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71.
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73.
J. Bonet L. Callau J. A. Reina M. Gali V. Cdiz 《Journal of polymer science. Part A, Polymer chemistry》2002,40(22):3883-3892
We modified poly(epichlorohydrin) (PECH) with biphenyl carboxylic and naphthalene carboxylic acid derivatives which contains propargyloxy moieties. The linear polymers were characterized by NMR and IR spectroscopy, elemental analysis, DSC and TGA. We obtained only one side chain liquid crystalline. A smectic A mesophase of this biphenyl derivative was identified by DSC, light polarized optical microscopy and X‐ray diffraction. Thermal crosslinking of the aryl propargyl ether group via sigmatropic rearrangement took place while the material was in the isotropic phase. Partially curing this reactive liquid crystalline polymer resulted in the formation of an anisotropic elastomer when the curing was radically initiated in the range of mesophase stability. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 3883–3892, 2002 相似文献
74.
Giacomo?Saielli Riccardo?Bini Alessandro?BagnoEmail author 《Theoretical chemistry accounts》2012,131(3):1140
Fluorine-19 NMR chemical shifts have been calculated for a wide variety of fluorine-containing inorganic and organic molecules
by relativistic DFT methods. The agreement with experimental values, spanning the whole range from ClF to FOOF, is satisfactory
but somewhat less accurate than for comparable light nuclei. 19F shifts in uranium chlorofluorides have been analyzed in detail, and the poor agreement with experiment is partly rationalized. 相似文献
75.
Alma Mejri Giacomo Mandriota Hamza Elfil Maria Lucia Curri Chiara Ingrosso Abdelmoneim Mars 《Molecules (Basel, Switzerland)》2022,27(23)
Monitoring hazardous chemical compounds such as hydrazine (N2H4), 4-nitrophenol (4-NP) and Hg2+ in natural water resources is a crucial issue due to their toxic effects on human health and catastrophic impact on the environment. Electrochemical nanostructured platforms integrating hybrid nanocomposites based on graphene derivatives and inorganic nanoparticles (NPs) are of great interest for such a purpose. In this work, disposable screen-printed carbon electrodes (SPCEs) have been modified with a hybrid nanocomposite formed by reduced graphene oxide (RGO), functionalized by 1-pyrene carboxylic acid (PCA), and decorated by colloidal Au NPs. These hybrid platforms have been tested for the electrocatalytic detection of N2H4 and 4-NP by differential pulse voltammetry and have been modified with an electropolymerized film of Hg2+ ions imprinted polycurcumin for the electroanalytical detection of Hg2+ by DPV. LODs, lower and in line with the lowest ones reported for state-of-the-art electrochemical sensors, integrating similar Au-graphene < nanocomposites, have been estimated. Additionally, good repeatability, reproducibility, and storage stability have been assessed, as well as a high selectivity in the presence of a 100-fold higher concentration of interfering species. The applicability of the proposed platforms for the detection of the compounds in real complex matrices, such as tap and river water samples, has been effectively demonstrated. 相似文献
76.
A major research field in mechanistic systems biology is represented by the development of methods for investigating the structural and dynamic features of systems with multiple interacting components, in order to understand their function. A combination of NMR techniques can be used in such respect, among which the employment of paramagnetic metal ions, 13C direct detection, and solid-state NMR, possibly supported by other techniques like small angle X-ray scattering. Among the results, the information on the conformational heterogeneity experienced by multicomponent systems in solution can be mentioned. The structural and functional characterization of large biological systems, not affordable with standard solution NMR techniques, can be tackled through a synergistic use of solution and MAS solid-state NMR. 13C direct detection NMR spectroscopy is on the other hand advantageous for improving the quality and quantity of observed nuclear signals, for their intrinsically smaller linewidths and larger signal breadth. Details on these approaches are reviewed here. 相似文献
77.
Barone V Bloino J Monti S Pedone A Prampolini G 《Physical chemistry chemical physics : PCCP》2011,13(6):2160-2166
Classical all-atom molecular dynamics (MD) simulations and quantum mechanical (QM) time-dependent density functional theory (TD-DFT) calculations are employed to study the conformational and photophysical properties of the first emitter excited state of tetramethyl-rhodamine iso-thiocyanate fluorophore in aqueous solution. For this purpose, a specific and accurate force field has been parameterised from QM data to model the fluorophore's first bright excited state. During the MD simulations, the consequences of the π→π* electronic transition on the structure and microsolvation sphere of the dye has been analysed in some detail and compared to the ground state behaviour. Thereafter, fluorescence has been calculated at the TD-DFT level on configurations sampled from the simulated MD trajectories, allowing us to include time dependent solvent effects in the computed emission spectrum. The latter, when compared with the absorption spectrum, reproduces well the experimental Stokes shift, further validating the proposed multilevel computational procedure. 相似文献
78.
Livraghi S Corazzari I Paganini MC Ceccone G Giamello E Fubini B Fenoglio I 《Chemical communications (Cambridge, England)》2010,46(44):8478-8480
A safe UV filter may be obtained by inhibiting the photo-generation of free radicals through modification of the surface of TiO(2) nanoparticles with carbon. 相似文献
79.
Rocco Angelone Dr. Francesco Ciardelli Prof. Arturo Colligiani Prof. Francesco Greco Dr. Paolo Masi Prof. Annalisa Romano Dr. Giacomo Ruggeri Prof. 《Chemphyschem》2010,11(2):460-465
A derivative of 2‐methylindole, 3‐[2‐(4‐nitrophenyl)ethenyl]‐1‐allyl‐2‐methylindole, NPEMI‐A, is studied for its photoconductivity and photorefractivity behaviour. Its blends with the organic polymer poly‐(2,3‐dimethyl‐N‐vinylindole), PVDMI, are also investigated. Due to the expected and devised mutual solubility of the two components of the blends, it is possible to carry out measurements with the weight percent of the chromophore NPEMI‐A changing from zero to 100. Films were produced by a squeezing process between two ITO‐covered glass sheets. No opacity phenomena, that are so common for many other organic blends due to the segregation of the dissolved chromophore, are observed. The photorefractive optical gain Γ2 is obtained as a function of the chromophore content. Differential scanning calorimetry measurements (DSC) are also carried out to obtain the whole change of the glass transition temperature Tg as a function of the amount of chromophore contained in the blends. From the experimental trend of Tg a meaningful quantitative estimate of the value of the electrostatic interactions acting in the studied blends, is obtained. The importance of the value of Tg, and of the electrostatic interactions, in determining the extent of the photorefractivity is clearly evident. The results are compared for NPEMI‐A (Γ2=210 cm?1) and for NPEMI‐E (Γ2 ≈ 2000 cm?1) that has a N‐2‐ethylhexyl group instead of a N‐allyl group. The Pockels and Kerr contributions and—for the first time—a “collaborative effect” of the photorefractivity of NPEMI‐A are distinguished and quantitatively evaluated. 相似文献
80.
Comparison of two laser-induced breakdown spectroscopy techniques for total carbon measurement in soils 总被引:1,自引:0,他引:1
M.V. Belkov V.S. Burakov A. De Giacomo V.V. Kiris S.N. Raikov N.V. Tarasenko 《Spectrochimica Acta Part B: Atomic Spectroscopy》2009
The potentials of two advanced laser-induced breakdown spectroscopy (LIBS) techniques which are used to determine the total carbon content in soils have been examined. The first one is the combination of a single-pulse laser ablation with spark excitation of plasma plume triggering the gap between electrodes close to the target surface. The second one is a more conventional double-pulse LIBS. In both modes the calibration graphs have a nonlinear trend in the actual range of carbon contents and present a good R2 value (0.97). In the combined laser-spark approach, using low-cost and portable laser instrumentation is possible, as well as inducing a micro-damage on the target surface. Certain regularities in the spectral line intensities of soil nutritious elements have been detected and appear to be connected to the total carbon content and to the soil origin. 相似文献