Carbocyanine cations

From these results, it would be reasonable to expect that we would also observe a similar isoviscous temperature dependence of feobs and kf in other systems, if the solute-solvent interactions are strong enough. In order to examine this possibility, we decided to undertake kinetic measurements on some carbocyanine cations because solute-solvent interactions are much stronger in charged species than in neutral ones. 

Carbocyanine cations are known to isomerize photochemically in their poly-methinic chain. 3,3 -Diethyloxacarbocyanine iodide (DOCI) and 3,3 -diethyloxadi-carbocyanine iodide (DODCI) are among the most extensively investigated compounds and the cations are believed to exist in solution in the all trans extended structure. After irradiation one of the carbon-carbon double bonds undergoes Z/ -type isomerization and unstable photoisomeric cations are formed as illustrated in Schemes 3.3 and 3.4 [45]. 

Judging from the Eaf/EarsT ratios, the correlation between the solvent and chemical coordinate in the isomerization of the carbocyanine cations was of the same order as that in the azobenzene isomerization in MPD. 

Fig. 3.25. Dependence of log(fe<,bs/(tTST) on log(/cTST d) thermal Z/E isomerization of N-benzylideneanilines and carbocyanine cations at various temperatures in MPD.

Crystal stmcture analyses of cyanine and related dyes are reviewed in Ref. 32. Most typical sensitizers are nearly planar, with angles of less than 15° between planes defined by heterocycHc rings. Distinct solvent of crystallization is present in most of the cationic dyes. X-ray crystal analyses also provide intermolecular data. Because of photographic use of cyanine and carbocyanine dyes, the cation-cation arrangements of most interest have been those for l,l -dieth5l-2,2 -quinocyanine chloride [2402-42-8] 5,5, 6,6 -tetrachloro-l,l, 3,3 -tetraethylbenzimidazolocarbocyanineiodide [3520-43-2] and 5,5 -dichloro-3,3, 9-triethylthiacarbocyanine bromide [18426-56-7] (32) (see Fig. 8). 

Fig. 8. Sensitizing dyes of the cyanine class. K. = N — alkyl or chalcogens (O, S, Se, Te) R = chloro, phenyl, or additional benzene ring R = methyl, ethyl, or hydrogen n = 0, 1, 2 and RPRIME, R " = alkyl or sulfoalkyl. Solubihty in methanol for a carbocyanine dye n = 1 X = S R = Cl R = ethyl. Cationic dye (R" = R " = ethyl anion = bromide) 9.5 mmol/T. neutral dye (R" = ethyl R " = sulfopropyl) 3.6 mmol/L anionic dye (R" = R = sulfopropyl ...

Substituents on the methine chain can stabilize the dye radical cation if the substituent (like methyl) is located on the high electron density carbons. However, no significant stabilization occurs when alkyl groups are on the alternate positions (like 9, 11 for the dication in Fig. 9). Current results for several dyes including die arbo cyanines and carbocyanines indicate that electronic stabilization of the dication radical lengthens the radical lifetime and also enhances the reversibiUty of the dimerization process (37). 

This chapter describes the synthesis, properties, and biomedical applications of cyanine and squaraine dyes encapsulated in CDs, CBs, Leigh-type tetralactam macrocycles, aptamers, and micro- or nano-particles. The optical and photochemical properties of supramolecular guest-host nanostructures that are based on intra-and intermolecular complexes of crown-containing styryl dyes with metal cations, and aggregates of carbocyanine dyes are discussed in a separate review [18]. 

The main classes of dyes nsed as potentiometric probes are cationic or zwitterionic styryl dyes, cationic carbocyanines and rhodamines, anionic oxonols and hybrid oxonols and merocyanines. The particular class of dye determines factors snch as accnmnlation in cells, response mechanism and toxicity. 

Using both a carbocyanine dye and another lipophilic cation, triphenylmethyl-phosphonium, Seligmann and Galhn found defective changes in the membrane potential in PMNs from patients with chronic granulomatous disease in response to FMLP or PMA, In PMNs from patients with other disorders of function the responses were normal. The resting membrane potential, the response to valinomycin, (an ionophore for potassium) and the response to the ionophore for Ca, were all normal or only slightly impaired. 

In addition to the methods described above a battery of other staining procedures are available. These include use of alcian blue (22) to stain glycoproteins, ethidium bromide (23) to stain DNA, and methylene blue (14) and pyronine (16) to stain RNA. A relatively new stain has been nicknamed stains-all, because of its ability to stain most macromolecules. This dye is a cationic carbocyanine and stains RNA bluish purple, DNA blue, protein red, acid mucopolysaccharides various shades of blue to purple, and phosphoproteins blue (24). It is presently the most widely used stain for RNA. 

M. R. Green, J. V. Pastewka, and A. C. Peacock, Anal. Biochem., 56 43-51 (1973). Differential Staining of Phosphoproteins on Polyacrylamide Gels with a Cationic Carbocyanine Dye. 

Carbocyanine dyes are salts that have fluorescent cations. To use this fluorescent property to indicate biological membrane potential, the dye cation... 

Glycoproteins containing sialic acid may be detected by staining with a cationic carbocyanine dye before and after digestion with neuraminidase a change in the colour of the stain from blue to red-purple indicates the presence of sialic acid. The n.m.r. spectra of iV-acetylneuraminic acid and its methyl ester in DMSO and in water have indicated that the acid exists predominantly in the /S-form in solution. The finding supports the assumption that 7V-acetyl-neuraminic acid, produced by the enzymic cleavage of its a-ketosides, leaves the catalytic site of Vibrio cholerae neuraminidase as the j3-anomer. 

A cationic carbocyanine dye ( Stains-all ) has been used to distinguish between sialoglycoproteins, proteins, and lipids following gel electrophoresis in the presence of sodium dodecyl sulphate. Treatment in turn with periodate and dansylhydrazine is claimed to be a very sensitive method for detecting glycoproteins in polyacrylamide gels. ... 

Campbell, K. R MacLennan, D. H. Jorgensen, A. O. Staining of the calcium-binding proteins, calsequestrin, calmodulin, troponin C, and S-100, with the cationic carbocyanine dye Stains-aU . J. Biol. Chem. 1983, 258, 11267-11273. 

Green, M. R. Simultaneous differential staining of nucleic acids, proteins, conjugated proteins, and polar lipids by a cationic carbocyanine dye. J. Histochem. Cytochem. 1975, 23, 411-423. 

Green, M. R. Pastewka, J. V. Peacock, A. C. Differential staining of phosphoproteins on polyacrylamide gels with a cationic carbocyanine dye. Anal. Biochem. 1973, 56, 43-51. 

Milligan, G. Strange, P. G. Reduction in accumulation of [3H]triphenylmethylphosphonium cation in neuroblastoma cells caused by optical probes of membrane potential. Evidence for interactions between carbocyanine dyes and... 

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