Triton X-100 Micellar Solution Research Articles

Spectral and electrochemical studies of bis(diimine)copper(II) complexes in anionic, cationic and nonionic micelles

The spectral and redox behavior of bis(diimine)copper(II) complexes, where diimine is bipyridine, 1,10-phenanthroline, 4-methyl-1,10-phenanthroline, 5-methyl-1,10-phenanthroline, 5-nitro-1,10-phenanthroline, 4,7-dimethyl-1,10-phenanthroline, 5,6-dimethyl-1,10-phenanthroline, 2,9-dimethyl-1,10-phenanthroline, 3,4,7,8-tetramethyl-1,10-phenanthroline and dipyrido-[3,2-d:2′,3′-f]-quinoxaline, are significantly different in aqueous and in aqueous SDS, CTAB and Triton X-100 micellar solutions. The 1H NMR spectral study in aqueous (D2O) and aqueous micelles reveals that the Cu(II) complexes interact more strongly with SDS than with CTAB and Triton X-100 micelles and at sites on SDS micelles different from those on the latter. Ligand Field spectral studies reveal that the complexes exist as the dicationic aquated species [Cu(diimine)2(H2O)2]2+, which interacts strongly with the anionic SDS micelles through columbic forces. However, they exist as [Cu(diimine)2(H2O)Cl]+ and/or [Cu(diimine)2H2] located in the hydrophobic microenvironments in Triton X-100 and CTAB micelles. The attainment of reversibility of the redox systems in the micellar microenvironments is remarkable and this illustrates that the Cu(II) and Cu(I) species undergo stereochemical changes suitable for reversible electron-transfer. The remarkable differences in spectral and electrochemical properties of Cu(II) complexes in aqueous and aqueous micellar solutions illustrate that the complexes are nestled largely within the micellar environments and imply that the accessibilities of the complexes to electron-transfer are different and are dependent on the nature of micelles as well as the nature and hydrophobicity of the diimine ligands.

Kinetic Study of the Quenching Reaction of Singlet Oxygen by Pyrroloquinolinequinol (PQQH2, a Reduced Form of Pyrroloquinolinequinone) in Micellar Solution

A kinetic study of the quenching reaction of singlet oxygen ((1)O(2)) with pyrroloquinolinequinol (PQQH(2), a reduced form of pyrroloquinolinequinone (PQQ)), PQQNa(2) (disodium salt of PQQ), and seven kinds of natural antioxidants (vitamin C (Vit C), uric acid (UA), epicatechin (EC), epigallocatechin (EGC), α-tocopherol (α-Toc), ubiquinol-10 (UQ(10)H(2)), and β-carotene (β-Car)) has been performed. The second-order rate constants k(Q) (k(Q) = k(q) + k(r), physical quenching and chemical reaction) for the reaction of (1)O(2) with PQQH(2), PQQNa(2), and seven kinds of antioxidants were measured in 5.0 wt % Triton X-100 micellar solution (pH 7.4), using UV-visible spectrophotometry. The k(Q) values decreased in the order of β-Car > PQQH(2) > α-Toc > UA > UQ(10)H(2) > Vit C ∼ EGC > EC ≫ PQQNa(2). PQQH(2) is a water-soluble antioxidant. The singlet oxygen-quenching activity of PQQH(2) was found to be 6.3, 2.2, 6.1, and 22 times as large as the corresponding those of water-soluble antioxidants (Vit C, UA, EGC, and EC). Further, the activity of PQQH(2) was found to be 2.2 and 3.1 times as large as the corresponding activity of lipid-soluble antioxidants (α-Toc and UQ(10)H(2)). On the other hand, the activity of PQQH(2) is 6.4 times as small as that of β-Car. It was observed that the chemical reaction (k(r)) is almost negligible in the quenching reaction of (1)O(2) by PQQH(2). The result suggests that PQQH(2) may contribute to the protection of oxidative damage in biological systems, by quenching (1)O(2).

Impact of ultrasonication time on elution of super heavy oil and its biomarkers from aging soils using a Triton X-100 micellar solution

An ultrasound-enhanced elution system with Triton X-100 solution was used to remediate aging soils contaminated with super heavy oil. We used GC/MS, SEM, and X-ray diffraction (XRD) to analyze the effect of ultrasonic time (0–1800 s) on the elution of super heavy oil and its three characteristic biomarkers (C 26–34 17α 25-norhopanes, C 26–28 triaromatic steroid [TAS], and C 27–29 methyl triaromatic steroid [MTAS]). The oil and biomarkers remaining in the treated soils followed similar second-order functions with increasing ultrasonication times. Biomarker elution was closely related to carbon numbers in the marker. For C 26–34 17α 25-norhopanes, the smaller molecules were more readily eluted during 0–360 s ultrasound. This trend was reversed upon application of ultrasound during 1080–1800 s, with improved elution of larger molecules and elution followed a similar second-order function. For C 26–28 TAS, smaller molecules were more readily eluted but the elution of larger molecules followed a similar second-order function. For C 27–29 MTAS, elution of larger molecules was close to that of C 26–34 17α 25-norhopanes. Results of SEM and XRD indicated that the mineral and chemical compositions of soils eluted at ultrasonication times of 1080–1800 s closely resembled clean soils.

Physicochemistry of dispersions of HgO, HgS and ‘Makardhwaj’ (an Ayurvedic medicine) prepared in micelle and microemulsion templates

Micelle and microemulsion templates are used to prepare dispersions of HgO and HgS. The prepared HgO dispersions are obtained in four different colors viz. yellow, orange, red, and bluish-white, though the bulk HgO shows only two colors, red and yellow. The synthesized HgS particles in micellar solutions appear faintly grayish. These dispersions of HgO and HgS show characteristic spectral features. They are characterized by spectral, X-ray diffraction (XRD) and transmission electron microscopic (TEM) techniques. The products formed in water/CTAB + n-butanol/n-heptane microemulsion (CTAB being cetyltrimethylammonium bromide) evidence characteristic differences from that prepared in micellar media. Both HgO and HgS preparations show low semiconductivity. Their band gaps range between 3.6 and 5.71 eV. HgO dispersions prepared in Triton X-100 (TX-100) micellar solution are spherical (∼150 nm diameter) whereas that prepared in Tween-20 (TW-20) medium are prolate type (major axis ∼300 nm). In CTAB micellar solution tubes of diameter 150 nm are formed. The HgS preparation in the aforesaid w/o microemulsion appears grayish and transparent. The shapes of the particles are spherical with a size in the range 10–25 nm as found from the TEM study. ‘Makardhwaj’, an Ayurvedic medicine (comprising of HgS, Au and Au 2S), also shows characteristic spectral features in micellar and microemulsion media. The grinded dispersed ‘Makardhwaj’ particles are nearly spherical with average size of 10 nm, and evidence the presence of Au, S and Hg in the ratio 1:3.4:30 from electron dispersive X-ray analysis (EDAX) measurements. The results suggest that HgS dispersions fall well within the conventional nano-domain (100 nm) whereas HgO dispersions are moderately out of the domain.

Impact of ultrasonic power density on elution of super heavy oil and its biomarkers from aging soils using Triton X-100 micellar solution

An ultrasound-enhanced elution system employing Triton X-100 solutions was used for remedying aging soils contaminated with super heavy oil. The effect of varying the ultrasonic power density on the elution of the oil and three characteristic biomarkers was analyzed using GC/MS and FTRS. The oil and biomarkers remaining in treated soils decreased as a similar first-order function of increasing ultrasonic power density. Elution of the three biomarkers in the absence of ultrasound was closely related to carbon numbers in the marker: smaller molecules were more readily eluted. This trend was reversed upon application of ultrasound at higher power densities, with improved elution of molecules containing a greater carbon numbers. The two ratios, both 22 S/(22 S + 22 R) of C 26–34 17α 25-norhopanes and 20 S/(20 S + 20 R) of C 26–28 triaromatic steroids, in treated soils decreased with increasing power density from 20 to 100 W L −1. The results of SEM, FTRS, XRD, and energy spectroscopy experiments indicated that the mineral and chemical compositions of soils eluted at power densities greater than 60 W L −1 closely resembled clean soils.

Effects of pH and Micelle on the Radical Scavenging Ability of Puerarin

The radical scavenging properties of puerarin are investigated in buffered hydroalcoholic media and Triton X-100 micellar solutions using the free-radical diphenylpicrylhydrazyl (DPPH•) method. The reactions, which follow the mixed second-order rate law, are investigated under pseudo-first-order condition by use of a large excess of puerarin. The rate constants (k 2) observed for puerarin show notable pH dependence. These differences in reactivity of puerarin toward the oxidants at different acidity of the solution have been assumed to arise from the acid-base equilibrium of puerarin. The influence of acid-base equilibrium on bond dissociation energy for puerarin has also been investigated by means of DFT calculations. It has been concluded on the basis of these calculations that monoanionic form of puerarin is more powerful radical scavenger than the neutral molecule. When the reactions take place in Triton X-100 micelles, the radical scavenging properties of puerarin are enhanced. The results may be due to the special location of puerarin in Triton X-100 micelles.

Photophysical Properties of C60 Colloids Suspended in Water with Triton X-100 Surfactant: Excited-State Properties with Femtosecond Resolution

We examine the photophysics of a colloidal suspension of C(60) particles in a micellar solution of Triton X-100 and water, prepared via a new synthesis which allows high-concentration suspensions. The particle sizes are characterized by transmission electron microscopy and dynamic light scattering and found to be somewhat polydisperse in the range of 10-100 nm. The suspension is characterized optically by UV-vis spectroscopy, femtosecond transient absorption spectroscopy, laser flash photolysis, and z-scan. The ground-state absorbance spectrum shows a broad absorbance feature centered near 450 nm which is indicative of colloidal C(60). The transient absorption dynamics, presented for the first time with femtosecond resolution, are very similar to that of thin films of C(60) and indicate a strong quenching of the singlet excited state on short time scales and evidence of little intersystem crossing to a triplet excited state. Laser flash photolysis reveals that a triplet excited-state absorption spectrum, which is essentially identical in shape to that of molecular C(60) solutions, does indeed arise, but with much lower magnitude and somewhat shorter lifetime. Z-scan analysis confirms that the optical response of this material is dominated by nonlinear scattering.

Extraction of lanthanum and gadolinium(III) at the cloud point using p-sulfonatocalyx[n]arenes as chelating agents

The extraction of gadolinium(III) and lanthanum(III) ions at the cloud point is studied in Triton X100 micellar solutions in a wide range of pH. In the absence of chelating agents, lanthanum(III) and gadolinium(III) ions are unselectively extracted at pH > 6. It is shown that the use of p-sulfonatothiacalyx[6(8)]arenes as chelating agents noticeably enhances the degree of extraction at pH 2–6. The composition and stability of lanthanum-p-sulfonatothiacalyx[n]arene complexes (n = 4, 6, 8) are estimated in a wide range of pH by pH-potentiometry. The degree of Gd3+ and La3+ ions extraction, which is performed at the cloud points employing calyxarene macrocycles of different sizes, is depended on the acidity of a medium.

Kinetic Study of the Antioxidant Activity of Pyrroloquinolinequinol (PQQH2, a Reduced Form of Pyrroloquinolinequinone) in Micellar Solution

Kinetic study of the aroxyl radical-scavenging action of pyrroloquinolinequinol [PQQH(2), a reduced form of pyrroloquinolinequinone (PQQ)] and water-soluble antioxidants (vitamin C, cysteine, glutathione, and uric acid) has been performed. The second-order rate constants (k(s)) for the reaction of aroxyl radical with PQQH(2) and water-soluble antioxidants were measured in Triton X-100 micellar solution (5.0 wt %) (pH 7.4), using stopped-flow and UV-visible spectrophotometers. The k(s) values decreased in the order PQQH(2) > vitamin C >> cysteine > uric acid > glutathione. The aroxyl radical-scavenging activity of PQQH(2) was 7.4 times higher than that of vitamin C, which is well-known as the most active water-soluble antioxidant. Furthermore, PQQNa(2) (disodium salt of PQQ) was easily reduced to PQQH(2) by reaction of PQQNa(2) with glutathione and cysteine in buffer solution (pH 7.4) under nitrogen atmosphere. The result suggests that PQQ exists as a reduced form throughout the cell and plays a role as antioxidant.

Spectrophotometric study of interaction and solubilization of procaine hydrochloride in micellar systems

AbstractThe 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.

The fluorescence resonance energy transfer between dye compounds in micellar media

The fluorescence resonance energy transfer from fluorescein to merocyanine 540 in aqueous sodium dodecyl sulfate, cetyltrimethylammonium bromide and Triton X-100 micellar solutions as well as deionized water was investigated at room temperature using steady-state and time-resolved fluorescence spectroscopy techniques. Fluorescence resonance energy transfer rate constants ( k T), obtained using both Stern–Volmer and Förster theories, were in good agreement. Moreover, energy transfer efficiency values of 0.14, 0.38, 0.77 and 0.85 for deionized water, sodium dodecyl sulfate, TX-100 and cetyltrimethylammonium bromide micellar solution were obtained at the highest acceptor concentration at which fluorescence resonance energy transfer was achieved. The data obtained from steady-state absorption, fluorescence spectral studies and time-resolved lifetime measurements indicated that the fluorescence resonance energy transfer from fluorescein to merocyanine 540 occurred most effectively in aqueous cetyltrimethylammonium bromide micellar solutions.

Stopped-Flow Kinetic Study of the Aroxyl Radical-Scavenging Action of Catechins and Vitamin C in Ethanol and Micellar Solutions

Kinetic study of the aroxyl radical-scavenging action of catechins (epicatechin (EC), epicatechin gallate (ECG), epigallocatechin (EGC), and epigallocatechin gallate (EGCG)) and related compounds (methyl gallate (MG), 4-methylcatechol (MC), and 5-methoxyresorcinol (MR)) has been performed. The second-order rate constant ( k s) for the reaction of these antioxidants with aroxyl radical has been measured in ethanol and aqueous Triton X-100 micellar solution (5.0 wt %). The k s values decreased in the order of EGCG > EGC > MC > ECG > EC > MG >> MR in ethanol, indicating that the reactivity of the OH groups in catechins decreased in the order of pyrogallol B-ring > catechol B-ring > gallate G-ring > resorcinol A-ring. The structure-activity relationship in the free radical-scavenging reaction by catechins has been clarified by the detailed analyses of the pH dependence of k s values. From the results, the p K a values have been determined for catechins. The monoanion form at catechol B- and resorcinol A-rings and dianion form at pyrogallol B- and gallate G-rings show the highest activity for free radical scavenging. It was found that the free radical-scavenging activities of catechins are 3.2-13 times larger than that of vitamin C at pH 7.0.

Characteristics of solubilization and encapsulation of fullerene C 60 in non-ionic Triton X-100 micelles

The solubilization and encapsulation of monomeric C 60 in Triton X-100 micelles were investigated. Characteristic hydrophobic interactions of the type π–π and CH–π between the Triton X-100 micelle and C 60 resulted in stable aqueous dispersions of C 60 in the micellar medium, as evidenced from UV–vis, fluorescence emission and micro-Raman spectroscopy. Cyclic voltammetry of C 60 encapsulated Triton X-100 in aqueous 5 mM LiClO 4 solution revealed a quasi-reversible one-electron reduction peak with E 1/2 = −0.61 V and a reversible reduction peak at E 1/2 = −1.11 V vs. Ag/AgCl reference electrode at a scan rate of 10 mV s −1, a redox behaviour drifting substantially from that of pure C 60. An onset concentration of ∼0.025 mM for C 60 aggregation in the micellar core was substantiated from the characteristic absorption spectral broadening and quenching of pyrene fluorescence. The molar solubilization capacity of C 60 in aqueous Triton X-100 micellar solution was estimated spectrophotometrically to be 0.22.

A new separation method: combination of CO2 and surfactant aqueous solutions

In this work, the effect of CO2 on the cloud point temperature (CPT) of an aqueous solution of p-tert-octylphenoxy polyethylene (Triton X-100) was studied at different temperatures, pressures and surfactant concentrations. It was demonstrated that CO2 could reduce the CPT of the micellar solutions considerably. On the basis of this finding, we proposed a new route to separate different substances from water by combination of Triton X-100 and CO2. It was discovered that phenol or vanadium ion in aqueous solutions could be separated efficiently from water by combination of CO2 and Triton X-100. Our study also showed that the gold nanoparticles synthesized in Triton X-100 micellar solutions could be recovered using CO2 while the surfactant remained in the solution. This is attractive because recovery of gold nanoparticles is very convenient. This separation method has some unusual advantages, such as high separation efficiency, simple post-treatment process, and lower separation temperature, which is especially advantageous when temperature-sensitive substances are involved.

Catalyzed oxidation of 2,6-dimethylphenol in Triton X-100 micellar solution

The oxidative coupling reaction of 2,6-dimethylphenol with H 2O 2 catalyzed by a copper(II) Schiff complex in aqueous and Triton X-100 micellar solution under mild conditions was investigated. The kinetics of formation of 3,3′,5,5′-tetramethyl-4,4′-diphenoquinone (DPQ) was studied. Rate constant k 2 were obtained. The optimum pH for DPQ generation reaction is 7.25. The main product was DPQ in aqueous buffer solution, but PPE and the oxidized products of PPE remained in Triton X-100 micellar solution.

Efficient peroxide decoloration of azo dye catalyzed by polyethylene glycol-linked manganese chlorin derivative

We reported here that polyethylene glycol (PEG)-linked manganese pyrochlorophyllide a (PEG-MnPChlide a) possesses remarkable catalytic activity comparable to horseradish peroxidase (HRP). The PEG-MnPChlide a catalyzed the oxidation decoloration reaction of C.I. Acid Orange 7 by hydrogen peroxide under a mild aqueous condition, pH 8.0 at 25 °C. The manganese pyrochlorophyride a methylester (MnPChlide a ME) dissolved in a Triton X-100 micellar solution also exhibited the catalytic activity, indicating the micellar environment plays an important role in the catalytic reaction. The reaction rate was accelerated by addition of imidazole. The catalytic reactions were analyzed by Michaelis–Menten kinetics, revealing that the higher reactivity of catalyst–substrate complex is responsible for the present catalytic reaction system.

Exciton Coupling of Tetra(p-hydroxyphenyl)porphyrin Controlled by Substituents of Counterions in Triton X-100 Micellar Solution

The interactions of nonionic meso-tetra(p-hydroxyphenyl)porphyrin (THPP) with CX3COOH (X = F, Cl, Br) in Triton X-100 (TX) micellar solution have been investigated by optical absorption, resonance light-scattering, and fluorescence spectroscopies. The double red-shifted absorption bands and strong resonance light scattering (RLS) signal imply that the assemblies induced by trihalo acetic acids belong to J-aggregates. The fluorescence of porphyrin is quenched due to the aggregate formation. The kinetics of assemblies trigged by CBr3COOH is studied via stopped-flow techniques. No characteristics of autocatalyzed reactions are observed, and there is only a log phase. The nature of the exciton coupling of transition dipole moment can be systematically changed by the haloid substituents of the organic counteranion.

Protolytic properties of some bis(dimethylaminomethyl)phenols in the presence of surfactants

Aggregation and protolytic properties of bis(dimethylaminomethyl)phenols containing methyl (HA) and nonyl (HL) substituents at the benzene ring are studied in aqueous solutions of isopropanol and various surfactants with potentiometric titration, tensiometry, and mathematical modeling of equilibria. Monomers, dimers, and tetramers of HA and HL are found. It is shown that the degree of compound aggregation depends on the solution concentration and pH. Sodium dodecyl sulfate and HA form associates, whereas SDS and HL form mixed micelles at the CMC-1 and CMC-2 critical micellization concentrations. In micellar solutions of Triton X-100 and cetyltrimethylammonium bromide, the mixed micelles are not found via tensiometry. Protonated species of tetramer, dimer, and monomer of investigated compounds are revealed, depending on the acidity of the medium. Phenolate forms of HA and HL do not exist under experimental conditions. Apparent protonation constants are determined and it is shown that, for the HA compound that does not form micelles, the protonation constants of the same-type species increase in the presence of the three surfactants used as compared to the water-isopropanol solution. Decreasing constants of analogous HL forms in the solutions of CTAB, nonionic surfactant (C Tx = 10 mM), and SDS (pH > 7) are attributed to the formation of associates or mixed micelles of this compound and surfactants under experimental conditions.

Acid–base equilibrium of anionic dyes partially bound to micelles of nonionic surfactants

The acid–base equilibria of the sulfonephthalein dyes, namely, bromothymol blue, thymol blue, and cresol red, in aqueous nonionic micellar solutions of Triton X-100, Tween-20, Tween-40, Tween-60, and Tween-80 have been investigated. The equilibrium constants of the partition of the dyes between micellar and aqueous pseudophases have been determined spectrophotometrically at fixed pH. The K ass increased with the surfactants in the order Tween-80 < Tween-60 < Tween-40 < Tween-20 < TX-100. The effect of such associations on the p K a 2 of the dyes at various concentrations of the nonionic surfactant has been studied. The p K a 2 of the dyes as a function of the concentrations of the surfactant was predicted from the equilibrium constants using a method developed to fit nonionic surfactants and was compared with experimental values determined directly. The p K a 2 s of the dyes predicted according to the present method have been found to be in good agreement with the experimental values.

Highly Selective and Simple Zero and First Order Derivative Spectrophotometric Determination of Palladium by Using α-Benzilmonoxime in Triton X-100 Micellar Solution

The reaction of <TEX>${\alpha}$</TEX>-Benzilmonoxime with palladium(II) produces a green complex in triton X-100 micellar media. Palladium has been determined using zero and first derivative spectrophotometric methods. The absorbances of Pd(II)- <TEX>${\alpha}$</TEX>--benzilmonoxime complex at 441.8 and 677.0 nm in 0.10 M perchloric acid solution were monitored and linear working ranges of 0.3-12.0 and 0.7-20 <TEX>${\mu}$</TEX>g mL<TEX>$^{-1}$</TEX> with detection limits of 0.07 and 0.10 <TEX>${\mu}$</TEX>g <TEX>$mL^-1$</TEX> were obtained, respectively. Also, recoveries in the range of 92.8 to 100.1% and relative standard deviations in the range of 0.4 to 7.1% were obtained. First derivative spectrophotometry has also been applied for palladium determination under the optimum condition. The linear dynamic range of 0.2-24.0 <TEX>${\mu}$</TEX>g <TEX>$mL^{-1}$</TEX> palladium with relative standard deviations of 0.6-6.9% and recoveries in the range of 94.9-102.5% has been obtained by first derivative spectrophotometry. The method shows high selectivity because of the high concentration of acid used, which prevents formation of complexes of <TEX>${\alpha}$</TEX>--benzilmonoxime with the other cations. The palladium complex formed was stable at least one day. The method was successfully applied to the determination of palladium in some synthetic palladium alloys and palladium-charcoal powder.