Tertiary fluorescence

FIGURE 6.28 Effects in a sample irradiated with x-rays. The characteristic (fluorescence) emission is the desired analytical effect that needs to be separated from the other secondary emissions. The primary x-ray beam scatters coherently (without loss in energy) and incoherently (losing energy) and is recorded to a small amount in the detector. The characteristic fluorescence beam not only undergoes absorption by other metals in the sample but may also be excited by secondary or tertiary fluorescence from other elements. 

Tertiary fluorescence or third-element effects are occasionally significant when secondary fluorescence effects are extended to a third element. 

Ecole Nationale Superieure du Petrole et des Moteurs Formation Industrie end point (or FBP - final boiling point) electrostatic precipitation ethyl tertiary butyl ether European Union extra-urban driving cycle volume fraction distilled at 70-100-180-210°C Fachausschuss Mineralol-und-Brennstoff-Normung fluid catalytic cracking Food and Drug Administration front end octane number fluorescent indicator adsorption flame ionization detector... 

Principal component analysis has been used in combination with spectroscopy in other types of multicomponent analyses. For example, compatible and incompatible blends of polyphenzlene oxides and polystyrene were distinguished using Fourier-transform-infrared spectra (59). Raman spectra of sulfuric acid/water mixtures were used in conjunction with principal component analysis to identify different ions, compositions, and hydrates (60). The identity and number of species present in binary and tertiary mixtures of polycycHc aromatic hydrocarbons were deterrnined using fluorescence spectra (61). 

This order agrees with that of quenching constant (Aqr) vaiues of the fluorescence of amines by AN. That is, the easier the reaction between an excited aromatic tertiary amine and the ground state AN, the faster the initiation. 

Kurian, E., Fisher, P. J., Ward, W. W., and Prendergast, F. G. (1994). Characterization of secondary and tertiary structure of the green fluorescent protein from A. victoria. J. Biolumin. Chemilumin. 9 333. 

In 159 and 163-166 the tertiary amine function is coordinated to the boron atom and transmits the electronic change due to the ester formation to the chromophore. In 160-162 the boron atom is directly connected to the chromophore. After the complexation of the saccharide, the change of the charge transfer, e.g., for 159 [249-251], or the fluorescence bands, e.g., for 160-166 [252-255], can be measured and interpreted. The most selective binding of n-glucose has been achieved with host 164 that forms a 1 1 complex with a macrocyclic structure (Scheme 1). 

The blue derivatives formed with the reagent by alkaloids remain stable for at least one day and usually much longer (cover the chromatogram with a glass plate) [2, 6, 7]. The shade of color produced can be affected by fluorescence indicators incorporated in the silica gel layer [7]. Tertiary amine alkaloids do not react at room temperature with the acetaldehyde-containing reagent [2]. 

Amino acid sequences of eleven homologous sea anemone polypeptides have been elucidated. All possess three disulfide bonds. The six half-cysteine residues always occur in the same positions (7,8). Initial studies concerning the toxin secondary and tertiary structures relied upon circular dichroism, laser Raman, and, to a lesser extent, fluorescence spectral measurements (15—18). The circular dichroism spectra of the four toxins so far examined are essentially superimpos-able and thus indicate a common secondary structure. The only peak observed, a negative ellipticity at 203 nm, largely results from a non-regular ("random")... 

Dendritic hosts can be used in aqueous solution to encapsulate water-soluble fluorescent probes. Changes in the photophysical properties of these encapsulated probes are useful to understand the properties of the microenvironment created by the dendritic interior. For example, adamantyl-terminated poly(pro-pylene amine) dendrimers from the first to the fifth generation (36 represents the third generation) can be dissolved in water at pH<7 in the presence of -cyclodextrin because of encapsulation of the hydrophobic adamantyl residue inside the /1-cyclodextrin cavity and the presence of protonated tertiary amine units inside the dendrimer [72]. Under these experimental conditions, 8-anifi-... 

X-ray fluorescence spectra of tertiary phosphines (52 Ar = Ph, Y = alkyl) indicated that when the PY2 group is in the best geometry for p-it conjugation the interaction is still only 25% of that of the dimethylamino group.131... 

Determination of protein secondary structure has long been a major application of optical spectroscopic studies of biopolymers (Fasman, 1996 Havel, 1996 Mantsch and Chapman, 1996). These efforts have primarily sought to determine the average fractional amount of overall secondary structure, typically represented as helix and sheet contributions, which comprise the extended, coherent structural elements in well-structured proteins. In some cases further interpretations in terms of turns and specific helix and sheet segment types have developed. Only more limited applications of optical spectra to determination of tertiary structure have appeared, and these normally have used fluorescence or near-UV electronic circular dichroism (ECD) of aromatic residues to sense a change in the fold (Haas, 1995 Woody and Dunker, 1996). 

Refaat et al. [24] used a spectrophotometric method for the determination of primaquine, and 16 other tertiary amine drugs, in bulk or in pharmaceuticals. The method involved the condensation of malonic acid with acetic anhydride in the presence of a tertiary amine in an aliphatic or a heterocyclic system. The condensation product is highly fluorescent and allows the spectrofluorimetric determination of the drug in the ng/mL ranges (Xcx = 415 nm and >.em = 455 nm). 

Bigelow, D.J., and Inesi, G. (1991) Frequency-domain fluorescence spectroscopy resolves the location of maleimide-directed spectroscopic probes within the tertiary structure of the Ca-ATPase of sarcoplasmic reticulum. Biochemistry 30, 2113-2125. 

The second chromophore involves another a,g-unsaturated ketone that is in conjugation with an anomalously behaving amide (7). The tertiary amine is responsible for the basic character and the phenolic group is acidic. CTC is fluorescent and can be assayed polarographically (8). 

Other limitations involve both the mass absorption coefficient of soil components and secondary and tertiary excitation. The mass absorption coefficient can be calculated and used to correct fluorescence determinations if the exact composition of the material being analyzed is known. This is not possible in soil. Secondary and tertiary excitations occur when X-rays emitted by an element other than the one of interest may cause emission or fluorescence of the element of interest. These potential sources of error are possible in any soil analysis using XRF. 

No fluorescence is observed at room temperature from TIN in non-polar solvents such as cyclohexane. In these solvents only the intramolecularly hydrogen-bonded form, which can undergo rapid ESIPT upon excitation, is present. The t-Bu-STIN derivative (see Table II) is very weakly fluorescent in all of the solvents examined. This is attributable to the protection of the intramolecular hydrogen bond from the solvent by the tertiary butyl group which is adjacent to the labile proton. 

A distinct advantage of PET sensors is the very large change in fluorescence intensity usually observed upon cation binding, so that the expressions off-on and on-off fluorescent sensors are often used. Another characteristic is the absence of shift of the fluorescence or excitation spectra, which precludes the possibility of intensity-ratio measurements at two wavelengths. Furthermore, PET often arises from a tertiary amine whose pH sensitivity may affect the response to cations. 

Photoinduced intramolecular interaction of t-S and tertiary amine moieties linked with a polymethylene chain has also been studied24. The photoexcitation of fraws-stilbene in which a tertiary amine is attached to the ortho position with a (CH2)i-3 linker leads to fluorescent exciplexes by intramolecular electron transfer, and results in no more than trans-cis isomerization. The failure to give adducts from the intramolecular exciplexes could arise from the unfavourable exciplex geometry to undergo the necessary bond formation. 

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