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1.
Narayanasamy Kumaraguru Sankarlingam Arunachalam Mahadevimanglam Narayanasamy Arumugham Kannappan Santhakumar 《Transition Metal Chemistry》2006,31(2):250-255
A number of mixed ligand chromium(III)–surfactant coordination complexes, of the type cis-[Cr(en)2(A)X]2+ and cis-α-[Cr(trien)(A)X]2+ (A = Dodecyl or Cetylamine; X = F−, Cl−, Br−) were synthesized from the corresponding dihalogeno complexes by ligand substitution. These compounds form foam in aqueous
solution when shaken. The critical micelle concentration (CMC) values of these surfactant metal complexes in aqueous solution
were obtained from conductance measurements. Specific conductivity data (at 303, 308 and 313 K) served for evaluation of the
temperature-dependent critical micelle concentration (cmc) and the thermodynamics of micellization (Δ Gm0, Δ Hm0 and Δ Sm0). 相似文献
2.
The interactions of non-ionic amphiphilic diblock copolymer poly(oxyethylene/oxybutylene)(E39B18) with anionic surfactant sodium dodecyl sulphate(SDS) and cationic surfactant hexadecyltrimethylammonium bromide(CTAB) were studied by using various techniques such as surface tension,conductivity,steady-state fluorescence and dynamic light scattering.Surface tension measurements were used to determine the critical micelle concentration(CMC) and thereby the free energy of micellization(△Gmic),free energy of adsorption(△Gads),surface excess concentration(Γ) and minimum area per molecule(A).Conductivity measurements were used to determine the critical micelle concentration(CMC),critical aggregation concentration(CAC),polymer saturation point(PSP),degree of ionization(α) and counter ion binding(β). Dynamic light scattering experiments were performed to check the changes in physiochemical properties of the block copolymer micelles taken place due to the interactions of diblock copolymers with ionic surfactants.The ratio of the first and third vibronic peaks(I1/I3) indicated the polarity of the pyrene micro environment and was used for the detection of micelle as well as polymer-surfactant interactions.Aggregation number(N),number of binding sites(n) and free energy of binding (△Gb) for pure surfactants as well as for polymer-surfactant mixed micellar systems were determined by the fluorescence quenching method. 相似文献
3.
The surfactant effect on the lower critical solution temperature (LCST) of thermosensitive poly(organophosphazenes) with
methoxy-poly(ethylene glycol) and amino acid esters as side groups was examined in terms of molecular interactions between
the polyphosphazenes and surfactants including various anionic, cationic, and nonionic surfactants in aqueous solution. Most
of the anionic and cationic surfactants increased the LCST of the polymers: the LCST increased more sharply with increasing
length and hydrophobicity of the hydrophobic part of the surfactant molecule. The ΔLCSTs (T
0.03M − T
0M), the change in the LCST by addition of 0 and 0.03 M sodium dodecyl sulfate (SDS), were found to be 7.0 and 14.5 °C for the
polymers bearing ethyl esters of glycine and aspartic acid, respectively. The LCST increase of poly(organophosphazene) having
a more hydrophobic aspartic acid ethyl ester was 2 times larger compared with that of the polymer having glycine ethyl ester
as a side group. The binding behavior of SDS to the polymer bearing glycine ethyl ester as a hydrophobic group was explained
from the results of titration of the polymer solutions containing SDS with tetrapropylammonium bromide. Graphic models for
the molecular interactions of polymer/surfactant and polymer/surfactant/salt in aqueous solutions were proposed.
Received: 17 February 2000/Accepted: 25 April 2000 相似文献
4.
Boris N. Afanasyev Yulia P. Akulova Maria M. Kotlyar 《Journal of Solid State Electrochemistry》1997,1(1):68-76
The function Δ(ΔG
A
0), which is the difference of Gibbs energies characterizing surface-active substance (surfactant, SAS) adsorption at metal/solution
and air/solution surfaces, has been introduced. The equation connecting the function Δ(ΔG
A
0) with SAS ionization potential has been obtained using the elementary theory of donor-acceptor interactions. Published experimental
data on SAS adsorption at mercury, bismuth and gold have been used for Δ(ΔG
A
0) calculation. The dependence of Δ(ΔG
A
0) on ionization potentials can be described by an equation derived in this work. It has been demonstrated that the value of
the hydrophilicity of gold is much higher than the values for mercury and bismuth. The lifetime of SAS molecules at a metal
surface has been estimated. The question of the possibility of theoretica
l estimation of standard energies ΔG
A
0 characterizing SAS adsorption at a metal/solution surface has been discussed.
Received: 9 December 1996 / Accepted: 13 January 1997 相似文献
5.
Hong-lin Zhang Yue Zhu Ke Zhang Ting-ting Hou Hai-ying Liu Mao-jin Cui Gan-zuo Li Li Yu 《Journal of solution chemistry》2009,38(2):187-198
The power-time curves of the micelle formation process were determined at four temperatures for a cationic surfactant [cetyltrimethylammonium
bromide (CTAB)] in a non-aqueous solvent [N,N-dimethylformamide (DMF)] by titration microcalorimetry. From the data of the
minimum of the titration point and the area of the power-time curves, values of their CMC and ΔH
m
θ
were obtained. Values of ΔG
m
θ
and ΔS
m
θ
were also calculated according to standard thermodynamic relations. For the cationic surfactant CTAB, the relationships involving
the carbon numbers of the alcohols, the alcohol’s concentration, and the temperature on the CMC, and also the thermodynamic
functions for micellization are discussed. For systems containing an identical concentration of various alcohols, values of
the CMC, ΔH
m
θ
and ΔS
m
θ
increased whereas those of ΔG
m
θ
decreased with increasing temperature. For systems containing identical alcohol concentrations at the same constant temperature,
values of the CMC, ΔH
m
θ
,ΔG
m
θ
and ΔS
m
θ
decreased with increasing carbon number of the alcohol. For systems containing the same alcohol at the same temperature,
the CMC and ΔG
m
θ
values increased whereas ΔH
m
θ
and ΔS
m
θ
decreased with increasing alcohol concentration. 相似文献
6.
Elena Blanco J. M. Ruso J. Sabín G. Prieto F. Sarmiento 《Journal of Thermal Analysis and Calorimetry》2007,87(1):211-215
The interactions of lysozyme and myoglobin with anionic surfactants
(hydrogenated and fluorinated), at surfactant concentrations below the critical
micelle concentration, in aqueous solution were studied using spectroscopic
techniques. The temperature conformational transition of globular proteins
by anionic surfactants was analysed as a function of denaturant concentration
through absorbance measurements at 280 nm. Changes in absorbance of protein-surfactant
system with temperature were used to determine the unfolding thermodynamics
parameters, melting temperature, T
m,
enthalpy, ΔH
m,
entropy, ΔS
m
and the heat capacity change, ΔC
p,
between the native and denatured states. 相似文献
7.
R. Zarganian A. K. Bordbar R. Amiri M. Tamannaei A. R. Khosropour I. Mohammadpoor-Baltork 《Journal of solution chemistry》2011,40(6):921-928
Pentanediyl-1,5-bis (hydroxyethylmethylhexadecylammonium bromide) was synthesized and characterized as a type of novel gemini
cationic surfactant. Its solution properties were determined at various temperatures by conductivity measurements and the
fluorescence quenching technique. The CMC increased in the range of 1.85 to 2.77 μmol⋅L−1 as the temperature increased. The aggregation number was determined at various concentrations of NaBr solutions by the fluorescence
quenching of pyrene. The thermodynamic parameters of micellization were determined using the mass law equation and the values
of ΔG °, ΔH °and ΔS ° were determined for the micellization process. 相似文献
8.
Ahmed A. El-Sherif 《Journal of solution chemistry》2010,39(1):131-150
The formation equilibria of copper(II) complexes and the ternary complexes Cu(HMI)L (HMI=4-Hydroxymethyl-imidazole, L=amino
acid, amides or DNA constituents) have been investigated. Ternary complexes are formed by a simultaneous mechanism. The results
showed the formation of Cu(HMI)L and Cu(HMI,H−1)(L) complexes. The stability of ternary complexes was quantitatively compared with their corresponding binary complexes in
terms of the parameters Δlog 10
K and log 10
X. The effect of the side chains of amino acid ligands (ΔR) on complex formation was discussed. The concentration distributions of various species formed in solution were also evaluated
as a function of pH. The thermodynamic parameters ΔH° and ΔS° calculated from the temperature dependence of the equilibrium constants are investigated. The effects of dioxane as a solvent,
on the protonation constant of HMI and the formation constants of CuII–HMI complexes, were discussed. 相似文献
9.
Muhammad A. Motin Tapan K. Biswas Entazul M. Huque 《Monatshefte für Chemie / Chemical Monthly》2003,134(4):475-487
Summary. Density and viscosity of NaNO3 and KNO3 in aqueous and in H2O-urea solutions were determined as a function of electrolyte concentrations at 308, 313, 318, 323, and 328 K, respectively.
The apparent molal volume (φ
v
) of the electrolytes were found to be linear functions of the square root of the solute molality (b). The φ
v
and data were fitted to the Masson equation [1] by the least square method to obtain the apparent molar volume at infinite dilution (φ
v
^), which is practically equal to the partial molar volume . The viscosity coefficients A and B were calculated on the basis of the viscosity of the solutions and the solvent concerned using the Jones–Dole [2] equation. The activation parameters for viscous flow (ΔG
≠, ΔS
≠, and ΔH
≠) were calculated according to Eyring [3]. The values of for the two systems were also calculated from B-coefficient data. The results were found to be of opposite nature in the two electrolyte systems. Where sodium nitrate showed
structure making behaviour both in aqueous and in H2O-urea solutions, KNO3 showed structure breaking behaviour in aqueous solutions and structure making behaviour in 5 molal H2O-urea solutions in the studied temperature range. The behaviour of these two electrolytes in aqueous binary and in aqueous-urea
ternary systems are discussed in terms of charge, size, and hydrogen bonding effects.
Corresponding author. E-mail: chemistry_ru@yahoo.com
Received January 24, 2002; accepted (revised) April 5, 2002 相似文献
10.
Nika Veronovski Patrizia Andreozzi Camillo La Mesa Majda Sfiligoj-Smole Volker Ribitsch 《Colloid and polymer science》2010,288(4):387-394
Photocatalytically active TiO2 P25 nanoparticles, widely used for practical applications, were investigated. The nominal size of TiO2 P25 nanoparticles is 21 nm, but they easily agglomerate in aqueous media, depending on pH and ionic strength. TiO2 P25 aqueous dispersions were stabilized by alkanediyl-α,ω-bis-N-dodecyl-N, N′-dimethyl-ammonium bromide, cationic Gemini surfactant. The optimal conditions required to obtain stable dispersions, without
formation of large agglomerates, were experienced. The stabilization of TiO2 P25 nanoparticles by cationic Gemini surfactant was investigated in some details. Different amounts of Gemini surfactant
were used, at concentrations between 1.0 and 250 × 10−6 mol L−1, well below the critical micelle concentration. Dynamic light scattering and zeta potential analyses estimated the particle
size and the dispersions stability. When the proper amount of Gemini surfactant was used, the resulting nanoparticles were
still poly-disperse, but large agglomerates disappeared and were remarkably redispersible. 相似文献
11.
The mixing fraction of didodecyldimethylammonium bromide (DDAB) in dodecyltrimethylammonium bromide + DDAB to produce a lamellar
liquid crystal (L
α) abruptly decreases upon addition of a small amount of m-xylene, whereas the mixing fraction becomes constant at high m-xylene content. Similar results were obtained in saturated hydrocarbon systems. It is considered that oil molecules in the
surfactant palisade layer increases the effective cross-sectional area per surfactant head group, as, whereas as is constant if the oil molecules are solubilized in the core of the liquid crystal. The volume fraction of penetrating oil
in the total solubilized oil is defined as a penetration parameter, Pe, which is calculated from small-angle X-ray scattering
data. Pe is high in the m-xylene system, whereas it is low in the n-decane system. Even in the same oil system, Pe decreases dramatically with increasing solubilization. Hence, most of the
oil added penetrates into a palisade layer at an early stage of oil addition. This causes a change in the mixing fraction
of surfactant in the L
α phase. Thereafter the oil is solubilized in the core of the bilayer with further addition of oil.
Received: 20 April 1998 Accepted: 16 July 1998 相似文献
12.
The effects of Co alloying to Pt catalyst and Nafion pretreatment by NaClO4 solution on the rate-determining step (RDS) of oxygen reduction at Nafion-impregnated Pt-dispersed carbon (Pt/C) electrode
were investigated as a function of the potential step ΔE employing potentiostatic current transient (PCT) technique. For this purpose, the cathodic PCTs were measured on the pure
Nafion-impregnated and partially Na+-doped Nafion-impregnated Pt/C and PtCo/C electrodes in an oxygen-saturated 1 M H2SO4 solution and analyzed. From the shape of the cathodic PCTs and the dependence of the instantaneous current on the value of
ΔE, it was confirmed that oxygen reduction at the pure Nafion-impregnated electrodes is controlled by charge transfer at the
electrode surface mixed with oxygen diffusion in the solution below the transition potential step |ΔE
tr| in absolute value, whereas oxygen reduction is purely governed by oxygen diffusion above |ΔE
tr|. On the other hand, the RDS of oxygen reduction at the partially Na+-doped Nafion-impregnated electrodes below |ΔE
tr| is charge transfer coupled with proton migration, whereas above |ΔE
tr|, it becomes proton migration in the Nafion electrolyte instead of oxygen diffusion. Consequently, it is expected in real
fuel cell system that the cell performance is improved by Co alloying since the electrode reaches the maximum diffusion (migration)
current even at small value of |ΔE|, whereas the cell performance is aggravated by Nafion pretreatment due to the decrease in the maximum diffusion (migration)
current. 相似文献
13.
Influence of the Degree of Dehydroxylation of Kaolinite on the Properties of Aluminosilicate Glasses
The degree of dehydroxylation of kaolinite, DTG and DIR, respectively, is characterized by thermogravimetric analysis (TG) and Fourier transform infrared spectroscopy (FTIR). The
relation between DTG and DIR based on the infrared absorptions at 3600–3700, 915, 810, and 540 cm−1 is established. Three regions can clearly be distinguished: the dehydroxylation region (DTG<0.9), the metakaolinite region (0.9<DTG<1) and the ‘spinel’ region(DTG=1). The effect of the degree of dehydroxylation of kaolinite on the amount of reactive material is measured by the reaction
enthalpy, ΔH, of the low-temperature reaction of the dehydroxylated kaolinite with a potassium silicate solution using differential scanning
calorimetry (DSC). |ΔH| increases almost linearly with DTG in the dehydroxylation region. In the metakaolinite region, ΔH and thus the amount of reactive material, becomes constant. |ΔH| is sharply decreasing when metakaolinite transforms into other phases in the ‘spinel’ region. No significant differences
in the reactivity of the dehydroxylates is detected with DSC. According to FTIR, the use of partially dehydroxylated kaolinite
is not influencing the molecular structure of the low-temperature synthesized aluminosilicates, but residual kaolinite is
retrieved as an additive.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
14.
The excitation yield of the singlet molecular oxygen 1Δ
g
[φ(1O2)] in the reaction of the dimethyldioxirane with the chloride ion in benzene, acetone, methylene chloride, and acetonitrile
solutions has been determined. The φ(1O2) value depends on the solvent nature and is in the range 50–84%. Correlation between the value of the singlet oxygen yield
and the Kamlet-Taft parameter (α) characterizing the acidity of the solvent as a hydrogen bond donor has been established:
the higher the α value, the higher the 1O2 yield. 相似文献
15.
S. Chauhan M. S. Chauhan Deepika Kaushal V. K. Syal J. Jyoti 《Journal of solution chemistry》2010,39(5):622-638
Sound velocity and density measurements of aqueous solutions of the anionic surfactant SDS (sodium dodecyl sulfate) and the
cationic surfactant CTAB (cetyltrimethylammonium bromide) with the drug furosemide (0.002 and 0.02 mol⋅dm−3) have been carried out in the temperature range 20–40 °C. From these measurements, the compressibility coefficient (β), apparent molar volume (φ
v
) and apparent molar compressibility (φ
κ
) have been computed. From electrical conductivity measurements, the critical micelle concentrations (CMCs) of SDS and CTAB
has been determined in the above aqueous furosemide solutions. From the CMC values as a function of temperature, various thermodynamic
parameters have been evaluated: the standard enthalpy change (DHmo\Delta H_{\mathrm{m}}^{\mathrm{o}}), standard entropy change (DSmo\Delta S_{\mathrm{m}}^{\mathrm{o}}), and standard Gibbs energy change (DGmo\Delta G_{\mathrm{m}}^{\mathrm{o}}) for micellization. This work also included viscosity studies of aqueous solutions of SDS and CTAB with the drug in order
to determine the relative viscosity (η
r). UV-Vis studies have also been carried for the ternary drug/surfactant/water system having SDS in the concentration range
0.002–0.014 mol⋅dm−3. All of these parameters are discussed in terms of drug–drug, drug–solvent and drug–surfactant interactions resulting from
of various electrostatic and hydrophobic interactions. 相似文献
16.
Densities (ρ) and viscosities (η) of different strengths of magnesium sulphate (MgSO4) in varying proportions of formamide (FA) + ethylene glycol as mixed solvents were measured at room temperature. The experimental
values of ρ and η were used to calculate the values of the apparent molar volume, (φ1,), partial molar volume, (φ1,ℴ) at infinite dilution,A- andB-coefficients of the Jones-Dole equation and free energies of activation of viscous flow, (Δμ
1
0*
) and (Δμ
2
0*
), per mole of solvent and solute respectively. The behaviour of these parameters suggests strong ion-solvent interactions
in these systems and also that MgSO4 acts as structure-maker in FA + ethylene glycol mixed solvents. 相似文献
17.
V. A. Lukyanova T. S. Papina K. V. Didenko A. S. Alikhanyan 《Journal of Thermal Analysis and Calorimetry》2008,92(3):743-746
The standard enthalpy of combustion of crystalline silver pivalate, (CH3)3CC(O)OAg (AgPiv), was determined in an isoperibolic calorimeter with a self-sealing steel bomb, Δc
H
0 (AgPiv, cr)= −2786.9±5.6 kJ mol−1. The value of standard enthalpy of formation was derived for crystalline state: Δf
H
0(AgPiv,cr)= −466.9±5.6 kJ mol−1. Using the enthalpy of sublimation, measured earlier, the enthalpy of formation of gaseous dimer was obtained: Δf
H
0(Ag2Piv2,g)= −787±14 kJ mol−1. The enthalpy of reaction (CH3)3CC(O)OAg(cr)=Ag(cr)+(CH3)3CC(O)O.(g) was estimated, Δr
H
0=202 kJ mol−1. 相似文献
18.
Viscosity B-coefficients for cesium chloride and lithium sulfate in methanol + water mixtures at 25 and 35 °C are reported. A general
treatment of the quasi-thermodynamics of viscous flow of electrolyte solutions is described. ΔG
3
Θ
(1→1′), the contribution made to the Gibbs energy of activation of the solution by the influence of the solute on the solvent,
is a function of solute–solvent interactions only; but, ΔH
3
Θ
(1→1′) and ΔS
3
Θ
(1→1′) also reflect the solvent–solvent interactions. In aqueous solution all alkali-metal ions except Li+ are sterically unsaturated, having solvent co-ordination numbers n<n
max , the maximum allowed sterically. Such complexes exchange molecules with the solvent more readily than saturated ones and
have energy–reaction co-ordinate diagrams in forms that explain the negative B or ΔG
3
Θ
(1→1′) values found in aqueous solution. Saturated complexes are the norm in non-aqueous solvents, and the ΔG
3
Θ
(1→1′) values are determined mainly by the secondary solvation. Behavior in mixed solvents reflects the transition from aqueous
to non-aqueous behavior across the range of solvent composition. 相似文献
19.
Parimal C. Dey Muhammad A. Motin Tapan K. Biswas Entazul M. Huque 《Monatshefte für Chemie / Chemical Monthly》2003,37(2):797-809
The apparent molar volume (φv) and viscosity (η) of L(+)-arabinose, D(+)-galactose, D(−)-fructose, D(+)-glucose, sucrose, lactose, and maltose in water and in 0.1% and 0.3% water-Surf Excel solutions were measured as a function of solute concentrations at 308.15, 313.15, and 323.15 K, respectively. The apparent molar volume (φv) of the carbohydrates was found to be a linear function of the concentration. From a φv versus molality (b) plot, the apparent molar volume at infinite dilution (), which is practically equal to the partial molar volume at infinite dilutions () of these substances was determined. The viscosity coefficients B and D for the carbohydrates were calculated on the basis of the viscosity of the solutions and the solvent using the Jones-Dole equation. The activation free energy for viscous flow (ΔG ≠) of the solutions was also calculated using the Eyring equation. The carbohydrates showed structure making behaviour both in water and in water-Surf Excel solutions. When water-Surf Excel solutions and pure water solutions containing carbohydrate molecules are compared, the former were found to be more structured. The behaviour of these solutes in water and in water-Surf Excel solution systems is discussed in the light of solute–solvent interactions. 相似文献
20.
Annia Galano J. Raúl Alvarez-Idaboy Annik Vivier-Bunge 《Theoretical chemistry accounts》2007,118(3):597-606
Eight cyclopropane derivatives (Δ − R) have been modeled, with R = −H, −CH3, −NH2, −C ≡ CH, −C ≡ CCH3, −OH, −F and −C ≡ N. All geometries have been fully optimized at the MP2/ AUG-cc-pVTZ level of calculations. Natural bond
orbital analyses reveal extra p character (spλ, λ > 3) in the C-C bonds of the cyclopropyl rings. The banana-like σ
CC
bonds in the rings are described in detail. Alkene-like complexes between Δ − R molecules and hydrogen fluoride are identified. These weakly bonded complexes are formed through unconventional hydrogen
bond interactions between the hydrogen atom in the HF molecule and the carbon–carbon bonds in the cyclopropane ring. A topological
analysis of the electronic charge density and its Laplacian has been used to characterize the interactions. The possible relevance
of such complexes in the modeling of substrate–receptor interactions in some anti-AIDS drugs is discussed.
Contribution to the Serafin Fraga Memorial Issue. 相似文献