In this review, we deal with the formation and application of biocompatible water-in-oil microemu... more In this review, we deal with the formation and application of biocompatible water-in-oil microemulsions commonly known as reverse micelles (RMs). These RMs are extremely important to facilitate the dissolution of hydrophilic and hydrophobic compounds for biocompatibility in applications in drug delivery, food science, and nanomedicine. The combination of two wisely chosen types of compounds such as biocompatible non-polar solvents and ionic liquids (ILs) with amphiphilic character (surface-active ionic liquids, SAILs) can be used to generate organized systems that perfectly align with the Green Chemistry concepts. Thus, we describe the current state of SAILs (protic and aprotic) to prepare RMs using non-polar but safe solvents such as esters derived from fatty acids, among others. Moreover, the use of the biocompatible solvents as the external phase in RMs and microemulsions/nanoemulsions with the other commonly used biocompatible surfactants is detailed showing the diversity of pre...
We evaluatein vitroandin vivotoxicity and stability in an acidic environment of new vesicles form... more We evaluatein vitroandin vivotoxicity and stability in an acidic environment of new vesicles formed by the catanionic surfactant AOT-BHD in order to investigate their potential application as an oral drug delivery system.
In this contribution a strategy is shown to covalently immobilize gold nanoparticles (AuNPs) onto... more In this contribution a strategy is shown to covalently immobilize gold nanoparticles (AuNPs) onto vesicle bilayers with the aim of using this nanomaterial as platform for the future design of immunosensors. A novel methodology for the self-assembly of AuNPs onto large unilamellar vesicle structures is described. The vesicles were formed with 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) and 1-undecanethiol (SH). After, the AuNPs photochemically synthesized in pure glycerol were mixed and anchored onto SH-DOPC vesicles. The data provided by voltammetry, spectrometry and microscopy techniques indicated that the AuNPs were successfully covalently anchored onto the vesicle bilayer and decorated vesicles exhibit a spherical shape with a size of 190 ± 10 nm. The developed procedure is easy, rapid and reproducible to start designing a possible immunosensor by using environmentally friendly procedures.
The limited amount of information about reverse micelles (RMs) made with gemini surfactants, the ... more The limited amount of information about reverse micelles (RMs) made with gemini surfactants, the effect of the n-alcohols in their interface and the water entrapped structure in the polar core motivated us to perform this work. Thus, in the present contribution we use Dynamic Light Scattering (DLS), Static Light Scattering (SLS) and FT-IR techniques to obtain information on RMs structure created, with the gemini dimethylene-1,2bis(dodecyldimethylammonium) bromide (G12-2-12) surfactant and compare the results with its monomer: dodecyltrimethylammonium bromide (DTAB). In this way the size of the aggregates formed in different nonpolar organic solvents, the effect of the chain length of n-alcohols used as cosurfactants and the water entrapped structure were explored. The data show that the structure of the cosurfactant needed to stabilize the RMs plays a fundamental role, affecting the size and behavior of the aggregates. In contrast to what happen with the RMs formed with the monomer DTAB, water entrapped inside G12-2-12 RMs displays different interaction with the interface depending on the hydrocarbon chain length of the n-alcohol used as cosurfactant. Thus, n-pentanol and n-octanol molecules are located in different regions in the RMs interfaces formed with the gemini surfactant. n-Octanol locates at the RMs interface among the surfactant hydrocarbon tails increasing the water-surfactant polar head group interaction. On the other hand, n-pentanol locates at the RMs interface near the polar core limiting the interaction of water with the micellar inner interface and, favoring the water-water interaction in the polar core.
Se realiza un estudio sistematico de interacciones moleculares en particular especificas, como pu... more Se realiza un estudio sistematico de interacciones moleculares en particular especificas, como puente de hidrogeno y electron-donor-aceptor (EDA). Se estudian en principio moleculas sencillas (modelos), para luego aplicar los resultados a sistemas complejos de interes biologico y macromoleculas de interes analitico y tecnologico. Se busca detectar y cuantificar interacciones no-especificas. El efecto de estas interacciones se estudia tanto en medio homogeneo como en sistemas organizados: micelas y microemulsiones. Interesa establecer la influencia que ejerce el medio micelar sobre las distintas interacciones y la localizacion de los solutos en el sistema. Se estudiaran preferentemente micelas inversas. Esto permite no solo conocer la influencia del medio organizado en las propiedades espectroscopicas y cataliticas del soluto sino tambien las propiedades de estos medios tan peculiares que en muchos aspectos mimetizan los naturales. Ademas interesa sensar la polaridad en el microentorno micelar a traves del estudio espectroscopico con moleculas prueba. Estos estudios se extienden a la elucidacion de mecanismos de reaccion donde los complejos EDA se postulan como intermediarios. En particular interesan reacciones de sustitucion nucleofilica aromatica en solventes aproticos y con agregado de surfactantes. Tambien se estudian las implicancias cineticas del uso de catalisis por transferencia organica para optimizar rendimientos. Por otro, se estudian los aspectos mecanisticos de reacciones de sustitucion nucleofilica aromatica que involucran sustratos aromaticos activados por complejacion con metales de transicion y sus posibles aplicaciones en sintesis.
AOT-BHD vesicles present a bilayer completely different to the traditional DOPC vesicles, with lo... more AOT-BHD vesicles present a bilayer completely different to the traditional DOPC vesicles, with low polarity, high viscosity and more electron donor capacity.
A study was carried out on the hydrolysis of phenyl trifluoroacetate (PTFA) in AOT/n-heptane/wate... more A study was carried out on the hydrolysis of phenyl trifluoroacetate (PTFA) in AOT/n-heptane/water reverse micelles.
In this contribution electrochemical and dynamic light scattering methods are used on the system ... more In this contribution electrochemical and dynamic light scattering methods are used on the system water/BHDC/benzene:n-heptane to unravel the unusual interdroplet interactions.
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2014
In this work two different non-toxic solvents/sodium 1,4-bis-2-ethylhexylsulfosuccinate (AOT)/wat... more In this work two different non-toxic solvents/sodium 1,4-bis-2-ethylhexylsulfosuccinate (AOT)/water reverse micelles (RMs) have been investigated by dynamic (DLS) and static (SLS) light scattering techniques. Methyl laurate (ML) and isopropyl myristate (IPM) were used as external non-polar solvents to formulate the AOT RMs without cosurfactant. DLS results reveal the formation of IPM and ML AOT RMs containing water as a polar component since the droplet sizes values increase as the W 0 values increase. To the best of our knowledge this is the first report where ML is used to formulate AOT RMs. The droplets size values, the maximum amount of water solubilized and the aggregation numbers (N agg , determined by SLS) of both AOT RMs are dissimilar considering the chemical structure of the external solvents and they can be explained taking into account the different non-polar solvent penetration to the interface. The results suggest that IPM penetrate more the interface than ML in AOT RMs, diminishing the interdroplets interactions and producing RMs with smaller sizes and N agg than ML/AOT. The higher viscosity and polarity of IPM in comparison with ML promotes the interface penetration. Thus, the penetration of IPM into the interface is higher than ML, making the interface of IPM/AOT RMs more rigid and, in consequence with smaller droplets sizes values. Finally, a peculiar comparable behavior (droplets size, maximum amount of water solubilized and N agg) between n-heptane and ML AOT RMs and benzene and IPM AOT RMs was observed. These results present a very promissory field since that the unique properties of the alkanes/AOT/water RMs can be obtained using non-toxic lipophilic oils and, in the same way the opportunity to formulate environmentally friendly AOT RMs.
Schematic representation of different interfaces in the novel nonaqueous NaDEHP/n-heptane reverse... more Schematic representation of different interfaces in the novel nonaqueous NaDEHP/n-heptane reverse micelle.
Microenvironment of HPEI based core shell amphiphilic macromolecules has been assessed by using Q... more Microenvironment of HPEI based core shell amphiphilic macromolecules has been assessed by using QB probe.
The proportion of TOPO in water/AOT:TOPO/n-heptane reverse micelles produces dramatic changes in ... more The proportion of TOPO in water/AOT:TOPO/n-heptane reverse micelles produces dramatic changes in the water structure, droplet size and composition of the interface.
A detailed study of the electrochemical behavior of the [Fe(CN) 6 ] 4-/3redox couple was performe... more A detailed study of the electrochemical behavior of the [Fe(CN) 6 ] 4-/3redox couple was performed in water/ AOT/n-heptane reverse micelles using a Pt microelectrode according to the high resistivity of the media. The results of varying the surfactant concentration at W 0) [H 2 O]/[AOT]) 10 and constant [Fe(CN) 6 ] 4concentration show an anomalous response of the limiting current value, i L. Despite the invariant reverse micelles size the i L value, expected to be constant, increases with the AOT concentration. These interesting results are explained as due to the ion pairing that [Fe(CN) 6 ] 4may undergo with K + counterions giving less charged species that tend to reside at the AOT reverse micelles interface and need more energy to undergo the oxidation process. The association process is favored when the molecular probe occupation number is greater than 2 because of the low water availability for ion solvation. As the water content increases, the ion solvation increases and reduces the degree of association. The free [Fe(CN) 6 ] 4ion resides in the water pool where the electrochemical response is close to the one obtained in bulk water for the nonassociated species. Absorption spectroscopy experiments confirm these assumptions. As AOT reverse micelles can be considered monodisperse systems which make the entrance of the molecules or ions inside the reverse micelles a random effect and the [Fe(CN) 6 ] 4-/3couple resides exclusively in their water pool due to Coulombic repulsion with the surfactant headgroups, we propose a model based in the Poisson distribution to account for different properties. The model and the measurements allow us to determine: (i) the real concentration of the electroactive species, the one that it is not associated with the K + counterions; (ii) the AOT reverse micelle diffusion coefficient, and (iii) the micellar hydrodynamic radius. The values are in very good agreement with results obtained by other techniques which clearly show that electrochemical measurements can be a powerful alternative approach to investigate organized media such as reverse micelles.
The formation of reverse micelles (RMs) of sodium 1,4-bis(2-ethylhexyl)sulfosuccinate (AOT) in n-... more The formation of reverse micelles (RMs) of sodium 1,4-bis(2-ethylhexyl)sulfosuccinate (AOT) in n-heptane including two different beta-cyclodextrin (beta-CD) derivatives (hydroxypropyl-beta-CD, hp-beta-CD, and decenyl succinyl-beta-CD, Mod-beta-CD) is reported. Both cyclodextrins can be incorporated into AOT RMs in different zones within the aggregate, while beta-CD cannot. Using UV-vis and induced circular dichroism (ICD) spectroscopy and different achiral molecular probes (some azo dyes, p-nitroaniline and ferrocene), it was possible to determine that Mod-beta-CD is located with its cavity at the oil side of the AOT RM interface, while for hp-beta-CD the cavity is inside the RM water pool. Among the molecular probes used, methyl orange (MO) was the only one which gave the ICD signal when dissolved in the AOT RMs with hp-beta-CD, so a detailed study of MO behavior in homogeneous media was also performed to compare with the microheterogeneous media. The solvatochromic behavior of the dye depends not only on the polarity of the media but also on other specific solvent properties. A Kamlet-Taft analysis shows that the MO absorption spectrum shifts to longer wavelength with an increase in the solvent polarity-polarizability (pi*) and the hydrogen donor ability (alpha) of the medium. MO appears to be almost 3 times more sensitive to the pi* parameter than to the alpha parameter. In addition, from the MO absorption spectral changes with the hp-beta-CD concentration, the association equilibrium constants in pure water (K11W) and inside the RMs (K11RM) were computed. The results show that K11W is almost 10 times larger than the value inside the RMs. The latter can be explained considering that MO resides anchored to the RM interface through hydrogen bond interaction with the hydration bound water. This study shows for the first time that the cyclodextrin chiral cavity is available for a guest in an organic medium such as the RMs; therefore, we have created a potentially powerful nanoreactor with two different confined regions in the same aggregate: the polar core of the RMs and the chiral hydrophobic cavity of cyclodextrin.
In this work we investigate the behavior of the glycerol (GY):N,N-dimethylformamide (DMF) mixture... more In this work we investigate the behavior of the glycerol (GY):N,N-dimethylformamide (DMF) mixture in homogeneous and sodium 1,4-bis(2-ethylhexyl)sulfosuccinate (AOT)/n-heptane reversed micelles (RMs) media. To achieve this goal we have used the solvatochromic behavior of 1-methyl-8-oxyquinolinium betaine (QB) as an absorption probe, and dynamic light scattering (DLS). QB shows strong preferential solvation when it is dissolved in the GY:DMF mixture, and, as QB is a good hydrogen bond acceptor molecular probe, it is preferentially solvated by the GYÀDMF hydrogen-bonded (H-bonded) species. On the other hand, when the GY:DMF mixture was investigated in AOT RMs, the results show that the mixture is encapsulated in the polar core of the AOT RMs. DLS confirms the formation of the GY:DMF/AOT/n-heptane RMs since an increase in the W s = ([GY] þ [DMF])/[AOT] values causes an increment in the RMs droplets sizes. The solvatochromic behavior of QB, which resides at the AOT RMs interface, shows that QB is mostly solvated by GY molecules, especially at low W s values. Thus, it seems that upon encapsulation inside the polar core of the AOT RMs, the GYÀDMF interaction diminishes due to the strong AOTÀGY interaction. 1 H NMR chemical shifts of GY and DMF measured in the different AOT RMs investigated shows that GY and DMF behave practically as noninteracting solvents inside the RMs.
In this review, we deal with the formation and application of biocompatible water-in-oil microemu... more In this review, we deal with the formation and application of biocompatible water-in-oil microemulsions commonly known as reverse micelles (RMs). These RMs are extremely important to facilitate the dissolution of hydrophilic and hydrophobic compounds for biocompatibility in applications in drug delivery, food science, and nanomedicine. The combination of two wisely chosen types of compounds such as biocompatible non-polar solvents and ionic liquids (ILs) with amphiphilic character (surface-active ionic liquids, SAILs) can be used to generate organized systems that perfectly align with the Green Chemistry concepts. Thus, we describe the current state of SAILs (protic and aprotic) to prepare RMs using non-polar but safe solvents such as esters derived from fatty acids, among others. Moreover, the use of the biocompatible solvents as the external phase in RMs and microemulsions/nanoemulsions with the other commonly used biocompatible surfactants is detailed showing the diversity of pre...
We evaluatein vitroandin vivotoxicity and stability in an acidic environment of new vesicles form... more We evaluatein vitroandin vivotoxicity and stability in an acidic environment of new vesicles formed by the catanionic surfactant AOT-BHD in order to investigate their potential application as an oral drug delivery system.
In this contribution a strategy is shown to covalently immobilize gold nanoparticles (AuNPs) onto... more In this contribution a strategy is shown to covalently immobilize gold nanoparticles (AuNPs) onto vesicle bilayers with the aim of using this nanomaterial as platform for the future design of immunosensors. A novel methodology for the self-assembly of AuNPs onto large unilamellar vesicle structures is described. The vesicles were formed with 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) and 1-undecanethiol (SH). After, the AuNPs photochemically synthesized in pure glycerol were mixed and anchored onto SH-DOPC vesicles. The data provided by voltammetry, spectrometry and microscopy techniques indicated that the AuNPs were successfully covalently anchored onto the vesicle bilayer and decorated vesicles exhibit a spherical shape with a size of 190 ± 10 nm. The developed procedure is easy, rapid and reproducible to start designing a possible immunosensor by using environmentally friendly procedures.
The limited amount of information about reverse micelles (RMs) made with gemini surfactants, the ... more The limited amount of information about reverse micelles (RMs) made with gemini surfactants, the effect of the n-alcohols in their interface and the water entrapped structure in the polar core motivated us to perform this work. Thus, in the present contribution we use Dynamic Light Scattering (DLS), Static Light Scattering (SLS) and FT-IR techniques to obtain information on RMs structure created, with the gemini dimethylene-1,2bis(dodecyldimethylammonium) bromide (G12-2-12) surfactant and compare the results with its monomer: dodecyltrimethylammonium bromide (DTAB). In this way the size of the aggregates formed in different nonpolar organic solvents, the effect of the chain length of n-alcohols used as cosurfactants and the water entrapped structure were explored. The data show that the structure of the cosurfactant needed to stabilize the RMs plays a fundamental role, affecting the size and behavior of the aggregates. In contrast to what happen with the RMs formed with the monomer DTAB, water entrapped inside G12-2-12 RMs displays different interaction with the interface depending on the hydrocarbon chain length of the n-alcohol used as cosurfactant. Thus, n-pentanol and n-octanol molecules are located in different regions in the RMs interfaces formed with the gemini surfactant. n-Octanol locates at the RMs interface among the surfactant hydrocarbon tails increasing the water-surfactant polar head group interaction. On the other hand, n-pentanol locates at the RMs interface near the polar core limiting the interaction of water with the micellar inner interface and, favoring the water-water interaction in the polar core.
Se realiza un estudio sistematico de interacciones moleculares en particular especificas, como pu... more Se realiza un estudio sistematico de interacciones moleculares en particular especificas, como puente de hidrogeno y electron-donor-aceptor (EDA). Se estudian en principio moleculas sencillas (modelos), para luego aplicar los resultados a sistemas complejos de interes biologico y macromoleculas de interes analitico y tecnologico. Se busca detectar y cuantificar interacciones no-especificas. El efecto de estas interacciones se estudia tanto en medio homogeneo como en sistemas organizados: micelas y microemulsiones. Interesa establecer la influencia que ejerce el medio micelar sobre las distintas interacciones y la localizacion de los solutos en el sistema. Se estudiaran preferentemente micelas inversas. Esto permite no solo conocer la influencia del medio organizado en las propiedades espectroscopicas y cataliticas del soluto sino tambien las propiedades de estos medios tan peculiares que en muchos aspectos mimetizan los naturales. Ademas interesa sensar la polaridad en el microentorno micelar a traves del estudio espectroscopico con moleculas prueba. Estos estudios se extienden a la elucidacion de mecanismos de reaccion donde los complejos EDA se postulan como intermediarios. En particular interesan reacciones de sustitucion nucleofilica aromatica en solventes aproticos y con agregado de surfactantes. Tambien se estudian las implicancias cineticas del uso de catalisis por transferencia organica para optimizar rendimientos. Por otro, se estudian los aspectos mecanisticos de reacciones de sustitucion nucleofilica aromatica que involucran sustratos aromaticos activados por complejacion con metales de transicion y sus posibles aplicaciones en sintesis.
AOT-BHD vesicles present a bilayer completely different to the traditional DOPC vesicles, with lo... more AOT-BHD vesicles present a bilayer completely different to the traditional DOPC vesicles, with low polarity, high viscosity and more electron donor capacity.
A study was carried out on the hydrolysis of phenyl trifluoroacetate (PTFA) in AOT/n-heptane/wate... more A study was carried out on the hydrolysis of phenyl trifluoroacetate (PTFA) in AOT/n-heptane/water reverse micelles.
In this contribution electrochemical and dynamic light scattering methods are used on the system ... more In this contribution electrochemical and dynamic light scattering methods are used on the system water/BHDC/benzene:n-heptane to unravel the unusual interdroplet interactions.
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2014
In this work two different non-toxic solvents/sodium 1,4-bis-2-ethylhexylsulfosuccinate (AOT)/wat... more In this work two different non-toxic solvents/sodium 1,4-bis-2-ethylhexylsulfosuccinate (AOT)/water reverse micelles (RMs) have been investigated by dynamic (DLS) and static (SLS) light scattering techniques. Methyl laurate (ML) and isopropyl myristate (IPM) were used as external non-polar solvents to formulate the AOT RMs without cosurfactant. DLS results reveal the formation of IPM and ML AOT RMs containing water as a polar component since the droplet sizes values increase as the W 0 values increase. To the best of our knowledge this is the first report where ML is used to formulate AOT RMs. The droplets size values, the maximum amount of water solubilized and the aggregation numbers (N agg , determined by SLS) of both AOT RMs are dissimilar considering the chemical structure of the external solvents and they can be explained taking into account the different non-polar solvent penetration to the interface. The results suggest that IPM penetrate more the interface than ML in AOT RMs, diminishing the interdroplets interactions and producing RMs with smaller sizes and N agg than ML/AOT. The higher viscosity and polarity of IPM in comparison with ML promotes the interface penetration. Thus, the penetration of IPM into the interface is higher than ML, making the interface of IPM/AOT RMs more rigid and, in consequence with smaller droplets sizes values. Finally, a peculiar comparable behavior (droplets size, maximum amount of water solubilized and N agg) between n-heptane and ML AOT RMs and benzene and IPM AOT RMs was observed. These results present a very promissory field since that the unique properties of the alkanes/AOT/water RMs can be obtained using non-toxic lipophilic oils and, in the same way the opportunity to formulate environmentally friendly AOT RMs.
Schematic representation of different interfaces in the novel nonaqueous NaDEHP/n-heptane reverse... more Schematic representation of different interfaces in the novel nonaqueous NaDEHP/n-heptane reverse micelle.
Microenvironment of HPEI based core shell amphiphilic macromolecules has been assessed by using Q... more Microenvironment of HPEI based core shell amphiphilic macromolecules has been assessed by using QB probe.
The proportion of TOPO in water/AOT:TOPO/n-heptane reverse micelles produces dramatic changes in ... more The proportion of TOPO in water/AOT:TOPO/n-heptane reverse micelles produces dramatic changes in the water structure, droplet size and composition of the interface.
A detailed study of the electrochemical behavior of the [Fe(CN) 6 ] 4-/3redox couple was performe... more A detailed study of the electrochemical behavior of the [Fe(CN) 6 ] 4-/3redox couple was performed in water/ AOT/n-heptane reverse micelles using a Pt microelectrode according to the high resistivity of the media. The results of varying the surfactant concentration at W 0) [H 2 O]/[AOT]) 10 and constant [Fe(CN) 6 ] 4concentration show an anomalous response of the limiting current value, i L. Despite the invariant reverse micelles size the i L value, expected to be constant, increases with the AOT concentration. These interesting results are explained as due to the ion pairing that [Fe(CN) 6 ] 4may undergo with K + counterions giving less charged species that tend to reside at the AOT reverse micelles interface and need more energy to undergo the oxidation process. The association process is favored when the molecular probe occupation number is greater than 2 because of the low water availability for ion solvation. As the water content increases, the ion solvation increases and reduces the degree of association. The free [Fe(CN) 6 ] 4ion resides in the water pool where the electrochemical response is close to the one obtained in bulk water for the nonassociated species. Absorption spectroscopy experiments confirm these assumptions. As AOT reverse micelles can be considered monodisperse systems which make the entrance of the molecules or ions inside the reverse micelles a random effect and the [Fe(CN) 6 ] 4-/3couple resides exclusively in their water pool due to Coulombic repulsion with the surfactant headgroups, we propose a model based in the Poisson distribution to account for different properties. The model and the measurements allow us to determine: (i) the real concentration of the electroactive species, the one that it is not associated with the K + counterions; (ii) the AOT reverse micelle diffusion coefficient, and (iii) the micellar hydrodynamic radius. The values are in very good agreement with results obtained by other techniques which clearly show that electrochemical measurements can be a powerful alternative approach to investigate organized media such as reverse micelles.
The formation of reverse micelles (RMs) of sodium 1,4-bis(2-ethylhexyl)sulfosuccinate (AOT) in n-... more The formation of reverse micelles (RMs) of sodium 1,4-bis(2-ethylhexyl)sulfosuccinate (AOT) in n-heptane including two different beta-cyclodextrin (beta-CD) derivatives (hydroxypropyl-beta-CD, hp-beta-CD, and decenyl succinyl-beta-CD, Mod-beta-CD) is reported. Both cyclodextrins can be incorporated into AOT RMs in different zones within the aggregate, while beta-CD cannot. Using UV-vis and induced circular dichroism (ICD) spectroscopy and different achiral molecular probes (some azo dyes, p-nitroaniline and ferrocene), it was possible to determine that Mod-beta-CD is located with its cavity at the oil side of the AOT RM interface, while for hp-beta-CD the cavity is inside the RM water pool. Among the molecular probes used, methyl orange (MO) was the only one which gave the ICD signal when dissolved in the AOT RMs with hp-beta-CD, so a detailed study of MO behavior in homogeneous media was also performed to compare with the microheterogeneous media. The solvatochromic behavior of the dye depends not only on the polarity of the media but also on other specific solvent properties. A Kamlet-Taft analysis shows that the MO absorption spectrum shifts to longer wavelength with an increase in the solvent polarity-polarizability (pi*) and the hydrogen donor ability (alpha) of the medium. MO appears to be almost 3 times more sensitive to the pi* parameter than to the alpha parameter. In addition, from the MO absorption spectral changes with the hp-beta-CD concentration, the association equilibrium constants in pure water (K11W) and inside the RMs (K11RM) were computed. The results show that K11W is almost 10 times larger than the value inside the RMs. The latter can be explained considering that MO resides anchored to the RM interface through hydrogen bond interaction with the hydration bound water. This study shows for the first time that the cyclodextrin chiral cavity is available for a guest in an organic medium such as the RMs; therefore, we have created a potentially powerful nanoreactor with two different confined regions in the same aggregate: the polar core of the RMs and the chiral hydrophobic cavity of cyclodextrin.
In this work we investigate the behavior of the glycerol (GY):N,N-dimethylformamide (DMF) mixture... more In this work we investigate the behavior of the glycerol (GY):N,N-dimethylformamide (DMF) mixture in homogeneous and sodium 1,4-bis(2-ethylhexyl)sulfosuccinate (AOT)/n-heptane reversed micelles (RMs) media. To achieve this goal we have used the solvatochromic behavior of 1-methyl-8-oxyquinolinium betaine (QB) as an absorption probe, and dynamic light scattering (DLS). QB shows strong preferential solvation when it is dissolved in the GY:DMF mixture, and, as QB is a good hydrogen bond acceptor molecular probe, it is preferentially solvated by the GYÀDMF hydrogen-bonded (H-bonded) species. On the other hand, when the GY:DMF mixture was investigated in AOT RMs, the results show that the mixture is encapsulated in the polar core of the AOT RMs. DLS confirms the formation of the GY:DMF/AOT/n-heptane RMs since an increase in the W s = ([GY] þ [DMF])/[AOT] values causes an increment in the RMs droplets sizes. The solvatochromic behavior of QB, which resides at the AOT RMs interface, shows that QB is mostly solvated by GY molecules, especially at low W s values. Thus, it seems that upon encapsulation inside the polar core of the AOT RMs, the GYÀDMF interaction diminishes due to the strong AOTÀGY interaction. 1 H NMR chemical shifts of GY and DMF measured in the different AOT RMs investigated shows that GY and DMF behave practically as noninteracting solvents inside the RMs.
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Papers by Mariano Correa