Micelle studies using a metal ion/murexide indicator system

Fischer, Michael; Knoche, Wilhelm; Fletcher, Paul D. I.; Robinson, Brian H.; White, N. C.

doi:10.1007/bf01384364

Cited by 16 publications

(6 citation statements)

References 12 publications

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“…The binding constants of aromatic hydrocarbons like benzene, anthracene, and pyrene are in the range 4 î 10 5 ±2 î 10 6 m À1 and correlate with the hydrophobicity of the solutes. [29] ADD molecules are neutral and electrostatic interactions in the binding of ADDs with micelles are ruled out. The binding of these dyes is mainly attributed to hydrophobic interactions of the ADDs with the micelles.…”

Section: Time-resolved Fluorescence Techniquementioning

confidence: 99%

“…In contrast, the binding of the solute with the micelles is hydrophobic when the strength of the binding is determined by the tendency of the solute to reduce its interaction with aqueous dipole. The binding of inorganic ions such as Ag + , Cu + , and Ni + with SDS micelles [28,29] is purely electrostatic and does not involve any covalent interactions with the sulfate groups on the micellar surface. The binding constants of aromatic hydrocarbons like benzene, anthracene, and pyrene are in the range 4 î 10 5 ±2 î 10 6 m À1 and correlate with the hydrophobicity of the solutes.…”

Section: Time-resolved Fluorescence Techniquementioning

confidence: 99%

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Excited‐State Behavior and Photoionization of 1,8‐Acridinedione Dyes in Micelles—Comparison with NADH Oxidation

Selvaraju

Ramamurthy

2004

Chemistry A European J

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The photophysics and photochemistry of 1,8-acridinedione dyes, which are analogues of reduced nicotinamide adenine dinucleotide (NADH), are studied in anionic and cationic micelles. Acridinedione dyes (ADDs) are solubilized in micelles at the micelle-water interface and are in equilibrium between the aqueous and micellar phase. The binding of the ADDs with micelles is attributed to hydrophobic interactions and the binding constants are determined with steady-state and time-resolved techniques. Nanosecond laser flash photolysis studies are carried out in aqueous, anionic, and cationic micellar solutions. The ADD undergoes photoionization in the excited state to give a solvated electron. The solvated electron reacts with the ADD to give an anion radical. In anionic micelles, the yield of the solvated electron increases because of the efficient separation of the cation radical and the electron. Cation radicals derived from the photooxidation of ADDs are involved in keto-enol tautomerization. Under acidic conditions, an enol radical cation of the acridinedione dye is formed from the keto form of the cation radical by intramolecular hydrogen atom transfer. In cationic micelles, due to electrostatic attraction, the electron cannot escape from the micelle and recombination of the cation radical and the electron results in the formation of a triplet state. For the first time, a solvated electron is observed in the laser flash photolysis of ADDs in anionic micelles. The photoionization of ADDs depends on the excitation wavelength and is biphotonic at 355 nm and monophotonic at 248 nm. From the results with this NADH model compound, the sequential electron-proton-electron transfer oxidation of NADH is confirmed and the nature of the intermediates involved in the oxidation is unraveled; these intermediates are found to depend on the pH value of the medium.

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Section: Time-resolved Fluorescence Techniquementioning

confidence: 99%

Section: Time-resolved Fluorescence Techniquementioning

confidence: 99%

Excited‐State Behavior and Photoionization of 1,8‐Acridinedione Dyes in Micelles—Comparison with NADH Oxidation

Selvaraju

Ramamurthy

2004

Chemistry A European J

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“…KNI was determined using the murexide complexation technique (7,8) for SDS and SOS solutions. The negatively-charged murexide ion avoids the anionic micelles so that, when Ni2+ ion is also present in solution, any complex formation between Ni2+ and murexide will occur only in the bulk water.…”

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confidence: 99%

Effect of short-chained sodium alkylsulfate micelles on the kinetics of metal complex formation

Fletcher¹,

Reinsborough²

1981

Can. J. Chem.

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. Can. J. Chem. 59, 1361 (1981). The kinetics of the reaction between NiaqZ+ and the bidentate ligand pyridine-2-azo-p-dimethylaniline (PADA) have been investigated in micellar solutions of sodium decyl-, octyl-, and hexylsulfates using the stopped-flow technique. The rate of enhancement decreased with decreasing alkyl-chain length and from the Berezin or Robinson model could be quantitatively related to the independently measured binding constants of NiZ+ ion and PADA to the micelle surface. The dramatic effect of micelles upon the reaction rates in different directions of the NiZ+/PADA and the NiZ+/ murexide reactions served as sensitive indicators of the cmc even at the very limit of micelle formation which relatively concentrated sodium hexylsulfate solutions reoresent. IntroductionThe effect of significant partitioning of the other ~h~ whereby sodium dodecylsulfate reactant, Ni2+, into the bulk water from the micel-(SLS) micelles increase the rate of complex forma-lar surface Won the enhancement Of the rate Of tion between ~i,,z+ and neutral bidentate ligands these reactions has not hitherto been reported. such as pyridine-2-azo-p-dimethylaniline (PADA) White2 had noted in a preliminary study that has been adequately characterized (1-4). The decreasing the length of the carbon chain in the kinetic model successfully predicts the effect of members of the sodium alkylsulfate series had led changes of pH, of ligand, and of reactant concen-to a decrease in the rate enhancing effect of the trations. The reaction occurs in the surface region micelles for this particular of the micelle and the rate increase depends uponIn the case of both reactants partitioning signifithe independently measured extent of binding of cantly between the micelle surface and the bulk ligand to the micelle.water, the more complex kinetic expression can SLS micellar solutions at concentrations still be readily interpreted. It was for this reason greater than twice the critical micelle concentration that the reaction between NiaqZ+ and the ligand (cmc)7 both the nickel ion and PADA are strongly PADA was studied kinetically in sodium decyladsorbed into the surface region of the micelle so sulfate (SDS) solutions, in sodium oct~lsulfate that any effects of partitioning of the reactants at (SOS) ~olutions7 and in sodium hex~lsulfate (SHS) low ionic strength into the bulk water upon the solutions. We wished also to gain more information apparent rate are negligible. with ligands less on the micellization phenomenon as it occurs with hydrophobic than PADA, where an appreciable short-chained surfactants with which little work amount of the ligand is in the bulk water, the rate has been done. enhancement of the SLS micelles upon the NiZ+-Experimental

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“…2 X lo3 dm3 mol-I s-') (8). Values of KNi and KpADA are obtained independently by the murexide technique (4,15) and by solubility measurements respectively (8,9). Curvefitting of the kinetic data yields parameter V and (or) KNi.…”

Section: Sdes/spfh Systemmentioning

confidence: 99%

Micellar rate enhancement studies in mixed sodium fluorocarbon/hydrocarbon surfactant solutions

Connolly¹,

Reinsborough²

1992

Can. J. Chem.

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. Can. J. Chem. 70, 1581Chem. 70, (1992. Stopped-flow kinetic studies were conducted in mixed micellar solutions of fluorocarbon and hydrocarbon anionic surfactants to determine the prevalent micellar form. The probe reaction was the ~i,~~/~~ridine-2-azo-~-dimeth~lani-line (PADA) complexation, which is many times accelerated in the presence of anionic micelles. Binding constants for Ni,;+ and PADA partitioning between bulk solution and micelles were determined through the murexide technique and solubility measurements respectively and the molar reaction volume was obtained from the Robinson equation. The three binary surfactant systems investigated had sodium perfluoroheptanoate as the fluorocarbon surfactant while the hydrocarbon surfactants were sodium decylsulfate, sodium nonanesulfonate, and sodium octanesulfonate. The kinetic results were consistent with unimicellar composition in all three systems which was not the behaviour previously found with the sodium octane sulfonate / sodium perfluoroctanoate system. The difference was attributed to closer similarity in the surfactant pair hydrophobicities as revealed through their critical micelle concentrations. Another finding was that mixed micelles synergistically can lead to a much greater solubilization of PADA than is possible through either of the pure surfactants.TERRENCE J. CONNOLLY et VINCENT C. REINSBOROUGH. Can. J. Chem. 70, 158 1 (1992). Dans le but de determiner la forme micellaire prevalante, on a realis6 des Ctudes cinetiques a flux stoppC sur des solutions micellaires d'agents de surface anioniques fluoro-et hydro-carbonCs. La rCaction indicatrice utilisCe est la complexation ~i,~+/~~ridine-2-azo-~-dim~th~laniline (PADA) qui est fortement accC1CrCe en prCsence de micelles anioniques. Les constantes de fixation du Ni$+ et de partition du PADA entre la masse de la solution et les micelles ont Ct C dCterminCes respectivement B l'aide de la technique du murexide et de mesures de solubilitC et on a CvaluC le volume molaire de la reaction grdce B 1'Cquation de Robinson. Les trois systkmes binaires d'agents de surface Ctudies contenaient du perfluoroheptanoate de sodium comme agent de surface fluorocarbonC alors que les agents de surface hydrocarbonCs Ctaient le dCcylsulfate de sodium, nonanesulfonate de sodium et octanesulfonate de sodium. Dans les trois systbmes, les rCsultats cinetiques sont en accord avec la composition unirnicellaire; ce comportement est diffCrent de celui observe antkrieurement avec le systbme octanesulfonate de sodium / perfluorooctanoate de.sodium. On attribue la difference B la plus grande similarit6 dans les hydrophobicites des paires d'agents de surface qui sont rCvClCes par leurs concentrations micellaires critiques. Une autre observation a trait au fait que les micelles mixtes peuvent agir par synergie pour conduire i une solubilisation beaucoup plus grande du PADA que celle possible par chacun des agents de surface agissant seuls.[Traduit par la rCdaction]

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Micelle studies using a metal ion/murexide indicator system

Cited by 16 publications

References 12 publications

Excited‐State Behavior and Photoionization of 1,8‐Acridinedione Dyes in Micelles—Comparison with NADH Oxidation

Excited‐State Behavior and Photoionization of 1,8‐Acridinedione Dyes in Micelles—Comparison with NADH Oxidation

Effect of short-chained sodium alkylsulfate micelles on the kinetics of metal complex formation

Micellar rate enhancement studies in mixed sodium fluorocarbon/hydrocarbon surfactant solutions

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