301
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Adsorption of alkali metal cations and halide anions on metal oxides: prediction of Hofmeister series using 1-pK triple layer model. ADSORPTION 2010. [DOI: 10.1007/s10450-010-9245-y] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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302
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Jäger CM, Hirsch A, Schade B, Ludwig K, Böttcher C, Clark T. Self-assembly of structurally persistent micelles is controlled by specific-ion effects and hydrophobic guests. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2010; 26:10460-10466. [PMID: 19957972 DOI: 10.1021/la9038123] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
A combined study using cryo-TEM experiments and molecular dynamics simulations reveals remarkable details of the factors that affect the self-organization of specifically designed T-shaped amphiphilic dendrimers upon treatment of an aqueous solution with ultrasound under a layer of hexane. This treatment leads to dodecameric, structured micelles rather than the heptameric ones observed without hexane. Three-dimensional reconstruction of the cryo-TEM images provides very detailed structures of the micelles, and molecular dynamics simulations suggest that approximately 36 hexane molecules are needed to stabilize the dodecameric micelles. Sodium counterions are found to exert a significant stabilizing effect that results in an apparent attraction between the highly negatively charged polycarboxylate headgroups. DFT calculations support the observation that the formation of ion multiplets is especially crucial for this stabilizing counterion effect, which reduces headgroup repulsion. This and the increased hydrophobic stabilization that results from the hexane-enlarged core of the micelle lead to stable dodecameric micelles. The specific effects found for sodium counterions are largely absent for potassium.
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Affiliation(s)
- Christof M Jäger
- Computer-Chemie-Centrum, Friedrich-Alexander-Universität Erlangen-Nürnberg, 91052 Erlangen, Germany
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303
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Manet S, Karpichev Y, Bassani D, Kiagus-Ahmad R, Oda R. Counteranion effect on micellization of cationic gemini surfactants 14-2-14: Hofmeister and other counterions. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2010; 26:10645-56. [PMID: 20394385 DOI: 10.1021/la1008768] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
The effect of counterions was investigated and analyzed to probe the principal ionic effects influencing the micellization behavior of dimeric cationic surfactant ethanediylbis(dimethyltetradecylammonium), referred to as gemini 14-2-14. The 30 counterions were classified to four different families depending on their nature: (1) small and inorganic counterions which are typically taken from the Hofmeister series were studied to focus on the effect of ion type; (2) n-alkyl carboxylate counterions were studied to focus on the effect of the hydrophobicity of counterions; (3) aromatic carboxylate counterions were included to focus on the effect of the position of substitutions; and (4) other counterions were included in order to shed light on other parameters. By investigating the critical micelle concentration (CMC), ionization degree of micelle (alpha), free energy of micellization (DeltaG(M)), and aggregation numbers N of the gemini surfactant with these different types of anions, we demonstrated the effect of different ion properties independently. This approach allowed us to describe the effect of counterions on the micellization behavior of the gemini surfactant in terms of complex interplay between hydrophobicity of anions and other ion properties such as counterion hydration, interfacial packing of ions, and ionic morphology. Indeed, our results clearly demonstrate that a counterion effect on micellization properties cannot be described as a result of one single parameter of ions, as is too often assumed, but rather the balancing effects cooperatively affect the propensity of counterions to form ion pairs with surfactant headgroups and the entropy gain upon micellization. These results provide new insight in understanding the effect of ions on the delicate balance of forces controlling aggregate morphology and solution properties of charged amphiphilic molecules.
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Affiliation(s)
- Sabine Manet
- Institut Européen de Chimie et Biologie, UMR 5248 CBMN, CNRS-Université de Bordeaux-ENITAB, 2 rue Robert Escarpit, F-33607 Pessac, France
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304
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Vácha R, Jurkiewicz P, Petrov M, Berkowitz ML, Böckmann RA, Barucha-Kraszewska J, Hof M, Jungwirth P. Mechanism of Interaction of Monovalent Ions with Phosphatidylcholine Lipid Membranes. J Phys Chem B 2010; 114:9504-9. [DOI: 10.1021/jp102389k] [Citation(s) in RCA: 82] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Affiliation(s)
- Robert Vácha
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic and Center for Biomolecules and Complex Molecular Systems, Flemingovo nám. 2, 16610 Prague 6, Czech Republic; Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB21EW, United Kingdom; J. Heyrovský Institute of Physical Chemistry, Academy of Sciences of the Czech Republic, v. v. i., Dolejškova 3, 18223 Prague 8, Czech Republic; Department of Chemistry, University of North Carolina, Chapel
| | - Piotr Jurkiewicz
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic and Center for Biomolecules and Complex Molecular Systems, Flemingovo nám. 2, 16610 Prague 6, Czech Republic; Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB21EW, United Kingdom; J. Heyrovský Institute of Physical Chemistry, Academy of Sciences of the Czech Republic, v. v. i., Dolejškova 3, 18223 Prague 8, Czech Republic; Department of Chemistry, University of North Carolina, Chapel
| | - Michal Petrov
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic and Center for Biomolecules and Complex Molecular Systems, Flemingovo nám. 2, 16610 Prague 6, Czech Republic; Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB21EW, United Kingdom; J. Heyrovský Institute of Physical Chemistry, Academy of Sciences of the Czech Republic, v. v. i., Dolejškova 3, 18223 Prague 8, Czech Republic; Department of Chemistry, University of North Carolina, Chapel
| | - Max L. Berkowitz
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic and Center for Biomolecules and Complex Molecular Systems, Flemingovo nám. 2, 16610 Prague 6, Czech Republic; Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB21EW, United Kingdom; J. Heyrovský Institute of Physical Chemistry, Academy of Sciences of the Czech Republic, v. v. i., Dolejškova 3, 18223 Prague 8, Czech Republic; Department of Chemistry, University of North Carolina, Chapel
| | - Rainer A. Böckmann
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic and Center for Biomolecules and Complex Molecular Systems, Flemingovo nám. 2, 16610 Prague 6, Czech Republic; Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB21EW, United Kingdom; J. Heyrovský Institute of Physical Chemistry, Academy of Sciences of the Czech Republic, v. v. i., Dolejškova 3, 18223 Prague 8, Czech Republic; Department of Chemistry, University of North Carolina, Chapel
| | - Justyna Barucha-Kraszewska
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic and Center for Biomolecules and Complex Molecular Systems, Flemingovo nám. 2, 16610 Prague 6, Czech Republic; Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB21EW, United Kingdom; J. Heyrovský Institute of Physical Chemistry, Academy of Sciences of the Czech Republic, v. v. i., Dolejškova 3, 18223 Prague 8, Czech Republic; Department of Chemistry, University of North Carolina, Chapel
| | - Martin Hof
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic and Center for Biomolecules and Complex Molecular Systems, Flemingovo nám. 2, 16610 Prague 6, Czech Republic; Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB21EW, United Kingdom; J. Heyrovský Institute of Physical Chemistry, Academy of Sciences of the Czech Republic, v. v. i., Dolejškova 3, 18223 Prague 8, Czech Republic; Department of Chemistry, University of North Carolina, Chapel
| | - Pavel Jungwirth
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic and Center for Biomolecules and Complex Molecular Systems, Flemingovo nám. 2, 16610 Prague 6, Czech Republic; Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB21EW, United Kingdom; J. Heyrovský Institute of Physical Chemistry, Academy of Sciences of the Czech Republic, v. v. i., Dolejškova 3, 18223 Prague 8, Czech Republic; Department of Chemistry, University of North Carolina, Chapel
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305
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Oelschlaeger C, Suwita P, Willenbacher N. Effect of counterion binding efficiency on structure and dynamics of wormlike micelles. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2010; 26:7045-53. [PMID: 20180526 DOI: 10.1021/la9043705] [Citation(s) in RCA: 95] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
We have studied the effect of counterion binding efficiency on the linear viscoelastic properties of wormlike micelles formed from hexadecyltrimethylammonium bromide (CTAB) in the presence of different nonpenetrating inorganic salts: potassium bromide (KBr), sodium nitrate (NaNO(3)), and sodium chlorate (NaClO(3)). We have varied the salt/surfactant ratio R at fixed surfactant concentration of 350 mM. Results are compared to data for the system cetylpyridinium chloride (CPyCl) and the penetrating counterion sodium salicylate (NaSal) (Oelschlaeger, C.; Schopferer, M.; Scheffold, F.; Willenbacher, N. Langmuir 2009, 25, 716-723). Mechanical high-frequency rheology and diffusing wave spectroscopy (DWS) based tracer microrheology are used to determine the shear moduli G' and G'' in the frequency range from 0.1 Hz up to 1 MHz (Willenbacher, N.; Oelschlaeger, C.; Schopferer, M.; Fischer, P.; Cardinaux, F.; Scheffold, F. Phys. Rev. Lett. 2007, 99, 068302, 1-4). This enables us to determine the plateau modulus G(0), which is related to the cross-link density or mesh size of the entanglement network, the bending stiffness kappa (also expressed as persistence length l(p) = kappa/k(B)T) corresponding to the semiflexible nature of the micelles, and the scission energy E(sciss), which is related to their contour length. The viscosity maximum shifts to higher R values, and the variation of viscosity with R is less pronounced as the binding strength decreases. The plateau modulus increases with R at low ionic strength and is constant around the viscosity maximum; the increase in G(0) at high R, which is presumably due to branching, is weak compared to the system with penetrating counterion. The scission energy E(sciss) approximately = 20 k(B)T is independent of counterion binding efficiency irrespective of R and is slightly higher compared to the system CPyCl/NaSal, indicating that branching may be significant already at the viscosity maximum in this latter case. The micellar flexibility increases with increasing binding efficiency of counterions according to the Hofmeister series. The persistence length values for systems CTAB/KBr, CTAB/NaNO(3), and CTAB/NaClO(3) are 40, 34, and 29 nm, respectively, independent of R, and are significantly higher than in the case of CPyCl/NaSal.
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Affiliation(s)
- C Oelschlaeger
- Institute for Mechanical Process Engineering and Mechanics, Karlsruhe Institute of Technology, 76131 Karlsruhe, Germany.
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306
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Anghel DF, Saito S, Iovescu A, Băran A, Stîngă G. Counterion Effect of Cationic Surfactants Upon the Interaction with Poly(methacrylic acid). J SURFACTANTS DETERG 2010. [DOI: 10.1007/s11743-010-1202-y] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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307
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Characterization of the binding of multivalent ions to modified pluronic micelles by isothermal titration calorimetry and modified conductometry. Colloids Surf A Physicochem Eng Asp 2010. [DOI: 10.1016/j.colsurfa.2010.03.010] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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308
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309
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Effective interactions between charged nanoparticles in water: What is left from the DLVO theory? Curr Opin Colloid Interface Sci 2010. [DOI: 10.1016/j.cocis.2009.05.006] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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310
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Abezgauz L, Kuperkar K, Hassan PA, Ramon O, Bahadur P, Danino D. Effect of Hofmeister anions on micellization and micellar growth of the surfactant cetylpyridinium chloride. J Colloid Interface Sci 2010; 342:83-92. [DOI: 10.1016/j.jcis.2009.08.045] [Citation(s) in RCA: 128] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2009] [Revised: 08/16/2009] [Accepted: 08/31/2009] [Indexed: 11/16/2022]
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311
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Messina PV, Ruso JM, Prieto G, Fernández-Leyes MD, Schulz PC, Sarmiento F. Ca2+- and Mg2+-induced molecular interactions in a dehydrocholic acid/didodecyldimethylammonium bromide mixed monolayer. Colloid Polym Sci 2010. [DOI: 10.1007/s00396-009-2170-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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312
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On the origin of the Hofmeister effect in anion-selective potentiometric electrodes with tetraalkylammonium salts. J Electroanal Chem (Lausanne) 2010. [DOI: 10.1016/j.jelechem.2009.11.015] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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313
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Wong JE, Zastrow H, Jaeger W, von Klitzing R. Specific ion versus electrostatic effects on the construction of polyelectrolyte multilayers. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2009; 25:14061-14070. [PMID: 19705859 DOI: 10.1021/la901673u] [Citation(s) in RCA: 84] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Self-assembled multilayers of a strong polyanion, poly(sodium 4-styrenesulfonate) (PSS), and a strong polycation, poly[(diallyl-dimethyl-ammonium chloride)-stat-(N-methyl-N-vinyl acetamide)] (P(DADMAC-stat-NMVA)), are fabricated on silicon substrates. This article addresses the effect of electrostatics versus ion specificity. Therefore, multilayer formation and growth are investigated as a function of the charge density of the polycation, the type of salt in the polyelectrolyte dipping solution, and its ionic strength. This study focuses on monovalent ions (Li(+), Na(+), K(+), Cs(+), Rb(+), F(-), Cl(-), Br(-), and ClO(3)(-)). Ellipsometry and X-ray reflectometry data indicate that anions have a significantly larger effect on the thickness of the multilayer, but contrary to other studies on ion-specific effects, the influence of the type of cation is not negligible at higher salt concentrations. Larger ions, with smaller hydration shells, are highly polarizable and consequently interact strongly with charged polyelectrolytes, resulting in thicker and rougher multilayers. AFM studies confirm a higher roughness of the multilayer prepared from larger anions. The substrate can mask ion-specific effects over a distance of about 10 nm. Ion-specific effects become important above an ionic strength of 0.1 M in the case of anions and above an ionic strength of 0.25 M for cations. At lower ionic strengths, electrostatic interactions between and within the polyelectrolyte chains are dominating. Reducing the degree of polymer charge down to 75% does not shift this threshold of ionic strength. It is shown that a combination of ionic strength, polymer charge, and type of ion is a suitable tool for tuning the mobility and stability of polyelectrolyte multilayers.
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Affiliation(s)
- John E Wong
- Stranski-Laboratorium für Physikalische und Theoretische Chemie, Institut für Chemie, Technische Universität Berlin, Strasse des 17. Juni 124, 10623 Berlin, Germany.
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314
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Mahiuddin S, Zech O, Raith S, Touraud D, Kunz W. Catanionic micelles as a model to mimic biological membranes in the presence of anesthetic alcohols. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2009; 25:12516-12521. [PMID: 19856990 DOI: 10.1021/la901771x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
We show here the influence of n-alcohols (C(2)OH-C(8)OH) on the solubility behavior of cationic-anionic surfactant mixtures, so-called "catanionics". We studied catanionics of different compositions composed of sodium dodecyl sulfate (SDS)/cetyltrimethylammonium bromide (CTAB) and sodium dodecanoate (SDod)/CTAB mixtures. Interestingly, with a molar excess of SDS, long chain n-alcohols (C(4)OH-C(8)OH) significantly depress the solubility temperature of the SDS+CTAB catanionic and increase the kinetic stability of the solution. The visual observations of solubility temperatures of catanionics were further confirmed by differential scanning calorimetry (DSC) measurements. For the catanionics a multistep solubilization was observed by DSC, for which the sulfate headgroup is responsible. This was probed by replacing SDS by SDod. A remarkable analogy was found between the influence of the alcohols on the solubility patterns of the catanionic mixtures and on the anesthesia of tadpoles. Possible reasons for this analogy are discussed also in this paper.
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Affiliation(s)
- Sekh Mahiuddin
- Materials Science Division, North-East Institute of Science and Technology, CSIR, Jorhat-785006, Assam, India.
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315
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Ben-Yaakov D, Andelman D, Harries D, Podgornik R. Beyond standard Poisson-Boltzmann theory: ion-specific interactions in aqueous solutions. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2009; 21:424106. [PMID: 21715841 DOI: 10.1088/0953-8984/21/42/424106] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The Poisson-Boltzmann mean-field description of ionic solutions has been successfully used in predicting charge distributions and interactions between charged macromolecules. While the electrostatic model of charged fluids, on which the Poisson-Boltzmann description rests, and its statistical mechanical consequences have been scrutinized in great detail, much less is understood about its probable shortcomings when dealing with various aspects of real physical, chemical and biological systems. These shortcomings are not only a consequence of the limitations of the mean-field approximation per se, but perhaps are primarily due to the fact that the purely Coulombic model Hamiltonian does not take into account various additional interactions that are not electrostatic in their origin. We explore several possible non-electrostatic contributions to the free energy of ions in confined aqueous solutions and investigate their ramifications and consequences on ionic profiles and interactions between charged surfaces and macromolecules.
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Affiliation(s)
- Dan Ben-Yaakov
- Raymond and Beverly Sackler School of Physics and Astronomy, Tel Aviv University, Ramat Aviv, Tel Aviv 69978, Israel
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316
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Counterion specificity of surfactants based on dicarboxylic amino acids. J Colloid Interface Sci 2009; 338:529-36. [DOI: 10.1016/j.jcis.2009.06.032] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2009] [Revised: 06/12/2009] [Accepted: 06/12/2009] [Indexed: 11/21/2022]
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317
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Hallberg F, Furó I, Stilbs P. Ion Pairing in Ethanol/Water Solution Probed by Electrophoretic and Diffusion NMR. J Am Chem Soc 2009; 131:13900-1. [DOI: 10.1021/ja904959y] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Fredrik Hallberg
- Division of Physical Chemistry and Industrial NMR Centre, Department of Chemistry, Royal Institute of Technology, SE-10044 Stockholm, Sweden
| | - István Furó
- Division of Physical Chemistry and Industrial NMR Centre, Department of Chemistry, Royal Institute of Technology, SE-10044 Stockholm, Sweden
| | - Peter Stilbs
- Division of Physical Chemistry and Industrial NMR Centre, Department of Chemistry, Royal Institute of Technology, SE-10044 Stockholm, Sweden
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318
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Varhač R, Tomášková N, Fabián M, Sedlák E. Kinetics of cyanide binding as a probe of local stability/flexibility of cytochrome c. Biophys Chem 2009; 144:21-6. [DOI: 10.1016/j.bpc.2009.06.001] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2009] [Revised: 05/30/2009] [Accepted: 06/01/2009] [Indexed: 10/20/2022]
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319
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Adsorption of thiocyanate ions to the dodecanol/water interface characterized by UV second harmonic generation. Proc Natl Acad Sci U S A 2009; 106:15176-80. [PMID: 19706409 DOI: 10.1073/pnas.0904800106] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Recent experimental and theoretical results have firmly established the existence of enhanced concentrations of selected ions at the air/water interface. Ion adsorption to aqueous interfaces involving complex organic molecules is relevant to biology in connection with the familiar but incompletely understood Hofmeister effects. Here, we describe resonant UV second harmonic generation (SHG) studies of the strongly chaotropic thiocyanate ion adsorbed to the interface formed by water and a monolayer of dodecanol, wherein the Gibbs free energy of adsorption was determined to be -6.7 +/- 1.1 and -6.3 +/- 1.8 kJ/mol for sodium and potassium thiocyanate, respectively, coincident with the value determined for thiocyanate at the air/water interface. Interestingly, near 4 M and higher concentrations, the resonant SHG signal increases discontinuously, indicating a structural change in the interfacial region.
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320
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Spontaneous vesicle formation with an ionic liquid amphiphile. J Colloid Interface Sci 2009; 335:105-11. [DOI: 10.1016/j.jcis.2009.03.075] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2008] [Revised: 02/28/2009] [Accepted: 03/03/2009] [Indexed: 11/17/2022]
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321
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SANS investigation of the microstructures in catanionic mixtures of SDS/DTAC and the effect of various added salts. J Colloid Interface Sci 2009; 337:472-84. [PMID: 19540508 DOI: 10.1016/j.jcis.2009.05.039] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2009] [Revised: 05/16/2009] [Accepted: 05/18/2009] [Indexed: 11/24/2022]
Abstract
The aggregation behavior of two common ionic surfactants with opposite charges, sodium dodecylsulfate (SDS) and dodecyltrimethylammonium chloride (DTAC), was studied for their mixtures and for different added salts. The aggregates formed were characterized by means of small-angle neutron scattering (SANS), at two temperatures: 25 and 50 degrees C (below and above the "Krafft point" of the catanionic salt) and at two overall concentrations (50 and 200 mM). Results have been compared to the well-known SDS+DTAB system. Similar results are found, showing that with no excess of salt the nature of the counter-ion, bromide or chloride, has no dominant effect on this mixture of oppositely charged surfactants. Further SANS experiments were carried out to check the effect of ions on the pure surfactants, the ions being chosen to mimic the head group of the paired surfactant in the catanionic mixture. Tetramethylammonium chloride (TMACl) was added to SDS and sodium methylsulfate (SMS) to DTAC. Their effects were compared to NaCl, which was included in this study as a reference, and explained in terms of competition between the behavior of simple ions (screening) and that of a "binding ion" (attachment to the micellar surface). Apparently the effect of salt addition to these two surfactants is clearly strongly ion-specific.
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322
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Tang CY, Allen HC. Ionic Binding of Na+ versus K+ to the Carboxylic Acid Headgroup of Palmitic Acid Monolayers Studied by Vibrational Sum Frequency Generation Spectroscopy. J Phys Chem A 2009; 113:7383-93. [PMID: 19453122 DOI: 10.1021/jp9000434] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Cheng Y. Tang
- The Ohio State University, Department of Chemistry, 100 West 18th Avenue, Columbus, Ohio 43210
| | - Heather C. Allen
- The Ohio State University, Department of Chemistry, 100 West 18th Avenue, Columbus, Ohio 43210
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323
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Vlachy N, Drechsler M, Touraud D, Kunz W. Anion specificity influencing morphology in catanionic surfactant mixtures with an excess of cationic surfactant. CR CHIM 2009. [DOI: 10.1016/j.crci.2008.10.010] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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