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The micellization phenomena in the mixed system of the amphiphilic antidepressant drug imipramine hydrochloride (IPH) and cationic hydrotropes - aniline hydrochloride (AnH), ortho-toluidine hydrochloride (o-ToH), as well as para-toluidine hydrochloride (p-ToH)- in a water solution at a range of temperatures (288.15, 293.15, 298.15, and 303.15 K) was investigated using the conductometry method. In accordance with the regular solution theory (RST), along with other models, such as Rubingh's model, Rodenas's model, and so forth, various parameters were determined to attain a complete picture of the association behaviours of IPH and the hydrotrope mixtures. For every IPH-hydrotrope mixture, the critical micelle concentration (cmc) of the mixture along with the composition of the hydrotropes in the mixed micelle diverged from what they would have been in an ideal system, demonstrating non-ideal behaviour. The divergence amongst evaluated cmc and ideal cmc (cmcid) values viewing interaction amid studied constituents. The effects of the hydrotropes on the cmc of IPH (drug) were found to occur in the following order: p-ToH > AnH > o-ToH. The interaction parameters (β) were also evaluated to obtain detailed insights into the interactions amongst the studied constituents by applying a theoretical model introduced by Rubingh. The β values were negative, showing the presence of interactions between the binary mixtures of IPH and the hydrotropes. Micellar mole fraction (X1) data estimated via the applied models in present system showed the attractive interactions between the IPH and hydrotropes as well as the intercalation of hydrotrope monomers between the drug IPH monomers constituting the micelle. Through the achieved thermodynamic parameters of the micellization of IPH under different conditions, the effects of temperature and the cationic hydrotropes, along with the impact of their concentrations on their association behaviours, were deduced.

The krafft temperature (Tk) of sodium tetradecyl sulfate (STS) has been determined conductometrically in aqueous, different aquo-organic solvent media (dioxane, formamide, and ethylene glycol), different concentrations of additives viz. NaCl, β-CD, and octadecyltrimethylammonium bromide (OTAB). The change in Tk in different media has been notified and summarized in tabular form. The micellar properties of STS also have been determined in binary aqueous mixtures of dioxane (DO) and formamide (FA) by tensiometry, conductometry and isothermal titration calorimetry. Different interfacial parameters, Gibbs surface excess (Γmax), area minima per surfactant (Amin), surface pressure (ΠCMC), and packing parameter (P) have been calculated from related well-known equations. Thermodynamic parameters, such as free energy for micellization (ΔGm0), free energy of adsorption (ΔGads0), change in enthalpy (ΔHm0), and entropy change associated with micellization (ΔSm0) have been also deduced. Aggregation number and Stern Volmer constant of STS in DO and FA have been determined from steady state fluorescence quenching study using fluorimetric technique.

Micellar parameters (critical micelle concentration (cmc), degree of micellar ionization (α), Krafft temperature (Tk), micro-polarity, aggregation number (Nagg) and dielectric constant (ea)) of aqueous cationic geminis (denoted as m-s-m; where, m = 12 or 14 and s = polymethylene, diester, diamido or diester isosorbate) have been studied by multi-technique approach (conductometry, fluorescence and 1H NMR) and compared with alkyltrimethylammonium bromide (CmTAB). Geminis show lower cmc and Tk than CmTAB. Among the geminis, hydrophilic spacer containing geminis show even lower cmc and Tk than the polymethylene spacer geminis. Temperature dependence of cmc shows a decrease, constancy followed by an increase (U-shaped behaviour) as s or m changes. Thermodynamic parameters have been obtained by temperature dependence of cmc. Intra-micellar monomeric arrangement and micellar size information have been acquired by 2D NOESY/COSY 1H NMR and dynamic light scattering (DLS), respectively. Data suggest that the hydrophilic spacer based geminis produce compact micelles with higher polarity compared to polymethylene spacer geminis (or CmTAB). The approach might be employed to tune the micellar interior environment/size, by changing the nature of the spacer or m.

Non-aqueous solvents are applicable in industrial and chemical reactions as well as some analytical methods such as electrochemistry. Application of quantitative structure-electrochemistry relationship (QSER) modeling in non-aqueous media can reduce trial-and-error experiments and more accurate estimation of target properties with lower number of runs. In the current study, for the first time, QSER was applied in conductometry as a wide field in electrochemistry. The target properties for modeling were the limiting molar conductivities of three alkali metal ions (Li+, Na+, K+) in water and various organic solvents; and empirical scales of the utilized solvents were applied as the independent set of variables. R2 in training sets of Li+, Na+ and K+ models were 0.94, 0.95 and 0.90 respectively. Models also showed good prediction ability and R2 in test sets of Li+, Na+ and K+ models were 0.95, 0.94 and 0.98 respectively. In addition, more statistical evaluations were done to show the predictability and stability of proposed QSERs. One of the advantages of suggested QSER models based on solvent empirical scales is the clear meaning of the solvent scales and their ability in description of solute-solvent interactions. Based on obtained results, the impact of some solvent features such as electron-donating power, electron-donating power, dipolarity-dipolarizability, hydrogen bonding, hydrogen-bond acceptor basicity and solvent acceptor number on the conductivity of lithium, sodium and potassium ions were discussed.

Ball milling was used to obtain new Schiff-base complexes from Co(II), Fe(III), Ni(II), and Zn(II) ions in their solid form, which is considered a green method of preparation. Several spectroscopic (IR, UV–Vis, 1H NMR, Mass, SEM, EDX, XRD) and analytical approaches were used to suggest the geometries of isolated compounds. Coats–Redfern and Horowitz–Metzger methods were used to compute the kinetic and thermodynamic parameters of Zn(II) complex (i.e.). Furthermore, conductometry was used to estimate both formation/association constants of Co(II) complex (i.e.) in solution at 290.15 K. The feature of the complex in solution may offer a good view about it in its solid state. Standard methods were applied to test the antibacterial activity of ligand and complexes to TOS aureus, E. coli and Candida albicans fungus. To assess their inhibitory effect, ABTS-antioxidant screening and cytotoxicity against liver cancer cells (HepG2) were also performed. Most complexes showed mild to considerable activity towards the selected microorganisms and liver cancer cell line, respectively. The structural forms were optimized using molecular modeling, which then confirmed the binding mechanism provided by spectral analyses. To investigate the degree of inhibition for new drugs versus three selected proteins (1dee, 5uw2 and 7jx9), two in-silico techniques were used: Pharmit link and Molecular Operating Environmental module (MOE, vs 2018). The docking patterns as well as the interaction data were acquired and analyzed. The high consistency of in-vitro and in-silico outcomes lends credence to computational treatments that must be done on developed medications before they can be used in practice.

In the present research we studied ionic liquids of 1-alkyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, [CnMIm][TFSI], where n = 2 (ethyl, C2), 3 (propyl, C3) and 4 (butyl, C4) with small water impurity absorbed though the contact with air. IR spectra, thermodynamic, electrochemical and the bulk properties, such as density and viscosity, were determined by means of FT-IR spectroscopy, conductometry, densimetry, viscosimetry, TG and DSC methods. The influence of temperature, absorbed water and elongation of the cation alkyl chain on the physicochemical properties was studied. It was found that the absorbed water (approximately 0.24–0.25% by weight) is frozen at a temperature from −40.5 to −46.3 °C, has little effect on thermal stability and significantly affects the phase behavior of ionic liquids. The linearly dependence of the density on the temperature was observed. The conductivity increases and the viscosity decreases with increasing temperature according with the VFT equation. Physicochemical properties depend on alkyl chain length, but not linearly, so that C3 is close to the transition between C2 and C4. Such tendency was explained in terms of Van der Waals forces and hydrogen bonds.

Micellization and related thermodynamic parameters of conventional cationic surfactants (cetyltrimethylammonium bromide and dodecyltrimethylammonium bromide) at different concentrations of cefepime (0.00, 0.001, 0.005, and 0.010 mol·kg−1) in aqueous medium have been thoroughly assessed by means of conductivity at different temperatures (293.15–313.15 K) and fluorescence spectroscopy at temperature 298.15 K. The thermodynamic data on micellization and degree of ionization have been obtained by conductometry. The effect of drug cefepime on the CMC (critical micelle concentration) and energetics of micellization of the surfactant has also been examined. From CMC values as a function of temperature, it is observed that micellization tendency of the surfactant increases in the presence of cefepime. The applicability of fluorescence spectroscopy to study cefepime/surfactant systems has also been investigated using pyrene as a probe. The interaction of cationic surfactant with the drug changes the micropolarity of ternary system as well as the micellar assembly of surfactant. The results have been rationalized in terms of physico-chemical concepts and relations. It would therefore, be interesting to evaluate the region of micelle formation in order to assess and develop surfactant immobilized cefepime for better biological activity.

This work deals with development of polyfunctional biocompatible cationic surfactant systems based on bioactive saturated bicyclic alkaloid quinuclidine. It is focused on the effect of the chemical structure of surfactants on their aggregation behavior, their physicochemical estimation of solubility of model water insoluble dye Orange OT and drugs, quercetin and rutin, microbiology and cytotoxicity. Quaternary ammonium derivatives of quinuclidine (Q-Nuc-n) with different hydrophobicity (R = CnH2n+1, where n = 14, 16, 18) were synthesized. Self-assembly of Q-Nuc-n was investigated by tensiometry, conductometry, spectrophotometry, fluorimetry and dynamic light scattering. The critical micelle concentration, thermodynamic and adsorption parameters at water-air interface, size and aggregation numbers of Q-Nuc-n micelles were determined. The looser packing of surfactant molecules in Q-Nuc-n micelles compared to its analogues, quaternized derivatives of 1,4‑diazabicyclo[2.2.2]octane (DABCO-n), was established. The hydrophobic dye Orange OT and drugs quercetin and rutin were solubilized in micellar Q-Nuc-n solutions better than in solutions of classical surfactant CTAB and its analogue DABCO-n. Solubilization capacity of Q-Nuc-18 is 5 times higher than that of classical surfactant CTAB. Q-Nuc-18 1.95 μg·mL−1 has also bactericidal and fungicidal activity 2 times (against S. aureus 209P) and 8 times (against B. cereus 8035) higher than antibiotics Norfloxacin and antifungal Ketoconazole. Q-Nuc-16 has the highest bactericidal activity. It is 6 times (against S. aureus 209P) and 15 times (against B. cereus 8035) higher than the bactericidal activity value of Norfloxacin. Synthesized cationic surfactants based on quinuclidine are new multifunctional biocompatible compounds with high potential in nanomedicine and biotechnology.

The corrosion inhibition efficiency of two cationic gemini surfactants with different counterions with polyamine platform on AISI 304 stainless steel in 3 M HCl was investigated by polarisation measurements and electrochemical impedance spectroscopy (EIS). The surface of the samples was characterised before and after the corrosion experiments using scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM). The results showed that the effectiveness of corrosion inhibiton depends on counterion belongs to surfactant molecule. The dimeric surfactant with the iodine counterion out–performs its bromine counterpart with respect to providing corrosion inhibition of stainless steel, in 3 M HCl. In the present study, the Langmuir adsorption isotherm was found to be suitable parameter for the correlating the experimental results with a possible mechanism of protection. In the case of two tested compounds the highest inhibition efficiency was found around the critical micelle concentration. Critical micelle concentration was determined using conductometric titration.

The present investigations concern the mixed aggregation of anionic surfactant sodium dodecyl sulfate (SDS) and aminomethylated calix[4]resorcinol (ACR) with ethylsulfonate groups on the lower rim. The interaction between these compounds was investigated by DOSY NMR, tensiometry, conductometry, dynamic and electrophoretic light scattering, atomic force microscopy and drug solubilization. The mixed supramolecular systems based on ACR and SDS can be derived due to pH-switchable properties. Supramolecular assembly took place in acidic medium which caused protonation of the amine groups of ACR and thereby the interaction of charged species in solution. Remarkably, the globular SDS micelles were observed to transform into rod-like micelles in the presence of ACR at lower pH, which can be used to encapsulate the hydrophobic guest molecules.

The development and optimization of systems consist of polymers and surfactants are strongly related to the presence of interactions between them. Therefore, the interpolymer complexes between biopolymer xanthan gum and synthetic polymer Carbopol 940 were investigated before and after the addition of surfactant. The mechanism of interactions in ternary system consisted of xanthan gum, Carbopol 940 and anionic surfactant (sodium dodecylsulfate) as well as nonionic surfactant (Tween 80) was studied by the combination of different techniques such as viscometry, conductometry, tensiometry, spectrophotometry and fluorimetry. Xanthan gum and Carbopol 940 formed complexes through hydrogen bonding and hydrophobic interactions. Therefore, the calculated specific viscosities of polymer blends were much lower than experimentally determined values. Namely, both polymers participated in the association process with sodium dodecylsulfate or Tween 80. In case of anionic surfactant hydrophobic interactions between sodium dodecylsulfate and xanthan gum-Carbopol 940 complexes exist together with electrostatic repulsive forces between the same charged groups. Tween 80 interacts with xanthan gum-Carbopol 940 complexes through hydrogen bonds and hydrophobic interactions. The formed xanthan gum-Carbopol 940 complexes with sodium dodecylsulfate or Tween80 could find their application by optimizing the interactions in the system of xanthan gum and Carbopol 940 using the appropriate concentration of surfactant.

To rigorously characterize the interactions of sodium dodecyl sulfate (SDS) with bovine serum albumin (BSA) a set of experimental methods, namely isothermal titration calorimetry, conductometric titration, steady-state fluorescence spectroscopy, differential scanning calorimetry and circular dichroism spectroscopy, supported by in silico analysis have been applied. The influence of pH and temperature on the binding mode has been revealed. At a low molar ratio of SDS to BSA up to ca. 16:1, there are at least two structurally distinct binding sites in BSA. The formation of SDS-BSA complexes is an enthalpy-driven process in which the van der Waals interactions play a crucial role. The first binding site, located close to the Trp-134 residue within the sub-domain IA, is pH-independent and binds two molecules of SDS per one molecule of BSA whereas the total number of SDS molecules bound to the second site of albumin is affected by temperature and pH. The saturation of the first binding site of BSA (ca. 0.009 mg of SDS per 1 mg of BSA) is sufficient to thermally stabilize the helical conformation of BSA. The presented results have important structural and thermodynamic implications to understand the influence of a widely used anionic surfactant on globular protein functionality in modern branches of chemistry.

Inulin, a carbohydrate based polymer has immense applications in industries of human aids. There are very limited interactive studies on this polymer although there are numerous applications. In the present study, interactions of inulin with different amphiphiles lead to interesting characteristics as identified by various physicochemical methods. Tensiometry, conductometry, isothermal titration calorimetry, turbidimetry, etc. have been employed to characterize the phenomenological changes. Cationic type amphiphiles, e.g., surface active ionic liquid, conventional, and gemini surfactants provide very fruitful interactions. These amphiphiles form small aggregates with the polymer at low concentration, coacervates at moderate concentration and free micelles at higher concentrations of the amphiphiles. Inulin-amphiphiles interaction has been supported by different morphological studies also.

Hydrazone derivative was used to prepare 1:1 M ratio with Cr(III) & Co(II) ions as well as 1:2 ratio with Zn(II) & Cd(II) ions. The ligand (H2L) coordinated as bidentate/tridentate via neutral/ monobasic towards the metal ions. This proposal depends on the size of metal ion and the conjugated anion in its salt used. The octahedral geometry of Cr(III) or Co(II) complex was confirmed via ligand field transition bands as well as the magnetic moment values. While, Cd(II) and Zn(II) geometries were assumed according to d10-systematic forms and the mode of bonding was supported by 1H NMR spectra. SEM, XRD, EDX and TGA were mainly used to detect surface morphology, particle-sizes, elemental percentages, and thermal stability, respectively. Molecular modeling was carried out to optimize the structural forms and then confirms the binding manner proposed from spectral studies. Consequently, the ligand showed a well distribution for C(8)-O(11) and C(13) = O(12) groups, which promotes their coordination easily without twisting or strain for the bonds. The electrostatic potential confirms nucleophilicity of O(11) and O(12) atoms, which improved after coordination with Cr(III) and Co(II) ions due to M → L charge transfer. The dipole moment of the ligand (4.08 debye) predicts a distinguish biological activity for the ligand, while it is not expected for its complexes. Antimicrobial, antioxidant and cytotoxicity results of the ligand are extremely promising, which agreed perfectly with that expected from computations. Upon ZnSO4 solution prepared as a bulk or from nano-sized particles, in H2O or in mixed solvents (EtOH + H2O), the conductance parameters were estimated according to Fuoss-Hsia-Fernandez-Prini (FHFP) method. The limiting molar conductance commonly decreased by increasing ethanol percentage in solvent mixtures. In presence or absence of the ligand, the association constant, thermodynamic parameters and activation energy, were calculated in addition to complex formation constants and molar ratios [M:L].

The micellization behavior and the molecular interaction of quasi-binary mixture constituted by an amphoteric sodium N-acyl amino sulfonate based on castor oil (AAS-CO) with a cationic stearyltrimethyl ammonium bromide (STAB) in aqueous solution at 298.15 K were investigated using both the tensiometry and the conductometry and the two techniques were adopted to determine the mixed critical micelle concentration (cmc). Based on the regular solution theory and in the framework of the pseudophase separation model, Rubingh’s model and Clint’s model were adopted to estimate the mole fractions and the activity coefficients in mixed micelle, the interaction parameters between quasi-one AAS-CO and STAB. Also, thermodynamic parameters were obtained by thermodynamic models. Synergistic interaction between surfactants and non-ideal mixing were observed in the entire range of composition in this investigation. The addition of quasi-one AAS-CO into aqueous solution can induce the alteration of interaction behavior between surfactants, which can be explained rationally by the shielding effect, the electrostatic repulsion and the steric hindrance. Thermodynamic parameters imply that it appears an enthalpically spontaneous behavior in the process of micellization and there exists a largest negative deviation of free energy change of micellization from the ideal case at the optimum composition in which a maximum synergism happens. These findings will help with understanding the molecular interaction between quasi-one component and other one in surfactant mixtures.

Nonaqueous redox flow batteries use liquid electrolytes containing redox-active organic molecules (redoxmers) as their energy storage medium. To maximize energy density, the redoxmer concentration needs to be maximized while maintaining low viscosity and high ionic conductivity. During charge, a redoxmer molecule pairs with an ion in the electrolyte while another ion migrates across the membrane to maintain electric neutrality. In a crowded electrolyte, this reconstitution changes physical and chemical properties of the solution. To explore these behaviors, a phenothiazine redoxmer fully miscible with acetonitrile was used, and electrochemical charge was mimicked by chemical oxidation. The solutions were examined using small-angle X-ray scattering, nuclear magnetic resonance, and conductometry and modeled using classical molecular dynamics. Our study indicates that physical and structural properties of redoxmer solutions in both states of charge make it exceedingly difficult to increase the redoxmer concentrations over 2 M at any temperature without compromising dynamic properties of such solutions. The cause for this limitation is proximity to a gel-like regime in which fluidity, diffusivity, and ionic conductivity exponentially decrease with increasing concentration. This tendency is compounded by non-Arrhenius behavior of the electrolyte: a small increase in the concentration outruns gains in fluidity and conductivity at a higher temperature. Thus the properties of crowded electrolytes generally make it impossible to operate when gel-like behavior sets in. Pushing the redoxmer concentration to 2.5–3 M might be possible for small redoxmer molecules, but it would require the use of ionic liquid electrolytes at 340–360 K.

The interfacial and micellization behavior of binary mixture of an amino sulfonate amphoteric 3-(N-dodecyl ethylenediamino)-2-hydropropyl sulfonate (C12AS) and a cationic octadecyltrimethyl ammonium bromide (OTAB) were investigated in aqueous solution without or with a 70 g/L alcohol (including methanol, ethanol, 1-propanol and 1-butanol) at 313.15 K by both the tensiometry and the conductometry. The surface excess concentration, the minimum area per surfactant molecule at the saturated interface and the standard free energy of adsorption at the air-liquid interface were adopted to be characteristic of the interfacial adsorption monolayer. Based on the pseudophase separation model and the regular solution theory, the Clint’s model and the Rubingh’s model was used to obtain the related parameters including the interaction parameters between two surfactant molecules, the compositions and the activity coefficients in mixed micelle and thermodynamic parameters. The effect of the alcohol chain length on the interfacial adsorption and the mixed micellization was discussed. The addition of short chain alcohol influences the properties of mixed cosolvent, the conformation of C12AS molecule and the electrostatic interaction between two surfactant molecules. Thermodynamic data shows that the presence of alcohol with a longer chain is beneficial to form the adsorption monolayer and the mixed micelle, and also it depresses the contribution of entropy to the process of micellization. These findings help with understanding the mechanism on the effect of short chain alcohol on the interfacial and micellization behavior of binary surfactant mixtures and further designing the surfactant formulations.

Aim of the present investigation is to broaden an understanding of the interactions between imidazolium based cationic surface active ionic liquid (SAIL) 1-dodecyl-3-methylimidazolium bromide [C 12 mim][Br] and an anionic polyelectrolyte poly(4-styrenesufonic acid- co -maleic acid) sodium salt (PSSA-co-MA) in aqueous media by using fluorimetry, conductometry and tensiometry techniques. The various states of interaction and critical micelle concentration (cmc) have been reviewed due to the strong hydrophobic and electrostatic interactions. Also degree of ionization, α, cmc and various thermodynamic parameters were determined by conductivity measurement in the temperature range 298.15–318.15 K. The surface tension curve displays the presence of pronounced knap in the surface tension at SAIL concentrations below cmc of the SAIL. The various surface parameters are calculated from surface tension measurement. Aggregation number ( N agg ) and cmc were determined by fluorimetric measurements at temperature 298 K. In all cases it was observed that the cmc values were decreased with increase in the concentration of polyelectrolyte this is attributed to the strong electrostatic interactions between SAIL and polyelectrolyte. Also the aggregation behaviour of SAIL begins shifting from entropy-driven to enthalpy-driven with increasing the concentration of polyelectrolyte and increase in temperature. The results obtained from different measurements are in good agreement with each other.

The alternative models of ionic equilibria in acetonitrile solutions of alkaline earth percholorates in the presence of 3-hydroxyflavone (HL) were studied by conductometry at 288.15, 298.15, 308.15, 318.15, and 328.15 K. Using a procedure specially developed for this task it was shown that in the solutions containing Ca(ClO 4 ) 2 and Sr(ClO 4 ) 2 the complexation of the cation (M 2 + ) by the HL molecule leads to the formation of the doubly-charged [M(HL)] 2 + complex species. In contrast to them, in the presence of Ba(ClO 4 ) 2 HL interacts with the ion pair BaClO 4 + forming the singly-charged [BaClO 4 (HL)] + complex. The limiting equivalent conductivities as well as the constants of complexation were estimated. The latter were calculated by taking into account the ion association between cation and anion of initial salts and activity coefficients, that is the ‘true’ thermodynamic constants were found. The reliability of the proposed approach was additionally checked by analyzing artificially noised model experimental data. It was shown that the fitted parameters can be satisfactorily reproduced even at the noise level equal to 2%. The limiting equivalent conductivities of the [Ca(HL)] 2 + , [Sr(HL)] 2 + and [BaClO 4 (HL)] + complex species were interpreted in terms of the Stokes radii whose values indicate very weak solvation of the formed complexes. The variation of the constants of complexation among cations was found to be in agreement with the values of primary association constants.

Electrical conductance of sodium polystyrene sulfonate (NaPSS) have been measured in aqueous solutions of 1–butyl–3–methylimidazolium bromide ([BMIm]Br) at three different temperatures T = (288.15, 298.15 and 308.15) K. The scaling theory is applied for the explanation of electrical conductance of polyelectrolytes. From the obtained results can be seen that the fraction of uncondensed counterions is decreased by increasing temperature and concentration of [BMIm]Br. Also, conductivity measurements of 1–butyl–3–methylimidazolium bromide were carried out in aqueous solution of sodium polystyrene sulfonate. Data analysis was performed by the Quint-Viallard (QV) conductivity equation and low concentration chemical model (lcCM). Limiting molar conductivities of [BMIm]Br ( Λ 0 ) and the association constant ( K A ) were determined. Molar conductivity of [BMIm]Br in aqueous solutions of NaPSS was increased with increasing temperature. The values of activation energy for viscous flow and the values of activation enthalpy of charge transport were calculated. The results of Quantum chemical calculations were confirmed the existence of hydrogen bonding between [BMIm] + and [PSS] − .

Solubilization of anionic azo dyes, methyl red and alizarin yellow, in micelles of cationic surfactant, cetyltrimethylammonium bromide, was studied in aqueous solutions with pH ~ 10 by conductometry and UV–Vis spectroscopy. The electro-conductivity measurements were used to evaluate influence of azo dyes on critical micelle concentration of cetyltrimethylammonium bromide and estimate standard thermodynamic parameters of micellization process. It was found that solubilization of azo dyes by micelles of surfactant is spontaneous process which causes lowering of critical micelle concentration of long-chain quaternary ammonium salt. The phenomenon of azo dyes solubilization by surfactant micelles was confirmed by analysis of the effect of different concentrations of cetyltrimethylammonium bromide on the UV-Vis spectra of azo dyes solutions. Differential spectroscopic technique was employed to obtain quantitative characteristics of azo dyes solubilization in micellar media. The values of binding constant, partition coefficient, and free energy change of partition for azo dyes were calculated. Obtained results proved that methyl red and alizarin yellow incorporate into the CTAB micelle in such a way that their carboxylic groups are lying near by positively charged head group of surfactant and the rest of the molecule is oriented towards center of micelle. Micelles of cetyltrimethylammonium bromide with solubilized azo dyes were used as template in base catalysed hydrothermal-assisted sol-gel synthesis of mesoporous aminosilicas of MSM-41 type. The mesoporous structure of synthesized materials was characterized by low-temperature nitrogen adsorption-desorption and x-ray diffraction analysis. It was proved that incorporation of azo dye additives as solubilizates into the surfactant micelles in sol-gel synthesis leads to the formation of silica materials with improved long-range ordered mesoporous structure.

The inhibiting action of pyrazinamide derivatives toward the dissolution of aluminum electrode in 1.0 M HCl solution was investigated by weight loss, galvanostatic polarization and electrochemical impedance spectroscopy (EIS) measurements. The percentage inhibition efficiency increases with increasing concentrations of pyrazinamide compounds, and with decreasing temperature. The interpretation of the inhibition due to the adsorption of its compounds on the aluminum surface is according to Temkin's isotherm. The interaction between the pyrazinamide compounds and aluminum ions led to the formation of a stable five membered ring complex through the formation two coordination bonds between the lone pairs of electron of the nitrogen and oxygen donor atoms and Al + 3 ion. Conductometric titration proved that the stoichiometry of Al + 3 /pyrazinamide (M/L) is 1:1. The adsorption of the complex led to slow down the rate of corrosion and improvement of the inhibition process. The addition of KI ameliorates the inhibition efficiency due to the synergistic effect. Some activated thermodynamic parameters are calculated and interpreted.

The influence of four sodium salts (NaCl, NaBr, Na2SO4, and Na3PO4) on the self-aggregation, interfacial, and thermodynamic properties of a surface active ionic liquid (1-hexadecyl-3-methylimidazolium chloride, C16MImCl) has been explored in aqueous solutions by conductometry, tensiometry, spectrofluorimetry, isothermal titration calorimetry and dynamic light scattering (DLS). Analyses of the critical micellar concentration (cmc) values indicate that the anions of the added salts promote the self-aggregation of C16MImCl in the order: Cl−

In the framework of this investigation novel cationic amphiphiles of N-(2-butylaminocarbonyloxyethyl)-N-alkylimidazolium bromides series have been synthesized and characterized in terms of their aggregation capacity in aqueous solutions, antimicrobial properties and solubilization action toward hydrophobic dye. Using tensiometry, conductometry and fluorescence spectroscopy techniques it has been demonstrated, that the presence of urethane fragment with butyl moiety is responsible for the one order of magnitude decrease of critical micelle concentration of amphiphiles in comparison with unsubstituted analogs. Fabrication of aggregates with hydrodynamic diameter in the range of 4–10 nm has been exhibited for all amphiphiles. Transmission electron microscopy technique allows to establish the spherical shape of aggregates formed. These amphiphiles were shown as effective solubilizers of hydrophobic azodye, which efficacy could be 2.5-fold increased by elongation of the length of hydrophobic tail by four methylene units. Estimation of interaction of amphiphiles with biological objects has revealed, that all compounds exhibit high bacteriostatic and bactericide properties preferably toward gram-positive strains, as well as they have low hemolytic activity at active concentrations. Antibacterial properties of tetradecyl amphiphilic derivative have surpassed norfloxacin by 5 and 8.5 times in relation to Staphylococcus aureus and Bacillus cereus, respectively.

The corrosion inhibition efficiency of three cationic clevelable surfactants with different chain length on AISI 304 stainless steel in 3 M HCl was investigated by polarisation measurements and electrochemical impedance spectroscopy (EIS). The surface of the samples was characterized before and after the corrosion experiments using scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM). The results showed that the effectiveness of corrosion inhibition depends on chain length. In the present study, the Langmuir adsorption isotherm was found to be suitable parameter for the correlating the experimental results with a possible mechanism of protection. In the case of tested compounds the highest inhibition efficiency was found around the critical micelle concentration. Critical micelle concentration (CMC) was determined using conductometric titration.

Acylated amino acids, a group of amino acid-based surfactants have been the focus of recent studies as green alternatives to petrochemical-based surfactants yet their enhanced oil recovery (EOR) potential is understudied. The few reported amino acid-based surfactants in literature showed less satisfactory performance compared to conventional surfactants with regards to their EOR application. In this present study, however, sodium cocoyl alaninate (SCA); an amino acid-based surfactant has been proven to have excellent properties relevant to its EOR application. It proved to have comparable or even better performance to commonly deployed surfactants for EOR application. Its surface activity and thermodynamic properties of aggregation are evaluated. The aggregation behaviour was considered employing surface tensiometry and conductometry data. With EOR application in mind, the interfacial tension (IFT) and wettability modification studies were made as well. The results were compared to conventional surfactants and other amino acid-based surfactants. SCA has surface tension reduction efficiency and effectiveness of 2.74 and 40.79 mN/m respectively compared to sodium dodecyl sulfate (SDS) with 2.51 and 32.5 mN/m. This proves that SCA is superior to SDS in terms of surface activity. Furthermore, with 91% reduction in IFT by SCA compared to 89% reduction by SDS, the superior surface activity of SCA to SDS was confirmed. There was evidence of synergy in reducing IFT when salt was added. About 47% improvement in IFT reduction was observed. SCA also has a superior ability to SDS and CTAB in modifying quartz and carbonate surfaces' wettability respectively. Quartz surface was altered from intermediate wet to water wet while carbonate surface was altered from oil wet to water wet. SCA, therefore, proves to be an excellent alternative to conventional EOR surfactants due to its superb surface activity coupled with its environmentally benign nature.

Ionic liquids (ILs) with single bis(trifluoromethylsulfonyl)imide anion (TFSI−) and different cation, such as methyltrioctylammonium (MTOAm+), butylmethylpyrrolidinium (BMPyrr+) and 1-butyl-3-methylimidazolium (BMIm+), were studied using FT-IR, TG, DSC, densimetry, viscosimetry and conductometry methods. All ionic liquids contained equilibrium water absorbed from air in an amount of about 0.13–0.24 wt%. It was found that, the density, conductivity and crystallization ability decrease in the following order MTOAm+ ≪ BMPyrr+ BMIm+. A small amount of water (

The noticeable change in self-aggregation nature (rod-like micelle) of cetyl trimethylammonium p-toluene sulfonate (CTAT) in presence of various electrolytes and non-electrolytes was probed using tensiometry, conductometry, isothermal titration calorimetry and fluorimetry. The impact of electrolytes and non-electrolytes on the critical micelle concentration (CMC) of the surfactant was found to be opposite of each other. The non-electrolytes having lower dielectric constants than water increased the repulsion between the surfactant head groups, thereby increasing the CMC. Less negative value of ΔG0m with increase in solvent concentration indicated delayed process of micellization. On the contrary, electrolytes decreased the CMC by a large extent due to suppression of the repulsion between the charged head groups by supplying more counter ions from the salts. The aggregation number of CTAT solution in presence of electrolytes increased with increase in salt concentration but decreased in presence of non-electrolytes, with increase of its concentration. The packing parameter value indicated the transition towards spherical shape with increase in concentration of non-electrolytes and increase in more non-spherical shape with increase in concentration of electrolytes for rod-like micelles of CTAT.

In this article, we have investigated the micellization behaviour of cationic surfactant tetradecyltrimethylammonium bromide (TTAB) and imidazolium based biamphiphilic surface active ionic liquid (BAIL), 3-methyl-1-pentylimidazolium dodecylsulfate [C5mim][DS] in aqueous solution, by employing various state of art techniques such as conductometry, tensiometry, spectrofluorometry, turbidity, dynamic light scattering (DLS), zeta potential (ζ), 1H NMR, freeze scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM). The conductometry, and tensiometry measurements have revealed that the micelle formation takes place at lower concentration due to strong synergistic interactions. The aggregation number (Nagg) determined from fluorescence using pyrene as a probe confirms the presence of micelle/vesicles or micelles or vesicles together at different mole fraction ratio of pure components. The various surface parameters have been evaluated by using the tensiometry. Turbidity and DLS measurements have confirmed the formation of micelles as well as vesicles over an exceptionally wide range of concentration (mole fraction = 0.1–0.9). The shape and morphology of the aggregates has been studied by using the FE-SEM and TEM measurements. The 1H NMR measurements shed light on the type of interactions prevail in the two oppositely charged mixed system.

Five structurally related morpholinium derived ionic liquids containing N-acetyl-glycinate anion were synthesized and their thermal stability, surface properties and activity as phase transfer catalysts investigated. The thermal properties were studied by differential scanning calorimetry, while the adsorption at the air/water interface and micellization behavior was analyzed by surface tension measurements, conductometry and isothermal titration calorimetry. The catalytic activity was assessed in two model reactions that were N-alkylation of dibenzoazepine and C-alkylation reaction of fluorene derivatives. The effect of the chain length, thus surface activity of the newly synthetized ionic liquids on the yields of N- and C-alkylation reactions was discussed.

Chromium(III)-amino acid ([Cr(III)-His]2+) and ninhydrin in an aqueous-micellar system were combined in acetate buffer at 353 K and analyzed by UV–vis spectroscopy. Dimeric geminis (16-s-16, s, spacer, = 4 to 6) were chosen as a surfactant and their influence on the reaction rate was determined. To show this behavior of gemini surfactants on rate constant (kψ), kψ was plotted against different surfactant concentrations. kψ increases with increasing [16-s-16] (at concentrations lesser than their cmc values, segment I) and levelling-off regions attain (concentration upto 400 × 10−5 mol dm−3, segment II). Later, [16-s-16] generates a third region of increasing kψ at higher [16-s-16] ([16-s-16] > 400 × 10−5 mol dm−3, segment III). The uncommon plot behavior of kψ vs. [16-s-16] was revealed, effectively, by utilizing a pseudo-phase model of micellar activity. Critical micellar concentration of pure gemini surfactants, as well as their mixed solution with reactants, was determined by conductometry. Based on the data, various thermodynamic parameters and binding constants were calculated under different experimental reaction conditions.

The present study reports the enhanced solubilizing power of mixed micellar media in comparison to single micellar media. The solubilization of anionic direct dye, Direct Brown 2 (DB-2) has been investigated in micellar media of cationic surfactants; cetyltrimethyl ammonium bromide (CTAB), cetylpyridinium chloride (CPC) and in mixed micellar media of each with nonionic surfactant Triton X-100 (TX-100) using UV–visible spectroscopy and conductometry. The UV–visible spectroscopy has been used to evaluate the degree of solubilization in terms of binding constant, Kb, Gibbs energy of binding, ΔGb, partition coefficient, Kx, and Gibbs energy of partition, ΔGp. Furthermore, electrical conductivity data, taken at different temperatures, has been employed to find out critical micelle concentration (CMC) and different thermodynamic parameters like enthalpy, ΔHm, entropy, ΔSm and Gibbs energy of micellization, ΔGm of reported surfactants in presence of dye. Results reveal spontaneous nature solubilization and binding of dye in both micellar and mixed micellar solutions of surfactants. The micellar system of CTAB as well as mixed micellar solutions of CTAB/TX-100 are recommended to be used to achieve higher degree of solubilization.

Herein, multi-techniques approaches such as conductometry, tensiometry, fluorometry, and FT-IR were engaged to evaluate the interaction between sodium salt of ibuprofen (IB) and gelatin (GN) at 298.15 K in 250 mmol·kg−1 urea (UR) solution. The current employed drug is used for relief of pain. The employed IB drug interacts through GN protein like the interaction between surfactants and polymers. It is clear that the graph obtained from the conductometric and tensiometry methods shows two clear breaks. Urea acts as water structure breaker and their presence in solution enhance in surface charge of aggregates occurs. The obtained first break spot is labeled critical aggregation concentration (cc) which is quit beneath the usual critical micelle concentration (cmc) besides this the subsequently break spot denotes second one is regarded as polymer saturation point (pp) and this akin to cmc. The interaction between IB and GN in UR solution increases as concentration of protein increases in the solution mixtures as clear from their obtained cc value because the value of cc reduces through enhancing the concentration of GN (%w/v), in spite of this the value of pp value increases with increase in concentration of GN means more drug needed for complete saturation of binding site of protein. In UR solution, the Gibbs free energy of micellization (ΔGmic) for singular IB was achieved negative exploring that micellization process is spontaneous in nature. The other different evaluated thermodynamic parameters such as free energy of aggregation (ΔGagg), free energy of transfer (ΔGt), etc. were found in favor of interaction between IB and GN. Fluorometry technique was utilized to find out the various parameters such as micropolarity, aggregation numbers (Nagg), etc. to verify the interaction amongst studied constituents and with the interaction between them were also assessed by FT-IR study.