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Murakami H, Kanahara Y, Sasaki K. Freezing of Water Solvation Dynamics in Nanoconfinement by Reverse Micelles at Room Temperature. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2024; 40:13082-13091. [PMID: 38867455 DOI: 10.1021/acs.langmuir.4c00926] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2024]
Abstract
Much attention has recently been paid to anomalously low dielectric constants of nanoconfined water between two slabs at room temperature (Fumagalli et al. Science, 2018, 360, 1339). These low values imply that the dipole rotation of the interfacial water on the slab is completely suppressed. Such freezing has so far been observed for water confined between solids. In contrast, it remains unclear whether this holds for water in soft confinement, which is omnipresent naturally and artificially. Here, we address this question using encapsulated reverse micelles with a dye molecule, allowing us to study water sandwiched between the surfactant and dye molecules in solution. Moreover, we examine the solvation related to the dielectric property of water, which is reorientational motion in the hydration layer of the dye molecule, by persistent hole-burning spectroscopy. We first show that the dye molecule is surrounded by water without contact with the surfactant and that the dye molecule has two or three hydration layers on average. We next demonstrate that the solvation dynamics is frozen below the water droplet size of ∼4 nm, whereas they become liquid-like when the RM size is further increased. The average gap distance (∼1.5 nm) for freezing the solvation agrees with the gap distance with no rotational water motions between slabs. Our findings may have biological relevance, providing a new aspect for understanding biological function in cells.
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Affiliation(s)
- Hiroshi Murakami
- Institute for Quantum Life Science, National Institutes for Quantum Science and Technology (QST), Kyoto 619-0215, Japan
| | - Yuko Kanahara
- Faculty of Human Life and Environment, Nara Women's University, Nara 630-8506, Japan
| | - Kaito Sasaki
- Department of Physics, School of Science, and Micro/Nano Technology Center, Tokai University, Kanagawa 259-1292, Japan
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Vuorte M, Lokka A, Scacchi A, Sammalkorpi M. Dioctyl sodium sulfosuccinate surfactant self-assembly dependency of solvent hydrophilicity: a modelling study. Phys Chem Chem Phys 2023; 25:27250-27263. [PMID: 37791412 DOI: 10.1039/d3cp02173d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/05/2023]
Abstract
The self-assembly of dioctyl sodium sulfosuccinate (AOT) model surfactant in solvent environments of differing polarity is examined by means of dissipative particle dynamics (DPD) bead model parametrized against Hildebrand solubility parameters from atomistic molecular dynamics (MD) simulations. The model predicts that in hydrophobic solvents (e.g. dodecane) the surfactant forms small (Nagg ∼ 8) reverse micellar aggregates, while in a solvent corresponding to water lamellar assembly takes place, in good agreement with literature structural parameters. Interestingly, solvents of intermediate polarity lead to formation of large, internally structured aggregates. In these, the surfactant headgroups cluster within the aggregate, surrounded by a continuous phase formed by the hydrocarbon tails. We show that the partitioning of the headgroups between the aggregate surface layer and the inner clustered phase depends primarily on solvent polarity, and can be controlled by the solvent, but also system composition. Finally, we compare the DPD assembly response to simplified effective interaction potentials derived at dilute concentration limit for the interactions. The comparison reveals that the simplified effective potential descriptions provide good level of insight on the assembly morphologies, despite drastic, isotropic interactions simplification involved.
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Affiliation(s)
- Maisa Vuorte
- Department of Chemistry and Materials Science, School of Chemical Engineering, Aalto University, P.O. Box 16100, FI-00076 Aalto, Finland.
- Academy of Finland Center of Excellence in Life-Inspired Hybrid Materials (LIBER), Aalto University, P.O. Box 16100, FI-00076 Aalto, Finland
| | - Aapo Lokka
- Department of Chemistry and Materials Science, School of Chemical Engineering, Aalto University, P.O. Box 16100, FI-00076 Aalto, Finland.
- Academy of Finland Center of Excellence in Life-Inspired Hybrid Materials (LIBER), Aalto University, P.O. Box 16100, FI-00076 Aalto, Finland
| | - Alberto Scacchi
- Department of Chemistry and Materials Science, School of Chemical Engineering, Aalto University, P.O. Box 16100, FI-00076 Aalto, Finland.
- Academy of Finland Center of Excellence in Life-Inspired Hybrid Materials (LIBER), Aalto University, P.O. Box 16100, FI-00076 Aalto, Finland
- Department of Applied Physics, School of Science, Aalto University, P.O. Box 11000, FI-00076 Aalto, Finland
| | - Maria Sammalkorpi
- Department of Chemistry and Materials Science, School of Chemical Engineering, Aalto University, P.O. Box 16100, FI-00076 Aalto, Finland.
- Academy of Finland Center of Excellence in Life-Inspired Hybrid Materials (LIBER), Aalto University, P.O. Box 16100, FI-00076 Aalto, Finland
- Department of Bioproducts and Biosystems, School of Chemical Engineering, Aalto University, P.O. Box 16100, FI-00076 Aalto, Finland
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Ikehata A, Nakamura K, Ozaki Y. Extended molar absorption analysis of confined states of water in reverse micelles using near-infrared spectroscopy. Chem Phys Lett 2022. [DOI: 10.1016/j.cplett.2022.140055] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Enhanced Hydrodynamic Radius of AOT/n-heptane/Water Reverse Micellar System Through Altered Electrostatic Interactions and Molecular Self-Assemblies. J Fluoresc 2021; 31:1475-1488. [PMID: 34283329 DOI: 10.1007/s10895-021-02760-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2021] [Accepted: 06/01/2021] [Indexed: 02/01/2023]
Abstract
We have demonstrated a unique approach to alter the aqueous pool size of an AOT/n-heptane/water reverse micellar system. A positively charged dye Rhodamine B (RhB) and negatively charged Rose Bengal (RB) were incorporated in the reverse micellar pool to investigate the effect of electrostatic interactions and stacking effects among the dye molecules on the AOT/n-heptane/water interface. Dynamic light scattering revealed increase in reverse micellar pool size in presence of positively charged dye aggregates at the oil-water interface. However, less expansion was observed in presence of negatively charged dye aggregates (RB). This confirms the role of electrostatic interaction in modulating the hydrodynamic radius. A head-to-tail type of stacking of RhB molecules at the interface favors this expansion. The differences in stacking of the two dyes inside the reverse micelles and their torsional mobility indicated the role of the reverse micellar interface and H-bonding ability of the microenvironment on dye aggregation. Conductivity measurements demonstrated a significant drop in percolation temperature of the reverse micellar system in presence of dye aggregates. This confirms the effect of dye aggregation and electrostatic interaction on such expansion. This strategy can be exploited for solubilizing greater amounts and a wider variety of drug molecules in microemulsions.
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Sakai H, Harada M, Okada T. Reverse micelle chromatography for evaluation of partition of organic solutes to micellar pseudophases. J Colloid Interface Sci 2020; 577:191-198. [DOI: 10.1016/j.jcis.2020.05.074] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2020] [Revised: 05/18/2020] [Accepted: 05/18/2020] [Indexed: 10/24/2022]
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6
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Sun X, Bandara N. Applications of reverse micelles technique in food science: A comprehensive review. Trends Food Sci Technol 2019. [DOI: 10.1016/j.tifs.2019.07.001] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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Murakami H. Persistent optical hole-burning spectroscopy of nano-confined dye molecules in liquid at room temperature: Spectral narrowing due to a glassy state and extraordinary relaxation in a nano-cage. J Chem Phys 2018; 148:144505. [PMID: 29655335 DOI: 10.1063/1.5008448] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Persistent optical hole-burning spectroscopy has been conducted for a dye molecule within a very small (∼1 nm) reverse micelle at room temperature. The spectra show a spectral narrowing due to site-selective excitation. This definitely demonstrates that the surroundings of the dye molecule are in a glassy state regardless of a solution at room temperature. On the other hand, the hole-burning spectra exhibit large shifts from excitation frequencies, and their positions are almost independent of excitation frequencies. The hole-burning spectra have been theoretically calculated by taking account of a vibronic absorption band of the dye molecule under the assumption that the surroundings of the dye molecule are in a glassy state. The calculated results agree with the experimental ones that were obtained for the dye molecule in a polymer glass for comparison, where it has been found that the ratio of hole-burning efficiencies of vibronic- to electronic-band excitations is quite high. On the other hand, the theoretical results do not explain the large spectral shift from the excitation frequency and small spectral narrowing observed in the hole-burning spectra measured for the dye-containing reverse micelle. It is thought that the spectral shift and broadening occur within the measurement time owing to the relaxation process of the surroundings that are hot with the thermal energy deposited by the dye molecule optically excited. Furthermore, the relaxation should be temporary because the cooling of the inside of the reverse micelle takes place with the dissipation of the excess thermal energy to the outer oil solvent, and so the surroundings of the dye molecule return to the glassy state and do not attain the thermal equilibrium. These results suggest that a very small reverse micelle provides a unique reaction field in which the diffusional motion can be controlled by light in a glassy state.
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Affiliation(s)
- Hiroshi Murakami
- QST Advanced Study Laboratory and Kansai Photon Science Institute, National Institutes for Quantum and Radiological Science and Technology (QST), Kizugawa City, Kyoto 619-0215, Japan
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Kopanichuk IV, Vanin AA, Ostras’ A, Brodskaya EN. Computer Simulation of Luminophore Solubilization in Reverse Micelles. COLLOID JOURNAL 2018. [DOI: 10.1134/s1061933x18030067] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Rahdar A, Almasi-Kashi M, Khan AM, Aliahmad M, Salimi A, Guettari M, Kohne HEG. Effect of ion exchange in NaAOT surfactant on droplet size and location of dye within Rhodamine B (RhB)-containing microemulsion at low dye concentration. J Mol Liq 2018. [DOI: 10.1016/j.molliq.2018.01.004] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Rahdar A, Almasi-Kashi M, Aliahmad M. Effect of chain length of oil on location of dye within AOT nanometer-sized droplet microemulsions at constant water content. J Mol Liq 2017. [DOI: 10.1016/j.molliq.2017.03.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Masaoka M, Michitaka T, Hashidzume A. Formose reaction accelerated in aerosol-OT reverse micelles. Beilstein J Org Chem 2017; 12:2663-2667. [PMID: 28144336 PMCID: PMC5238542 DOI: 10.3762/bjoc.12.262] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2016] [Accepted: 11/22/2016] [Indexed: 11/23/2022] Open
Abstract
The formose reaction in reverse micelles of aerosol-OT (AOT), triton X-100 (TX), and hexadecyltrimethylammonium bromide (CTAB) was investigated. Time–conversion data have indicated that the interfacial water layer of AOT reverse micelles is a medium that accelerates formation of glycolaldehyde in the formose reaction. The 13C NMR spectra for the products of the formose reaction using formaldehyde-13C as starting material are indicative of the formation of ethylene glycol as a major product.
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Affiliation(s)
- Makoto Masaoka
- Department of Macromolecular Science, Graduate School of Science, Osaka University, 1-1 Machikaneyama-cho, Toyonaka, Osaka 560-0043, Japan
| | - Tomohiro Michitaka
- Department of Macromolecular Science, Graduate School of Science, Osaka University, 1-1 Machikaneyama-cho, Toyonaka, Osaka 560-0043, Japan
| | - Akihito Hashidzume
- Department of Macromolecular Science, Graduate School of Science, Osaka University, 1-1 Machikaneyama-cho, Toyonaka, Osaka 560-0043, Japan
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Rahdar A, Almasi-Kashi M. Dynamic and spectroscopic studies of nano-micelles comprising dye in water/ dioctyl sodium sulfosuccinate /decane droplet microemulsion at constant water content. J Mol Struct 2017. [DOI: 10.1016/j.molstruc.2016.08.076] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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14
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Rahdar A, Almasi-Kashi M. Photophysics of Rhodamine B in the nanosized water droplets: A concentration dependence study. J Mol Liq 2016. [DOI: 10.1016/j.molliq.2016.05.002] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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15
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Angulo G, Brucka M, Gerecke M, Grampp G, Jeannerat D, Milkiewicz J, Mitrev Y, Radzewicz C, Rosspeintner A, Vauthey E, Wnuk P. Characterization of dimethylsulfoxide/glycerol mixtures: a binary solvent system for the study of “friction-dependent” chemical reactivity. Phys Chem Chem Phys 2016; 18:18460-9. [DOI: 10.1039/c6cp02997c] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The properties of binary mixtures of dimethylsulfoxide and glycerol, measured using several techniques, are reported.
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16
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Chatterjee A, Maity B, Seth D. Influence of double confinement on photophysics of 7-(diethylamino)coumarin-3-carboxylic acid in water/AOT/isooctane reverse micelles. RSC Adv 2014. [DOI: 10.1039/c4ra00965g] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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17
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Vaz Serra V, Andrade SM, Silva EMP, Silva AMS, Neves MGPMS, Costa SMB. Structural effects of the β-vinyl linker in pyridinium porphyrins: spectroscopic studies in organic solvents and AOT reverse micelles. J Phys Chem B 2013; 117:15023-32. [PMID: 24175940 DOI: 10.1021/jp4076993] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Two isomeric β-vinylpyridinium porphyrins, 2-[2-(2-methylpyridinium)vinyl]-5,10,15,20-tetraphenylporphyrin (1, ortho isomer) and 2-[2-(4-methylpyridinium)vinyl]-5,10,15,20-tetraphenylporphyrin (2, para isomer), which have shown different photodynamic behavior were investigated in organic solvents and sodium 1,4-bis(2-ethylhexyl)sulfosuccinate (AOT) reverse micelles. In organic systems, the absorption spectra present a red-shifted band that is more intense in the para isomer, in addition to the usual Soret band. This new band presents interesting solvatochromic effects which obey the multiparametric Kamlet-Taft equation. In AOT reverse micelles, the ortho isomer exhibits a strong dependence with the parameter ω0 = [H2O]/[AOT] which indicates that the molecule resides at the interface toward the organic phase. By contrast, no evidence was detected for the encapsulation of para isomer 2 in AOT reverse micelles. The hypothesis of two ground state isomers with different contributions of trans and quinoid structures is advanced on the basis of the overall data collected from electronic absorption, steady-state, and transient-state fluorescence emission. A charge transfer state in which an electron is fully transferred from the porphyrin to the pyridinium moiety is associated to a quinoid structure in isomer 2. The trans/quinoid relative proportions may be accounted for by the orientation of the ortho-/para-pyridinium isomers relatively to the porphyrin core.
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Affiliation(s)
- Vanda Vaz Serra
- Centro de Química Estrutural, Complexo I, Instituto Superior Técnico, Universidade Técnica de Lisboa , Av. Rovisco Pais, 1049-001 Lisboa, Portugal
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Murakami H, Sada T, Yamada M, Harada M. Nanometer-scale water droplet free from the constraint of reverse micelles at low temperatures. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2013; 88:052304. [PMID: 24329261 DOI: 10.1103/physreve.88.052304] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/05/2012] [Revised: 07/02/2013] [Indexed: 06/03/2023]
Abstract
Temperature dependence of the configurational fluctuation of water confined in a reverse micellar solution has been studied by absorption spectroscopy of a probe molecule. We have found that the configurational fluctuation is liquidlike below the homogeneous nucleation temperature. This is proposed to be due to a large reduction in the confinement of water, and is explained in terms of water shedding from the reverse micelle. Further, the configurational fluctuation is frozen at ~210 K. A reverse micellar solution is considered to be a promising candidate for studies of supercooled water.
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Affiliation(s)
- H Murakami
- Kansai Photon Science Institute, Japan Atomic Energy Agency, Kyoto 619-0215, Japan
| | - T Sada
- Kansai Photon Science Institute, Japan Atomic Energy Agency, Kyoto 619-0215, Japan and Faculty of Human Life and Environment, Nara Women's University, Nara 630-8506, Japan
| | - M Yamada
- Kansai Photon Science Institute, Japan Atomic Energy Agency, Kyoto 619-0215, Japan and Faculty of Human Life and Environment, Nara Women's University, Nara 630-8506, Japan
| | - M Harada
- Faculty of Human Life and Environment, Nara Women's University, Nara 630-8506, Japan
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20
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Banerjee C, Mandal S, Ghosh S, Rao VG, Sarkar N. Tuning the Probe Location on Zwitterionic Micellar System with Variation of pH and Addition of Surfactants with Different Alkyl Chains: Solvent and Rotational Relaxation Studies. J Phys Chem B 2012; 116:11313-22. [DOI: 10.1021/jp307045v] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Affiliation(s)
- Chiranjib Banerjee
- Department
of Chemistry, Indian Institute of Technology, Kharagpur 721302, WB,
India
| | - Sarthak Mandal
- Department
of Chemistry, Indian Institute of Technology, Kharagpur 721302, WB,
India
| | - Surajit Ghosh
- Department
of Chemistry, Indian Institute of Technology, Kharagpur 721302, WB,
India
| | - Vishal Govind Rao
- Department
of Chemistry, Indian Institute of Technology, Kharagpur 721302, WB,
India
| | - Nilmoni Sarkar
- Department
of Chemistry, Indian Institute of Technology, Kharagpur 721302, WB,
India
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21
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Correa NM, Silber JJ, Riter RE, Levinger NE. Nonaqueous Polar Solvents in Reverse Micelle Systems. Chem Rev 2012; 112:4569-602. [DOI: 10.1021/cr200254q] [Citation(s) in RCA: 204] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- N. Mariano Correa
- Departamento de Química, Universidad Nacional de Río Cuarto, Agencia
Postal #3, C.P. X5804BYA Río Cuarto, Argentina
| | - Juana J. Silber
- Departamento de Química, Universidad Nacional de Río Cuarto, Agencia
Postal #3, C.P. X5804BYA Río Cuarto, Argentina
| | - Ruth E. Riter
- Department of Chemistry, Agnes Scott College, Decatur, Georgia 30030-3770, United
States
| | - Nancy E. Levinger
- Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523-1872,
United States
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22
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Sahu K, Kern SJ, Berg MA. Heterogeneous Reaction Rates in an Ionic Liquid: Quantitative Results from Two-Dimensional Multiple Population-Period Transient Spectroscopy. J Phys Chem A 2011; 115:7984-93. [DOI: 10.1021/jp2046068] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Affiliation(s)
- Kalyanasis Sahu
- Department of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina 29208, United States
| | - Sean J. Kern
- Department of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina 29208, United States
| | - Mark A. Berg
- Department of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina 29208, United States
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SOMEYA Y, YUI H. Measurements of Microproperties of Water Utilizing Charge-Transfer Dye Anilinonaphthalene Sulfonate. BUNSEKI KAGAKU 2011. [DOI: 10.2116/bunsekikagaku.60.11] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Affiliation(s)
- Yuu SOMEYA
- Department of Chemical Sciences and Technology, Graduate School of Chemical Sciences and Technology, Tokyo University of Science
| | - Hiroharu YUI
- Department of Chemical Sciences and Technology, Graduate School of Chemical Sciences and Technology, Tokyo University of Science
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Someya Y, Yui H. Fluorescence lifetime probe for solvent microviscosity utilizing anilinonaphthalene sulfonate. Anal Chem 2010; 82:5470-6. [PMID: 20524653 DOI: 10.1021/ac100116j] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The correlation between the fluorescent dynamics of excited anilinonaphthalene sulfonate (ANS) and the microviscosity of solvent molecules surrounding ANS is investigated by time-resolved fluorescence spectroscopy. ANS has been widely used to probe the local hydrophobicity due to the drastic change in its intensity. It is revealed that the fluorescence lifetime from the charge transfer (CT) state of ANS sensitively reflects the microviscosity. The higher sensitivity of 2,6-ANS than of 1,8-ANS demonstrates that the spatial freedom of the rotating phenylamino group in the photoexcited ANS is an important factor that determines the sensitivity. As an application, the measurements of the microviscosity of water in biologically important systems, such as hyaluronan, gellan gum, and gelatin aqueous solutions are also presented. The present results suggest that the fluorescence lifetime of ANS enables the estimation of the solvent microviscosity and provide a useful probe molecule for fluorescence lifetime imaging microscopy.
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Affiliation(s)
- Yuu Someya
- Department of Chemistry, Faculty of Science, Tokyo University of Science, 12 Ichigaya-Funagawaramachi, Shinjyuku-ku, Tokyo 162-0826, Japan
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25
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Ferreira JAB, Costa SMB. Electronic Excited-State Behavior of Rhodamine 3B in AOT Reverse Micelles Sensing Contact Ion Pair to Solvent Separated Ion Pair Interconversion. J Phys Chem B 2010; 114:10417-26. [DOI: 10.1021/jp100571t] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- José A. B. Ferreira
- Universidade Técnica de Lisboa, Instituto Superior Técnico, Centro de Química Estrutural, Complexo Interdisciplinar, Av. Rovisco Pais 1, 1049-001 Lisboa, Portugal
| | - Sílvia M. B. Costa
- Universidade Técnica de Lisboa, Instituto Superior Técnico, Centro de Química Estrutural, Complexo Interdisciplinar, Av. Rovisco Pais 1, 1049-001 Lisboa, Portugal
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3,3′-Diethyloxacarbocyanine iodide: A new microviscosity probe for micelles and microemulsions. Colloids Surf A Physicochem Eng Asp 2010. [DOI: 10.1016/j.colsurfa.2010.04.011] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Vakurov A, Pchelintsev NA, Forde J, O'Fágáin C, Gibson T, Millner P. The preparation of size-controlled functionalized polymeric nanoparticles in micelles. NANOTECHNOLOGY 2009; 20:295605. [PMID: 19567946 DOI: 10.1088/0957-4484/20/29/295605] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
The reverse micellar system of dioctyl-sulfosuccinate (AOT)/octane and toluene have been used as a template for polymerization of acrylamide (AA)/bisacrylamide (BAA)-based functionalized polymeric nanoparticles. Such nanoparticles are typically sized between 20 and 90 nm. They can be synthesized with different functional groups according to the monomers added to the polymerization mixture. In our experiments the nanoparticles carried amino and carboxyl groups following incorporation of allylamine (AAm) or methacrylic acid (MAA) monomers, respectively. The available amine or carboxyl groups can then be used for immobilization of enzymes or other biomolecules. These enzymes, subtilisin, laccase and lipase, were immobilized onto polyAA/BAA/MAA nanoparticles covalently after activating the MAA carboxylic groups with Woodward's K reagent. Non-covalent immobilization via electrostatic interaction was also performed.
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Affiliation(s)
- Alexander Vakurov
- Research Institute of Membrane and Systems Biology, University of Leeds, Leeds LS2 9JT, UK
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28
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Sedgwick MA, Crans DC, Levinger NE. What is inside a nonionic reverse micelle? Probing the interior of Igepal reverse micelles using decavanadate. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2009; 25:5496-5503. [PMID: 19388632 DOI: 10.1021/la8035067] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
The interiors of reverse micelles formed using nonionic surfactants to sequester water droplets in a nonpolar environment have been investigated using the decavanadate molecule as a probe. Chemical shifts and line widths of the three characteristic signals in the 51V NMR spectrum of decavanadate, corresponding to vanadium atoms in equatorial peripheral, equatorial interior, and axial locations, measure the local proton concentration and characteristics of the reverse micellar interior near the decavandate probe. All samples investigated indicate deprotonation of the vanadate probe in the reverse micelle environment. However, the relative mobility of the decavanadate molecule depends on the reverse micellar components. Specifically, the 51V NMR signals of the decavandate in reverse micelles formed using only the Igepal CO-520 surfactant display sharp signals indicating that the decavandate molecule tumbles relatively freely while reverse micelles formed from a mixture of Igepal CO-610 and -430 present a more viscous environment for the decavanadate molecule; the nature of the interior of the nonionic reverse water pool varies significantly depending on the specific Igepal. The 51V NMR spectra also indicate that the interior core water pool of the reverse micelles is less acidic than the bulk aqueous solution from which the samples were created. Together, these data provide a description that allows for a comparison of the water pools in these different nonionic reverse micelles.
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Affiliation(s)
- M A Sedgwick
- Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523-1872, USA
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Heisler IA, Kondo M, Meech SR. Reactive dynamics in confined liquids: ultrafast torsional dynamics of auramine O in nanoconfined water in aerosol OT reverse micelles. J Phys Chem B 2009; 113:1623-31. [PMID: 19146438 DOI: 10.1021/jp808989f] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The effects of confinement on the ultrafast torsional reaction of auramine O in aqueous solution are investigated through ultrafast fluorescence up-conversion with 50 fs time resolution. The aqueous solution is confined in nanoscale water droplets by an ionic surfactant. The torsional motion is orders of magnitude slower in the confined droplets than in bulk aqueous solution. The dynamics become faster with increasing radius of the nanodroplet but never reach the bulk value, even when the radius is as large as 10 nm. Time-dependent fluorescence spectra were constructed and subsequently analyzed using a one-dimensional generalized Smoluchowski equation. An accurate description of the data was achieved using a time-dependent diffusion coefficient. This is suggested to arise because the medium friction reflects dynamics on a broad range of time scales spanning the reaction dynamics. The friction recovered suggests strongly hindered motion in the confined droplet and can be qualitatively related to solvation dynamics measured in AOT, consistent with auramine O torsional dynamics being accompanied by intramolecular charge redistribution.
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Affiliation(s)
- Ismael A Heisler
- School of Chemical Sciences and Pharmacy, University of East Anglia, Norwich NR4 7TJ, UK
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30
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Verma PK, Makhal A, Mitra RK, Pal SK. Role of solvation dynamics in the kinetics of solvolysis reactions in microreactors. Phys Chem Chem Phys 2009; 11:8467-76. [DOI: 10.1039/b905573h] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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31
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Fluorometric analysis on physicochemical properties of phosphatidylcholine-based W/O microemulsion involved with enzymatic reactivity in phospholipid hydrolysis. KOREAN J CHEM ENG 2008. [DOI: 10.1007/s11814-008-0236-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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32
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Spectral and electrochemical behavior of manganese dioxide nanodispersions prepared in reverse micelle. J Electroanal Chem (Lausanne) 2008. [DOI: 10.1016/j.jelechem.2008.05.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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33
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Misra PK, Somasundaran P. Fluorescence Probing of the Surfactant Assemblies in Solutions and at Solid–Liquid Interfaces. ADVANCES IN POLYMER SCIENCE 2008. [DOI: 10.1007/12_2008_165] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/07/2023]
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Wilczura-Wachnik H, Yavuz AG, Myslinski A. Calorimetric study of the alpha-tocopherol solubility in reversed AOT micelles. J Colloid Interface Sci 2008; 319:520-5. [PMID: 18164308 DOI: 10.1016/j.jcis.2007.11.044] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2007] [Revised: 11/15/2007] [Accepted: 11/19/2007] [Indexed: 11/16/2022]
Abstract
The experimental data of heat of mixing (Q) for heterogeneous system alpha-tocopherol/AOT/n-heptane with and without water at 25 degrees C are presented. The Q dependence on AOT (sodium bis (2-ethylhexyl) sulfosuccinate) concentration, and R parameter defined as R=[H2O]/[AOT] with flow calorimetric method were investigated. Using the D'Aprano model (which is formally identical to that used earlier by Magid et al.) the binding constant (K), the distribution constant of alpha-tocopherol (K distr) between hydrocarbon and the micellar phase, and the standard enthalpy of transfer (DeltaH tr 0) of alpha-tocopherol from the hydrocarbon to AOT reversed micelles were calculated. The solubility of alpha-tocopherol in AOT reversed micelles explored with the calorimetric technique was compared to the literature data obtained respectively with UV spectrophotometry for reversed micelles and by other techniques for the phospholipid bilayer.
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Affiliation(s)
- H Wilczura-Wachnik
- Faculty of Chemistry, Warsaw University, Pasteura 1, 02-093 Warsaw, Poland.
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35
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Douhal A, Angulo G, Gil M, Organero JA, Sanz M, Tormo L. Observation of Three Behaviors in Confined Liquid Water within a Nanopool Hosting Proton-Transfer Reactions. J Phys Chem B 2007; 111:5487-93. [PMID: 17451268 DOI: 10.1021/jp068764+] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
In this contribution, we report on studies of rotational and diffusional dynamics of 7-hydroxyquinoline (7HQ) within a reverse micelle (RM) containing different amounts of water. Analyzed in terms of the wobbling-in-a-cone model, the data reveal structural and dynamical properties of the nanopool. We clearly observed three regions in the behavior of confined water molecules within the RM hosting a double proton-transfer reaction between the probe and water. This observation remarkably reproduces the change of calculated water density within this life-mimicking medium. The number of water molecules per AOT head in the transition regions changes from 2 to 5, the latter being very near to the full solvation number (6) of the RM heads. Moreover, the H-bonds breaking and making within the RM to give new structures of the probe strongly affect the environment fluidization in different extents, reflected in different relaxation times of these structures; however, they are of similar sizes. We discuss the role of RM confinement and the proton-transfer dynamics on the behavior of water and their relationships to the packing of water molecules in the studied range of concentrations.
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Affiliation(s)
- Abderrazzak Douhal
- Departamento de Química Física, Sección de Químicas, Facultad de Ciencias del Medio Ambiente, Universidad de Castilla-La Mancha, Avenida Carlos III, S.N., 45071 Toledo, Spain.
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Angulo G, Organero JA, Carranza MA, Douhal A. Probing the Behavior of Confined Water by Proton-Transfer Reactions. J Phys Chem B 2006; 110:24231-7. [PMID: 17125396 DOI: 10.1021/jp064257g] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
The picosecond dynamics of a bifunctional and H-bonding molecule, 7-hydroxyquinoline (7HQ), has been studied in a reverse micelle with increasing water content. The fluorescence kinetics has a complex behavior as the water content is changed. All reactions are irreversible, and a two-step mechanism is invoked to explain the observations. H2O/D2O exchange and excitation energy effects show that the second step has a higher barrier and that the corresponding reaction occurs through tunneling. The results clearly indicate two regimes of water nanopool behavior switching at W0 approximately 5 (W0 = [water]/[surfactant]). Water collective dynamics explains these observations. The lower fluidity of confined water within the reverse micelle with respect to normal bulk water alters the related H-bond network dynamics and therefore is responsible for the slower proton-transfer processes.
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Affiliation(s)
- G Angulo
- Departamento de Química Física, Sección de Químicas, Facultad de Ciencias del Medio Ambiente, Universidad de Castilla-La Mancha, Avenida Carlos III, S.N., 45071 Toledo, Spain
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Chatterjee S, Nandi S, Bhattacharya SC. Interface of AOT/Igepal CO720/cyclohexane/water mixed reverse micelle by spectroscopic approach. Colloids Surf A Physicochem Eng Asp 2006. [DOI: 10.1016/j.colsurfa.2005.12.040] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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38
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High static pressure alters water-pool properties in reversed micelles formed by aerosol OT (sodium bis(2-ethylhexyl)sulfosuccinate): A high pressure ESR study. Chem Phys Lett 2005. [DOI: 10.1016/j.cplett.2005.08.151] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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39
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Chen Y, Xu T, Shen X, Gao H. How do the novel substituted 3H-indole probe molecules reside in the AOT-based water-in-oil microemulsion? J Photochem Photobiol A Chem 2005. [DOI: 10.1016/j.jphotochem.2004.06.010] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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40
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Hirose Y, Yui H, Sawada T. The Ultrafast Relaxation Dynamics of a Viscosity Probe Molecule in an AOT-Reversed Micelle: Contribution of the Specific Interactions with the Local Environment. J Phys Chem B 2004. [DOI: 10.1021/jp0370775] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- Yasushi Hirose
- Department of Advanced Materials Science, Graduate School of Frontier Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-8656, Japan, and Core Research for Evolutional Science and Technology (CREST), Japan Science and Technology Agency (JST), 7-3-1 Hongo, Bunkyo, Tokyo 113-8656, Japan
| | - Hiroharu Yui
- Department of Advanced Materials Science, Graduate School of Frontier Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-8656, Japan, and Core Research for Evolutional Science and Technology (CREST), Japan Science and Technology Agency (JST), 7-3-1 Hongo, Bunkyo, Tokyo 113-8656, Japan
| | - Tsuguo Sawada
- Department of Advanced Materials Science, Graduate School of Frontier Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-8656, Japan, and Core Research for Evolutional Science and Technology (CREST), Japan Science and Technology Agency (JST), 7-3-1 Hongo, Bunkyo, Tokyo 113-8656, Japan
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García-Río L, Mejuto JC, Pérez-Lorenzo M. Modification of reactivity by changing microemulsion composition. Basic hydrolysis of nitrophenyl acetate in AOT/isooctane/water systems. NEW J CHEM 2004. [DOI: 10.1039/b401226g] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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43
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Yui H, Hirose Y, Sawada T. New Approaches to Liquid Interfaces through Changes in the Refractive Index and Nonlinear Susceptibility Utilizing Ultrashort Laser Pulses. ANAL SCI 2004; 20:1493-9. [PMID: 15566139 DOI: 10.2116/analsci.20.1493] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Molecules in inhomogeneous liquid environments, such as air/liquid, liquid/liquid, solid/liquid interfaces interact with each other specifically, and sometimes form characteristic structures and emerge unique properties. Here, we introduce two newly developed spectroscopic techniques, the total-internal-reflection ultrafast transient lens method (TIR-UTL) and second harmonic generation-coherent vibrational spectroscopy (SHG-CVS), to investigate the characteristic behaviors of molecules in such inhomogeneous environments. TIR-UTL probes the refractive-index change with sub-picosecond resolution and provides information on ultrafast changes in the population, density, and thermal properties, such as temperature increase and energy transfer from the solute molecules to the surrounding solvent molecules. On the other hand, SHG-CVS probes nonlinear susceptibility changes at the interfacial areas, and is expected to provide spectroscopic information on the low-frequency vibrational modes that reflect the corrective motion of the molecules in such an inhomogeneous environment. These new approaches are based on pump-probe techniques utilizing (ultra) short laser pulses. They are expected to provide further information on inhomogeneous environments from the viewpoints of solute-solvent interactions, changes in the molecular orientation, and the corrective motion of molecules at liquid interfaces.
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Affiliation(s)
- Hiroharu Yui
- CREST Japan Science and Technology Agency, Nanoarchitectonics Research Center, National Institute of Advanced Industrial Science and Technology, Tsukuba Central 4, 1-1-1 Higashi, Tsukuba, Ibaraki 305-8562, Japan.
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44
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Angulo G, Grampp G, Neufeld AA, Burshtein AI. Delayed Fluorescence Due to Annihilation of Triplets Produced in Recombination of Photo-Generated Ions. J Phys Chem A 2003. [DOI: 10.1021/jp0342475] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- G. Angulo
- Institute of Physical and Theoretical Chemistry, Graz University of Technology, Graz, Austria, and Department of Chemical Physics, Weizmann Institute of Science, 76100 Rehovot, Israel
| | - G. Grampp
- Institute of Physical and Theoretical Chemistry, Graz University of Technology, Graz, Austria, and Department of Chemical Physics, Weizmann Institute of Science, 76100 Rehovot, Israel
| | - A. A. Neufeld
- Institute of Physical and Theoretical Chemistry, Graz University of Technology, Graz, Austria, and Department of Chemical Physics, Weizmann Institute of Science, 76100 Rehovot, Israel
| | - A. I. Burshtein
- Institute of Physical and Theoretical Chemistry, Graz University of Technology, Graz, Austria, and Department of Chemical Physics, Weizmann Institute of Science, 76100 Rehovot, Israel
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Aoudia M, Rodgers MAJ. Photoprocesses in AOT Reverse Micelles Containing Metalloporphyrins and Oligopeptides. J Phys Chem B 2003. [DOI: 10.1021/jp027106w] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- M. Aoudia
- Department of Chemistry, College of Science, Sultan Qaboos University, P.O. Box 36, Al-Khod, Sultanate of Oman, and Center for Photochemical Science, Department of Chemistry, Bowling Green State University, Bowling Green, Ohio 43403
| | - M. A. J. Rodgers
- Department of Chemistry, College of Science, Sultan Qaboos University, P.O. Box 36, Al-Khod, Sultanate of Oman, and Center for Photochemical Science, Department of Chemistry, Bowling Green State University, Bowling Green, Ohio 43403
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Abuin E, Lissi E, Cerón A, Rubio MA. Spectroscopic probing of the effect of alkanols on the properties of the head group region in reverse micelles of AOT-heptane-water. J Colloid Interface Sci 2003; 258:363-6. [PMID: 12618106 DOI: 10.1016/s0021-9797(02)00102-9] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The effects of addition of alkanols (ethanol, n-hexanol, and 3-ethyl-3-pentanol) on the micropolarity and microviscosity of the head group region in reverse micelles of AOT-heptane-water have been investigated by fluorescence probing methods (ANS fluorescence yield and TMADPH fluorescence anisotropy), complemented by the use of the solvatochromic probe E(T)(30) in absorption spectroscopy. For all the alkanols considered, ANS fluorescence in AOT reverse micelles (at W=3) is quenched by additive incorporation, being the effect elicited almost independent of the alkanol chain length and topology. As sensed by the E(T)(30) parameter, the micropolarity of the micelle surface increases, remains unmodified, and decreases upon addition of ethanol, 3-ethyl-3-pentanol, and hexanol, respectively. While ethanol barely modifies the fluorescence anisotropy of TMADPH, 3-ethyl-3-pentanol and n-hexanol addition strongly decrease it. The similarity of the tendencies of ANS data to TMADPH anisotropies and the differences between ANS data and E(T)(30) values would indicate that, at least for 3-ethyl-3-pentanol and n-hexanol, microviscosity, rather than micropolarity, must be considered to interpret the effect of the alkanols upon the fluorescent behavior of ANS.
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Affiliation(s)
- Elsa Abuin
- Facultad de Química y Biología, Universidad de Santiago de Chile, Casilla 40, Correo 33, Santiago, Chile.
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Absorption and Emission Characteristics of 7-Hydroxycoumarin and 1-Hydroxypyrene-3,6,8-trisulfonate in Water/Oil Microemulsion with Reference to the Determination of the Interfacial and Bulk pH of the Water Pool. J Colloid Interface Sci 2001. [DOI: 10.1006/jcis.2001.7919] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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48
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Correa NM, Durantini EN, Silber JJ. Substituent Effects on Binding Constants of Carotenoids to n-Heptane/AOT Reverse Micelles. J Colloid Interface Sci 2001; 240:573-580. [PMID: 11482968 DOI: 10.1006/jcis.2001.7640] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The absorption spectra of 6'-apo-beta-caroten-6'-ol (1), 6'-apo-beta-caroten-6'-oic acid (2), and ethyl 6'-apo-beta-caroten-6'-oate (3) were analyzed in homogeneous media and in reversed micelles of AOT (sodium 1,4-bis(2-ethylhexyl) sulfosuccinate) in n-heptane. The possible solute-solvent interactions of these compounds were analyzed in pure solvents by Taft and Kamlet's solvatochromic comparison method. These carotenoids show sensitivity similar to that of medium polarity-polarizability as measured by pi*. Moreover, the absorption spectra of carotenoid 3 and to much less extent carotenoid 2 display broadening of the visible bands induced by polar solvents characteristic of carotenoids that contain a carbonyl functional group in conjugation with the carbon-carbon pi-electron system. They are also sensitive to the ability of the solvent to accept protons in a hydrogen bond interaction measured by beta. This sensitivity follows the expected order: 2>1>3. In the reverse micellar system, while the spectra for 3 remain unchanged, the intensity of the absorption band characteristic of n-heptane for 1 and 2 decreases as the AOT concentration increases, and a new band develops. This new band is attributed to the solute bound to the micelle interface. These changes allowed us to determine the binding constant (K(b)) between these compounds and AOT. At W(0)=[H(2)O]/[AOT]=0 the values of K(b) of 326+/-5 and 6.2+/-0.3 were found for the acid 2 and the alcohol 1, respectively. The strength of binding is interpreted considering their hydrogen-bond donor ability and the solubility in the organic pseudophase. For 1 K(b) decreases as W(0) is increased, while for 2 no variation was observed. These effects are discussed in terms of carotenoid-water competition for interfacial binding sites. Copyright 2001 Academic Press.
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Affiliation(s)
- N. Mariano Correa
- Departamento de Química y Física, Universidad Nacional de Río Cuarto, Agencia Postal Nro. 3, Río Cuarto, 5800, Argentina
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Exploring the locations of different groups of a cationic surface-active 3H-indole probe molecule in AOT-based water-in-oil microemulsions. Chem Phys Lett 2001. [DOI: 10.1016/s0009-2614(01)00640-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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50
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Andrade SM, Costa SM, Pansu R. STRUCTURAL CHANGES IN W/O TRITON X-100/Cyclohexane-Hexanol/Water Microemulsions Probed by a Fluorescent Drug Piroxicam. J Colloid Interface Sci 2000. [DOI: 10.1006/jcis.2000.6821] [Citation(s) in RCA: 115] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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