A series of double-chained phosphatidylcholines (PCs), 1,2-dioctadec-9′-ynoyl-sn-glycero-3-phosphocholine analogs containing perfluoroalkyl moieties (CF3, C2F5, n-C4F9 or n-C8F17) as the terminal segment in two hydrophobic chains, 1a-d, were synthesized. Equilibrium spreading pressures of these fluorinated PCs at the air-water interface were measured as an indication of monolayer stability, in order to obtain the minimal fluorine content in PC molecule efficient to exhibit monolayer stabilizing effect. The monolayer stability sigmoidally increased with the fluorine content in PC molecule and subsequently leveled off above a certain fluorine content, i.e., n-C4F9 moiety, at 25 °C. Under this condition, the replacement of at least five hydrogen atoms at the terminal hydrophobic segment in double-chained PC molecule by fluorine atoms, i.e., CF3CF2 moiety, is required to exhibit the monolayer stabilizing effect, whereas further fluorination of double-chained PC (F(CF2)n; n > 4) has a minor effect on the monolayer stability. 相似文献
The reaction of copper(II) chloride dihydrate with 2-hydroxy-3-methoxybenzaldehydethiosemicarbazone (HL) ligand in a 1:1 ratio
forms the complex [Cu(L)(Cl)] · H2O. The complex is characterized by spectroscopic, electrochemical, and thermal analysis. X-ray crystallographic analysis reveals
that the central copper atom displays the distorted square planar geometry. The water molecule present in the lattice participates
in a strong hydrogen bonding network, which leads to a 2D supramolecular arrangement. 相似文献
Abstract Two new square planar Cu(II) and Ni(II) complexes, [CuL1(NCO)] (1) and [NiL2(N3)] (2) have been synthesized with two different tridentate N2O donor Schiff base ligands L1H (1:1 condensation product of benzoylacetone and 2-diethylaminoethylamine) and L2H (1:1 condensation product of benzoylacetone and 2-dimethylaminoethylamine), respectively. Both the complexes 1 and 2 have been characterized by elemental analysis, IR, UV-Vis spectroscopy, room temperature magnetic susceptibility measurement,
electrochemical, thermal, and single crystal X-ray diffraction studies. Structural studies reveal that in both the complexes
metal centers have square planar environment with N2O donor set of Schiff base ligands and terminal pseudohalide anions (isocyanate for 1 and azide for 2) at four coordination sites of square plane.
Graphical abstract
Square planar complexes of Cu(II) and Ni(II) with N2O donor set of two Schiff base ligands: synthesis and structural aspects
Subhra Basak, Soma Sen, Samiran Mitra, C. Marschner, W. S. Sheldrick
Two new square planar Cu(II) and Ni(II) complexes, [CuL1(NCO)] (1) and [NiL2(N3)] (2) have been synthesized with two different tridentate N2O donor Schiff base ligands L1H and L2H respectively. Both the complexes 1 and 2 have been characterized by elemental analysis, IR, UV-Vis
spectroscopy, room temperature magnetic susceptibility measurement, electrochemical, thermal and single crystal X-ray diffraction
studies.
相似文献
The elastic stiffness constants under pressure of Si and Ge are studied theoretically using the higher-order perturbational formalism and the local Heine-Abarenkov model pseudopotential, and the mode Grüneisen parameters for long-wave phonons are estimated as a function of the compressed volume. The results obtained for atmospheric pressure are in good agreement with the experimental data. The long-wave LA mode Grüneisen parameters decrease slightly as the volume is reduced by compression. The TA mode Grüneisen parameters show a large decrease as function of the volume strain, and become negative near the covalent-metallic phase transition. The volume-dependences of the long-wave mode Grüneisen parameters are useful in the study of the anharmonic properties of Si and Ge. 相似文献
This communication reports the investigation of the pH effects on the interaction of a well-known lung surfactant, Dipalmitoylphosphatidylcholine (DPPC) with water soluble highly fluorescent dye Rhodamine B (RhB) in complex Langmuir monolayers at the air–water interface. The ionic nature of DPPC changes with the pH of the subphase in the Langmuir trough. At sufficiently low pH it becomes cationic whereas at higher pH it can be presented with a negative net charge and at normal pH it is zwitterionic. Being zwitterionic, RhB molecules can interact with DPPC at normal and higher pH, whereas at lower pH the interaction becomes less probable. This has been investigated in details at the air–water interface in Langmuir trough as well as in Langmuir Blodgett (LB) film by employing surface pressure versus area per molecule (π–A) isotherms, compressibility study, in-situ Fluorescence Imaging Microscopy (FIM), UV-vis absorption spectroscopy and Atomic Force Microscopy (AFM) study. 相似文献
New luminescent mononuclear and dinuclear copper(II) (S = 1/2) complexes [Cu(HL)(H2O)2](ClO4)2 (1a) and [Cu2(HL)2(μ-SO4)2]·2H2O (1b) were synthesized with the acyclic tridentate pyridine-2-carboxaldehyde-2-pyridylhydrazone ligand, HL (1). Interestingly, the mononuclear complex 1a can be converted into the disulfate bridged dimeric copper(II) complex 1b by passing freshly prepared SO2 through the basic medium. On excitation at 290 nm, the ligand fluoresces at 364 nm due to an intraligand 1(π–π1) transition. Upon complexation with copper(II), the emission peak is slightly blue shifted (356 nm, F/F0 0.76 for 1a and 354 nm, F/F0 0.89 for 1b) with a little quenching in the emission intensity. The association constants (Kass (5.06 ± 0.004) × 104 for 1a and Kass (5.46 ± 0.006) × 104 for 1b at 298 K) and the thermodynamic parameters have been determined by UV–Vis spectroscopy. The molecular structure of the complex 1b (Cu?Cu 4.456 Å) has been determined by single crystal X-ray diffraction studies. The complex 1b exhibits a strong interaction towards DNA as revealed from the Kb (intrinsic binding constant) 6.3 × 104 M?1 and Ksv (Stern–Volmer quenching constant) 2.93 values. 相似文献
Electrochemical and mechanical properties of thin poly(3,4-ethylenedioxythiophene) films deposited on gold have been investigated in aqueous sulfuric acid and sodium-sulfate solutions. It has been shown that at sufficiently positive electrode potentials, overoxidation of the polymer takes place. In some cases, only small changes could be observed in the shape of cyclic voltammograms taken in the “stability region” before and after overoxidation. In contrast to this, the impedance spectra recorded after overoxidation differed considerably from the impedance spectra of a freshly made electrode. Morphological changes of the polymer caused by overoxidation (degradation) could be detected by using the bending beam method.
A knowledge of flame stability regimes in the presence of cylindrical bluff-bodies of various dimensions is essential to design non-premixed burners. The reacting flow field in such cases is reported to be three-dimensional and unsteady. In the literature, only a few experimental investigations with limited measurements are available. Therefore, in this work, a detailed numerical study of laminar cross-flow non-premixed methane–air flames in the presence of a square cylinder is presented. The flow, temperature, species and reaction fields have been predicted using a comprehensive transient three-dimensional reacting flow model with detailed chemical kinetics and variable thermo-physical properties, in order to get a good insight into the flame stabilisation phenomena. Further, analyses of quantities such as local equivalence ratio, cell Damköhler number, species velocity, net consumption rate of methane, which are not easily obtained through experiments even with detailed diagnostics, have been carried out. The influence of the flow field due to varying inlet velocity of the oxidiser, in the presence of the bluff-body, on flame anchoring location has been analysed in detail. Local equivalence ratio contours obtained from non-reacting flow calculations are seen to be quite useful in analysing the mixing process and in the prediction of flame anchoring locations when the flames are not separated. Cell Damköhler number has been calculated using cell size, species velocity of the fuel, which is a derived quantity, and the net reaction rate of the fuel. The flame zone, which is customarily inferred from the contours of temperature, CO and OH, is also shown to be predicted well by the contour line corresponding to a Damköhler number equal to unity. The net reaction rate of CH4 and the net rates of two dominant reactions, which consume methane, show clearly the variation in the flame anchoring locations in these three cases. Further, the three-dimensionality of these flames are analysed by plotting the mean temperature contours in y–z planes. Finally, the unsteadiness in the separated flame case is analysed. 相似文献
Endothelin receptor antagonists (ERAs) such as, ambrisentan, macitentan and sitaxentan are primarily used for the treatment of pulmonary arterial hypertension. Considering the rise in endothelin in pre-eclampsia, ERAs may also be useful in its treatment. To evaluate the pharmacokinetics of ERAs, a rapid ultra-performance liquid chromatography tandem mass spectrometry method was developed and validated to determine the concentration of ambrisentan, macitentan and sitaxentan in human plasma. Plasma samples were treated with methanol to induce protein precipitation. A chromatographic separation was performed on a C18 column using a gradient of methanol–water containing 0.1% formic acid and 0.013% ammonium acetate and a flow rate of 0.5 ml/min. Multiple reaction monitoring was used for quantification. This method was validated in a linear range of 20.28–2028 μg/l for ambrisentan, 4.052–405.2 μg/l for macitentan and 205.4–10 270 μg/l for sitaxentan. The method was successfully validated according to US Food and Drug Administration guidelines to determine the concentrations of macitentan, ambrisentan and sitaxentan in human plasma. This method is now being used for study samples and clinical patient samples. 相似文献