Rhodamine composites

The ion- exchange properties of the composite films were studied by spectrophotometric and voltammetric methods using soi ption of Fe(Phen) + and rhodamine 6G for PVSA-SG or PSS-SG films and methyl orange or lumogallion (LG) for PDMDA-SG films. Tween-20 at its cmc and higher level was shown to be better stmcture directed additive than Triton X-100. 

SG sols were synthesized by hydrolysis of tetraethyloxysilane in the presence of polyelectrolyte and surfactant. Poly (vinylsulfonic acid) (PVSA) or poly (styrenesulfonic acid) (PSSA) were used as cation exchangers, Tween-20 or Triton X-100 were used as non- ionic surfactants. Obtained sol was dropped onto the surface of glass slide and dried over night. Template extraction from the composite film was performed in water- ethanol medium. The ion-exchange properties of the films were studied spectrophotometrically using adsorption of cationic dye Rhodamine 6G or Fe(Phen) and potentiometrically by sorption of protons. 

Signals for methyl paraben were monitored with UV detection at 254 nm. The signal for rhodamine 110 chloride was monitored via fluorescence detection with an excitation filter of 482 nm (35 nm bandwidth) and emission filter of 535 nm (40 nm bandwidth). A gradient method (same as the one in Figure 6.16) was used. The compositions of mobile phases A and B were 5 95 H20 CH3CN with 0.1 HCOOH and CH3CN with 0.085% HCOOH, respectively, with a total flow rate of 300 fiL/ min (corresponding to 12.5 /rL/min for each column). 

Figure 5.25 — Flow-through ion-selective optrode based on a multilayer lipidic membrane prepared by the Langmuir-Blodgett method. (A) Cross-sectional view of the composite six-layer membrane (four layers of arachidic acid/ valinomycin covered by an arachidic acid and rhodamine dye bilayer). (B) Optical arrangement integrated with the sensor, which is connected to a flow system. LS light source Ml and M2 excitation and emission monochromator, respectively FI and F2 primary filters M mirror LB lipid-sensitive membrane in a glass platelet FC flow-cell A amplifier D display P peristaltic pump. (Reproduced from [107] with permission of the Royal Society of Chemistry).

On addition of Na -saponite to the rhodamine-ethanol solution and the pyronine-ethanol solution, the color of the solutions gradually faded within a few hours, even at room temperature. All the composites were intensely colored, namely bright red for Rhodamine 590 and cardinal for Pyronine Y. 

As a function of the dye content intercalated, the relative intensity of fluorescence, the maximum wavelength in the fluorescence spectrum of lax d-spacing are illustrated in Fig. 2(a) for the pyronine Y-saponite composite (referred to as PY-SA), and Fig. 2(b) for the rhodamine 590-saponite composite (referred to as R590-SA). 

In experiments with rhodamine C mainly two types of curves (Figures 4 a, b, c, d) were constructed the first is characterized by fast colloid dissolution of dye and the solution stability (e.g., curves 2b, 3b) the other - by a longer stabilization period of solutions (curves 2a, 3 a), but with a sharp growth of solubilization effect for compositions in the area of the higher concentration (curve 9 a). For the compositions of the specified additives with cuccinimide the solubilization effect was more evident and the values of critical micelle concentration (CMC) were lower as compared with the features of individual substances in isooctane (Table 7). If sulfured piperylene fractions are characterized by the CMC interval of 0.05-0.45 mass.%, in the presence of 0.5 and 1.0 mass.% of cuccinimide the CMC areas correspond to the following values 0.02-0.50 and 0.01-0.50 mass.%. 

Figure 16. Transient photocurrent signal from a time-of-flight measurement of a photorefractive polymer composite containing 47.5 % electro-optic dye (EHDNPB), 1 % TNF with PVK polymer making up the remainder 21 V was applied across the 100 nm polymer film and a 10 nm thick rhodamine 6G charge generation layer was used. The hole mobility in this material is thus...

The base of the dye is a red powder, which is insoluble in water, but soluble in alcohol producing a red solution. The HCl salt, which is sold on the market as "Rhodamine B", is.a very fine violet black powder with yellow green fluorescence soluble in water to produce a deep red violet colour also soluble in alcohol producing a red solution melts at 2 0 C, boils at 310°C, but it begins to smoke gradually with the temperature rise from the melting point and is carbonized partly without vaporizing. The smoke particles of rhodamine B fro a smoke composition are insoluble in water. 

Mehrotra (31) as well as Sakka (534) recently reviewed the current literature on a number of gels with microstructures [e.g., porous gels (546)], optically useful gels containing dyes such as rhodamines (571), and inorganic-organic composites (572). 

A potassium opto-sensor was recently described [75] for the continuous determination of electrolytes. Certain fluorescent dyes respond to an electric potential at the interface between the aqueous and lipid phases. This potential is created by the neutral ion carrier. The lipid layer is formed on a glass support by the Langmuir-Blodgett thin-fllm technique. This layer incorporates Rhodamine B as a dye and valinomycin as the carrier. The lipid membrane is made of arachidic acid. The fluorescence intensity decreases when this layer is exposed to potassium ions (linearity between 0.01 and 10 mM). This optode is also sensitive to sodium ions [76]. The selectivity factor of potassium in comparison with sodium ions varies from 10 - to 10 , and in relation to ammonium ions by 10. Interferences can be compensated for by a reference optode. However, better selectivity is obtained with new lipid membrane compositions (octadecan-l-ol-valinomycin) [77]. Tetralayers (Figure 17-9) give a maximum response for K". The K /Na selectivity is about 10 in a wide range (0.01-100 mM). 

Figure 17-9. Schematic cross-seaion of a composite hexalayer membrane with an arachidic acid and a valinomycin tetralayer covered with an arachidic acid and Rhodamine B dye bilayer (from (771).

Recent advances in composite manufacturing techniques permit the fabrication of large optical elements. In Fig. 14, a wide range of organic dye-doped composites are presented. The largest of these measures 30 cm in diameter by 3.5 cm in thickness. Organic dyes represented include coumarin-314T, fluorescein, rhodamine 6G, rhodamine B, and poly(p-phenylene vinylene). 

Transparent mesoporous fibers with excellent order and parallel pores and doped by laser dye are prepared with good reliability. Influence of the nature of laser dye on the host - guest interaction is shown. Optical properties of Rhodamine 6G and Coumarine 120 embedded in mesoporous fiber waveguide have demonstrated utility for new laser materials, microphotonic devices or microreactors with increasing thermostability of dye component. The opportunity of preparation of the composite materieils mesoporous fiber / semiconductor is shown. 

A novel composite reactor through combination of photochemical and electrochemical systems was used for the degradation of organic pollutants [364]. In this process UV excited nanostructure Ti02 were used as the photocatalyst. The reactor was evaluated hy the degradation process of Rhodamine 6G (R-6G). 

Figure 4 Efficacy of Pluronic block copolymer compositions displayed in inhibiting drug efflux function in BBMEC monolayers. (A) Rhodamine 123 (R123) enhancement factors are defined here as the ratios of rhodamine 123 accumulation in the cells in the presence of the block copolymer to rhodamine 123 accumulation in the assay buffer. (B) A grid of Pluronic indicating four groups determined based on the activity of these copolymers displayed in BBMEC monolayers as shown in A. (From Ref. 95.)...

We would like to stress here the importance of X-ray photoelectron spectroscopy (XPS) for surface characterization, since it analyzes the first 10 or 20 atomic monolayers. It gives information regarding both composition and elemental concentration, as well as the probe-surface interactions. Quite recently [15, 16], this technique allowed the authors to study rhodamine and cyanine dyes physically and/or chemically bound to microcrystalline cellulose. 

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