Mass and NMR spectra of haplophyllidine and perforine and of their derivatives

Conclusions The mass and NMR spectra of haplophyllidine, perforine, and their derivatives have been studied. The influence of the open and cyclic forms of the molecular ion on the nature of the fragmentation has been discussed. The main routes of fragmentation of the compounds considered are due to the presence of substituents at C₈ and C₄.Khimiya Prirodnykh Soedinenii, Vol. 5, No. 4, pp. 273–279, 1969     

The chemical transport of molybdenum and tungsten and of their dioxides and sulfides

Experiments have been made and an extensive thermodynamic discussion has taken place concerning the chemical transport of Mo, W, MoO₂, WO₂, MoS₂ and WS₂ in the presence of iodine. Efforts have been made to find the species via which Mo and W can migrate within the gas phase.Results: In each case the transport proceeds via the oxide iodides MoO₂J₂ and WO₂J₂ respectively, as already known for the dioxides. Thus the chemical transport of Mo, W, MoS₂ and WS₂ needs not only J₂ but also H₂O, usually liberated from the wall of the quartz ampoule.By means of J₂ + H₂O, the metals can be transported into the high temperature region of the ampoule (e.g., 1050 → 1150°C), whereas the transport of the sulfides proceeds in the opposite direction (e.g., 900 → 700°C).For the sulfide-transport the influence of the ratio of the transport agents $\text{J}{}_2\text{H}{}_2\text{O}$ has been discussed.The water content of the quartz glass out of which the ampoules are made is an important source for water, influencing the reactions.The addition of graphite which considerably lowers the H₂O partial pressure prevents any transport of the metals or the sulfides, which proves that the use of J₂ alone as a transport agent is insufficient in these cases.The gaseous iodides MoJ_x and WJ_z are without any importance under the experimental conditions used for the transport of the metals, their dioxides and sulfides.The partial pressures of MoO₂(OH)₂ and WO₂(OH)₂ under the experimental conditions chosen may usually be neglected. But in the system $\text{MoO}{}_2\text{H}{}_2\text{O}$ the transport via MoO₂(OH)₂ (1000 → 800°C) has been observed.The synthesis of MoO₂ and WO₂, starting with the elements or with powder of metal and trioxide is promoted by the addition of J₂. The reaction steps involved are discussed.     

Quantification of polyphenols and flavonoid content and evaluation of anti-inflammatory and antimicrobial activities of Stenocereus stellatus extracts

The hexanic, ethyl acetate and methanolic extracts from branches of Stenocereus stellatus were tested in both the 12-O-tetradecanoylphorbol-13-acetate (TPA) – induced ear oedema model and antimicrobial activity assay. The % of oedema inhibition, the Minimum Inhibitory Concentration (MIC), as well as the polyphenolic and flavonoid content were determined. Also, extracts were analysed by gas chromatography–mass spectrometry (GC–MS). In TPA model, the three extracts showed moderate oedema inhibition. In the antimicrobial activity assay, methanolic extract shows better MIC against all strains. The lowest MICs were for Candida albicans (31 μg/mL) and Rhizopus sp. (15 μg/mL). Also, 50.78 mg eq. of gallic acid/g extract of polyphenol and 115.12 mg eq. of catequine/g extract of flavonoids content were founded in ethyl acetate extract. In the chromatographic analysis, β-sitosterol, β-amyrine, betulin and some other molecules were identified. The results show that S. stellatus possess antimicrobial activities against some fungus species.     

Ellipsometry and x-ray reflectometry characterization of self-assembly process of polystyrenesulfonate and polyallylamine

Self-assembly of polyelectrolytes-polystyrenesulfonate (PSS) and polyallylamine (PAH) with added salts of MnCl and NaBr was studied by x-ray reflectometry and ellipsometry technique. The thickness of PSS-PAH bilayer was measured to be 5.1±0.2 nm according to reflectometry and 6.1±0.7 nm according to ellipsometry. The discrepancy in data is attributed to the difference in the interaction of the interfaces with x-rays and visible light. The films are found to be rather homogeneous and the deposition process regular. The refraction indices of the deposited films were found to ben ₀=1.50±0.05,k ₀=0.07±0.05,n _e=1.53±0.05k _e=0, optical axis being perpendicular to the surface. The values of refractivity characterize the whole film (up to seven bilayers) and do not vary with increasing thickness.     

Synthesis and Structure of YbCuGe and YbIrGe

Summary. The equiatomic ytterbium–transition metal–germanides YbCuGe and YbIrGe were synthesized in single crystalline form from CuGe and IrGe master alloys and ytterbium via the Bridgman technique and they were characterized through their X-ray powder patterns. The structures were refined from X-ray single crystal diffractometer data: NdPtSb type, P6₃mc, a=421.36(8), c=703.9(1) pm, wR2=0.0234, 210 F² values, 11 variable parameters, BASF=0.35(9) for YbCuGe and TiNiSi type, Pnma, a=671.09(6), b=421.55(5), c=757.16(7) pm, wR2=0.0782, 519 F² values, 20 variable parameters for YbIrGe. The copper (iridium) and germanium atoms build up [CuGe] and [IrGe] networks. In YbCuGe the two-dimensional [CuGe] network consists of puckered layers of Cu₃Ge₃ hexagons (247pm Cu–Ge) that are charge balanced and separated by the ytterbium atoms. In contrast, the ordered Ir₃Ge₃ hexagons show a strong orthorhombic distortion and the [IrGe] network is three-dimensional with a distorted tetrahedral germanium coordination around iridium with almost equal Ir–Ge distances (252–259pm). The ytterbium atoms fill cages within this network. The cell volumes of YbCuGe and YbIrGe are indicative for purely trivalent ytterbium.     

On the synthesis and polymerization of t-butyl-p-vinylperbenzoate and the grafting of its homo- and copolymers

The monomer initiator t-butyl-p-vinylperbenzoate (TBVP) was synthesized and its homo- and copolymerization with styrene, methacrylonitrile, isoprene and phenylmethacrylate was investigated. TBVP is preponderantly incorporated in all four systems; values of Q = 2.27 and e = ?0.13 characterize TBVP as a weak donor with a high monomer reactivity. Kinetic considerations show that all propagation steps in which TBVP takes part are faster or at least as fast as the self-propagation steps of the comonomers used. Rate constants and activation energies of the thermal decomposition of poly(t-butyl-p-vinylperbenzoate) and poly(t-butyl-p-vinylperbenzoate-co-styrene) were determined. The polymer initiators were used for grafting experiments with styrene, acrylonitrile, and methyl methacrylate. The data evaluated for the grafting efficiency, the success of grafting, and the degree of grafting show that these polymers of p-vinylperbenzoate are efficient initiators.     

Measurements and predictions of density and carbon dioxide solubility in binary mixtures of ethanol and n-decane

The solubility of carbon dioxide (CO₂) in binary mixtures of ethanol and n-decane has been measured using an in-house developed pressure-volume-temperature (PVT) apparatus at pressures up to 6 MPa and two different temperatures (303.2 and 323.2 K). Three different binary mixtures of ethanol and n-decane were prepared, and the densities of the prepared mixtures were measured over the studied pressure and temperature ranges. The experimental data of CO₂ solubility in the prepared mixtures and their saturated liquid densities were then reported at each temperature and pressure. The solubility data indicated that the gas solubility reduced as the ethanol mole fraction in the liquid mixture increased. The dissolution of CO₂ in the liquid mixtures resulted in the increase in the saturated liquid densities. The impact of gas dissolution on the saturated liquid densities was more pronounced at the lower temperature and lower ethanol compositions. The experimental solubility and density data were compared with the results of two cubic equations of state (EOSs), Soave–Redlich–Kwong (SRK) and Peng–Robinson (PR). The modeling results demonstrated that both EOSs could predict the solubility data well, while the saturated liquid densities calculated with the PR EOS were much better than those predicted with the SRK EOS.     

Thermodynamic and spectroscopic properties of mixtures of β-lactoglobulin and dioleylphosphatidylcholine

 The behavior of the single spreading monolayers of β-lacto-globulin (β-LG) and dioleyl-phosphatidylcholine (DOPC), as well as their mixtures, has been studied on subphases containing Na⁺ or Ca⁺⁺ ions. The results show an influence of temperature and subphase on the studied systems. The behavior of the areas as a function of the weight fraction of the two components shows significative and prevalently positive deviations from the additivity and their bidimensional miscibility. The variation of ΔG ^ex, ΔH ^ex and ΔS ^ex calculated for the DOPC–β-LG mixture having maximum deviation on two different supports allows to deduce that the interactions are prevalently repulsive. FTIR–ATR spectra of transferred plurilayers show that DOPC has a surface orientation which can originate the miscibility between the protein and DOPC. Received: 3 February 1997 Accepted: 3 June 1997     

Absorption UV spectroscopy and electronic structure of ionic and tautomeric forms of hydroxy and methoxy derivatives of cytosine and adenine,and of some 5-substituted analogs of pyrimidines

The individual absorption spectra of various ionic and tautomeric species of some derivatives of nucleic-acid components have been determined by computer handling of the summary spectra of these compounds measured at different pH values. These individual spectra have been decomposed into separate bands represented by log-normal curves and corresponding to different electronic transitions. Using the parameter system calculated earlier for the molecules of the vitamin B₆ family, the calculation of the electronic spectra and electronic structure of various ionic and tautomeric species of the molecules studied have been carried out in the π-electron approximation. These properties have also been calculated by the all-valence electronic method CNDOS . The calculated results correlate well with both approximations and with our experimental spectral data. The localization of the molecular electronic excitation studied on the transition to the S₁ and T₁ states is considered in connection with the reactivity in these states.     

Structural and dynamical properties of aqueous mixtures of pectin and chitosan

In this study phase separation, structure, and dynamics of aqueous pectin-chitosan mixtures of different ratios and a pure aqueous pectin sample have been investigated under various conditions by turbidimetry, SANS and dynamic light scattering (DLS). Only the mixture with r = 0.75 gelled upon decreasing the temperature ((r ≡ m_pectin/(m_pectin + m_chitosan), where m denotes the mass of the considered component). The pure pectin sample (r = 1) did not gel and the decrease in temperature seemed to promote phase separation. The addition of chitosan reduced the tendency of pectin to phase separate in the mixtures of pectin and chitosan. The general trend when cooling the samples was that the turbidity and the growth of the turbidity became more pronounced as the amount of pectin in the mixture was increased. The wavelength dependence of the turbidity indicated a change of the conformation of pectin chains from an extended form to a more compact structure in pectin solutions without chitosan as the temperature decreased. This was not observed for the mixture of pectin and chitosan. SANS measurements revealed excess scattered intensity in the low wave vector area with the strongest upturn for the pure pectin sample (r = 1). DLS experiments showed longer slow relaxation times after a temperature quench for all samples, with the most pronounced effect for the mixture of pectin and chitosan with r = 0.75. The synergism between pectin and chitosan at high pectin contents (r = 0.75) generated large association complexes over time.     

Na0.33WO3溶胶及薄膜的制备与光致变色性质研究

无机光致变色材料在图像显示、光记录、信息存储和光转换方面有着巨大的潜在应用前景,引起了材料工作者的广泛重视[1￣3]。氧化钨是一种重要的无机光致变色材料,目前对氧化钨的研究多以无定     

Synthesis and pharmacological activities of some dibenzopyrazolocinnolines and dibenzopyridazinoquinoxalines

Derivatives of three new classes of heterocyclic compounds have been synthesized. The first class comprises the synthesis of pyrimidino- and imidazolopyrazolopyridazine using 11 H-dibenzo[f,h]pyrazolo[3,4-c]-cinnoline-13-amine. The second class involves the synthesis of triazine derivatives using 11 H-dibenzo-[f,h]pyrazolo[3,4-c]cinnoline-13-diazonium chloride. The third class deals with the synthesis of polycyclic compounds using dibenzo[f,h]pyridazino[4,5-b]quinoxaline-10,13-diamine. The pharmacological screening has shown that several of these compounds have good antiparkinsonian activities comparable to Benzatropine. The detailed synthesis, spectroscopic data, and pharmacological properties are reported.     

Plasma homo- and copolymerizations of tetrafluoroethylene and chlorotrifluoroethylene

The plasma homo- and copolymerizations of tetrafluoroethylene (TFE) and chlorotrifluoroethylene (CTFE) in a capacitively coupled tubular reactor (TR) with external electrodes were studied by means of microgravimetry and FT-IR and XPS analyses. The deposition rates for CTFE/TFE plasma copolymers, as well as the ratios of IR absorbances at 1180 and 1225 cm⁻¹, and the XPS-derived Cl/C and F/C ratios, varied regularly with mol % CTFE in the feed, all of which results were dependent upon the rf power at which the plasma copolymerizations were conducted. The deposition rates for the plasma homopolymers of TFE (PPTFE) and CTFE (PPTCFE) depended markedly on rf power (W) and monomer molar flow rate (F). The F/C ratio for PPTFE was nearly independent of the composite parameter,W/FM (whereM is the monomer molecular weight), while for PPCTFE, the F/C ratio decreased significantly and the Cl/C ratio increased slightly with increase inW/FM. The percentage of carbon as CF₃ was 20–24% in PPTFE and 7–14% in PPCTFE. Plots of deposition rate versusW/FM for PPTFE and PPCTFE obtained in a TR differed considerably from corresponding plots in the literature for the same homopolymers prepared in a glass-cross or bell-jar reactor.     

Design,synthesis and evaluation of the antioxidant and neuroprotective properties of alkyl- and terpenylphenolchlorin conjugates

The new amide conjugates were synthesized from methyl pheophorbide a and its carboxyl derivatives by reactions with aminomethyl derivatives of 2,4-dimethylphenol, 2-isocamphyl-4- methylphenol, 2-bornyl-4-methylphenol, and 2-isobornyl-4-methylphenol. The antioxidant activity of some conjugates was established by investigation of their ability to inhibit the accumulation of secondary products of lipid peroxidation in a brain of laboratory mice in vitro. The neuroprotective properties of porphyrin and terpenylphenol conjugates have been studied on the model of H₂O₂-induced oxidative stress in SH-SY5Y cells (neuroblastoma).

     

Synthesis and Structure of YbCuGe and YbIrGe

The equiatomic ytterbium–transition metal–germanides YbCuGe and YbIrGe were synthesized in single crystalline form from CuGe and IrGe master alloys and ytterbium via the Bridgman technique and they were characterized through their X-ray powder patterns. The structures were refined from X-ray single crystal diffractometer data: NdPtSb type, P6₃mc, a=421.36(8), c=703.9(1) pm, wR2=0.0234, 210 F² values, 11 variable parameters, BASF=0.35(9) for YbCuGe and TiNiSi type, Pnma, a=671.09(6), b=421.55(5), c=757.16(7) pm, wR2=0.0782, 519 F² values, 20 variable parameters for YbIrGe. The copper (iridium) and germanium atoms build up [CuGe] and [IrGe] networks. In YbCuGe the two-dimensional [CuGe] network consists of puckered layers of Cu₃Ge₃ hexagons (247pm Cu–Ge) that are charge balanced and separated by the ytterbium atoms. In contrast, the ordered Ir₃Ge₃ hexagons show a strong orthorhombic distortion and the [IrGe] network is three-dimensional with a distorted tetrahedral germanium coordination around iridium with almost equal Ir–Ge distances (252–259pm). The ytterbium atoms fill cages within this network. The cell volumes of YbCuGe and YbIrGe are indicative for purely trivalent ytterbium.     

Synthesis of pyrazolo-enaminones,bipyrazoles and pyrazolopyrimidines and evaluation of antioxidant and antimicrobial properties

A novel pyrazolo-enaminones, bipyrazoles and bipyrazolopyridines from 1-(5-hydroxy-3-methyl-1-phenyl-1H-pyrazol-4-yl)butane-1,3-dione and 4-methyl-2-phenyl-2H-pyrazolo[3,4-b]pyridine-3,6(3aH,7H)-dione have been synthesized by assisted heating with microwave radiation without any catalyst. The pyridine and pyrazole ring formation has been developed from easily accessible enamino keto esters by formylation followed by intramolecular cyclization. The general applicability for the synthesis of the important pyrazolo-enaminones, bipyrazoles and pyrazolo-pyridines heterocycles was attributed to simplicity of operation, synthesis without catalyst, energy efficiency (shorter reaction time under microwave irradiation), good yields, more environmentally friendly and more cost-effective procedure. The antioxidant activity of new heterocyclic compounds was evaluated by free radical scavenging by DPPH assay. Several of these compounds showed good activity against both Gram-positive (S. aureus) and Gram-negative (E. coli) bacteria.     

Hirshfeld surface analysis and spectroscopic and DFT studies of p-acetotoluidide and p-thioacetotoluidide

The Hirshfeld surface analysis, theoretical calculation, and IR and Raman spectra of p-acetotoluidide and p-thioacetotoluidide were reported. Hirshfeld surfaces and fingerprint plot have been used for visualizing, exploring, and quantifying intermolecular interactions in the crystal lattice of the title compounds. The packing of the molecules in the crystal structure of p-acetotoluidide and p-thioacetotoluidide forms the chains of N–H···O and N–H···S hydrogen bonds, respectively. The close contacts are also dominated by H···H and H···C/C···H interactions. The analysis of Hirshfeld surface has been well correlated with the spectroscopic studies. Theoretical calculations of the title compounds’ isolated molecule have been carried out using DFT at the B3LYP level.     

Characterization and kinetic study of sunflower oil and biodiesel

In this study, the physico-chemistry characterization and kinetic study of the thermal decomposition of sunflower oil and its biodiesel were carried out. Sunflower biodiesel was synthesized by the methanol route and basic homogeneous catalysis. The physicochemical characterization of the sunflower oil and biodiesel were performed according to standards set out in the ANP resolution, and both are in accordance to the specifications. The chromatographic analysis was obtained by GC-FID. The yield of conversion of 97.4 wt% of sunflower oil in methyl esters confirms the efficiency of the conversion of the fatty acids into esters. The thermal analysis was performed on a thermobalance, using heating rates of 5, 10, and 20 °C min⁻¹. In these three rates, we observed a single well-defined step of mass loss that describes the volatilization and decomposition of the sunflower oil and the biodiesel. The kinetic study was performed using equations of approximation and integration methods such as Coats–Redfern, Van Krevelen, and Horowitz–Metzger. The kinetic parameters reaction order (n) and apparent activation energy (E _a), obtained by applying these method were correlated.     

DFT and experimental investigation of catecholate derivatives of benzoic acid and pyridine

DFT calculations, at the B3LYP/TZVP level of theory for pyrocatechuic acid (2,3-dihydroxybenzoic acid, 2,3-DHBA), 2,3-dihydroxy-pyridine 2,3-DHPY and their ionized and oxidized forms, have been performed, in combination with experimental data. ¹H, ¹³C, 2D COSY NMR, IR and electronic spectra were coupled to the theoretical calculations. The geometrical parameters were checked by reported crystallographic data. The neutral form of pyrocatechuic acid is the most stable, regarding its ionized (mono-, di- or tri-anions) and oxidized ([2,3-DHBA-sqH]⁻, [2,3-DHBA-sq]²⁻, [2,3-DHBA-q]⁻) species. The most stable conformer 2,3-DHBA-H₃ displays the COOH– group co-planar to the catechol ring, hydrogen bonded with OH(2). In the [2,3-DHBA-H₂]⁻ the stable conformer shows the presence of protonated COOH, while OH(2) is ionized. The tri-anion is the form of 2,3-DHBA with the highest energy. Among the protonated semiquinone radical forms [2,3-DHBA-sqH]⁻, more stable is the OH(3)-oxidized, cited 21.3 kcal/mol lower in energy from the OH(2)-oxidized; in this latter the COO⁻ group lies perpendicular to the benzene ring. The same calculation procedure fitted on the oxygenated [2,3-DHBA-H-O₂]²⁻ shows a weak π-bonding between O(2) and dioxygen, strongly H–bonded to OH(3), while the C(2)–O bond order increases. The different way of 2,3-DHBA oxidation parallels the different, from 3,4-isomer, degradation products. Our DFT calculations show that the keto/enol tautomeric forms of the neutral 2,3-DHPY-H₂ differ by 5.02 kcal/mol. Both species give, upon ionization, the [2,3-DHPY-H]⁻ with the OH(2) deprotonated. The electronic density distribution of [2,3-DHPY-q] justifies further reactions (degradation or dienic addition) as experimentally observed.