Three-dye

Three dyes are triaryl- or triphenyhnethanes. Each, like FD C Blue No. 1, consists of three aromatic rings attached to a central carbon atom. AH are water-soluble, anionic, sulfonated compounds. FD C Blue No. 1 has the stmcture (1) shown in Figure 1. 

Image Formation and Stabilization. The sequence of reactions responsible for image formation and stabilization begins as alkaU in the reagent permeates the layers of the negative, ionizing each of the three dye developers (eq. 8) and the auxiUary developer (eq. 9), which may be present in one or more layers of the negative. 

The tolerance to high pHs is important in particular for industrial processes using reactive azo dyes, which are usually performed under alkaline conditions. A strain of C. bifermentans selected from a contaminated soil was tested for the ability to decolorize Reactive Red 3B-A at pHs from 5 to 12 while no decolorization was observed at pH 5, the dye was nearly completely decolorized across a broad range of pH values (6-12) after 48 h of incubation in this study a previous analysis of UV/Vis spectra of Reactive Red 3B-A, Reactive Black 5, and Reactive Yellow 3G-P after 0, 12, 24, and 36 h incubation was carried out, showing different decolorization rates for the three dyes, with no change in color content in the abiotic control [5]. 

An aqueous dispersion of a disperse dye contains an equilibrium distribution of solid dye particles of various sizes. Dyeing takes place from a saturated solution, which is maintained in this state by the presence of undissolved particles of dye. As dyeing proceeds, the smallest insoluble particles dissolve at a rate appropriate to maintain this saturated solution. Only the smallest moieties present, single molecules and dimers, are capable of becoming absorbed by cellulose acetate or polyester fibres. A recent study of three representative Cl Disperse dyes, namely the nitrodiphenylamine Yellow 42 (3.49), the monoazo Red 118 (3.50) and the anthraquinone Violet 26 (3.51), demonstrated that aggregation of dye molecules dissolved in aqueous surfactant solutions does not proceed beyond dimerisation. The proportion present as dimers reached a maximum at a surfactant dye molar ratio of 2 5 for all three dyes, implying the formation of mixed dye-surfactant micelles [52]. 

We reported the preparation of sophisticated bipolar three-dye photonic antenna materials for light harvesting and transport [22]. The principle is illustrated in Figure 1.12. Zeolite L microcrystals of cylinder morphology are used as host for organizing several thousand dyes as monomers into well-defined zones. 

Figure 1.12. Principle of a bipolar three-dye photonic antenna. A crystal is loaded with a blue, a green, and a red emitting dye. After selective excitation of the blue dye in the middle, energy transfer takes place to both ends of the crystal where the red dye fluoresces. (See insert for color representation.)...

Figure 1.18 shows fluorescence microscopy images of a bipolar three-dye antenna material with POPOP in the middle, followed by Py+ and then by Ox+. The different color regions that can be observed in this simple experiment are impressive. The red color of the luminescence (1) disappears, when the crystal is observed trough a polarizer parallel to the crystal axis while the blue emission disappears when turning the polarizer by 90°. This material is very stable and is easy to handle. 

Fig. 3.87. Chromatograms of the batch solutions before (dotted lines) and after hydrolysis (continuous lines) of three dyes on a diamond electrode. Hexane extract of SLB (org.) and aqueous extract of SLY (aq.) (right axis). Column Octyl, flow rate 0.8 ml/min, temperature 29°C, detection wavelength 220 nm, mobile phase aqueous phosphate buffer (pH 5)-methanol (50 50, v/v) (SLY, SNO) and linear gradient methanol-water (40 60, v/v) to 50 50 (SLB). Reprinted with permission from M. M. Davila et al. [149].

A similar experiment and numerical analysis was performed by positioning three dye drops in the same position and then rotating the helix and keeping the core stationary. The measured RTD and numerical simulation are shown in Fig. 8.f0. As shown by this figure, the three drops were better mixed than in extrusion mode, but the mixing was still poor as indicated by the magnitude of the first concentration peak. The long concentration tail was caused by the dye near the walls of the screw. 

Figure 28 Tandem solar cell where monodirectional antenna systems with three dyes are put between two w-type semiconductors with different hand gaps.

Remarkable tuning of reaction rates has been achieved for the isomerization of several dye molecules in supercritical fluid solvents using both small pressure changes and small additions of cosolvents. Rates of the thermal cis-trans relaxation were measured spectroscopically following irradiation for three dyes in supercritical carbon dioxide and ethane, pure and with several polar and protic cosolvents. These results demonstrate the versatility of supercritical fluid solvents, both to examine reaction mechanisms and as a means to tune rates (DiUow et al., 1998). 

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