Aqueous solution, polymethine dyes

Beryllium, calcium, boron, and aluminum act in a similar manner. Malonic acid is made from monochloroacetic acid by reaction with potassium cyanide followed by hydrolysis. The acid and the intermediate cyanoacetic acid are used for the synthesis of polymethine dyes, synthetic caffeine, and for the manufacture of diethyl malonate, which is used in the synthesis of barbiturates. Most metals dissolve in aqueous potassium cyanide solutions in the presence of oxygen to form complex cyanides (see Coordination compounds). 

First procedure consists of several stages. 11-molybdo-bismuthphosphate (MBP) is formed and extracted with butyl acetate, stripped with ammonia or acetate buffer solution and determined in aqueous solution using reaction of MBP with Astro Floxine (AF) or other polymethine dyes. Full separation from molybdate excess is not necessary in this procedure as spectiaim of lA differs considerable from dye spectiaim. Therefore sepai ation is simplified and used only as preconcentration step. Concentration factor 50 and good reproducibility make possible determination of low P(V) concentrations at 10 mol/1 level and lower. 

For dye K2, the kq value decreases by 40 times on passing from an aqueous solution to a complex with DNA. Similarly, kq obtained upon quenching of the triplet state of dye K1 bound to DNA is much lower than the values of the constants typical for the mechanism of acceleration of the intersystem crossing to the groimd state ( 1 x 10 1 mol s ). The possible reason for these phenomena is bulky substituents in the polymethine chain (OCH3 and SCH3), which create additional spatial hindrances to quencher molecules upon complexation with DNA. Hence, diffusion of the quencher to the triplet molecules is strongly impeded (ka and k ... 

Hydrophobic interactions are important in the aggregation of polymethine dyes [81] and in the stabilization of particular conformations of polypeptides and proteins in aqueous solution [222, 232]. They also play an important role in the biochemical com-plexation between an enzyme and a substrate [77, 78, 83, 84, 348]. 

Extraction of Re04 with basic polymethine dyes from aqueous and aqueous-organic solutions has been investigated [1]. The method based on the complex with rhodamine B and thiocyanate can be used for the determination of Re in the 1-3.63 ppm concentration range L2]. 

If the dye contains no mobile substituents ia the chain, nucleophiles attack primarily the end carbon atoms (changing of terminal residues). Streptocyanines can be hydroly2ed ia aqueous alkaline solution to form the corresponding merocyanines and then the oxonoles (71,72). These processes are reversible. Nucleophilic reactions with the methylene bases of the corresponding heterocycles result ia polymethines containing new end groups (Fig. 

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