共查询到20条相似文献,搜索用时 109 毫秒
1.
Yuhai Sun Yujun Feng Hongwei Dong Zhi Chen Likun Han 《Central European Journal of Chemistry》2007,5(2):620-634
A series of homologous gemini surfactants possessing identical hydrophobic chains but different ionic head groups (cationic,
anionic, zwitterionic) were synthesized, and their aqueous solution properties were examined. The results showed that the
surface activities of gemini surfactants are superior to those of corresponding conventional monomeric surfactants, and molecular
arrangements of gemini surfactants at the air-water interface are tighter than those of corresponding conventional surfactants.
It was also found that zwitterionic gemini surfactant possesses the highest surface activity among the three surfactants.
The behavior at the air-water interface is closely related to the molecular structural features of surfactants, which provide
an indication for synthesizing highly-efficient surfactants.
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2.
Reza Hosseinzadeh Mohammad Gheshlagi Rahele Tahmasebi Farnaz Hojjati 《Central European Journal of Chemistry》2009,7(1):90-95
The interaction of Procaine hydrochloride (PC) with cationic, anionic and non-ionic surfactants; cetyltrimethylammonium bromide
(CTAB), sodium dodecyl sulfate (SDS) and triton X-100, were investigated. The effect of ionic and non-ionic micelles on solubilization
of Procaine in aqueous micellar solution of SDS, CTAB and triton X-100 were studied at pH 6.8 and 29°C using absorption spectrophotometry.
By using pseudo-phase model, the partition coefficient between the bulk water and micelles, Kx, was calculated. The results showed that the micelles of CTAB enhanced the solubility of Procaine higher than SDS micelles
(Kx = 96 and 166 for SDS and CTAB micelles, respectively) but triton X-100 did not enhanced the solubility of drug because of
weak interaction with Procaine. From the resulting binding constant for Procaine-ionic surfactants interactions (Kb = 175 and 128 for SDS and CTAB surfactants, respectively), it was concluded that both electrostatic and hydrophobic interactions
affect the interaction of surfactants with cationic procaine. Electrostatic interactions have a great role in the binding
and consequently distribution of Procaine in micelle/water phases. These interactions for anionic surfactant (SDS) are higher
than for cationic surfactant (CTAB). Gibbs free energy of binding and distribution of procaine between the bulk water and
studied surfactant micelles were calculated.
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3.
Andris Zicmanis Galina Vavilina Svetlana Drozdova Peteris Mekss Maris Klavins 《Central European Journal of Chemistry》2007,5(1):156-168
Alkylation of indole salts in different ionic liquids is reported. Ionic liquids increase the alkylation reaction rate of
ambident indole anion and reduce the effects of counter ions and/or additives, the alkylation reaction rates being independent
of the presence of small amounts of protic solvents or water.
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4.
Sławomir Oszwałdowski Katarzyna Zawistowska Laura K. Grigsby Kenneth P. Roberts 《Central European Journal of Chemistry》2010,8(4):806-819
We have developed a capillary electrophoresis method to characterize the QD surface ligand interactions with various surfactant
systems. The method was demonstrated with 2–5 nm CdSe nanoparticles surface-passivated with trioctylphosphine oxide (TOPO).
Water solubility was accomplished by surfactant-assisted phase transfer via an oil-in-water microemulsion using either cationic,
anionic, or non-ionic surfactants. Interaction between the QD surface ligand (TOPO) and the alkyl chain of the surfactant
molecule produces a complex and dynamic surface coating that can be characterized through manipulation of CE separation buffer
composition and capillary surface modification. Additional characterization of the QD surface ligand interactions with surfactants
was accomplished by UV-VIS spectroscopy, photoluminescence, and TEM. It is anticipated that studies such as these will elucidate
the dynamics of QD surface ligand modifications for use in sensors.
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5.
Surface analysis of the size-fractioned urban aerosols by secondary ion mass spectrometry (ToF-SIMS)
The secondary ion mass spectrometry method (ToF-SIMS) has been applied to the analysis of some mineral and organic species
on the surface layers of airborne urban particulates. Particulate matter was collected on aluminum sheets of the 8-stage Anderson
type cascade impactor from three different sampling sites in the city of Lodz, Poland, which were different in terms of aerosol
source apportionment. The obtained results show that vehicle combustion products occur mainly in fine fraction with aerodynamic
diameters below 1μm. The main contribution to the mineral components comes from direct and traffic related soil resuspension.
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6.
A palladium complex with an aminophosphine ligand has been prepared and investigated as a catalyst precursor in Suzuki coupling
reactions in toluene. Nanoparticles composed of elemental palladium have been isolated from the reaction media and analyzed
using transmission electroscopic microscope (TEM), which shows the essential catalysts palladium nanoparticles to have a size
of ca. 3.0 nm.
dedicate to the 60th birthday of Prof. Dr. Yuan Kou 相似文献
7.
Owoyomi Olanrewaju Jide Ige Soriyan O. Omopariola 《Central European Journal of Chemistry》2011,9(1):106-111
Kinetic measurements were performed for the alkaline hydrolysis of brilliant green — a triphenylmethane dye used as a model
compound for probing micellar rate effects. This reaction was studied both in the presence of tetradecyltrimethylammonium
bromide (TTAB) and tetradecyltriphenylphosphonium bromide (TTPPBr) and also in binary mixtures of these surfactants at different
mole fractions of each. All rate surfactant profiles were analyzed using the pseudo-phase model in order to obtain the regression
parameters, including binding constants and rate constants in the micellar pseudo-phase. The reaction was catalyzed by both
surfactants. The catalytic factor increases from about 10 for pure TTPPBr to about 38 for pure TTAB. Binding of BG to micellar
surface is greater in pure TTAB than in pure TTPPBr but significantly reduced in the surfactant mixtures than in pure components.
Reduction of the binding constant becomes more significant as the mole fraction of TTAB is increased in the mixture. The kinetic
data have been analyzed in terms of models of Piszkiewicz and Raghavan-Srinivasan which are in good agreement.
相似文献
8.
A strange effect was observed while using the method of quasi-simultaneous determination of electrochemical voltage noise
and impedance to obtain information on the kinetics of the hydrogen evolution reaction on Ag and Cu microelectrodes. Beyond
a certain polarizing current density we found microvolt-amplitude potential oscillations on both electrodes with a frequency
in the 5 Hz–5 kHz range. The oscillations were observed in every single experiment with Ag and Cu, while no oscillatory behavior
was observed during the control experiments with the Pt microelectrode. The presence of the oscillations indicates that the
mechanism of hydrogen evolution is more complex compared to the original assumption.
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9.
Melinda Fekete Mercedesz Töröncsi Lajos Novak 《Central European Journal of Chemistry》2008,6(1):33-37
Palladium-catalyzed amination reactions of quinoline triflate and the effect of a Pd catalyst, its ligands, solvents, bases,
and temperature were studied. This method facilitated an easier pathway for the preparation of aminoquinoline derivatives
as potential precursors of new serotoninerg agents.
相似文献
10.
Paraskevas D. Tzanavaras Demetrius G. Themelis Fotini S. Kika 《Central European Journal of Chemistry》2007,5(1):1-12
The present study reviews more than twenty years (1985-present) of published research on the development and application of
analytical procedures for the determination of chlorine dioxide, a widely used disinfectant and bleaching agent. The review
covers a variety of techniques including batch and automated spectrophotometry and fluorimetry, electroanalysis and chromatography.
The analytical figures of merit to the methods are presented, while critical discussion regarding their advantages and disadvantages
is addressed.
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11.
Emil Ioan Muresan Spiridon Oprea Theodor Malutan Mihai Vata 《Central European Journal of Chemistry》2007,5(3):715-726
The esterification reaction of palmitic acid with epichlorohydrin catalyzed by an anionic macroporous resin was studied. Purolite
A-500 resin proved to be a very effective catalyst in the synthesis of 3-chloro-2-hydroxypropyl palmitate. The effects of
certain parameters such as speed of agitation, catalyst particle size, catalyst loading, temperature, initial molar ratio
between reactants on the rate of reaction were studied. It was found that the overall rate is intrinsically kinetically controlled.
The structure of synthesized ester was confirmed by FTIR and 1H NMR analyses.
相似文献
12.
Ksenija R. Kumrić Tatjana M. Trtić-Petrović Ljubiša M. Ignjatović Jožef J. Čomor 《Central European Journal of Chemistry》2008,6(1):65-69
Lutetium has been determined by differential pulse anodic stripping voltammetry in an acidic solution containing Zn-EDTA.
Lutetium (III) ions liberated zinc (II), which was preconcentrated on a hanging mercury drop electrode and stripped anodically,
resulting in peak current linearly dependent on lutetium (III) concentration. Less than 0.4 ng mL−1 lutetium could be detected after a 2 min deposition.
相似文献
13.
Agata Siwek Monika Wujec Maria Dobosz Ewa Jagiełło-Wójtowicz Anna Chodkowska Agnieszka Kleinrok Piotr Paneth 《Central European Journal of Chemistry》2008,6(1):47-53
By the reaction of 2-methyl-furan-3-carboxylic acid hydrazide with isothiocyanates, 1-[(2-methyl-furan-3-yl)carbonyl]-4-substituted
thiosemicarbazides 1 were obtained. Further cyclization with 2% NaOH led to the formation of 3-(2-methyl-furan-3-yl)-4-substituted-Δ2-1,2,4-triazoline-5-thiones 2. The pharmacological effects of 2 on the central nervous system in mice were investigated. Strong antinociceptive properties
of the investigated derivatives were observed in a wide range of doses.
相似文献
14.
Abdülhadi Baykal Yüksel Köseoğlu Mehmet Şenel 《Central European Journal of Chemistry》2007,5(1):169-176
Heating hydrous manganese (II) hydroxide gel at 85 °C for 12 hours produces Mn3O4 nanoparticles. They were characterized by X-ray powder diffraction (XRD) and infrared spectroscopy (FTIR). The particle size
estimated from the SEM and X-ray peak broadening is approximately 32 nm, showing them to be nanocrystalline. EPR measurements
confirm a typical Mn2+signal with a highly resolved hyperfine structure.
相似文献
15.
A simple and convenient method for the preparation of needle-shape nanoparticles of β-Ni(OH)2 has been developed. Results show that a needle-shaped β-Ni(OH)2 can be easily obtained in the presence of ethylenediamine and sodium dodecylbenzene sulfonate within a size from 100 to 200
nm. The shape and structure of the product were characterized by XRD, TEM and FT-IR. It is noteworthy that the formation of
needle-shape β-Ni(OH)2 benefits from the addition of sodium dodecylbenzene sulfonate. The optimum preparation conditions and the possible mechanism
are also discussed.
相似文献
16.
The determination of paeoniforin, paeonol, and censenoside Rg1 in traditional Chinese medicinal preparations, Tze Po San Pien pills and Liuwen Dihuang pills has been investigated by micellar
electrokinetic capillary electrophoresis with borate buffer (20 mM), sodium dodecylsulfate (30 mM) and acetonitrile (20%)
as background electrolytes (pH 9.30), 20 kV applied voltage and 203 nm UV detection. The effects of SDS concentration, borate,
buffer pH, and organic modifier on electrophoretic behavior and separation are discussed. Regression equations revealed linear
relationships between the peak-area of each component and the content with the correlation coefficients from 0.9982 to 0.9999.
In addition, the levels of the active compounds in two kinds of traditional Chinese medicinal preparations were easily determined
with the recoveries from 93.1% to 108.2%.
相似文献
17.
The geometry, frequency and intensity of the vibrational bands of 8-hydroxyquinoline and its 5,7-dichloro, 5,7-dibromo, 5,7-diiodo
and 5,7-dinitro derivatives were obtained by the density functional theory (DFT) calculations with Becke3-Lee-Parr (B3LYP)
functional and 6-31G* basis set. The effects of chloride, bromide, iodide and nitro substituent on the vibrational frequencies
of 8-hydroxyquinoline have been investigated. The assignments have been proposed with aid of the results of normal coordinate
analysis. The observed and calculated spectra are found to be in good agreement.
相似文献
18.
Saim M. Emin Ceco D. Dushkin Seiichiro Nakabayashi Eiki Adachi 《Central European Journal of Chemistry》2007,5(2):590-604
We first focus on the kinetics of nanoparticle growth in a microemulsion synthesis of CdSe semiconductor nanocrystals. The
process consists of a fast initial stage of typical time constant of the order of 103 s followed by a slow stage of time constant of the order of 104s. Growth proceeds similarly to that described for the hot-matrix synthesis of CdSe, underlining the generality of the two-stage
growth mechanism, irrespective of the matrix type and synthesis conditions. However, the time constant of each stage in the
microemulsion synthesis is much larger than in the hot-matrix one. Also, the ratio between the fast and slow time constant
is appreciably bigger. We also prove that larger size reverse micelles, obtained by increasing the water:surfactant ratio,
generally lead to larger CdSe nanoparticles. Bis(trimethylsilyl) selenium is the crucial precursor for the CdSe nanoparticle
synthesis. An intermediate stage of the chemical reaction limiting the bis(trimethylsilyl) selenium production is described
theoretically.
相似文献
19.
In this study, a series of new 5-phenylazo-6-aminouracil dyes were prepared by linking m-,p-nitroaniline, m-,p-chloroaniline,
m-,p-anisidine, m-,p-toluidine, m-,p-cyanoaniline, p-ethoxyaniline, p-phenoxyaniline, p-ethylaniline, p-acetamidoaniline,
p-acetylaniline, p-carboxyaniline and aniline to 6-aminouracil. The prepared dyes were characterized by UV-vis, FT-IR, 1H NMR spectroscopic techniques and elemental analysis. The effect of acid and base upon the UV-vis spectra of these dyes were
investigated. In addition, the solvatochromic behaviors and substituent effects in various solvents were evaluated.
相似文献
20.
Kateřina Vítková Markéta Pechová Jan Petr Joanna Znaleziona Václav Ranc Vítězslav Maier Juraj Ševčík 《Central European Journal of Chemistry》2010,8(2):273-277
A method for the fast determination of yohimbine, a potent adrenoreceptor antagonist used for the treatment of sexual dysfunctions,
is proposed in this article. MEKC under basic and acidic conditions (sodium borate, pH 9.5 and sodium phosphate, pH 2.5) with
SDS was developed. The effect of the experimental parameters, e.g. pH, SDS concentration and injection time, on yohimbine
migration was also studied. Both methods were validated in terms of linearity, limits of detection and quantification, accuracy,
and precision using caffeine as an internal standard. The application for the determination of yohimbine in hand-made medicaments
is also investigated in this study.
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