2,2 -Cyanines complexes

Apart from the catalytic properties of the Mn-porphyrin and Mn-phthalo-cyanine complexes, there is a rich catalytic chemistry of Mn with other ligands. This chemistry is largely bioinspired, and it involves mononuclear as well as bi- or oligonuclear complexes. For instance, in Photosystem II, a nonheme coordinated multinuclear Mn redox center oxidizes water the active center of catalase is a dinuclear manganese complex (75, 76). Models for these biological redox centers include ligands such as 2,2 -bipyridine (BPY), triaza- and tetraazacycloalkanes, and Schiff bases. Many Mn complexes are capable of heterolytically activating peroxides, with oxidations such as Mn(II) -> Mn(IV) or Mn(III) -> Mn(V). This chemistry opens some perspectives for alkene epoxidation. 

Sorokin AB, Quignard F, Valentin R, Mangematin S (2006) Chitosan supported phthalo-cyanine complexes Bifunctional catalysts with basic and oxidation active sites. Appl Cat A 309 162... 

The stable tannin-ethyl-anthocyanin structures are apparently transformed at varying rates into orange compounds, via the fixation of the polarized double bond of the vinyl-procyanidins on the anthocyanins, to form procyanidin-pyranoantho-cyanin complexes (Francia-Aricha et al., 1997). The rate of conversion depends on the wine s phenol content, the origin of the tannins (skins or seeds), and the phenolic structures (tannin-anthocyanin combinations) present at the end of the aging period. 

Molecules that exhibit donor functions include chlorophyll, phthalo-cyanine complexes, and perylene. Examples for molecules with acceptor functionality are fullerenes and MEH-PPV. 

The inverse process of election transfer is characteristic for lanthanide phthalo-cyanine complexes. Recovering green form to blue occurs in ethanol solution in the presence of nano-sized silica (Fig. 9.7). 

Dangles, O., Stoeckel, C., Wigand, M.C. BrouiUard, R. (1992a). Two very distinct t5q)es of antho-cyanin complexation copigmentation and inclusion. Tetrahedron Letters, 33, 5227 5230. 

As an illustration of the real complexity of Mill s reaction, when two molecules of heterocycloammoniums of different nature, one of them being thiazolium (2-substituted or not), are put together in a basic medium, nine dyes theoretically can be produced (depending on the nature of the substituent in the ring) three thiazolomonomethine cyanines (two symmetrical, one asymmetrical) and six trimethine cyanines (two symmetrical, two symmetrical mesosubstituted. one unsymmetrical, one unsymmetrical mesosubstituted). One cannot separate such a mixture by usual chromatographic means. 

Meta.1 Complexes. The importance of Ni complexes is based on their effectiveness as quenchers for singlet oxygen. Of disadvantage is their low colorfastness and their lower ir-reflectance compared to cyanine dyes (qv) therefore they are used in combination with suitable dyes. Numerous complexes are described in the Hterature, primarily tetrathiolate complexes of Pt or Ni, eg, dithiolatonickel complexes (3). Well known is the practical use of a combination of ben2othia2ole dyes with nickel thiol complexes in WORM disks (Ricoh, TDK) (17). 

Several types of nitrogen substituents occur in known dye stmetures. The most useful are the acid-substituted alkyl N-substituents such as sulfopropyl, which provide desirable solubiUty and adsorption characteristics for practical cyanine and merocyanine sensitizers. Patents in this area are numerous. Other types of substituents include N-aryl groups, heterocycHc substituents, and complexes of dye bases with metal ions (iridium, platinum, zinc, copper, nickel). Heteroatom substituents directly bonded to nitrogen (N—O, N—NR2, N—OR) provide photochemically reactive dyes. 

Excited-state properties of the cyanine and related dyes are complex. Most cyanine dyes exhibit small Stokes shifts for duorescence maxima. Typical carbocyanines (1) with n = 1 show 14- to 16-nm shifts in methanol solution with low quantum efficiencies for duorescence (Op ) of less than 0.05. The diearbocyanine analogues also show small Stokes shifts but higher quantum yields (Lpj = 0.3-0.5). 

The stmcture of the blue material was not elucidated until 1934, when it was shown to be the iron complex of (67). The new material was christened phthalocyanine [574-93-6] reflecting both its origin from phthaUc anhydride and its beautihil blue color (like cyanine dyes). A year later the stmcture was confirmed by one of the first uses of x-ray crystallography. 

The anthocyanins are pH sensitive. Their color, in part, is deterrnined by the pH of the sap. Cyanin, for example, is red at pH 3, violet at 8, and blue at 11. However, there are other factors that affect the colors of the anthocyanins metallic salts, notably iron and aluminum, react with those anthocyanins containing vicinal hydroxy groups and produce highly colored complex compounds. Other factors are the colloidal condition of the cell sap and copigmentation (91). 

Dyes, polymethine used for dyes having at least one electron donor and one electron acceptor group linked by methine groups or aza analogues aUopolar cyanine, dye bases, complex cyanine, hemicyanine, merocyanine, oxonol, streptocyanine, and styryl. Supersensitization has been reported for these types—18 cites for cyanines, 3 for merocyanine, and 6 for all other polymethine types. 

Fig. 9. Examples of dyes used in optical disks. (14), pentamethine cyanine [36536-22-8] (1 )> nickel dithiene complex [38465-55-3] and (16) lR-810.

Nonmedical uses envisaged include as growth promoters, indicators for copying processes, analytical complexing agents, cyanine dyes and dye-bleaching catalysts. 

The compounds obtained in solid state have the general formula [MefSCNf JR., (R-cations of cyanine dyes) and could be embedded into polyvinylchloride matrix. Using the matrix as work element of electrodes shows the anionic function concerning the anionic thiocyanate complexes of Pd, Hg, Zn and the response to sepai ately present thiocyanate and metallic ions is not exhibited. 

The results of the complexation study of Cu(II), Pb(II), Zn(II), Fe(III), Hg(II), Cd(II), Sn(IV), Zr(IV), Ti(IV) with arsenazo III, sulfonazo III, SPADNS, Eriochrome T, Acid Chrome Dai k Blue, Xylenol Orange, Methyl Thymol Blue, Pyrocatechol Violet, Chrome Azurol S, Eriochrome Cyanin R, Basic Blue K, Methyl Violet, Brilliant Green, Rhodamine C and Astraphoxin in solid phase. The obtained data ai e used for the working out of a new method of metal determination. 

Erbium, tris(2,2,6,6-tetrametbyl-3,5-hep tanedione) structure, 1, 65, 66 Erbium complexes acetylacetone, 2, 374 Erhium(ill) complexes glycolic acid, 2, 472 Eriochalcite, 6, 855 Eriochrome black T metallochromic indicators, 1, 555 Eriochrome blue black R metallochromic indicators, I, 556 Eriochrome cyanine R metallochromic indicator, 1, 556 Erythrocruorin, 6, 689 dioxygen transport, 6,683 stability... 

Detailed studies on this line are in progress in our laboratory in an attempt to reach equally clear conclusions for more complex cyanines characterized by the same (pentamethine) chromophore as BMPC (e.g. DOC and DTC). 

Reference [33] describes recent progress on cyanine probes that bind noncova-lently to DNA, with a special emphasis on the relationship between the dye structure and the DNA binding mode. Some of the featured dyes form well-defined helical aggregates using DNA as a template. This reference also includes spectroscopic data for characterizing these supramolecular assemblies as well as the monomeric complexes. 

The indole- and benzindole-cyanine dyes illustrated in Scheme 6 are used by many major manufacturers in optical disk recording applications. These types of dye tend to be more light-stable than many other readily synthesized polymethine dyes. To increase the photostability, the dyes are used in combination with various types of stabilizers such as nickel dithiolato complexes and selected tertiary aromatic amine compounds.199 The application of cyanine dyes for optical storage media was primarily developed in Japan203 and several dyes and compatible stabilizers are commercially available in pure form from Japanese suppliers.199... 

There are no clear advantages in terms of functional performance between the two classes of dyes, except that phthalocyanines are generally more light stable but tend to be more expensive to synthesize and modify. Phthalocyanine dyes are not suitable for DVD-R media, since the main chromophore cannot readily be modified to produce a sufficiently large hypsochromic shift. Other dyes potentially suitable for DVD-R include metal azo complexes, quinophthalones, and diphenyl-methanes. The cyanine dyes are particularly useful as they can be readily modified to tailor the optical absorbance requirements for all current optical disk recording applications.199... 

Lanthanides also have potential as DEFRET energy donors. Selvin et al. have reported the use of carbostyril-124 complexes (53) with europium and terbium as sensitizers for cyanine dyes (e.g., (54)) in a variety of immunoassays and DNA hybridization assays.138-140 The advantage of this is that the long lifetime of the lanthanide excited state means than it can transfer its excitation energy to the acceptor over a long distance (up to 100 A) sensitized emission from the acceptor, which occurs at a wavelength where there is minimal interference from residual lanthanide emission, is then measured. 

Kirstein, S. and Daehne, S. (2006). J-aggregates of amphiphilic cyanine dyes self-organization of artificial light harvesting complexes. Int. J. Photoenergy 5, 1-21. 

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