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51.
Riccardo Egris Mercedes Villacampa Prof. J. Carlos Menéndez Prof. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(41):10930-10939
The reaction of vinyl Grignard reagents with o‐methoxynitroarenes containing an electron‐releasing substituent para to the nitro group proceeds through a pathway that is different from the initially expected Bartoli indole synthesis. Thus, instead of giving fused indole derivatives, these reactions provide a very mild and efficient new procedure for the synthesis of synthetically relevant aromatic systems containing an o‐nitrovinyl moiety, such as 5‐nitro‐4‐vinylindoles, 6‐nitro‐7‐vinylindoles, 6‐nitro‐5‐vinyl‐2(1H)quinolinones, and 4‐nitro‐3‐vinylanilines. 相似文献
52.
Andreu R Blesa MJ Carrasquer L Garín J Orduna J Villacampa B Alcalá R Casado J Ruiz Delgado MC López Navarrete JT Allain M 《Journal of the American Chemical Society》2005,127(24):8835-8845
In this paper, we describe the second-order nonlinear optical properties of a series of 1,3-dithiole-based electron donor-acceptor systems incorporating proaromatic donor and spacer groups. Modification of the proaromaticity of the quinoid spacer gives rise to NLO-phores with mubeta values ranging from -2000 x 10(-)(48) esu to +3000 x 10(-)(48) esu. Quite surprisingly, compounds with a p-benzoquinoid spacer and a strong acceptor group show negative mubeta values, usually associated to zwitterionic ground states, and yet they are largely quinoid, as evidenced by crystallographic data and theoretical calculations. Progressive benzoannulation of the spacer and introduction of alkylsulfanyl substituents on the dithiole donor unit result in a shift to more positive mubeta values. DFT and ab initio calculations verify these empirical trends. 相似文献
53.
A. S. Ahmad MD N. Hoda M. Ahmad F. Islam S. Z. Qureshi 《Journal of Analytical Chemistry》2006,61(9):870-874
A simple, sensitive, and selective kinetic spectrophotometric method for the determination of kanamycin in pure form and pharmaceutical
formulations is described. The method is based on the measurement of the intensity of the yellow chromogen formed by the reaction
between kanamycin and acetylacetone-formaldehyde reagent in a N,N′-dimethyl formamide medium. The variable-time method was used to evaluate the rate of reaction of the colored chromogen formed
at 410 nm. The reaction conditions were optimized and the calibration graph was found to be linear in the range 60–160 μg/mL.
The results obtained by the developed and reference methods are in good agreement. Various statistical parameters were evaluated
to establish the precision, accuracy, repeatability, and reproducibility of the proposed method.
The text was submitted by the authors in English. 相似文献
54.
Insuasty B Atienza C Seoane C Martín N Garín J Orduna J Alcalá R Villacampa B 《The Journal of organic chemistry》2004,69(21):6986-6995
A novel D-pi-A system in which tetrathiafulvalene (TTF) and pi-extended TTFs as strong electron donors are covalently connected to a tricarbonyl (eta(6)-arene)chromium complex as the acceptor moiety through a systematically increased conjugated bridge of vinylene units (12a-c, 16a-c) have been synthesized by Wittig-Horner olefination reaction. The electronic spectra as well as the electrochemical data reveal a different behavior of TTF derivatives (12a-c) and of exTTF derivatives (16a-c). Cyclic voltammetry shows the influence of the tricarbonylchromium arene on the oxidation potentials in compounds 12a-c, and no remarkable effect is observed for exTTFs (16a-c). The nonlinear optical properties of 12a-c and 16a-c have been calculated by using the ab initio CPHF/6-31G//B3P86/6-31G model, and the time-dependent density functional theory (TD-DFT) method has been used for the calculation of the electronic transitions. The calculations reveal that an intraligand charge-transfer transition (ILCT) and the metal to ligand charge-transfer transition (MLCT) are responsible for the nonlinear response. In addition, the large angles formed by the ground-state dipole moment and the vectorial hyperpolarizability are responsible for the mubeta values determined experimentally by the EFISH technique. 相似文献
55.
Molecular recognition in water is challenging but water-soluble molecularly imprinted nanoparticle (MINP) receptors were produced readily by double cross-linking of surfactant micelles in the presence of suitable template molecules. When the micellar surface was decorated with different polyhydroxylated ligands, significant interactions could be introduced between the surface ligands and the template. Flexible surface ligands worked better than rigid ones to interact with the polar moiety of the template, especially for those template molecules whose water-exposed surface is not properly solvated by water. The importance of these hydrophilic interactions was examined in the context of different substrates, density of the surface ligands, and surface-cross-linking density of the MINP. Together with the hydrophobic interactions in the core, the surface hydrophilic interactions can be used to enhance the binding of guest molecules in water. 相似文献
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A network with its arc lengths as imprecise number, instead of a real number, namely, interval number and triangular fuzzy
number is considered here. Existing ideas on addition and comparison between two imprecise numbers of same type are introduced.
To obtain a fuzzy shortest path from a source vertex to all other vertices, a common algorithm is developed which works well
on both types of imprecise numbers under consideration. In the proposed algorithm, a decision-maker is to negotiate with the
obtained fuzzy shortest paths according to his/her view only when the means are same but the widths are different of the obtained
paths. Otherwise, a fuzzy optimal path is obtained to which the decision-maker always satisfies with different grades of satisfaction.
All pairs fuzzy shortest paths can be found by repeated use of the proposed algorithm. 相似文献
59.
To evaluate the functional difference of the pars recta and pars oblique during speech production, the electromyographic activities of these muscles were measured in thyroidectomized patients. The hooked wire electrodes were inserted into the normal side of the bellies of the pars recta and pars oblique bundles. Two kinds of sentences were used to obtain pitch changes, a simple interrogative sentence and a complex sentence with stress contrasts. The pars recta and pars oblique were simultaneously activated for initial lengthening and tensing of vocal folds to produce speech. The pars oblique might be initially more active than the pars recta at the initial task of speech and the pars recta might be more active at the pitch elevation in the interrogative sentence and the stress contrast of the complex sentence. The maximum electromyographic activity range of the pars recta and pars oblique seemed to be nearly equal. These results demonstrated that the patterns of electrical activities of the two bellies are different during speech and the combined activities of the pars recta and pars oblique are important in the adjustment of the vocal fold length during speech. 相似文献
60.
Structural and Photophysical Study on Heterobimetallic Complexes with d8–d10 Interactions Supported by Carborane Ligands: Theoretical Analysis of the Emissive Behaviour
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Dr. Olga Crespo Prof. M. Concepción Gimeno Prof. Antonio Laguna Dr. Olli Lehtonen Dr. Isaura Ospino Prof. Pekka Pyykkö Dr. M. Dolores Villacampa 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(11):3120-3127
Heterobimetallic complexes of formula [M{(PPh2)2C2B9H10}(S2C2B10H10)M′(PPh3)] (M=Pd, Pt; M′=Au, Ag, Cu) and [Ni{(PPh2)2C2B9H10}(S2C2B10H10)Au(PPh3)] were obtained from the reaction of [M{(PPh2)2C2B10H10}(S2C2B10H10)] (M=Pd, Pt) with [M′(PPh3)]+ (M′=Au, Ag, Cu) or by one‐pot synthesis from [(SH)2C2B10H10], (PPh2)2C2B10H10, NiCl2 ? 6 H2O, and [Au(PPh3)]+. They display d8–d10 intermetallic interactions and emit red light in the solid state at 77 K. Theoretical studies on [M{(PPh2)2C2B9H10}(S2C2B10H10)Au(PPh3)] (M=Pd, Pt, Ni) attribute the luminescence to ligand (thiolate, L)‐to‐“P2‐M‐S2” (ML′) charge‐transfer (LML′CT) transitions for M=Pt and to metal (M)‐to‐“P2‐M‐S2” (ML′) charge‐transfer (MML′CT) transitions for M=Ni, Pd. 相似文献