, SC₆F₅, S _py ) using the appropriate salts yields the new derivatives [Pd₂(η³-Me*C₃H₄)₂(μ-X)(μ-dppm)]Tf (2–4). All complexes exhibit a dinuclear half-A-frame structure with two isomers present in solution. The isomers differ in the relative orientation of the two allyl groups (cis or trans). The isomer interconversion was studied by variable temperature ¹H NMR spectroscopy. The molecular structures of 2 and 4 were solved by X-ray diffraction studies. A distorted boat conformation of the seven- or six-membered metallacycle was found in both cases. Received June 7, 2000. Accepted June 20, 2000     

Morpholine Adsorbed on Silica Gel: A Novel and Mild Basic Catalyst for the Synthesis of α,β-Unsaturated Nitroalkenes

Summary.  Syntheses of α,β-unsaturated nitroalkenes have been carried out under mild condition using morpholine adsorbed on silica gel as a novel catalyst. Received February 14, 2000. Accepted March 28, 2000     

X-Ray Emission from Thin Films on a Substrate – Calculation and Experiments

 Monte Carlo simulation of electron transport in solids is widely used in electron microscopy, spectroscopy and microanalysis. The reliability of physical models incorporated in a Monte Carlo code is usually checked by comparing with experimental results. Elastic or inelastic collisions are usually considered as the basic interactions of electrons with atoms. In our Monte Carlo code the single scattering model is employed for simulation of X-ray emission from thin films of Au on the Si substrate. The electron beam energy was in the range 10–30 keV, the take-off-angle was 40°. The simulated values of X-ray production were calculated in our Monte Carlo code using several models of ionisation cross-sections. For the emitted intensities the depths of inelastic collision and X-ray absorption were taken into account, then the k-ratios were calculated. These data were compared with experimental values of k-ratios calculated from X-ray intensities of Au M and Au L characteristic lines. We followed mainly the dependence of the k-ratios of the film element on film thickness. The film thickness was in the range 0.05–1 μm. Reasonably good agreement was found for dependences of X-ray intensity on film thickness in the whole energy range and for both lines, especially for Powell’s model of the ionisation cross-section.     

Synthesis,Characterization, and Electrochemical Properties of a Novel Macrocylic Ligand and its Transition Metal Complexes

Summary.  2,3-Dibromo-6,7,13,14,15,16,22,23-octahydro-14,15-bis-(hydroxyimino)-tribenzo [e,k,q][1,4,7,10,13,16]tetraoxadiazacyclohexadecine (LH₄) was prepared by condensation of 1,2-bis-(2′-aminophenoxyethoxy)-4,5-dibromobenzene with cyanogen-di-N-oxide. Mono-, di-, and trinuclear transition metal complexes of this ligand ((LH₃)₂Ni, (LH₃)₂Zn, (LH₃)₂Co, (LH₃)₂Cu, (LH₃)₂Fe, (LH₃)₂(UO₂)₂(OH)₂, (LH)₂Cu₃, (LH)₂Co₃) were synthesized under basic conditions. The electrochemical properties of the mono- and dinuclear complexes were studied by cyclic voltammetry in DMSO solution containing TBAP. The results showed that all redox processes are based on the metal center and the oxime ligands stabilize the Ni(III), Fe(III), Co(III), and Cu(III) species formed during oxidation. The Fe(II) and U(VI)O₂ complexes displayed a different behaviour: a reduction peak with the corresponding anodic signal during the reverse scan was observed. The oxime moiety also stabilizes U(V)O₂ which forms during the reduction process of the uranyl complex. Cu(II) was adsorbed on the electrode surface upon scanning cathodically. Received August 20, 2001. Accepted (revised) October 17, 2001     

Comparative Analysis of a Solar Control Coating on Glass by AES, EPMA, SNMS and SIMS

 A solar control coating was analysed by different methods of surface analysis with respect to the layer sequence and the composition and thickness of each sublayer. The methods used for depth profiling were Auger electron spectroscopy, electron probe microanalysis, secondary neutral mass spectroscopy and secondary ion mass spectroscopy based on MCs⁺. The structure of the coating was unknown at first. All methods found a system of two metallic Ag layers, embedded between dielectric SnO_X layers. Additionally, thin Ni-Cr layers of 1–2 nm were detected on top of the Ag layers. Thus the detected layer sequence is SnO_X/Ni-Cr/Ag/SnO_X/Ni-Cr/Ag/SnO_X/glass. The Ni:Cr ratio in the nm-thin layers could be quantified by every method, the Cr fraction corresponding to less than one monolayer. We compare the capabilities and limitations of each method in routinely investigating this solar control coating. Importance was attached to an effective investigation. Nevertheless, by combining all methods, measuring artefacts could be uncovered and a comprehensive characterisation of the system was obtained.     

Structural,Vibrational, and Gasochromic Properties of Porous WO<Subscript>3</Subscript> Films Templated with a Sol-Gel Organic–Inorganic Hybrid

Summary.  The structure and the gasochromic properties of sol-gel-derived WO₃ films with a monoclinic structure (m-WO₃) were studied by focusing attention on the size of the monoclinic grains. The size of the m-WO₃ grains is modified by the addition of an organic–inorganic hybrid to the initial peroxopolytungstic acid (W-PTA) sols which are based on chemically bonded poly-(propylene glycol) to triethoxysilane end-capping groups (ICS-PPG). The results obtained with scanning electron microscopy (SEM) and transmission electron microscopy (TEM) show that the heat treatment (500°C) of WO₃/ICS-PPG (0.5, 1, 2, 5, and 10 mol%) composite films results in a change of their morphology, and nanodimensional pores are formed between the grains. High-resolution TEM (HRTEM) analysis revealed the presence of an amorphous phase on the outside of the m-WO₃ grains, whereas energy-dispersive X-ray spectra (EDXS) showed that this amorphous phase contained W and Si. Impregnation of the WO₃/ICS-PPG film with H₂PtCl₆/i-propanol solution followed by heat treatment at 380°C gave the films their gasochromic properties. Infrared and Raman spectroscopic studies of the WO₃/ICS-PPG film confirmed the results of the corresponding HRTEM and EDXS analysis. In situ UV/Vis and in situ IR spectra of the films were measured in hydrogen and in air, and colouring/bleaching changes and the corresponding kinetics were assessed. The IR spectra of gasochromically coloured films showed that the mesoporous WO₃/ICS-PPG (1 mol%) film transforms to tetragonal H _x WO₃ bronze. The IR spectra of the H _x WO₃ bronze are discussed with the aim to establish the existence of the metal-OH vibrations of gasochromically formed oxyhydroxide tungsten bronze. Received October 4, 2001. Accepted (revised) November 19, 2001     

Film forming properties of asphaltenes and resins. A comparative Langmuir– Blodgett study of crude oils from North Sea, European continent and Venezuela

 Asphaltenes and resins were separated from different crude oils, dissolved in different paraffinic and aromatic solvents and studied by means of Langmuir technique. It was found that the resin films are more compressible and more polar than the corresponding asphaltene films. Intermolecular aggregation between asphaltene molecules was more prominent than between resin molecules, and the size of the final aggregates depended on the nature of the solvent and the bulk concentration of the aggregating species. Even when present in smaller amounts than asphaltenes on the surface, the resins dominate the film properties. Received: 19 January 1998 Accepted: 15 April 1998     

A Dehydrogenated Cycloadduct of N-Phenylmaleimide and the Azomethine Ylide Derived from Ninhydrine and Phenylalanine: Structure and Conformation

Summary.  The structure of the dehydrogenation product 1′,3a′-dihydro-3′-((1,3-dioxoindan-2-ylidene)-phenyl-methyl)-5′-phenyl-spiro-(indan-2,1′-pyrrolo[3,4-c]pyrrole)-1,3,4′,6′-(5′H, 6a′H)-tetrone derived from the cycloadducts (±)-(3a′S,6a′R)-1′,3a′-dihydro-3′-((R)-α-(1,3-dioxoindanyl)-benzyl)-5′-phenyl-spiro-(indan-2,1′-pyrrolo[3,4-c]pyrrole)-1,3,4′,6′(5H,6a′H)-tetrone and/or (±)-(3a′S,6a′R)-1′,3a′-dihydro-3′-((S)-α-(1,3-dioxoindanyl)-benzyl)-5′-phenyl-spiro-(indan-2,1′-pyrrolo[3,4-c]pyrrole)-1,3,4′,6′(5H,6a′H)-tetrone, which were synthesized by 1,3-dipolar cycloaddition of N-phenylmaleimide to 2-((2-(1,3-dioxoindan-2-yl)-2-phenyl-ethenyl)-imino)-indan-1,3-dione, was determined by X-ray analysis. Crystal data (CCD, 180 K): rhombohedral, R&3macr;;, a = 34.0871(7), c = 13.9358(5) ?, Z = 18; the structure was solved by direct methods and refined by full-matrix least-squares procedures to R(F, I ≥ 3σ(I)) = 0.053. The molecule contains a central folded ring system of two cis-fused 5-membered heterocyclic rings; each ring is nearly planar, and the angle between the rings amounts to 59.0°. Dynamic ¹H NMR spectroscopy of the product revealed an exchange process caused by restricted rotation of the double bonded 1,3-indandione moiety and the phenyl group about the C_sp2-C_sp2 single-bonds. Molecular modeling and complete lineshape analysis indicated a four site exchange process for which free energies of activation and free energies could be established. ΔG ^‡ values for the barriers of rotation are in the range of 57–59 kJ · mol^− 1 at 273 K, which is unusually high for an unsubstituted phenyl group. Received May 3, 2001. Accepted (revised) June 8, 2001     

Bis-(bis-(1,3-diaminopropane)-copper(II) Tetracyanonickellate(II)) Tetrahydrate: Preparation, Characterization, and Crystal Structure of a Novel Molecular Tetracyanonickellate

Summary.  [Cu(tn)₂Ni(CN)₄]₂ċ4H₂O and Cu(tn)₂Ni(CN)₄ (tn = 1,3-diaminopropane) were prepared and characterized. The hydrate is unstable on air and readily dehydrates to Cu(tn)₂Ni(CN)₄. Crystal structure analysis of the hydrate at 150 K revealed a novel tetranuclear molecular structure of the tetracyanonickellate. The building elements are two [Cu(tn)₂]²⁺ cations (coordination numbers of Cu: 5 and 6, respectively), two [Ni(CN)₄)²⁻ anions, and crystal water. The two cations are linked by one tetracyanonickellate anion via bridging cyano groups placed in cis positions. The second anion is bound weakly (Cu-N = 2.82 ?) via one μ₂-bridging cyano ligand. The tetranuclear molecules and pairs of solvate water molecules are linked by strong hydrogen bonds, thus forming infinite planes which are linked in the third dimension by considerably weaker hydrogen bonds. Received May 9, 2000. Accepted (revised) August 21, 2000     

Estimation of Li+, K+ and Ca2+ Complexation with [12] crown-4, [15] crown-5 and [18] crown-6 Using a Na+ ISE in Dioxane-Water, Part IV*

 The (1:1) Na⁺ equilibrium constants, Ke1, of macrocyclic ethers of [12]crown-4, [12]crown-5 and [18]crown-6 were determined with a Na⁺ ISE in the presence of a second cation e.g. Li⁺, K⁺ and Ca²⁺ in dioxane/water (50/50). We estimated the (1:1) equilibrium constants, K e2 of the macrocyclic ethers with Li⁺, K⁺ and Ca²⁺ by this way. The binding selectivity of a macrocyclic ether between two cations was estimated in the same binary solvent mixture where the water hydration role is diminished. Results showed clearly the effect of macrocyclic size and cation radii in a solution. Received October 27, 1998. Revision March 22, 1999.