1
|
Mora AK, Singh PK, Nadkarni SA, Nath S. How mobile is the water in the reverse micelles? A 2DIR study with an ultrasmall IR probe. J Mol Liq 2021. [DOI: 10.1016/j.molliq.2020.114819] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
|
2
|
Mills AJ, Britton MM. NMR study of the influence of n-alkanol co-surfactants on reverse micelles in quaternary microemulsions of cetyltrimethylammonium bromide (CTAB). MAGNETIC RESONANCE IN CHEMISTRY : MRC 2017; 55:425-432. [PMID: 26857914 DOI: 10.1002/mrc.4392] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2015] [Revised: 10/23/2015] [Accepted: 11/03/2015] [Indexed: 06/05/2023]
Abstract
The effects of different n-alkanol co-surfactants on the size, shape, composition and dynamics of reverse micelles (RMs) in cetyltrimethylammonium bromide (CTAB)/n-alkanol/n-hexane/water and CTAB/n-alkanol/n-pentane/water microemulsions were investigated using T2 relaxation and pulsed gradient stimulated echo nuclear magnetic resonance (NMR) measurements and molecular modelling. NMR T2 relaxation times and diffusion coefficients were determined for the surfactant and co-surfactant in these CTAB quaternary reverse microemulsions, for a range of medium chain length alcohol co-surfactants, from 1-butanol to 1-heptanol. These data revealed a slight RM size dependency on co-surfactant chain length, with RM sizes tending to decrease with increasing alcohol chain length. Molecular modelling of CTAB/n-alkanol/n-hexane/water RMs suggested a variation in RM shape with co-surfactant chain length, where those formed with pentanol were found to be least spherical and those formed with heptanol the most spherical. The NMR data also revealed differences in the behaviour of the micellar structures in the CTAB/n-pentanol/n-hexane/water reverse microemulsion, compared with the other reverse microemulsions in this study, where CTAB was found to be distributed between two environments, which then combined to form larger micelles. The origins of these differences remain unclear. Copyright © 2016 John Wiley & Sons, Ltd.
Collapse
Affiliation(s)
- Amanda J Mills
- School of Chemistry, University of Birmingham, Birmingham, UK
| | | |
Collapse
|
3
|
Sripradite J, Miller SA, Johnson MD, Tongraar A, Crans DC. How Interfaces Affect the Acidity of the Anilinium Ion. Chemistry 2016; 22:3873-80. [DOI: 10.1002/chem.201504804] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2015] [Indexed: 11/07/2022]
Affiliation(s)
- Jarukorn Sripradite
- School of Chemistry; Institute of Science; Suranaree University of Technology; Nakhon Ratchasima 30000 Thailand
- Department of Chemistry; Colorado State University; Fort Collins CO 80523 USA
- College of Industrial Technology; King Mongkut's University of Technology North Bangkok; Bangkok 10800 Thailand
| | - Susannah A. Miller
- Department of Chemistry; Colorado State University; Fort Collins CO 80523 USA
| | - Michael D. Johnson
- Department of Chemistry and Biochemistry; New Mexico State University; Las Cruces NM 88003 USA
| | - Anan Tongraar
- School of Chemistry; Institute of Science; Suranaree University of Technology; Nakhon Ratchasima 30000 Thailand
| | - Debbie C. Crans
- Department of Chemistry; Colorado State University; Fort Collins CO 80523 USA
| |
Collapse
|
4
|
Photoinduced electron transfer reactions of ruthenium(II) phenanthroline complexes with dimethylaniline in aqueous and micellar media. J Fluoresc 2014; 25:147-57. [PMID: 25524086 DOI: 10.1007/s10895-014-1491-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2014] [Accepted: 12/02/2014] [Indexed: 10/24/2022]
Abstract
Four [Ru(NN)(3)](2+) complexes (NN = polypyridine) with ligands of varying hydrophobicity with different charges +2, 0 and -4 were synthesized. The photophysics and photoinduced electron transfer reactions of these Ru(II)-complexes with dimethylaniline (DMA) as the quencher have been studied in aqueous medium and ionic and non-ionic micellar medium. The extent of binding of the complexes with the surfactant interface is evident from the calculated binding constant values (K). Dimethylaniline (DMA) being a neutral quencher, the hydrophobic and electrostatic interactions competing with one another and their combined effect with the surfactants were reported by observing the quenching rate constant (k(q)) values. The formation of anilinium cation radical in transient absorption spectrum confirms the excited state electron transfer reactions of ruthenium(II) complexes with dimethylaniline. The calculated rate constant values (k(q)) are in good agreement with the experimental k(q) values giving quantitative evidence for the bimolecular reductive quenching rate constant for the complexes with DMA. Pseudophase ion exchange model is successfully applied to analyse the quenching data.
Collapse
|
5
|
Mills AJ, Wilkie J, Britton MM. NMR and Molecular Dynamics Study of the Size, Shape, and Composition of Reverse Micelles in a Cetyltrimethylammonium Bromide (CTAB)/n-Hexane/Pentanol/Water Microemulsion. J Phys Chem B 2014; 118:10767-75. [DOI: 10.1021/jp504585k] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- Amanda J. Mills
- School of Chemistry, University of Birmingham, Edgbaston, B15 2TT, United Kingdom
| | - John Wilkie
- School of Chemistry, University of Birmingham, Edgbaston, B15 2TT, United Kingdom
| | - Melanie M. Britton
- School of Chemistry, University of Birmingham, Edgbaston, B15 2TT, United Kingdom
| |
Collapse
|
6
|
Maity A, Das S, Ghosh P, Das T, Seth SK, Mondal S, Gupta P, Purkayastha P. Dynamics of pyrenesemicarbazide and pyrenethiosemicarbazide in reverse micelle of AOT in n-heptane: Probing critical penetration of water molecules toward the palisade. Chem Phys Lett 2013. [DOI: 10.1016/j.cplett.2013.09.055] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
|
7
|
Fathi H, Kelly JP, Vasquez VR, Graeve OA. Ionic concentration effects on reverse micelle size and stability: implications for the synthesis of nanoparticles. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2012; 28:9267-9274. [PMID: 22642604 DOI: 10.1021/la300586f] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
We present a systematic investigation and analysis of the structure and stability of reverse micelle systems with the addition of NH(4)OH, ZrOCl(2), and Al(NO(3))(3) salts. We demonstrate that the reverse micelle size decreases with increasing salt additions until one reaches a critical concentration, which characterizes the onset of system destabilization. The concept of an electrical double layer, as it applies to reverse micelles, is considered for explaining features of destabilization, including the initial decrease in reverse micelle size, the destabilization concentration, and the effect of cation valence. We propose that the reduction in size prior to instability is caused by compression of the reverse micelle electrical double layers, as higher concentrations of salts are present. The reduced thickness of the electrical double layers allows the decaying potentials to move into closer proximity to each other before generating enough repulsion to balance the forces for reverse micelle formation and form a new equilibrium average reverse micelle size. The point of reverse micelle instability has been related to the formation of a two-phase system as a result of the inability to further compress the salt co-ions in the core of the reverse micelles, which would cause an excessive repulsive force between the overlapping potentials. We have extracted a critical potential of -89 nV between the two overlapping potentials for the AOT/water/isooctane (ω(0) = 10) systems studied. All these effects have important implications for the preparation of nanopowders by reverse micelle synthesis. If the reverse micelles are unstable before the precipitates are formed, then the advantage of reverse micelle synthesis is immediately lost.
Collapse
Affiliation(s)
- Hoorshad Fathi
- Kazuo Inamori School of Engineering, Alfred University, 2 Pine Street, Alfred, New York 14802, United States
| | | | | | | |
Collapse
|
8
|
Antidiabetic vanadium compound and membrane interfaces: interface-facilitated metal complex hydrolysis. J Biol Inorg Chem 2011; 16:961-72. [DOI: 10.1007/s00775-011-0796-5] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2011] [Accepted: 05/09/2011] [Indexed: 10/25/2022]
|
9
|
Sedgwick MA, Trujillo AM, Hendricks N, Levinger NE, Crans DC. Coexisting aggregates in mixed aerosol OT and cholesterol microemulsions. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2011; 27:948-954. [PMID: 21188993 DOI: 10.1021/la103875w] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Dynamic light scattering and NMR spectroscopic experimental evidence suggest the coexistence of two compositionally different self-assembled particles in solution. The self-assembled particles form in solutions containing water, Aerosol OT (AOT, sodium bis(2-ethylhexyl) sulfosuccinate) surfactant, and cholesterol in cyclohexane. In a similar series of studies carried out in 1-octanol only one aggregate type, that is, reverse micelles, is observed. Dynamic light scattering measurements reveal the presence of two different types of aggregates in the microemulsions formed in cyclohexane, demonstrating the coexistence of two compositionally distinct structures with very similar Gibbs energies. One particle type consists of standard AOT reverse micelles while the second type of particle consists of submicellar aggregates including cholesterol as well as small amounts of AOT and water. In microemulsions employing 1-octanol as the continuous medium, AOT reverse micelles form in a dispersed solution of cholesterol in 1-octanol. Although the size distribution of self-assembled particles is well-known for many different systems, evidence for simultaneous formation of two distinctly sized particles in solution that are chemically different is unprecedented. The ability to form microemulsion solutions that contain coexisting particles may have important applications in drug formulation and administration, particularly as applied to drug delivery using cholesterol as a targeting agent.
Collapse
Affiliation(s)
- Myles A Sedgwick
- Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523, United States
| | | | | | | | | |
Collapse
|
10
|
Halliday NA, Peet AC, Britton MM. Detection of pH in Microemulsions, without a Probe Molecule, Using Magnetic Resonance. J Phys Chem B 2010; 114:13745-51. [DOI: 10.1021/jp108649x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Nicola A. Halliday
- School of Chemistry and School of Cancer Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, United Kingdom
| | - Andrew C. Peet
- School of Chemistry and School of Cancer Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, United Kingdom
| | - Melanie M. Britton
- School of Chemistry and School of Cancer Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, United Kingdom
| |
Collapse
|
11
|
Binks DA, Spencer N, Wilkie J, Britton MM. Magnetic Resonance Studies of a Redox Probe in a Reverse Sodium Bis(2-ethylhexyl)sulfosuccinate/Octane/Water Microemulsion. J Phys Chem B 2010; 114:12558-64. [DOI: 10.1021/jp106709m] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Daniel A. Binks
- School of Chemistry, University of Birmingham, Edgbaston, Birmingham, B15 2TT
| | - Neil Spencer
- School of Chemistry, University of Birmingham, Edgbaston, Birmingham, B15 2TT
| | - John Wilkie
- School of Chemistry, University of Birmingham, Edgbaston, Birmingham, B15 2TT
| | - Melanie M. Britton
- School of Chemistry, University of Birmingham, Edgbaston, Birmingham, B15 2TT
| |
Collapse
|
12
|
Effect on the water pool properties of reverse micelles by addition of glycols. Colloids Surf A Physicochem Eng Asp 2009. [DOI: 10.1016/j.colsurfa.2009.02.024] [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]
|
13
|
Guerrero-Martínez A, Vida Y, Domínguez-Gutiérrez D, Albuquerque RQ, De Cola L. Tuning Emission Properties of Iridium and Ruthenium Metallosurfactants in Micellar Systems. Inorg Chem 2008; 47:9131-3. [DOI: 10.1021/ic800849y] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Andrés Guerrero-Martínez
- Physikalisches Institut, Westfälische Wilhelms-Universität Münster, Mendelstrasse 7, 48149 Münster, Germany
| | - Yolanda Vida
- Physikalisches Institut, Westfälische Wilhelms-Universität Münster, Mendelstrasse 7, 48149 Münster, Germany
| | - David Domínguez-Gutiérrez
- Physikalisches Institut, Westfälische Wilhelms-Universität Münster, Mendelstrasse 7, 48149 Münster, Germany
| | - Rodrigo Q. Albuquerque
- Physikalisches Institut, Westfälische Wilhelms-Universität Münster, Mendelstrasse 7, 48149 Münster, Germany
| | - Luisa De Cola
- Physikalisches Institut, Westfälische Wilhelms-Universität Münster, Mendelstrasse 7, 48149 Münster, Germany
| |
Collapse
|
14
|
Mehta SK, Kaur K, Sharma S, Bhasin KK. Behavior of acetyl modified amino acids in reverse micelles: A non-invasive and physiochemical approach. J Colloid Interface Sci 2007; 314:689-98. [PMID: 17586520 DOI: 10.1016/j.jcis.2007.05.084] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2007] [Revised: 05/30/2007] [Accepted: 05/30/2007] [Indexed: 10/23/2022]
Abstract
The well-characterized, monodisperse nature of reverse micelles formed by sodium bis-(2-ethylhexyl)sulfosuccinate/water/isooctane and their usefulness in assimilating compounds of varied interests have been exploited to investigate the effect of acetyl modified amino acids (MAA) viz., N-acetyl-L-glycine (NAG), N-acetyl-L-aspartic acid (NAA) and N-acetyl-L-cysteine (NAC), on the water pool and physiochemical properties. Non-invasive techniques such as FTIR and UV-vis absorption spectroscopy have been employed to analyze the interactions of MAA with core water and the AOT headgroup. The micropolarities on both sides of AOT interface have further been investigated by UV-vis absorption probes, methyl orange (MO) and methylene blue (MB). The dynamics of water and temperature induced percolation process have also been studied. The MAA molecules have been found to assist the process with the increase in water content where as a contrary behavior has been observed with the increase in temperature. Conductivity results have been further rationalized in terms of scaling equations, which delineate the dynamic nature of the percolation process. The results have also been analyzed in the light of activation energy of the percolation process and thermodynamics of droplet clustering.
Collapse
Affiliation(s)
- S K Mehta
- Department of Chemistry and Centre of Advanced Studies in Chemistry, Panjab University, Chandigarh 160014, India.
| | | | | | | |
Collapse
|
15
|
Study on the Structure Transition of CTAB/1-Butanol/Heptane/Water Microemulsions by Pt Ultramicroelectrode. Z PHYS CHEM 2006. [DOI: 10.1524/zpch.2006.220.6.723] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Summary
Ultramicroelectrode voltammetric measurements have been used in the microemulsions of CTAB/1-butanol/heptane/water to calculate the diffusion coefficient which can reflect the structure transition of the microemulsions. It is found that with increasing water content of microemulsions, the apparent diffusion coefficient (D
app) of the probe decreases monotonically with three transition points. The first two transition points indicate the change in the structure of microemulsions, that is from water in oil region to bicontinuous phase and then to oil in water region, while the third one differs from previous reports. The time resolved fluorescence quenching (TRFQ) technique has been carried out to obtain the aggregation number of the microemulsions in order to analyze the abnormal transition point. According to the TRFQ experiment, we find that the aggregation number of the microemulsion decrease with water content increasing between 50%–60%, and then tend to identical. These results suggest that the last transition point of the diffusion coefficient is because of the forces between oil droplets. The self-diffusion coefficient of oil droplet in the o/w region is calculated simultaneously. Based on these experimental results, we analyze the composition of the interface between oil and water.
Collapse
|
16
|
Sando GM, Dahl K, Owrutsky JC. Surfactant Charge Effects on the Location, Vibrational Spectra, and Relaxation Dynamics of Cyanoferrates in Reverse Micelles. J Phys Chem B 2005; 109:4084-95. [PMID: 16851467 DOI: 10.1021/jp045287r] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Ultrafast infrared spectroscopy has been used to measure vibrational energy relaxation (VER) and reorientation (Tr) times for the high frequency CN stretches of potassium ferrocyanide and ferricyanide and the NO stretch of sodium nitroprusside (SNP) in several reverse micelle (RM) systems using cationic, anionic, and nonionic surfactants. The confinement effects on anion vibrational spectra and dynamics in aqueous RMs depend on the charge of the surfactant that is used to form the RMs. Spectra and VER dynamics of ferrocyanide are not significantly altered in the limited number of RMs in which it could be solubilized. The static spectra of ferricyanide suggest an environment that is most bulklike in anionic RMs and least bulklike in cationic RMs. The dynamics of ferricyanide are slower in cationic RMs and indistinguishable from the bulk in nonionic RMs. The VER dynamics and static spectra of SNP are indistinguishable from the bulk in anionic RMs, but much slower in cationic RMs. This suggests a strong surfactant-solute repulsion in the former and an attraction in the latter. Broad static spectra and probe frequency dependent dynamics are seen for SNP in nonionic RMs, indicating an inhomogeneous distribution of environments. Similar measurements were carried out for SNP in mixtures of water and a model compound containing only the hydrophilic portion of the nonionic surfactants in which RMs are not formed. The results closely resemble those observed for SNP in nonionic RMs and provide evidence that in the latter water penetrates the interface and hydrates the ethylene oxide groups before forming a water pool. The results are consistent with the explanation that Coulombic forces determine the anion location. The anions are repelled to the interior of the water pool, which has a bulklike environment in anionic RMs, and are attracted to the interface in cationic RMs, resulting in a strong interaction with the surfactant. The solute location in the nonionic RMs depends on the hydrophilic nature of the probe, with ferrocyanide and ferricyanide being more hydrophilic than SNP. These results and the dependence on surfactant charge are similar to those reported for azide.
Collapse
Affiliation(s)
- Gerald M Sando
- Code 6111, U.S. Naval Research Laboratory, Washington, D.C. 20375-5342, USA
| | | | | |
Collapse
|
17
|
|