Dye coumarine

An important advance with regard to light stabiUty was made with a group of yellow coumarin dyes with heterocycHc systems attached to the coumarin nucleus (4), eg, a greenish yellow cationic dye that is sold under the name Maxilon Brilliant Flavine 10 GFF [12221 -86-2] (Blue Wool 4), designated Cl Basic Yellow 40, available from several manufacturers. 

Overall, the significant Stokes shift of 100 nm and the good quantum yields make the coumarin dye a powerful fluorescent probe for nucleic acids assays or cell biology. The postsynthetic click chemistry makes this fluorophore readily accessible for fluorescent labeling of nucleic acids. 

In the emission spectra of coumarins 9a, 10a, 10c, and 9d in BSA/SDS mixture, the most pronounced bands revealed similar wavelengths to those in the presence of BSA. Observed Stokes shifts values for dyes 9a-d and lOa-d occurred between 8 and 102 nm. The fluorescence increase of the dye upon BSA/SDS addition varied from 2.5 times (9b) to 330 times (lOd), while the brightest complex resulted from dye 10a, its quantum yield being about 0.27. Despite the observed emission enhancement value, the fluorescence intensity of other coumarin dyes in the presence of BSA/SDS mixture was only low to moderate. 

Moylan CR (1994) Molecular hyperpolarizabilities of coumarin dyes. J Phys Chem 98 ... 

The introduction of FRET pairs with improved properties allows the generation of probes suitable for the measurement of spatio-temporal activities in living cells and in vivo. One example is the imaging of caspase-3 activation in HeLa cells after inducing apoptosis. Previous fluorogenic substrates, such as DEVD-MCA, could not be used in living cells because the autofluorescence interfered with the low emission wavelength of the coumarin dye MCA [123], With the incorporation of the FRET pair 6-carboxydichlorofluorescein and 5-carboxytetramethylrhodamine into another peptide sequence cleavable by caspase-3, Mizukami et al. measured caspase-3-like activity in HeLa cells stimulated by an inducer of apoptosis [124],... 

Fig. 5.6. Multiple filamentation in a 5 cm long glass cell containing coumarin dye in ethanol. Control over filamentation was obtained by means of a wire mesh (see text)...

SCHEME 3.40 Chemical structures of green dopants of Coumarin dyes. 

The sensing of fluoride with a reaction-based indicator can be based on its unique reactivity with silicon. As shown in Fig. 20, the O-Si bond cleavage with fluoride can be used to produce the coumarin dye 53. For this system, a 100-fold sensitivity increase was seen after incorporation of the reaction scheme into a conjugated polymer [143]. 

Figure 16 Photocurrent-voltage curve obtained for a nanocrystalline Ti02 solar cell sensitized by coumarin dye.

Molecular Dynamics study of the time-dependent fluorescence of coumarin 153 (C153 - see Fig. 1) in benzene-acetonitrile and benzene-methanol mixtures. The solvation dynamics in benzene-acetonitrile mixtures will be analyzed by inspection of the time-dependent local populations of the two constituents around the coumarin dye. 

Stepwise electron injection in the dye-sensitized nanocrystalline films of ZnO and Ti02 with novel coumarin dye... 

Both experiments and theory show that solvation may proceed exceedingly rapidly. Figure 2 shows the fluorescence Stokes shift function S(f) for a coumarin dye in water obtained by experiment and simulation [4]. Here, S(t) is a normalized function describing the progress toward equilibrium ... 

Hie dye-doped ORMOSIL materials exhibit much higher photostability than the reported polymer-doped materials. For example, optical gain was reported for several coumarin dyes in PMMA (13), It is significant to note that the best dyes reported could only be used to several hundred pulses and that most of the coumarin dyes could not even oscillate for 100 pulses. The ORMOSIL gels thus represent an improvement of at least 1-2 orders of magnitude in photostability. Optical gain was also reported for R6G doped into modified poly(methyl methacrylate) (14L These materials exhibited loss of 20% output after 180 pump pulses (1 J/cm ) at 532 nm. The reported plots indicate that these materials would have dropped by 90% after 275-300 pulses due to rapid steady state photodegradation once the pulse count exceeded the critical pulse number. In this case the R6G doped ORMOSIL gel laser offers a useful lifetime improvement by a factor of more than 15 over the reported polymer material. 

Figure 7.20 Chromatogram of the separation of coumarin dyes (C440, C450, and C460) [48],...

The main advantages of dye lasers are spectrum coverage (from less than 400 to 1000 nm) and tunability. In general, the laser dyes used nowadays have changed little from those used a decade ago [3]. Coumarins such as (73) and xanthenes such as Rhodamine 6G (74), are the main types. However, fluorinated coumarin dyes such as (75) have higher light stability than their nonfluorinated counterparts [39],... 

Another format of chromatography which has been performed on electrophoresis chips is micellar electrokinetic capillary chromatography (MECC). This technique represents a very powerful extension of CE for the separation of both neutral species and ionic compounds, and has been originally developed by Terabe et al. [76]. Transfer of MECC to CE microchips has been first demonstrated by Moore et al. [77]. The experimental procedure used is identical to high speed CE, apart from the fact that a MECC buffer with 50 mM SDS and 10% methanol was used. Again three coumarin dyes were used as a model sample. Separation was achieved within a few minutes. At low applied field strengths (< 400 V/cm), the reproducibility was found to be excellent (below 1 %). 

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