共查询到20条相似文献,搜索用时 10 毫秒
1.
The voltammetry of copper in organic ligand/chloride media is dominated by the formation of CuCl?2 species and by induced adsorption of Cu(I) in organic coatings on the electrodes. These phenomena are utilised in a novel method for evaluating Cu(II)/organic ligand interactions, based on the principle of ligand exchange. The Cu(II)/organic species competes with glycine which forms copper glycinate. These two complexes can be distinguished voltammetrically: copper glycinate gives a higher surface excess of copper at a gelatin-coated hanging mercury drop electrode, partly because of the increased production of CuCl?2 from copper glycinate at the electrode surface. The method proved satisfactory for pure ligand/surfactant/chloride media and for estuarine waters. It is shown that there are two type of Cu(II)-binding ligand in estuarine waters: humic material (> 10?6 mol l?1, assuming 1:1 site binding) with polyelectrolyte-type binding, and discrete ligands (? 10?6 M) with stability constants around 109. The extent of Cu(II) binding by the humic material decreases down the estuary because of dilution and increased salinity. 相似文献
2.
Zh. V. Faustova Yu. G. Slizhov M. A. Gavrilenko 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2013,87(7):1215-1217
New mesoporous materials prepared from tetraethoxysilane, i.e., sorbents obtained with the use of surfactants, are synthesized. Their chromatographic polarity is assessed quantitatively. Their Kovats retention indices and Rohrschneider polarity coefficients are calculated. Based on physicohemical data, it is demonstrated that modifying supports with metal chelates changes the structure and properties of the initial sorbents: the differential molar Gibbs free energies rise considerably for sorbent modified with copper acetylacetonate with respect to ethanol (?ΔG′ i = 7.09 kJ/mol) and nitromethane (?ΔG′ i = 6.75 kJ/mol), relative to the initial silica gel (5.43 and 4.15 kJ/mol, respectively). 相似文献
3.
Jayabharathi J Thanikachalam V Saravanan K Srinivasan N Perumal MV 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2011,78(2):794-802
2-(4-fluorophenyl)-1-(4-methoxyphenyl)-4,5-dimethyl-1H-imidazole (fpmpdi) was synthesised and its structure was characterized by 1H, 13C, mass, elemental analysis and X-ray techniques. It belongs to monoclinic crystal system having the lattice dimensions of monoclinic with point group, P21/c; a=8.5132 (1) ?, b=9.5128 (2) ?, c=19.2610 (3) ?, β=96.798 (2). Since (fpmpdi) is highly sensitive to different external stimulations such as UV irradiation, heat, increasing pressure and changing the environmental pH causing color change and so they can be used as a "multi-way" optically switchable material. A prominent fluorescence enhancement was found in the presence of transition metal ions such as Hg2+, Pb2+ and Cu2+ and this was suggested to result from the suppression of radiationless transitions from the n-π* state in the chemosensors. The optimized geometrical parameters obtained by DFT calculation is in good agreement with single crystal XRD data. The Mulliken, NBO charge analysis and the HOMO-LUMO energies were also calculated. The molecular electrostatic potential surface (MEP) and first static hyperpolarisability have also been employed theoretically which reveal that the fpmpdi have non-linear optical (NLO) behavior with non-zero values. Ground and excited states DFT calculations were carried out in order to find out dipole moment and energy. 相似文献
4.
A brief survey is given on our recent work on the linear and nonlinear optical properties of thin films of polymers with a conjugated π–electron system. Third harmonic generation and degenerate four wave mixing experiments are used to study magnitude and response time of the third order nonlinear optical susceptibility of poly(p-phenylenevinylene) and poly(phenyl acetylene). Phthalocyanine derivatives show a strong influence of the intermolecular electronic coupling on the response time of transient gratings. The influence of energy transfer on the relaxation process is discussed. 相似文献
5.
Aligned nanowires of organic luminescent material were prepared by introducing the organic luminants into nanochannels of variable size in an anodic aluminum oxide (AAO) membrane, and the emission spectra from these nanowire arrays exhibited novel size-dependent luminescent properties. 相似文献
6.
7.
Ingrid G. Voigt-Martin Ute Kolb Hans Kothe Alexander V. Yakimanski Ri-Cheng Yu Galina N. Matveeva Andrey V. Tenkovtsev 《Macromolecular Symposia》1999,146(1):153-162
Results of electron microscopic studies of crystal structures of a number of bis-benzylidene cyclohexanones are presented. It is shown that some of these compounds are efficient crystalline non-linear optically active (NLO) chromophores with second harmonic generation (SHG) properties. Appropriately functionalized chromophores of this type can be used as a polycondensation comonomer to produce partly crystalline main-chain NLO-active polymers. Electron diffraction crystal structural data, obtained for very small crystals, allowed us to get reasonable estimations of macroscopic crystal NLO-coefficients, relating quantum-chemically calculated molecular first hyperpolarizability components to crystal axes. 相似文献
8.
Copper nanocrystals are obtained by chemical reduction of copper ions in mixed reverse micelles. A large excess of reducing agent favors producing a new generation of shaped copper nanocrystals as nanodisks, elongated nanocrystals, and cubes. By using UV-Visible spectroscopy and numerical optical simulations we demonstrate that the optical properties are tuned by the relative proportions of spheres and nanodisks. 相似文献
9.
The complexation of copper by natural organic ligands in sea water was measured by cathodic stripping voltammetry with ligand (catechol and quinolin-8-ol) competition. Two methods to determine copper complexation in estuarine waters were compared, one based on a complete titration of the complexing capacity of the sample and the other on measurement of the labile and total dissolved metal concentrations only. Values for log αCuL (ihe α-coefficient for complexation of Cu2+ by natural organic ligands) ranging from 3.2 to 7.7 and from 3.3 to 7.8 could be detected by varying long αCuAL (the α-coefficient for complexation of Cu2+ by the added competing ligand) from 3.4 to 8.9 in samples from the Tamar estuary and from the Channel. The two methods gave comparable results and showed that the type of sites detected depends on the detection window of the technique. This effect is due to the sea and estuarine water samples containing a series of complexing ligands forming complexes of greatly varying strength, thus causing a rnage of complex stabilities to be measured as a function of the detection window of each technique. A comparison showed that lower values for αCuL are obtained by anodic stripping voltammetry as a result of that technique having a lower detection window. A detailed study of the Tamar estuary revealed a decrease in log αCuL from 10.8 to 8.3 with increasing salinity, demonstrating that major cations compete with copper for the complexing sites. The free Cu2+ concentrations were very low throughout the estuary (16.2 < pCu2+ < 18.2) even though the total measurements to establish potential toxic effects of copper in natural waters. 相似文献
10.
V. V. Shelkovnikov V. P. Safonov A. I. Plekhanov F. A. Zhuravlev 《Journal of Structural Chemistry》1993,34(6):909-922
The paper overviews progress in the development of molecular media based on organic compounds possessing a high third-order nonlinear optical susceptibility. Such media are useful in the design of elements for optical data processing devices. TheX
(3) values of polyconjugated polymers and organic dyes are presented; these depend on the film production method and molecular assembly organization. The review discusses nonlinear optical properties of metallic fractal clusters. The nonlinear response of a molecular medium is shown to be greatly enhanced by aggregation of molecules and by their location in a local field of a metallic cluster.Novosibirsk Institute of Organic Chemistry, Siberian Branch, Russian Academy of Sciences. Translated fromZhurnal Strukturnoi Khimii, Vol. 34, No. 6, pp. 90–105, November–December, 1993.Translated by L. Smolina 相似文献
11.
Khalihena Groune Mohammed Halim Laurent Lemée Mohammed Benmakhlouf André Amblès 《Arabian Journal of Chemistry》2019,12(7):1552-1562
The bituminous rocks of the Upper Cretaceous in the Moroccan Rif have been assessed and characterized in detail using organic geochemical techniques and a variety of organic geochemical parameters. The organic matter from 4 sites was studied in order to determine its thermal maturity and its depositional environments. The organic extracts (bitumens) were fractionated on silica-potassium hydroxide column according to the aliphatic hydrocarbons, acid compounds and polar compounds. Aliphatic hydrocarbons were identified by gas chromatography and mass spectrometry (GC/MS).The distribution of the aliphatic hydrocarbon fractions, and the various organic geochemical parameters (pristane/phytane, isoprenoids/n-alkanes, CPI, C27:C28:C29 regular, C2920S/(20S+20R), C29ββ/(ββ+αα), C29/C30 hopanes and Ts/Tm) showed that the studied samples were generally mature. Two of the 4 samples appeared to be derived from source rocks deposited under anoxic conditions while suboxic to oxic conditions seemed to have been dominant for the remaining two samples. Rock–Eval pyrolysis data in addition to GC results suggested types II, III and IV kerogens for the studied samples. 相似文献
12.
13.
14.
We demonstrate the synthesis of copper selenide quantum dots (QDs) by element directed, inexpensive, straight forward wet
chemical method which is free from any surfactant or template. Copper selenide QDs have been synthesized by elemental copper
and selenium in the presence of ethylene glycol, hydrazine hydrate, and a defined amount of water at 70 °C within 8 h. The
product is in strong quantum confinement regime, phase analysis, purity and morphology of the product has been well studied
by X-ray diffraction (XRD), UV–Visible spectroscopy (UV–Vis), Photo-luminescent spectroscopy (PL), Fourier transform infrared
spectroscopy (FTIR), Transmission electron microscopy (TEM), High resolution transmission electron microscopy (HRTEM), and
by Atomic force microscopy (AFM) techniques. The absorption and photoluminescence studies display large “blue shift”. TEM
and HRTEM analyses revealed that the QDs diameters are in the range 2–5 nm. Due to the quantum confinement effect copper selenide
QDs could be potential building blocks to construct functional devices and solar cell. The possible mechanism is also discussed. 相似文献
15.
Two aliphatic alpha-hydroxyoximes have been synthesized and characterized. These reagents are highly selective for the extraction of copper(II) from weakly acidic aqueous solution. A column containing a hydroxyoxime on a solid support effects a quantitative separation of copper(II) from most other metal ions. 相似文献
16.
The cations and readily dissociable complexes of copper are separated from copper adsorbed on inorganic and organic particulate species in river and pond waters by selective sorption on a strong-acid cation-exchange resin, AG 50W-X12, and a chelating resin, Chelex-100, for atomic absorption spectrometry. The sorption behaviour after the pH change and removal of carbon dioxide suggests that the dominant low-molecular-weight copper species in river waters are neutral CuCO03 and Cu2+ ions. 相似文献
17.
《Comptes Rendus Chimie》2005,8(8):1276-1281
Microcrystals of an organic fluorescent dye, 4-octylamino-7-nitrobenz-2-oxa-1,3-diazole, were prepared using a reprecipitation method, based on solvent-exchange. We show here that their shape and size can be nicely tuned by the presence of various macromolecules in the reprecipitation medium. To do so, poly(acrylic acid) and calf thymus DNA were used as additives. Homogeneous populations of microcrystals were thus obtained in a reproducible way. Their size and morphology varied with the additive used. The UV/vis absorption and luminescence properties of these microcrystals in suspension are briefly reported. To cite this article: M. Abyan et al., C. R. Chimie 8 (2005). 相似文献
18.
Eazhilarasi G Nagalakshmi R Krishnakumar V 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2008,71(2):502-507
p-Aminoazobenzene (p-AAZB), an organic nonlinear optical (NLO) crystal having good optical quality has been grown by slow evaporation solution technique using ethanol as a solvent. Solubility studies were performed at different temperatures. The structural characterization of the grown crystals was carried out by X-ray diffraction. Group theoretical analysis was carried out to calculate the number of modes of vibration. The lowering of the wave numbers of azo group suggests the existence of strong intermolecular N-H...H hydrogen bonding. This has been analysed based on the vibrational spectral features. Optical absorption studies show the effective transmission in the entire UV-vis region. The second harmonic generation results show the suitability of this material for NLO applications. 相似文献
19.
V. V. Semenov N. V. Zolotareva M. A. Lopatin V. I. Faerman G. A. Domrachev O. N. Gorshkov A. P. Kasatkin D. V. Skamnitskii M. E. Shenina A. V. Kruglov V. M. Treushnikov V. V. Treushnikov 《Polymer Science Series A》2010,52(6):599-609
The effect of prolonged UV irradiation on optical and spectral luminescent properties of two types of high-quality optical organic glasses are studied by electronic absorption spectroscopy, spectrofluorimetry, IR spectroscopy, and atomic force microscopy. Glasses 2.3 mm in thickness are obtained through the layer-by-layer photopolymerization of an oligo(epoxy diacrylate) mixture with benzyl methacrylate and oligo(carbonate dimethacrylate). After the addition of europium tris(benzoyltrifluoroacetonate) to the photopolymerizing compositions, glasses that luminesce in the red spectral region are produced. The action of light gives rise to a slow photodecomposition of the luminescent component and causes a decline in the intensity of the band due to 5 D 0 → 7 F 2 transition of the europium cation. The growth of absorption in the yellow-green spectral region favors formation of an internal light filter; as a result, the photodecomposition of the europium complex in deep layers proceeds at a smaller rate than that in surface layers. IR-spectroscopy measurements demonstrate the accumulation of hydroxyl groups in oligo(carbonate dimethacrylate) films during irradiation in air. In an inert atmosphere, practically no photodegradation products are evolved from the matrix material. 相似文献