Solubilization of Ni Imidazole Complex in Micellar Media of Anionic Surfactants, Sodium Dodecyl Sulfate and Sodium Stearate (original) (raw)
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Colloid and Interface Science Communications, 2018
reports the investigation of physicochemical behavior of [Ni(phen) 3 ]F 2 .EtOH.MeOH.8H 2 O (Tris(1,10-phenanthroline)nickel(II) fluoride Ethanol(1/ 2)Methanol(1/2) octahydrate) complex with anionic surfactants (sodium dodecyl sulphate SDS and sodium stearate SS). Binding and partitioning parameters were determined by UV-Visible spectroscopy while CMC and thermodynamic parameters of complex-surfactant interactions were determined by electrical conductivity measurements. Ni-complex increased critical micellar concentration (CMC) of both surfactants. The investigated Ni-complex showed quite significant antioxidant activity against DPPH, hemolytic activity against RBCs, while there was no substantial cytotoxic activity against 3 T3 cell line.
Colloid and Interface Science Communications, 2020
Present study describes the physicochemical behavior of the coordination complex of copper i.e. [Cu(im) 6 ] F 2 .4H 2 O (Hexakis(imidazole)copper(II) fluoride tetrahydrate) and its solubilization by anionic surfactants sodium dodecyl sulphate (SDS) and sodium stearate (SS). The detailed investigation was accomplished by electrical conductivity measurements and UV-visible spectroscopy in aqueous solutions of anionic surfactants in the sub micellar and micellar concentration ranges. Furthermore, thermodynamic parameters of complex-surfactant interaction and CMC of both surfactants in the presence of copper imidazole complex were evaluated by electrical conductivity and experimental results revealed an increase in CMC of both surfactants in the presence of complex. CMC increases with rise in temperature and the trend of variation in thermodynamic parameters indicates that the solubilization of copper imidazole complex in micelles of both surfactants is spontaneous and enthalpy as well as entropy driven. Spectroscopic investigation indicates high degree of solubilization and strong interaction in case of complex and SDS than for SS.
Physical Chemistry Chemical Physics, 2002
The micellization process of three sulfonate surfactants [CH 3 (CH 2 ) nÀ1 SO 3 Na (n ¼ 6,8,10), C n SO 3 Na] has been studied by electron paramagnetic resonance (EPR) spectroscopy by employing )ammonium-2,2,6,6-tetramethylpiperidine-1-oxyl chloride, TC) as a spin label. The dependence of both the nitrogen isotropic hyperfine coupling constant (hA N i) and the correlation time (t C ) of the label on the surfactant molality have been analysed. In order to allow a correct interpretation of the experimental evidence a preliminary study on the factors influencing the EPR spectrum of TC in solution has been performed. EPR spectra of TC in various solvents show that the hA N i value increases with increasing the solvent polarity and, especially, H-bonding ability. The experimental values have been compared with those obtained by a composite ab initio computational approach, in which hA N i is determined by a suitable combination of post-Hartree-Fock and density functional calculations. Solvent effects are modelled by using the polarizable continuum model (PCM) and, for solvents with H-bonding ability, by including a few explicit solvent molecules. The experimental and computed values are in good agreement, confirming the reliability of the adopted computational strategy. The effect of the ionic strength on the EPR spectrum of TC in NaCl and Na 2 SO 4 aqueous solution has been also investigated, finding that the hA N i value is almost constant, whereas t C increases with the electrolyte molality. In surfactants' aqueous solution, both hA N i and t C of TC, plotted as a function of the surfactant molality, show a slope change, corresponding to the critical micellar composition (c.m.c.). The t C increase can be interpreted in terms of a reduction of the label mobility determined by the strong electrostatic interaction between the TC positive charge and the anionic micelles' surface. The hA N i decrease can be ascribed to the embedding of the NO moiety of TC in the outer part of the micellar hydrophobic core. By comparing the data collected for the different surfactants, it can be seen that the variation of both t C and hA N i upon micellization increases with the surfactant chain length. This evidence can be interpreted in terms of an increasing strength of the TC-micelle surface interaction, and of an increasing hydrophobic behaviour of the outer part of the micellar core in which the NO moiety of TC is solubilized. The TC affinity for the micellar pseudo-phase has been estimated by evaluating the distribution coefficient, K d , of the spin label between the micelles and the aqueous medium. The K d value increases with the length of the surfactant hydrophobic chain.
Langmuir, 2002
Kamlet-Taft solvatochromic scales have been used for the characterization of three different micellar electrokinetic chromatography (MEKC) systems, providing information about the polarity parameters of both the aqueous phase and the micellar phase of each system. The surfactants studied are sodium cholate (SC), which belongs to the family of bile salts, lithium perfluoro-n-octanesulfonate (LPFOS), a fluorosurfactant, and n-hexadecyl-trimethylammonium bromide (HTAB), a cationic surfactant. Sodium n-dodecyl sulfate, the most commonly used surfactant in MEKC, was already studied in a previous work. The solvatochromic measurements allow the determination of the critical micellar concentration (cmc) of the surfactants and also the partition coefficients of the solvatochromic indicators in each system. Both cmc and partition coefficients have been also determined through MEKC experiments, and good agreement is observed between the two methods. The results of the solvatochromic study indicate that LPFOS is the surfactant that has properties more similar to those of the aqueous phase, whereas SC is the most hydrogenbond basic and acidic surfactant, and HTAB has the lowest hydrogen-bond acidity.
Russian journal of …, 2002
1-Cetyl-3-(2-hydroxyiminopropyl)imidazolium chloride and bromide were synthesized for the first time. These compounds are functionalized zwitterionic surfactants which give rise to micelle formation in aqueous solution. Kinetic and thermodynamic analysis of nucleophilic cleavage of p-nitrophenyl p-toluenesulfonate, diethyl p-nitrophenyl phosphate, and ethyl p-nitrophenyl ethylphosphonate in the presence of 1-cetyl-3-(2-hydroxyiminopropyl)imidazolium halide micelles showed that the latter are powerful nucleophilic reagents whose kinetic behavior can be described in terms of a simple pseudophase distribution model. The efficiency of substrate solubilization with zwitterionic surfactant micelles and the reactivity of the oximate fragment in the micelle phase were estimated on a quantitative level. The observed acceleration of S N 2 reactions with the examined p-nitrophenyl esters relative to analogous reactions of zwitterionic 1-methyl-3-(2-hydroxyiminopropyl)imidazolium halides is, respectively, 12 800, 550, and 900 times; it is explained mainly by increased concentration of the reactants in micelles.
Journal of Dispersion Science and Technology, 2019
Influence of dimeric gemini surfactant micelles on the study of nickel-glycylleucine dipeptide ([Ni(II)-Gly-Leu] þ) and ninhydrin was carried out in the temperature ranging from 333 K to 353 K. An UV-vis spectrophotometer was employed to record the absorbance of product at definite time intervals. Rate of reaction was strongly catalyzed by the gemini surfactants. In the present reaction, the first-order dependence in metal-dipeptide complex and fractional-order dependence in ninhydrin were observed. For the measurements of critical micelle concentration (CMC), conductivity method was used. Rate constants (k w) increase and levelling-off regions are detected with [gemini] (just like conventional monocationic surfactant). Later, gemini produces a third region at higher [gemini] where, fast increment in k w is observed. The catalytic role of surfactants has been described below and above the CMC of gemini surfactants. From this study, binding constants of reactants and thermodynamic parameters have been evaluated. The kinetic results and observed catalysis could plausibly be rationalized by Menger and Portnoy's pseudo-phase model of micellar catalysis.
Journal of Colloid and Interface Science, 2009
The confinement of finite amounts of nickel chloride in the hydrophilic core of sodium bis(2-ethylhexyl) sulfosuccinate (AOT) reverse micelles dispersed in n-heptane has been investigated by FT-IR, UV-vis-NIR and fluorescence spectroscopies. The analysis of experimental data consistently leads to hypothesize that NiCl 2 forms small size ionic clusters stabilized by a monolayer of oriented surfactant molecules. Due to confinement and interfacial effects, these ionic clusters show peculiar photophysical properties, which are different from those possessed by the bulk material. From NiCl 2 /AOT/n-heptane solutions, by evaporation of the organic solvent, interesting salt/surfactant nanocomposites at various salt concentrations have been prepared and characterised by WAXS. On the other hand, after mix with Na 2 S-containing dry micellar systems, the formation of NiS nanoparticles have been ascertained by UV-vis spectroscopy.
Microchemical Journal, 2001
The significant shift in kinetic and equilibrium behavior of complex formation between Ni 2q and 2-amino-cyclo-Ž. Ž. pentene-1-dithiocarboxylic acid ACDA in a solution of ionic surfactant cetyltrimethylammonium bromide CTAB was studied spectrophotometrically in 0.1 M NaBr medium at 30ЊC. A model based on distributions of ligand Ž. w Ž. x ACDA and complex Ni ACDA between aqueous and micellar pseudo-phase was applied to account for the shift 2 in the apparent formation constant and observed pseudo-first order rate constant. Partition constants were evaluated by using a technique based on the principal component analysis method. The proposed model, states that the reaction occurs only in the aqueous phase. Apparent formation constants and the observed rate constants decreased with increasing the micelle concentration. Good agreement between experimental and calculated values indicates that, the applied model provides a good description of the micellar effects on complex formation between Ni 2q and ACDA.
Aggregation of sodium dodecylsulfate in aqueous nitric acid medium
Journal of Colloid and Interface Science, 2012
Nitric acid medium is invariably used for nitration of organic molecules. Although surfactants are known to influence reaction rates, little is known about the aggregation behavior of surfactants in nitric acid medium. Micellization characteristics of sodium dodecylsulfate (SDS) in aqueous nitric acid are investigated in this work by using the conductance method. The critical micelle concentration (cmc) and the aggregation number were also determined by the surface tension and the steady-state fluorescence methods, respectively. This study reveals that in acidic medium SDS exhibits both normal and unusual conductivity behaviors. Equations developed on the basis of the mixed electrolyte model, Debye-Hückel-Onsager approach, and the pseudophase ion-exchange model successfully simulate the conductivity data. The exchange of sodium and hydrogen counterions at the micellar surface has no significant effect on the cmc of SDS. Acid concentration, surfactant concentration, and cmc control the competitive binding of sodium and hydrogen counterions. Analysis of conductivity data revealed hydrolysis of about 12% SDS when [HNO 3 ] P 0.02 mol dm À3 . Hydrolysis of SDS has been confirmed by nitrating some of the substituted phenols. It has been predicted that SDS + aqueous HNO 3 medium with [HNO 3 ] P 0.02 mol dm À3 may be used as a green medium for nitration.