Fluorescence quenching of naphthalene

ABSTRACT. The fluorescence quenching of naphthalene, 1-methylnaph-thalene, and acenaphthene by trimethylamine (TMA) was studied in aqueous 3-cyclodextrin (3-CD) solutions to know the structural requirements for guest molecules to form three-component complexes. The apparent rates for the fluorescence quenching of the naphthalene derivatives by TMA markedly increased in the presence of3-CD. The fluorescence quenching of 1-methylnaphthalene and acenaphthene by TMA was accelerated by 3-CD more efficently than that of naphthalene. These results suggest the structures of the three-component complexes as the arene-capped 3-CD including TMA in its cavity. 

The fluorescence quenching can be regarded as a probe reaction for investigating the effects of CD on bimolecular reactions. Especially, the structural requirements for guest molecules to form three-component complex can be studied by this method. Formation of three-component complexes is essentially important to realize CD-catalyzed bimolecular reactions. In the present work, we studied the fluorescence quenching of naphthalene, 1-methylnaphthalene, and acenaphthene by TMA in aqueous 3-CD solutions to clarify the steric factors affecting the formation of the three-component complexes. 

Then we reexamined the fluorescence quenching of naphthalene the 1 X 10 M 6-CD solution. Although the reproducibility... 

A singlet naphthalene or a singlet exciplex is thought to be the reactive species in this reaction since the quantum yield of cycloaddition parallels the quenching of naphthalene fluorescence by acrylonitrile. 

Photo-oxidation of protoporphyrin IX and its dimethyl ester Norrish type II reaction of amphiphilic ketoacid Quenching of naphthalene fluorescence by Ni2 +... 

When considering the rates of chemical processes in polymers which require diffusion of reagents and products, it is necessary to estimate the internal viscosity q. to substitute in expressions such as Equations 6 and 7. We ave made estimates for q in solid polyethylene from luminescence quenching of naphthalene fluorescence in ethylene -OO copolymers [24]. (Table VII)... 

Roek, D.P. Chateauneuf, J.E. Brennecke, J.F. A fluorescence lifetime and integral equation study of the quenching of naphthalene fluorescenceby bromoethane in super-and subcritical ethane. Ind. Eng. Chem. Res. 2000, 39, 3090. 

The fluorescence quenching of 1-methoxynaphthalene by strong acids is attributed to the attack of H3O on the 5 position of the naphthalene ring. The quenching was reduced about one order of magnitude by the presence of 2 X 10" M -CD owing to the inclusion of the aromatic ring in the CD cavity [172]. 

Triplet energy migration can be probed by addition of free quenchers to the polymer, and observing which kinetics, Stern-Volmer or Perrin (see Section II above), pertain. In the case of the quenching of naphthalene phosphorescence or delayed fluorescence in a variety of co-polymers by the dloleflns plperylene and cycloocta-1,3-diene at low temperature where material diffusion... 

The fluorescence intensity of naphthalene in aqueous solution decreases upon aeration. However, the quenching of naphthalene by aeration is totally suppressed in the presence of a water-soluble sulfopropylated fi-CD [70]. Similarly, the quenching of halonaphthalene phosphorescence in water by NaN02 can be substantially inhibited by j8-CD. The rate of inhibition depends on the bond-tightness between the analyte and the CD. Retinal, which is normally insoluble in water and is not fluorescent in solution at room temperature, emits luminescence in the region of 450 nm and permits fluorescence detection when incorporated by j8- or y-CD even in air-saturated aqueous solution [71]. In the luminescence detection of volatile compounds, CDs can be used as solid matrices which efficiently trap the volatile compounds for obtaining room temperature... 

In order to develop catalytic effects of cyclodextrins for bimolecular reactions, it needs to include two guest molecules simultaneously in a cyclodextrin (CD) cavity. Several examples of cyclodextrin-catalyzed bimolecular reactions have been reported. Rideout and Breslow have found that Diels-Alder reactions of cyclo-pentadiene with butenone, cyclopentadiene with acrylonitrile, and anthracene-9-carbinol with N-ethylmaleimide in water are markedly accelerated by 3-cyclodextrin (3-CD) (1). Komiyama and Hirai have reported site-selective Reimer-Tiemann reactions of phenols in cyclodextrin solutions (2). In most of these reactions, however, each substrate molecule is relatively small so that a 3-CD cavity may include simultaneously an additional reactant molecules. We found previously that the fluorescence quenching of pyrene and naphthalene by trimethylamine (TMA) or dimethylamine (DMA) in water is catalyzed by g-CD (3) Since the pyrene molecule is too large to be incorporated completely in the 3-CD cavity, it has been assumed that pyrene binds to a rim of the CD cavity to form a pyrene-capped CD complex and a remain-... 

The fluorescence quenching experiments were carried out according to the following procedures. The stock solution of naphthalene derivative in methanol (1 x 10 M) was injected to the 1 x 10 M aqueous 3-CD solution to adjust [naphthalene derivative] = 1 x 10 M. An appropriate amount of TMA was added and the sample solution was shaken gently before fluorescence spectral measurement. Since the fluorescence intensities of naphthalene derivatives gradually decreased upon aging and no reproducible result was obtained, the fluorescence spectrum of each solution was measured immediately after the preparation of sample by using a Hitachi 650-60 spectrofluorimeter. The... 

A. Meanwhile, 1-methylnaphthalene has a size of 8.5 A x 7.6 A and may bind shallowly to 3-CD. Acenaphthene will bind more shallowly than 1-methylnaphthalene. We studied how the difference in the structures between these naphthalene derivatives affects the fluorescence quenching of these fluorescers by TMA in 3-CD solutions. 

The fluorescence quenching of the naphthalene derivatives by TMA in water was markedly accelerated by 3-CD (Table I). The effect of 3-... 

Proteases are enzymes that break peptide bonds in proteins. As such they lend themselves to a variety of homogeneous assay techniques. Most employ labeling both ends of the substrate with a different tag, and looking for the appearance (disappearance) of the signal generated in the intact substrate (product). As an example, for a fluorescence quench assay, the N-terminal of a peptide is labeled with DNP and the C-terminal with MCA. As such, the peptide is fluorescently silent since the fluorescence from DNP is quenched by absorption by the MCA. Another very popular donor/acceptor pair is EDANS 5-[(2-aminoethyl)amino] naphthalene-1-sulfonic acid and DABCYL 4-(4-dimethylaminophenylazo)benzoic acid) (a sulfonyl derivative (DABSYL) [27], Upon peptide cleavage, the two products diffuse, and due to a lack of proximity, the fluorescence increases. 

A recent study of Murov and co-workers<106) indicates that the activation energies for isomerization are not the controlling factors. Thus the fluorescence of naphthalene is quenched (5 x 108M-1sec-1) by cis-trans-1,3-cyclooctadiene with isomerization to form cis-cis-1,3-cyclooctadiene. However, the compound bicyclo[4,2.0]oct-7-ene is not formed despite the low activation energy for this process ... 

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