Phosphorus-nitrogen compounds: Reinvestigation of the reactions of hexachlorocyclotriphosphazene with 1,4-butane- and 1,6-hexane-diols—NMR studies of the products

Reactions of hexachlorocyclotriphosphazene N₃P₃Cl₆ (1) with 1,4-butane-(2) and 1,6-hexane-diols (3) in (1:1:2, 1:2:4, and 1:3:6) stoichiometries in THF solution at room temperature (r.t.) and under refluxing conditions yield a total of 15 products: two open chain, N₃P₃Cl₅[O(CH₂)_nOH] (n = 4, 6) (4, 5), two mono-spiro, N₃P₃Cl₄[O(CH₂)_nO] (n = 4, 6) (6, 7), two mono-ansa, N₃P₃Cl₄[O(CH₂)_nO] (n = 4,6) (8, 9), two dispiro, N₃P₃Cl₂[O(CH₂)_nO]₂ (n = 4, 6) (10, 11), two spiro-ansa, N₃P₃Cl₂[O(CH₂)_nO]₂ (n = 4, 6) (12, 13), one tri-spiro, N₃P₃[O(CH₂)₄O]₃ (14), two single-bridged, N₃P₃Cl₅[O(CH₂)_nO]N₃P₃Cl₅ (n = 4, 6) (15, 16), one double-bridged, N₃P₃Cl₄[O(CH₂)₆O]₂N₃P₃Cl₄ (17), and one tri-bridged, N₃P₃Cl₃[O(CH₂)₆O]₃N₃P₃Cl₃ (18) derivatives. Their structures have been elucidated by MS, ³¹P, and ¹H NMR spectroscopy. The results obtained, based on the synthesis, characterization, product types, and the relative yields, are compared with those of previous studies on the reactions of 1 with 1,2-ethane-, 1,3-propane-, 1,4-butane-, 1,5-pentane-, and 1,6-hexane-diols.     

Electrical and dielectric properties of Al/p-Si and Al/perylene/p-Si type diodes in a wide frequency range

The perylene(C20H12) layer effect on the electrical and dielectric properties of Al/p-Si(MS) and Al/perylene/p-Si(MPS) diodes have been investigated and compared in the frequency range of 0.7 kHz–2 MHz. Experimental results show that C–V characteristics give an anomalous peak for two structures at low frequencies due to interface states(Nss) and series resistance(Rs). The increases in C and G/ω at low frequencies confirm that the charges at interface can easily follow an ac signal and yield excess capacitance and conductance. The frequency-dependent dielectric constant(ε) and dielectric loss(ε) are subtracted using C and G/ω data at 1.5 V. The ε and ε values are found to be strongly dependent on frequency and voltage, and their large values at low frequencies can be attributed to the excess polarization coming from charges at traps. Plots of ln(σac)–ln(ω) for two structures have two linear regions, with slopes of 0.369 and 1.166 for MS, and of 0.077 and 1.061 for MPS, respectively. From the C 2–V characteristics, the doping acceptor atom concentration(NA) and barrier height(ΦB) for Schottky barrier diodes(SBDs) of MS and MPS types are also obtained to be 1.484 × 1015 and 1.303 × 1015cm 3, and 1.10 and 1.13 eV, respectively.     

Synthesis and proton conductivity studies of azole functional organic electrolytes

As an attempt to produce azole functional proton conductors, organic electrolytes with triazole and tetrazole functional groups were synthesized via substitution reaction of 1,3,5-benzenetricarbonyl trichloride with aminotriazole and aminotetrazole. The samples were doped with triflic acid with molar ratios of 0.25 and 0.50. FTIR, nuclear magnetic resonance (NMR), and elemental analysis were used to characterize the resulting materials. Thermogravimetric analysis showed that the samples are thermally stable up to 150?°C. The effect of acid doping on proton conductivity was investigated with impedance spectrometer. Both pure samples and the doped ones revealed high proton conductivity. In anhydrous conditions (TMA)-TriTA_0.50 and TMA-TetTA_0.50 have proton conductivities of 1.8 and 19?mS/cm at 150?°C, respectively. Solid-state NMR studies revealed that there are three different types of hydrogen-bonded acidic proton in the systems. Moreover, these different types of acidic protons present at different ratio in triazole and tetrazole systems.     

Active control of the turbulent drag by a localized periodical blowing dissymmetric in time

Experimental results on the reaction of the near wall turbulence and drag to a localized time periodical blowing are reported. The injection velocity is periodical and dissymmetric in time, with a rapid acceleration phase followed by a slow deceleration one. The flow is relaminarized during 70% of the oscillation period mainly during the deceleration phase. The latter maintains stable the vorticity layer induced by the blowing and prevents its roll-up contrarily to a sinusoidal time periodical blowing. Thus, a time mean drag reduction of 50% is obtained in the region recovering 200 wall units downstream of the blowing slot and this is 40% larger than the drag reduction obtained by a steady blowing with the same time mean severity parameter. The dissymmetric blowing annihilates considerably the wall turbulence activity and gives better results in terms of drag reduction compared with steady and sinusoidal blowing.

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Synthesis and characterization of spiro-, ansa-, and spiro-ansa-cyclic derivatives of cyclotetraphosphazene with the reactions of pentane-1,5-diol

The reactions of octachlorocyclotetraphosphazatetraene, N₄P₄Cl₈ (1) with difunctional aliphatic reagent, HO-(CH₂)₅-OH (3) have aroused a good deal of attention, and four types of products have been realized: one 2-open chain-(1′-oxy-5′-hidroxy-pentane)-2,4,4,6,6,8,8-heptachlorocylotetraphosphazatetraene, N₄P₄Cl₇[O(CH₂)₅OH] (4); one 2,2-mono-spiro-(1′,5′-pentanedioxy)-4,4,6,6,8,8-hexachlorocyclotetraphosphazatetraene, N₄P₄Cl₆[O(CH₂)₅O] (5); its isomers 2,4-mono-ansa-((1′,5′-pentanedioxy)-2,4,6,6,8,8- hexachlorocyclotetraphosphazatetraene (6) and 2,6-mono-ansa-(1′,5′-pentanedioxy)-2,4,6,6,8,8-hexachlorocyclotetraphosphazatetraene (7); one 2,2,6,6-dispiro-(1′,5′-pentanedioxy)-4,4,8,8-tetrachlorocyclo- tetraphosphazatetraene, N₄P₄Cl₄[O(CH₂)₅O]₂ (8); two isomeric 2,4,6,8-bisansa-(1′,5′-pentanedioxy)-2,4,6,8-tetrachlorocyclotetraphosphazatetraene (9) and 2,6,4,8-bisansa-(1′,5′-pentanedioxy)-2,4,6,8-tetrachloro-cyclotetraphosphazatetraene (10); one 4,4,8,8-dispiro-2,6-ansa- (1′,5′-pentanedioxy)-2,6-dichlorocyclotetra-phosphazatetraene, N₄P₄Cl₂[O(CH₂)₅O]₃ (11), one 2,2,4,4,6,6-trispiro-(1′,5′-pentanedioxy)-8,8-dichlorocyclo-tetraphosphazatetraene, N₄P₄Cl₂[O(CH₂)₅O]₃ (12); and a 2,2,4,4,6,6,8,8-tetraspiro-(1′,5′-pentanedioxy)-cyclotetraphosphazatetraene derivative, N₄P₄[O(CH₂)₅O]₄, (13). The respective structures were deduced by means of elemental analysis, mass spectrum, and ³¹P, ¹H, and ¹³C nuclear magnetic resonance spectroscopic investigations.     

Effect of extraction conditions on measured total polyphenol contents and antioxidant and antibacterial activities of black tea

Black tea was extracted for 2, 8 and 18 h with absolute acetone, N,N-dimethyl-formamide (DMF), ethanol and methanol and their 50% aqueous solutions. The extracts were screened for total polyphenol contents, antioxidant and antibacterial activities. The polyphenol content of the extracts was found to be in the range of 0.44-114.01 mg gallic acid equivalents (GAE)/g dry weight tea, depending on the solvent used and the length of the extraction process. In general, aqueous acetone or DMF extracts displayed the highest polyphenol contents and antioxidant activity, while absolute acetone was the least efficient solvent. Antioxidant activities of tea extracts tested using the reducing power and 2,2-diphenyl-1-picryhydrazyl (DPPH) radical methods ranged from 0.09 to 1.18 and from 2.60 to 95.42 %, respectively, depending on the extraction conditions and the antioxidant activities correlated well with the polyphenol concentrations. Aqueous solvent black tea extracts also possessed antibacterial activity, depending on the solvent used and bacterial species tested. Staphylococcus aureus was found to be the most sensitive to all tea extracts, except for the methanol extract. Tea extracts were not effective against Y. enterocolitica, L. monocytogenes and E. coli O157:H7.     

A new hybrid (experimental–theoretical) quantitative method for detection of relative anomer concentrations in water

A novel and inexpensive hybrid (combined experimental and theoretical) approach was used to quantitatively identify anomer proportions of d-glucose, d-galactose and d-mannose in water. The study involves three parts: recording of experimental FT-IR spectra of monosaccharides in water, calculation of vibrational frequencies of all stable anomers of monosaccharides and regression analysis of theoretical and experimental intensities. No expensive experimental processes and high-level calculations were needed during the study. The results were compared with the data from pure experimental and molecular dynamic studies. It has been concluded that in water while d-glucose and d-mannose have two stable anomers, α-pyranose and β-pyranose, d-galactose has four stable anomers, α-pyranose, β-pyranose, α-furanose and β-furanose. Comparison of detected results with the literature data showed that the developed method is working for the quantitative detection of anomer proportions of monosaccharides in water.     

1,3-二烷基咪唑啉/Pd催化卤代芳烃的Heck和Suzuki反应

合成并表征了一种新型的有空间需求的N-杂环卡宾前驱体 1,3-二烷基咪唑啉盐. 这些咪唑啉盐与乙酸钯结合形成的高活性催化剂,可在温和条件下催化氯代和溴代芳烃的He ck和Suzuki交叉偶联反应.     

Molecular dynamics study of structure and glass forming ability of Zr<Subscript>70</Subscript>Pd<Subscript>30</Subscript> alloy

In this study, the temperature effects on the structural evolution of theZr₇₀Pd₃₀ binary alloy in the glassy and liquid states werestudied using the molecular dynamics simulations based on the many-body type tight-bindingpotential. We considered the following properties in detail: the temperature dependence ofthe volume, the partial and total pair distribution functions and the simulated glasstransition temperature. The effects of the cooling rates on the glass transitiontemperature were examined. The Wendt-Abraham parameter was calculated to determine theglass transition temperature of Zr₇₀Pd₃₀ glassy alloy. The pair analysis technique ofHoneycutt-Andersen was applied to define local atomic arrangements produced from moleculardynamics simulations. The results show that the icosahedral ordering in glassy state hasbeen composed during quenching period, and the simulated glass transition temperature andthe total pair distribution functions are in good agreement with the experimental data.     

Halogenated secondary metabolites from Laurencia obtusa

A new sesquiterpene (1), and a halogenated C15 acetogenin (2), a stereoisomer of neoisoprelaurefucin were isolated from Laurencia obtusa. Four known compounds laurencienyne (3), rogiolenyne B (4), obtusenol (5), and (3E)-dactomelyne (6) were also isolated from this alga. Rogiolenyne B (4) and (3E)-dactomelyne (6) were found for the first from this species. The structures of these compounds were elucidated by spectroscopic methods. The unambiguous assignments of the 1H and 13C NMR spectral data of (5) and 13C NMR data of (6) were also reported for the first time.