Neutral Blue

The product of the interaction of nitrosodimethylaniline and phenyl- 8-naphthylamine is a bluish-violet dyestuff, probably a dimethyl derivative of the former [52] Neutral Blue. 

Nitrosodimethylaniline reacts with paratoluyl-/3-naphthylamine also, and produces a bluish-violet dyestuff of the composition 

From the salts, a red base may be separated, which dissolves in alcohol with an orange-yellow fluorescence. 

The compound dissolves in concentrated sulphuric acid with a red-violet colour, which on dilution changes through green and blue to violet. The nitrate is very sparingly soluble [52]. 

This compound is formed by continued boiling of phenosaffra-nine with baryta water, or alcoholic potash solution. It may be regarded as phenosaffraniue in which both amido-groups are replaced by hydroxyl. The compound agrees with this assumption inasmuch as it possesses simultaneously acid and weak basic properties. 

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Each of the forms of ETF isolated from the different sources contain FAD as coenzyme and form an anionic semiquinone on one-electron reduction. Stopped-flow kinetic studies on the pig liver ETF showed the anionic flavin semiquinone to be formed at times faster than catalytic turnover and thus demonstrate the participation of the anionic FAD semiquinone as an intermediate in the acceptance of reducing equivalents from the dehydrogenase. These studies would also imply the intermediacy of the semiquinone form of the acyl CoA dehydrogenase which would have been expected to form a neutral flavin semiquinone at the time the studies of Hall and Lambeth were performed, however, no spectral evidence for its formation were found. Recent studies have shown that the binding of CoA analogs to the dehydrogenase results in the perturbation of the pKa of the FAD semiquinone such that an anionic (red) rather than the neutral (blue) semiquinone is formed. This perturbation was estimated to reduce the pKa by at least 2.5 units to a value of... 

Methylene blue, new methylene blue, thionine blue, Capri blue, cresyl blue, brilliant cresyl blue, Nile blue, Basle blue, Mel-dola s blue, fast navy blue, new blue, metamine blue, naphthol u, blue, metaphenylene blue, paraphenylene blue, mdamine blue, indazine, neutral blue, muscanne, diphene blue, rhoduline blue, rhoduline sky blue frl ... 

Live, Brown Neutral, Blue Earth, Green/yellow. 

Fig. 1.2. COSMO surface polarity of nitrobenzene, 4-amino-nitroben-zene, and p-dinitrobenzene (red = negative, green = neutral, blue = positive polarity). Due to intramolecular electron redistributions the oxygen atoms of the nitro group are much more polarized in 4-amino-nitrobenzene, and much less polarized in p-dinitrobenzene.

Fig. 25 Comparison of the predicted hydrophobicity of a laulimalide b epothilone B c pacli-taxel. Structures a and b correspond to a common solution conformation for the two macrolides. Solvent accessible surfaces are colored according to the degree of hydrophobicity brown hydro-phobic, green neutral, blue hydrophilic, d Laulimalide binding site on (1-tubulin- after (3—H9 movement described in text. The view is from the outside of the microtubule. The paclitaxel (PTX) site is labeled too, but it is accessed from the lumen...

Most reductases and dehydrogenases form neutral (blue) semi-quinones while most oxidases form anionic (red) semiquinones upon reduction by dithionite or anaerobic photoirradiation in the presence of EDTA (I). 

Fio. 3. (a) Typical neutral (blue) flavin semiquinone produced upon anaerobic... 

CARBOWHITE CEC is an optical brightener with a neutral/blue cast for cellulosic fibers, nylon, and blends of these fibers. CARBOWHITE CEC has very good leveling properties. Because of its low substantivity, the product is very well suited for continuous processes. 

OBA for cellulosics and nylon. Recommended for continuous application. Offers good leveling. Neutral/blue cast. 

The redox states of the flavin cofactor in a purified flavoenzyme can be conveniently studied by optical spectroscopy (see also Elavoprotein Protocols article). Oxidized (yellow) flavin has characteristic absorption maxima around 375 and 450 nm (Fig. lb and Ic). The anionic (red) and neutral (blue) semiquinone show typical absorption maxima around 370 nm and 580 nm, respectively (Fig. lb and Ic). During two-electron reduction to the (anionic) hydroquinone state, the flavin turns pale, and the absorption at 450 nm almost completely disappears (Fig. lb and Ic). The optical properties of the flavin can be influenced through the binding of ligands (substrates, coenzymes, inhibitors) or the interaction with certain amino acid residues. In many cases, these interactions result in so-called charge-transfer complexes that give the protein a peculiar color. 

NEUTRAL BLUE-SHIFTING AND BLUE-SHIFTED HYDROGEN BONDS ... 

Neutral Blue-shifting and Blue-shifted Hydrogen Bonds... 

Table 6. The selected neutral blue-shifted hydrogen bonds. For the notations see the legend to Table 3...

Scheme 34. Mechanism for pyrimidine dimer cleavage by blue photolyase and fully reduced enzyme (163). FIH-, FAD neutral blue radical FIH2, FADH2 SC, second chromophore , excited state due to absorption of light +, radical cation radical anion fT, pyrimidine dimer 2T, repaired pyrimidine monomers.

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