Effects of surfactant charge and structure on excited-state protolytic dissociation of 1-naphthol in vesicles

Il'ichev, Yurii V.; Solntsev, Kyrill M.; Kuz’min, M. G.; Lemmetyinen, Helge

doi:10.1039/ft9949002717

Cited by 12 publications

(11 citation statements)

References 20 publications

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“…Ortiz-Sanchez et al proposed that emission of HAN may result from relaxation of both E* and K* assuming that they are in equilibrium because of a very small potential energy barrier. However, the emission from the proton-transferred keto tautomer has been supported by previously reported results for the ESIPT of HNA, a structural analogue of HAN, 20,21,70 and here it is important to note that the spectral properties of HNA are similar to that of HAN.…”

Section: Introductionsupporting

confidence: 89%

“…A similar observation has also been made for HNA in pure aqueous solvent. However, Guchhait et al reported that the absorption band at 300 nm is responsible for the open conformer of HNA. ,, Gradual addition of surfactants, both ionic and nonionic, to the aqueous solution of HAN leads to the increase of absorbance at 368 nm along with slight red shift of the absorbance maxima (Figures S1 and S2, Supporting Information). The same observation is also found when the absorbance spectra of HAN are recorded in niosome solution varying the concentration of Tween-80 (Figure S3, Supporting Information).…”

Section: Resultsmentioning

confidence: 99%

“…In recent years, there has been an increasing interest in studying excited -state proton transfer (ESPT) dynamics in different selforganized supramolecular assemblies like cyclodextrins, 1À8 microemulsions, 9,10 micelles, 11À14 reverse micelles, 15À17 mixed micelles, 18,19 vesicles, 20,21 and so on. Basically, interest in such systems originates from a broad range of applications and also because of their unique ability to mimic many complex biological systems in a much simpler form.…”

Section: Introductionmentioning

confidence: 99%

“…In recent years, there has been an increasing interest in studying excited -state proton transfer (ESPT) dynamics in different self-organized supramolecular assemblies like cyclodextrins, − microemulsions, , micelles, − reverse micelles, − mixed micelles, , vesicles, , and so on. Basically, interest in such systems originates from a broad range of applications and also because of their unique ability to mimic many complex biological systems in a much simpler form. , Surfactant molecules, the common and useful amphiphilic molecules, self-assembled into a variety of organized assemblies depending on their structures, concentrations, compositions, solubilizing media, and the method used to prepare them .…”

Section: Introductionmentioning

confidence: 99%

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Photophysics and Photodynamics of 1′-Hydroxy-2′-acetonaphthone (HAN) in Micelles and Nonionic Surfactants Forming Vesicles: A Comparative Study of Different Microenvironments of Surfactant Assemblies

et al. 2011

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The effect of different microenvironments inside various biomimicking supramolecular assemblies of ionic (SDS/CTAB) and nonionic (TX100) micelles and nonionic surfactants (Tween-80/PEG-6000) forming vesicles (niosome) on the photophysical and rotational dynamical properties of 1'-hydroxy-2'-acetonaphthone (HAN) have been studied using steady-state and time-resolved fluorescence spectroscopy. Enhanced fluorescence intensity with a significant blue shift and longer emission lifetime of the caged tautomers of HAN indicate modulation of photophysics of HAN upon encapsulation in both micellar assemblies and the niosome system. The binding constant and free energy change for the complexation of HAN with micelles and niosome demonstrate a comparative study on the binding efficiency of the different assemblies depending on the nature of microenvironments toward HAN. The enhancement in the steady-state anisotropy in niosome solutions compared with that in pure aqueous solution indicates that HAN is located inside the motionally restricted bilayer region of niosome. The fluorescence quenching experiment further reveals the probable location of HAN in micelles and niosome. In TX100 micelles, the obtained lifetime values are 417 ps and 1.63 ns for the caged tautomers, whereas in the comparatively more rigid and confined environment provided by niosome those values are 444 ps and 2.5 ns. The rotational relaxation time constants for the caged tautomers in niosome are also found to be higher than those in micelles. The observed difference in binding ability of the different assemblies is due to the difference in the extent of water penetration and different extent of rigidity around the fluorophore.

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Section: Introductionsupporting

confidence: 89%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Photophysics and Photodynamics of 1′-Hydroxy-2′-acetonaphthone (HAN) in Micelles and Nonionic Surfactants Forming Vesicles: A Comparative Study of Different Microenvironments of Surfactant Assemblies

et al. 2011

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“…Micellar systems also offer convenient model systems for the investigation of the effects of the binding and the local microenvironment on the reactivity. For instance, the effects of the microenvironment on the excited-state acidity of a molecule − and on the excited-state electron transfer − has been studied in restricted systems. The difference in shifts of p K a found for positively charged and uncharged micelles indicates a difference of the interfacial potential between cationic and anionic micelles of about 100 mV .…”

Section: Introductionmentioning

confidence: 99%

Electron-Transfer Reactions in SDS Micelles: Reactivity of Pyrene and Tris(2,2‘-bipyridyl)ruthenium(II) Excited States Investigated by Time-Resolved Luminescence Quenching

et al. 1999

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The effects of micellization on the rate constants and Gibbs energy of electron transfer (ΔG et) are studied by time-resolved luminescence quenching of tris(2,2‘-bipyridyl)ruthenium(II) (RUBIPY) and pyrene (PY) by electron acceptors and donors in sodium dodecylsulfate (SDS) micelles. For RUBIPY, which is bound to the SDS micelles and accessible to water, ΔG et is considerably smaller than what is found in organic solutions, though the spectral properties of RUBIPY and the value of diffusion-controlled quenching rate constant are typical for the micellar interior. For this system, dissolution in micelles enables a change of the local reactant concentration and mobility, retaining their higher reactivity in aqueous solution. In contrast, for PY, which is known to be localized in the palisade layer of an SDS micelle, the quenching rate constants coincide well with those found in acetonitrile.

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Fluorescence in Organized Assemblies

Hinze¹

2000

Encyclopedia of Analytical Chemistry

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This article provides an overview of the general properties of organized assembly (ordered media) systems such as aqueous surfactant and bile salt micelles, lipid and surfactant vesicles (liposomes) and cyclodextrins (CDs) and summarizes their utilization to enhance the performance of analytical fluorescence measurements. In many instances, organic molecules and metal complex species, when included within a CD cavity or solubilized and bound to surfactant aggregates, exhibit enhanced fluorescence. This gives rise to improved detectability of such analytes. The altered microenvironment within the organized medium is capable of impeding the interfering action of other species (inorganic or organic) present in the sample matrix. This often can improve the selectivity of the analytical method. These benefits of improved sensitivity and selectivity arise from the compartmentalization, isolation and shielding of the excited singlet state of the guest analyte from quenching and nonradiative decay processes as well as prevent side reactions that otherwise can occur in bulk solution (or sample matrix). In addition, organic solvents or time‐consuming extraction steps can be avoided owing to the increased solubility of the nonpolar organic or inorganic reagents and/or analyte molecules in water in the presence of the organized medium; allowing for the use of an aqueous medium to perform the procedure. The possibility of conducting reactions and forming fluorescent organic or metal chelates in micellar (or other organized) media that are not observed in a bulk homogeneous solvent system serves to expand the scope of chemistries that one can consider using to design/develop new, unique and improved fluorescent assays. Numerous representative examples of fluorescent methods for determination of both organic and inorganic analytes are provided which serve to illustrate the advantages and benefits accrued from the use of the micelles, vesicles, liposomes or CDs in such procedures. Some experimental considerations and cautions to keep in mind when utilizing organized media are also delineated. An extensive reference section is provided so that the interested reader can easily refer to such for more detailed information on these systems and topics.

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Effects of surfactant charge and structure on excited-state protolytic dissociation of 1-naphthol in vesicles

Cited by 12 publications

References 20 publications

Photophysics and Photodynamics of 1′-Hydroxy-2′-acetonaphthone (HAN) in Micelles and Nonionic Surfactants Forming Vesicles: A Comparative Study of Different Microenvironments of Surfactant Assemblies

Photophysics and Photodynamics of 1′-Hydroxy-2′-acetonaphthone (HAN) in Micelles and Nonionic Surfactants Forming Vesicles: A Comparative Study of Different Microenvironments of Surfactant Assemblies

Electron-Transfer Reactions in SDS Micelles: Reactivity of Pyrene and Tris(2,2‘-bipyridyl)ruthenium(II) Excited States Investigated by Time-Resolved Luminescence Quenching

Fluorescence in Organized Assemblies

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