Cationic Styryl dyes

Thus, the condensation of 2-phenyl-l,3,6-trimethyl-2-azaazulenium perchlorate with 5-nitrosalicylaldehyde gave the cationic styryl dye (A,max 510 nm) in 56% yield.139 This dye is the salt of the open form of the corresponding spiropyran, and upon treatment with base, a reaction which was not originally reported, was found to give the expected dye (126), which absorbs at 733 and 536 nm. This material did not thermally fade or photobleach to any significant extent with visible light in either polar or nonpolar solvents.7... 

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 mechanisms of regioselective and stereoselective 2 -E 2-photocycloadditions have been extensively reviewed. The intramolecular 2 -E 2-photocycloaddition of 2-allyl-2-(l//)-naphthalenone (13) on the surface of silica produces all four cycloadducts (14)-(17) (Scheme 4). ° Molecular mechanics have been used to study the regio- and stereo-selectivity of the 2 -E 2-photocycloadditions in complexes containing crown ether styryl dyes and alkaline earth metal cations."... 

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. 

It was found that the linking of styryl dye fragment to benzocrown ether results in novel photochromic compounds CESD (Crown Ether Styryl Dyes) possessing interesting physico-chemical properties (Scheme 1) [13], The dyes are intensively colored and show significant hypsochromic shifts upon complexation with alkaline earth metal cations in acetonitrile solution. Reversible photochemical reaction E,Z-isomerization is observed for both dyes and their complexes. 

Bis-crown-containing styryl dye (E,E)-1 having the structure and properties of molecular pincers has been synthesized. In acetonitrile solution, dye (E,E)-1 is able to form intramolecular sandwich complexes with Ca2+ and Ba2+ cations (Scheme 7) [28,29],... 

Alfimov, M.V., Vedernikov, A.I., Gromov, S.P., Fedorov, Yu.V., Fedorova, O.A., Churakov, AV., Kuz mina, L.G., Howard, J.A.K., Bossmann, S., Braun, A, Woemer, M., Sears, D.F., Saltiel, J. (1999) Synthesis, structure and ion selective complexation of trans and cis isomers of photochromic dithia-18-crown-6 ethers, J. Am. Chem. Soc., 121, 4992-5000 b) Stanislavskii, O.B., Ushakov, E.N., Gromov, S.P., Fedorova, O.A, Alfimov, M.V. (1996) Crown-containing styryl dyes. 14. The influence of N-substitute length on the complex formation of betainic chromogenic 15-crown-5-ether with alkaline earth metal cations, Russ. Chem. Bull, 45, 564-572. 

Alfimov, M.V., Gromov, S.P., Stanislavskii, O.B., Ushakov, E.N., Fedorova, O.A. (1993) Crown-containing styryl dyes. 8. Cation-dependent concerted [2+2]-autophotocycloaddition of photochromic 15-crown-5 ether betaines, Russ. Chem. Bull, 42, 1385-1389. 

Photolysis of 1-phenylcyclopentene (106) and 1,4-dicyanobenzene in acetonitrile gives [2+4] cycloadducts based upon the tetralin skeleton, and a 2 1 adduct derived from the substrates. However, although 1-phenylcyclohexene (107) leads to l-cyano-2-phenyl-cyclohexane, no 1 1 products are formed. Radical cations are seen which have been shown by the PM3 method to be fully planar (106 ), and which will dimerise by reaction with (106) in contrast, the optimised structure of (107 ) has a chair-like structure. Styryl dyes containing both a crown ether group and a heteroaromatic residue with a sulfoalkyl N-substituent in acetonitrile solution and in the presence of Mg ions will undergo photo-dimerisation. Only one cyclobutane dimer is produced and this is interpreted... 

Interest in cationic photopolymerisations has increased dramatically over the last year. Novel crown ether styryl dyes have been developed for 2+2 cycloaddition reactions while a tris(2,2 -bipyridyl)ruthenium complex has been successful in inducing the photopolymerisation of aniline. New hybrid vinyl... 

Scheme 4). ° Molecular mechanics have been used to study the regio- and stereo-selectivity of the 2 -E 2-photocycloadditions in complexes containing crown ether styryl dyes and alkaline earth metal cations."... 

The styrylpyrilium salt derivatives (130) undergo (2 + 2)-cycloaddition to afford the corresponding dimers. The magnetic properties of the radical cations formed from these dimers were compared with those formed from (130). Styryl dyes of the type shown as (131) undergo E-Z isomerization on irradiation at 436 nm. The dyes align themselves in the pattern shown in (132, where the filled blob represents the crown ether complex). These undergo dimerization on irradiation to afford compounds (133), from which the magnesium ions can be removed. 

Photodimerizations with charged compounds have been studied in several styryl dyes wherein alkylation of an V-heterocycle (e.g., pyridine, benzothiazole) generates a salt." Gromov and coworkers have also shown that when a styryl dye and a crown ether (e.g., 18-C-6 Scheme 9) are covalently connected, stereospecific [2- -2] reactions are facilitated by inclusion of the cation within the ethereal host." In addition, Gromov also showed that counteranion... 

Many methine cationic dyes, styrylic (141), pyrrolic. or amino-substituted (142) derivatives of thiazolium, possess interesting anthelmintic properties (143). This last class has been used as accelerators of the catabolism and activators of cellular exchanges (144). 

Rettig W, Rurack K, Sczepan M (2001) From cyanines to styryl bases - photophysical properties, photochemical mechanisms, and cation sensing abilities of charged and neutral polymethinic dyes. In Valeur B, Brochon JC (eds) New trends in fluorescence spectroscopy applications to chemical and life sciences. Springer, Berlin, pp 125-155... 

From Cyanines to Styryl Bases -Photophysical Properties, Photochemical Mechanisms, and Cation Sensing Abilities of Charged and Neutral Polymethinic Dyes, in Valeur B. and Brochon J. C. (Eds),... 

Spectroscopic methods can be used to specify the position of donors and acceptors before photoexcitation [50]. This spatial arrangement can obviously influence the equilibrium eomplexation in charge transfer complexes, and hence, the optical transitions accessible to such species [51]. This ordered environment also allows for effective separation of a sensitizing dye from the location of subsequent chemical reactions [52], For example, the efficiency of cis-trans isomerization of A -methyl-4-(p-styryl)pyridinium halides via electron transfer sensitization by Ru(bpy) + was markedly enhanced in the presence of anionic surfactants (about 100-fold) [53], The authors postulate the operation of an electron-relay chain on the anionic surface for the sensitization of ions attached electrostatically. High adsorptivity of the salt on the anionic micelle could also be adduced from salt effects [53, 54]. The micellar order also influenced the attainable electron transfer rates for intramolecular and intermolecular reactions of analogous molecules (pyrene-viologen and pyrene-ferrocene) solubilized within a cationic micelle because the difference in location of the solubilized substances affects the effective distance separating the units [55]. 

Closely related to cyanine dyes are stilbazolium salts that are based on the styryl scaffold. Stilbazolium dyes are a class of fluorescent, lipophilic cations that have been used as mitochondrial labeling agents and membrane voltage-sensitive... 

R. Bartnik, S. Lesniak, G. Mloston, T. Zielinski, and K. Gebicki, Cationic l-(2-hydroxyethyl)-2-styryl-3,3-dimethyl-3 //-indole dyes, Chem. Stosow., 34, 325-334 (1990). 

By analyzing the ELD spectra of 2- and 4-[4-(dimethylamino)styryl]-l-ethylpyridinium cations on saponite suspended in DMF (Fig. 20), the tilt and roll angles of the dye were found to be controlled by the amount of the intercalated dye as well as the molecular structure (the position of cationic site within the dye) (103). The adsorption models of 4-[4-(dimethylamino)styryl]-l-ethylpyridinium cations on solid saponite are shown in Figure 21. Depending on the coverage, the orientation of 4-[4-(dimethylamino)styryl]-l-ethylpyridinium varied, as shown in Figure 21. The important role of the orientation of the stilbazolium cations will be discussed in a subsequent section. 

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