Excited State Processes in Surfactant Micelles

Khuanga, U; McDonald, Rod; Selinger, B. K.

doi:10.1524/zpch.1976.101.1-6.209

Cited by 26 publications

(3 citation statements)

References 12 publications

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“…It has been reported that T quenches only ROH*, from which RO"* is formed, and does not quench RO"* directly because of the repulsion between the like charges of the two ions. 35 In addition high concentrations of CT have been found36 to cause a decrease in the lifetime of the protonated form of 2-naphthamide in 8.8 X 10"2 M HC1 and C104" has been found34 to decrease significantly the fluorescence of the ROH* form of 2-naphthol. We conclude that CT quenches predominantly ROH* and that the quenching of RO"* shown in Figure 3 occurs indirectly via quenching of the initially excited ROH*.…”

Section: Resultsmentioning

confidence: 98%

Proton-induced fluorescence quenching of 2-naphthol

Harris¹,

Selinger²

1980

J. Phys. Chem.

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Section: Resultsmentioning

confidence: 98%

Proton-induced fluorescence quenching of 2-naphthol

Harris¹,

Selinger²

1980

J. Phys. Chem.

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“…Previous studies of the photophysics of 1 2-NpOH* have shown that the neutral form deprotonates, yielding the anionic naphthoate, which emits at λ max = 430 nm, while the neutral form fluoresces with λ max = 360 nm. The pH of the local environment around 2-NpOH determines the relative emission quantum yields 1 Kinetic Scheme Depicting the Proton Transfer Properties of 2-NpOH upon Excitation a a Note that the excited state K a 1* is much larger than the ground state K a . …”

Section: Introductionmentioning

confidence: 99%

“…The pH of the local environment around 2-NpOH determines the relative emission quantum yields. 22 Using Excited States to Investigate Dynamic Processes. Evaluation of dynamic processes can be furnished by using excited states, provided that the rate of the diffusive process being monitored is on the same order of magnitude as the rate of decay of the excited state.…”

Section: Introductionmentioning

confidence: 99%

Effect of Protonation and PAMAM Dendrimer Size on the Complexation and Dynamic Mobility of 2-Naphthol

et al. 2000

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noncovalently bound complex have been studied by fluorescence spectroscopy and laser flash photolysis. By varying the acidity and dendrimer size, polyamidoamine dendrimers are shown to possess both nonspecific and specific binding properties. For example, the studies show that 2-naphthol binds preferentially to the tertiary amine groups within the dendrimer interior and can be released by lowering the pH of the solution. On a per binding site basis, studies of the dynamics of 3 2-NpOH*@n-SBD reveal that the overall dynamics (entry and exit rate constants) are enhanced by increasing the acidity of the solution. Furthermore, the amount of protonation of tertiary amine groups within 2-SBD, 4-SBD, and 6-SBD was determined to be ∼12%, ∼10%, and <1%, respectively, at pH 6. The results presented here demonstrate that, in addition to being able to complex transition metals, organic molecules that are capable of hydrogen bonding to the internal amine moieties can also be bound to dendrimers.

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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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Excited State Processes in Surfactant Micelles

Cited by 26 publications

References 12 publications

Proton-induced fluorescence quenching of 2-naphthol

Proton-induced fluorescence quenching of 2-naphthol

Effect of Protonation and PAMAM Dendrimer Size on the Complexation and Dynamic Mobility of 2-Naphthol

Fluorescence in Organized Assemblies

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