With Pyronine

Sulphite and sulphur dioxide can be determined from the changes in colour, produced by their reducing effect on iron(III) in the presence of 1,10-phenanthroline [61,62], TPTZ [63], or ferrozine [64] (for formulae see Ch. 26). Sulphite may also be determined indirectly with Hg(II) chloranilate [59] or thiocyanate [65]. Other reagents for sulphite include 2,6-dichlorophenolindophenol [7] and 5,5 -dithio-bis(2-nitrobenzoic acid) [66-68]. Reaction of SO2 with IOb in the presence of excess of chloride yields ICU", which forms an ion-pair with Pyronine G [69]. 

Table I shows the standard oxidation potentials and other related thermodynamic quantities along with the free energies of activation for reactions with pyronin cation in aqueous solution for all nucleophiles for which we have data. Most of the data were reported previously (3), but several errors in...

Table I. Oxidation Potentials and Reactivities with Pyronin Cation in Water...

The other trends in values for the various Rs in Table V are consistent with the trends in pairwise interaction contributions to heats of formation evaluated by Allen (19) and discussed by Hine (20). For example, pyronin has a C-C-X pair interaction in place of an O-C-X interaction for pyridine-4-carboxaldehyde for X = OH this difference favors the aldehyde adduct by approximately 7 kcal, although for other Xs, the difference is somewhat smaller. Thus, the values given for the aldehyde are smaller than those for pyronin. We have already pointed out that steric effects are expected in the triarylmethyl derivatives and that the comparison of these with pyronin derivatives are consistent with that expectation (1). 

At this time, remarkable studies of Brachet [54, 55] proved that ribonucleic acid is present also in animal cells. He stained the preparations with pyronine and methyl green, and by comparing the staining properties of the cells before and after treating the preparation with ribonuclease, Brachet conclusively demonstrated the presence of ribonucleic acid in all cells investigated. 

Mikaelyan, D. A. Artsmni, V. Zh. Khachatryan, A. G. Extraction-fluorometric determination of thallium traces with pyronin B. J. Anal Ghem. 1995,50, 149. 

Wei, Q. Zhang, H. Duan, C. Li, Y Du, B. High sensitive fluorophotometric determination of nucleic acids with pyronine G sensitized by NJ4-dimethylformamide. Ann. Chim. 2006, 96, 273-284. 

Feng, S. Pan, Z. Fan, J. Determination of trace proteins with pyronine Y and SDS by resonance light scattering. Anal. Bioanal. Chem. 2005, 383, 255-260. 

For uniformity with the stmctures given in the Colourindex the ammonium radical (9) is used for the amino-substituted xanthenes and the keto form for the hydroxy derivatives. The xanthene dyes may be classified into two main groups diphenylmethane derivatives, called pyronines, and triphenylmethane derivatives (eg, (4)), which are mainly phthaleins made from phthaUc anhydride condensations. A third much smaller group of rosamines (9-phenylxanthenes) is prepared from substituted ben2aldehydes. The phthaleins may be further subdivided into the following fluoresceins (hydroxy-substituted) rhodamines (amino-substituted), eg, (6) and mixed hydroxy/amino-substituted. 

Pyronines. Pyronines are diphenylmethane derivatives synthesized by the condensation of y -dialkylarninophenols with formaldehyde, followed by oxidation of tiie xantiiene detivative (12) to the coiiesponding xanthydiol (13) which in the presence of acid forms the dye (14). If R is methyl, the dye produced is... 

Pyronin Y [3,6-bis(dimethylamino)xanthylium chloride] [92-32-0] M 302.8, m 250-260, Cl 45005, Xmax 522nm, pKesi Commercial material contained a large quantity of zinc. Purified by dissolving Ig in 50mL of hot water containing 5g NaEDTA. Cooled to 0, filtered, evapd to dryness and the residue extracted with EtOH. The soln was evaporated to 5-lOmL, filtered, and the dye pptd by addition of excess dry diethyl ether. It was centrifuged and the crystals were washed with dry ether. The procedure was repeated, then the product was dissolved in CHCI3, filtered and evapd. The dye was stored in a vacuum. 

This technique was employed to study the binding dynamics of Pyronine Y (31) and B (32) with /)-CD/ s The theoretical background for this particular system has been discussed with the description of the technique above. Separate analysis of the individual correlation curves obtained was difficult since the diffusion time for the complex could not be determined directly because, even at the highest concentration of CD employed, about 20% of the guest molecules were still free in solution. The curves were therefore analyzed using global analysis to obtain the dissociation rate constant for the 1 1 complex (Table 12). The association rate constant was then calculated from the definition of the equilibrium constant. 

The microsomal fraction was first obtained by Claude in 1943. In addition to lipid in the fraction, he noted the presence of RNA-rich granules, consistent with reports from Brachet that cytoplasm stained for RNA by the methyl-green/pyronin procedure. Glucose-6-phos-phatase was a prominent enzyme when the fraction was prepared from liver. Since density gradient sedimentation showed G-6-P-ase was absent from mitochondria and lysosomes, it was used as a marker for liver microsomes. 

Pyronine Y (PY) with beta cyclodextrin by using the temperature-jump technique. It was found that the kinetic data could be adequately explained by a mechanism involving the stepwise association of two beta cyclodextrin molecules (C) to the dye. Thus,... 

From the value of the CEC, the interlamellar surface area per cation equivalent could be calculated to be ca 91.7 A. With the assumption that the cross section of the dye molecule was a square, the approximate areas were estimated to be ca 90 A for pyronine and ca 180 A for rhodamine. In this... 

Other dyes for cathodic (acidic) electrophoresis systems are Pyronin Y, 1-napthyl red and methyl red, the latter only for systems with pH helow 3. 

Diaryl- and triaryl-methane dyes also fall into this class [(124) is known as Michler s Hydrol Blue] and a number of the heterocyclic derivatives of these dyes are well known. Introduction of a sulfur bridge into Michler s Hydrol Blue (124) results in the dye Thiopyronine (125) which absorbs at 565 nm. The analogous dye with an oxygen bridge, Pyronine, absorbs at 545 nm and that with an —NH— bridge, Acridine Orange, absorbs at 490 nm (B-76MI11201). 

The extent of this failure is evident from comparisons of experimental measurements of rate and equilibrium constants. One comparison in the literature is provided by Ritchie and coworkers study of the relatively stable cation, pyronin (the 3,6-bis(dimethylamino)xanthylium cation 71) with a series of nucleophiles.252 Another example is McClelland s measurements of rate and equilibrium constants for the reactions of halide and acetate ions with the trityl cation.19 As already mentioned fluoride and acetate are less reactive than bromide and chloride despite their equilibrium affinities being much greater. This is reflected indeed in the much lower rates of solvolysis of the fluoride and acetate than bromide or chloride as leaving groups... 

Common chromogen systems currently in use include diaminobenzidine (DAB), 3-amino-9-ethyl-carbazole (AEC), Hanker-Yates reagent, alpha-naphthol pyronin used with peroxidase as substrate fast blue, fast red, BCIP- (5-bromo-4-chloro-3-indolyl phosphate) NBT (nitroblue tetrazolium) used with alkaline phosphatase as substrate tetrazolium, tetranitroblue tetrazolium used with glucose oxidase as substrate, and immunogold with silver enhancement (Leong, 1993 Leong et al, 1997a). 

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