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141.
Alesi S Brancolini G Melucci M Capobianco ML Venturini A Camaioni N Barbarella G 《Chemistry (Weinheim an der Bergstrasse, Germany)》2008,14(2):513-521
Quaterthiophene-dinucleotide conjugates 5'TA3'-t4-3'AT5', 5'AA3'-t4-3'AA5', and 5'TT3'-t4-3'TT5' (TA: thymidine-adenosine, AA: adenosine-adenosine, TT: thymidine-thymidine) were synthesized and analyzed by a combination of spectroscopy and microscopy, electrical characterization, and theoretical calculations. Circular dichroism (CD) experiments demonstrated a transfer of chirality from the dinucleotides to quaterthiophene at high ionic strength and in cast films. The films were photoluminescent and electroactive. CD and photoluminescence spectra and current density/voltage plots (measured under dynamic vacuum) displayed significant variation on changing the dinucleotide scaffold. Molecular mechanics and molecular dynamics calculations indicated that the conformation and packing modes of the conjugates are the result of a balance between intra- and intermolecular nucleobase-thiophene stacking interactions and intramolecular hydrogen bonding between the nucleobases. 相似文献
142.
Roberts JC Kapernaum N Giesselmann F Lemieux RP 《Journal of the American Chemical Society》2008,130(42):13842-13843
According to a new design strategy for "de Vries-like" liquid crystal materials, we report the synthesis and characterization of an organosiloxane mesogen with a 5-phenylpyrimidine core that forms SmA and SmC liquid crystal phases. This new material is characterized by a maximum layer contraction of 1.2% upon SmA-SmC phase transition and is comparable to the best "de Vries-like" materials reported heretofore. 相似文献
143.
Nadia Zekri Nadia Handaq Abdelhamid El Caidi Touria Zair Mohamed Alaoui El Belghiti 《Research on Chemical Intermediates》2016,42(3):1639-1649
Essential oils proved their efficiency as natural insecticides to fight many pests of stored products and crops whereas the hydrosols have not been evaluated yet. The objective of this work is to assess the insecticidal effect of hydrosols extracted from Mentha suaveolens Ehrh. and Mentha pulegium L. toward an insect pest of citrus, Toxoptera aurantii (Homoptera, Aphididae). The extraction of hydrosols was carried out by hydro-distillation using Clevenger apparatus and then the chemical composition was identified by gas chromatography coupled with mass spectrometry. The chemical composition of two hydrosols revealed the abundance of hydrophilic and oxygenated compounds as piperitenone oxide and carvacrol. Different concentrations of each hydrosol were separately diluted in distilled water and applied topically to aphids. The results of this investigation have shown a high insecticidal effect, and the M. suaveolens hydrosol is more effective against citrus pests than that of M. pulegium L. Consequently, these natural compounds can be used in the management of aphids on citrus. 相似文献
144.
Electrochemical Capacitive K+ EMIS Chemical Sensor Based on the Dibromoaza[7]helicene as an Ionophore for Potassium Ions Detection 下载免费PDF全文
Moncef Tounsi Mourad Ben Braiek Abdoullatif Baraket Michael Lee Nadia Zine Miguel Zabala Joan Bausells Faouzi Aloui Béchir Ben Hassine Abderrazak Maaref Abdelhamid Errachid 《Electroanalysis》2016,28(12):2892-2899
A K+‐sensitive capacitive electrolyte‐membrane‐insulator‐semiconductor (EMIS) based on a novel dibromoaza[7]helicene ionophore has been developed. An ion‐sensitive membrane based on polyvinylchloride (PVC) doped with the ionophore was deposited on the Si3N4/SiO2/Si‐p/Cu‐Al transducer. The properties of the K+‐EMIS chemical sensor were investigated by electrochemical impedance spectroscopy (EIS). All the developed devices upon being tested have shown good sensitivity and linearity responses within the range 10?6 M to 10?1 M of potassium activity, with good selectivity over a wide variety of other cations (Na+, Li+, Cu2+, Ca2+, and Mg2+). To our knowledge, this is the first time that a capacitive field‐effect sensor has been fabricated using helicene as a carrier for K+‐detection, combined with the structure: Si3N4/SiO2/Si‐p/Cu‐Al as a transducer. 相似文献
145.
Determination of Esomeprazole on an Electropolymerized L‐arginine and β‐cyclodextrin Modified Screen Printed Carbon Electrode 下载免费PDF全文
The formation of an inclusion complex of the proton‐pump inhibitor (PPI) drug esomeprazole (ESO) with ß‐cyclodextrin (ß‐CD) has been investigated and proven by cyclic voltammetry (CV). The formation constant of the complex was determined. Thereafter, an electropolymerized β‐CD and L‐arginine (L‐arg) modified screen printed carbon electrode (P‐β‐CD‐L‐arg/SPCE) was developed for the determination of ESO using differential pulse adsorptive stripping voltammetry (DPAdSV). A significant enhancement of the peak current was observed when applying an accumulation step due to the effect of adsorption. Electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) further indicated that the polymer of β‐CD and L‐arg efficiently improved the electron transfer kinetic between analyte and electrode surface. Under the optimized conditions, the oxidation peak current was linearly proportional to the concentration of the drug in the range of 1.0×10?8 to 1.0×10?5 M. The DPAdSV method was successfully used to determine the concentrations of the drug in spiked human serum samples. 相似文献
146.
Nadia Benkhettou Artur M. C. Brito da Cruz Delfim F. M. Torres 《Mathematical Methods in the Applied Sciences》2016,39(2):261-279
We introduce a nabla, a delta, and a symmetric fractional calculus on arbitrary nonempty closed subsets of the real numbers. These fractional calculi provide a study of differentiation and integration of non‐integer order on discrete, continuous, and hybrid settings. Main properties of the new fractional operators are investigated and some fundamental results presented, illustrating the interplay between discrete and continuous behaviors. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
147.
A recently developed extended Lagrangian model employing localized basis functions and nonperiodic boundary conditions (GLOB/ADMP) was applied to the radicals issuing from the homolytic breaking of the C(alpha)-H(alpha) bond of glycine in aqueous solution at different pH values. Although the modifications of the structure and the magnetic properties of these species induced by the solvent are qualitatively reproduced by a static discrete-continuum model, magnetic parameters are further tuned by short-time dynamical effects (solute vibrations and solvent librations). The results delivered by GLOB/ADMP simulations for both hyperfine tensors and g-tensors are in remarkable agreement with their experimental counterparts, allowing a reliable disentanglement of the overall observables into well-defined contributions. The dominant role of out-of-plane vibrations in determining hyperfine splittings is confirmed and quantified, together with the remarkable sensitivity of the gyromagnetic tensor to bond lengths and valence angles defining the NC(alpha)C' moiety. Together with their specific interest for the title radical, our results suggest some interesting trends for other biologically significant radicals and point out the need of extending magneto-structural relationships to dynamical aspects. 相似文献
148.
Roots of Iostephane heterophylla (Cav.) Benth ex Hemsl are used mainly in Mexican traditional medicine to heal skin problems. The development of a column high-performance liquid chromatography (LC)-UV detector method for the determination of xanthorrhizol, the major and active component of the roots of I. heterophylla, is described in this paper. The content of this compound was quantitatively determined employing a Symmetry C18 5 microm particle size column with the isocratic mobile phase acetonitrile-water (85 + 15). The flow rate was 1.0 mL/min, and UV detection was at 230 nm. The limits of detection and quantitation were 0.2 and 0.5 microg/mL, respectively. Quantities of xanthorrhizol measured by this method ranged between 1.8 to 10.94 mg/g of root of the plant in 11 different samples of I. heterophylla. Xanthorrhizol was not detected in a sample of I. madrensis, so xanthorrhizol could be used as a marker compound of I. heterophylla. The LC method described here was shown to be reliable, reproducible, and accurate. 相似文献
149.
El-Gamel NE 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2007,68(3):860-866
Ternary Fe(III), Co(II), Ni(II), Cu(II), Zn(II) and UO(2)(II) chelates with tenoxicam (Ten) drug (H(2)L(1)) and dl-alanine (Ala) (HL(2)) and also the binary UO(2)(II) chelate with Ten were studied. The structures of the chelates were elucidated using elemental, molar conductance, magnetic moment, IR, diffused reflectance and thermal analyses. UO(2)(II) binary chelate was isolated in 1:2 ratio with the formula [UO(2)(H(2)L)(2)](NO(3))(2). The ternary chelates were isolated in 1:1:1 (M:H(2)L(1):L(2)) ratios and have the general formulae [M(H(2)L(1))(L(2))(Cl)(n)(H(2)O)(m)].yH(2)O (M=Fe(III) (n=2, m=0, y=2), Co(II) (n=1, m=1, y=2) and Ni(II) (n=1, m=1, y=3)); [M(H(2)L(1))(L(2))](X)(z).yH(2)O (M=Cu(II) (X=AcO, z=1, y=0), Zn(II) (X=AcO, z=1, y=3) and UO(2)(II) (X=NO(3), z=1, y=2)). IR spectra reveal that Ten behaves as a neutral bidentate ligand coordinated to the metal ions via the pyridine-N and carbonyl-O groups, while Ala behaves as a uninegatively bidentate ligand coordinated to the metal ions via the deprotonated carboxylate-O and amino-N. The magnetic and reflectance spectral data confirm that all the chelates have octahedral geometry except Cu(II) and Zn(II) chelates have tetrahedral structures. Thermal decomposition of the chelates was discussed in relation to structure and different thermodynamic parameters of the decomposition stages were evaluated. 相似文献
150.
Liquid-crystalline rigid-core semiconductor oligothiophenes: influence of molecular structure on phase behaviour and thin-film properties 总被引:1,自引:0,他引:1
Melucci M Favaretto L Bettini C Gazzano M Camaioni N Maccagnani P Ostoja P Monari M Barbarella G 《Chemistry (Weinheim an der Bergstrasse, Germany)》2007,13(36):10046-10054
The design, synthesis and properties of liquid-crystalline semiconducting oligothiophenes containing dithienothiophene (DTT), benzothiadiazole (BTZ) and carbazole (CBZ) rigid cores are described. The effect of molecular structure (shape, size and substitution) on their thermal behaviour and electrical properties has been investigated. Polarised optical microscopy (POM) and differential scanning calorimetry (DSC) analyses have revealed highly ordered smectic mesophases for most of the newly synthesised compounds. X-ray diffraction (XRD) studies performed at various temperatures have shown that the smectic order is retained in the crystalline state upon cooling across the transition temperature, affording cast films with a more favourable morphology for FET applications. 相似文献