The electrochemical behavior of a platinum electrode in a set of 1-alkyl ether (and 1-alkyl)-3-methylimidazolium room-temperature
ionic liquids (RTILs) 1–3 ([CxOyMim]+[Anion]− or [CxMim]+[Anion]−, where Mim = 3-methylimidazolium; CxOy = 1-alkyl ether; C7O3 = -(CH2)2O(CH2)2O(CH2)2OCH3; C3O1 = -(CH2)2OCH3; Cx = 1-alkyl; C10 = C10H21; C4 = C4H9; and ) was studied by cyclic voltammetry and electrical conductivity. This complementary set of imidazolium RTILs allowed us to
explore the effect of the imidazolium cation and the counter-ion, both of which affected the electrochemical window of these
RTILs. Various electrochemical events with low current values were observed, which diminished the electrochemical windows.
Interestingly, RTILs 2b [1-(2-methoxyethyl)-3-methylimidazolium tetrafluoroborate] and 2d [1-butyl-3-methylimidazolium tetrafluoroborate]
showed quasireversible charge transfer processes. The length of the functional group attached to the imidazolium cation was
shown to be of great influence as larger electrochemical windows, as well as lower electrical conductivities, were obtained
with the longer C7O3 and C10 functional groups. The largest electrochemical window of 2.0 V was achieved with RTIL 2c, 1-decyl-3-methylimidazolium tetrafluoroborate.
Dedicated to the memory of Prof. Francisco Nart. 相似文献
In this Letter we report on the thermal properties of macroporous silicon photonic crystals with the unit cell gradually varied along the pore axis. We show experimentally that arbitrarily large omnidirectional total-reflectance bands can be produced with such structures. We also demonstrate that those bands can be effectively used to reduce thermal radiation in large spectral bands. 相似文献
We report a ruthenium-catalyzed (2 + 2) intramolecular cycloaddition of allenes and alkenes. We have found that the use of the ruthenium complex RuH(2)Cl(2)(P(i)Pr(3))(2), which has previously gone unnoticed in catalytic applications, is crucial for the observed reactivity. The reaction proceeds under mild conditions and is fully diastereoselective, providing a practical entry to a variety of bicyclo[3.2.0]heptane skeletons featuring cyclobutane rings. 相似文献
Heats of adsorption of organic molecules are a useful tool for the characterization of porosity and surface chemistry of microporous
materials. This work describes the possibility of using heats of adsorption of organic molecules, estimated from a methodology
derived from the Dubinin-Astakhov equation, for the characterization of Pillared Interlayered Clays. The estimated heats were
compared with data determined directly by adsorption microcalorimetry. It is shown that the chemical nature of the organic
probe molecule strongly conditions the obtained results. The best agreement between calculated and experimental values, amongst
the probe molecules studied, was found for toluene. 相似文献
We report a joint computational and luminescence study on the low-lying excited states of sym-triazines, namely, 1,3,5-triazine (1) and the ubiquitous herbicides atrazine [6-chloro-N2-ethyl-N4-isopropyl-1,3,5-triazine-2,4-diamine (2)] and ametryn [6-methylthio-N2-ethyl-N4-isopropyl-1,3,5-triazine-2,4-diamine (3)]. Geometrical structures, energetics, and transition and state properties of I and 2 were computed at the TD-DFT, CASSCF, and CASPT2 levels of theory. The fluorescence and phosphorescence emission spectra, lifetimes, and fluorescence quantum yields were measured for the three compounds, and from these, the energies of the lowest excited states and their corresponding radiative rates were determined. The predictions from CASPT2 calculations are in good agreement with the experimental results obtained from the luminescence studies and allow the interpretation of different absorption and emission features. 相似文献
The mechanism of glyme catalyzed ester aminolysis in chlorobenzene should be modified by including a new reaction pathway that shows a first-order dependence on the concentration of the phase transfer catalyst and a second-order dependence on butylamine. 相似文献
A flow injection method is proposed for the determination of phenylephrine hydrochloride in pharmaceutical dosage forms. The method involves the use of on-line solid-phase extraction by means of a microcolumn containing Dowex 50W X8 ion-exchange resin for the separation of the analyte prior to colour development and spectrophotometric detection in the visible region.
The influence of preconcentration flow, preconcentration pH and elution volume was studied.
The method exhibits appropriate linearity (r2 = 0.9999) which was proved statistically by means of the “F”-test. When applied to commercial samples containing several active ingredients and excipients, a significant reduction of interferences was found. Accuracy, evaluated by means of the spike recovery method was in the range 99.7–100.8%, with precision (R.S.D., %) better than 1%.
In order to achieve the automation the system was controlled from a notebook computer by means of a program written in QuickBASIC language. Under these conditions, a sampling frequency of 40 samples per hour could be attained. 相似文献
The synthesis of NiCo2O4 spinel by several nanocasting strategies (i.e., multi-step nanocasting, one-step nanocasting and soft-templating), in which nickel and cobalt nitrates are used as precursors and Pluronic P123 as surfactant, is explored. First, in the multi-step nanocasting, the effect of the impregnation method (evaporation, solid–liquid and two-solvent) of the SBA-15 silica template on the morphology of NiCo2O4 replica is investigated. The evaporation method seems to be the best choice to obtain mesoporous NiCo2O4 powder which, after calcination at 375 °C and subsequent template removal, displays the highest surface area (93.1 m2/g). We have also checked the feasibility of the one-step nanoscating approach for the synthesis of ordered NiCo2O4 arrays, though this methodology entails severe difficulties, mainly related to the different decomposition temperature of the nitrate precursors and the P123 surfactant. Finally, randomly oriented, aggregated NiCo2O4 nanoparticles are obtained by means of P123 surfactant-assisted soft-templating approach. 相似文献