Cyanines structure

Historically, the terms simple cyanine, carbocyanine and dicarbocyanine have been used to designate generic cyanine structures containing one, three, and five methine carbons in the chain joining the two heterocycles (Figure 44). Dyes that differ only in the number of methines in the chain are called a vinylogous series. The... 

Bredas et al. studied theoretical TPA properties of the 4-dimethylamino-4 -formylstilbene (DAFS) with the degree of tt bond-order alternation (BOA) by the application of an external field [54]. This work shows two possible strategies to optimize TPA response in stilbenic molecules, as shown in Fig. 5 (1) In the case of TPA resonance in the lowest excited state at oi energy, the D term of Eq. 5 presents the main contribution and ajpA varies in the same way as and Afioi as a function of BOA, with a maximum for an intermediate regime between the neutral Brl and the cyanine Br2 Umits. (2) For a TPA resonance in the specific two-photon state S2, the structure presents huge ajpA values for the cyanine structure near the double resonance at Eoi =. ... 

Co MS, Hodgson KO, Eccles TK, Lontie R. 1981. Copper site of molluscan oxyhemo-cyanins structural evidence from x-ray absorption spectroscopy. J Am Chem Soc 103 984-986. 

Studies by Meyers and co-workers have shown that the NLO response of many strong donor-acceptor molecules suffer from too much bond length alternation (on the order of 0.01 nm), which inhibits charge transfer in the excited state (132). jS is zero in the cyanine limit, however, when there is no bond length alternation. Interestingly, /S peaks with opposite sign when the BLA is either intermediate between the polyene/cyanine structure or intermediate between a cyanine/zwitterionic structure (BLA 0.004 nm) (133). One important result... 

Ouchi et al. have used NMR titrations to find out details about the recognition mechanism and the stoichiometry of the recognition process of NeuSAc by fluorescent dyes like lanthanide-macrocyclic poly-azacarboxylate complexes, and boronic acid-functionalized squaiylium cyanine structures. ... 

Structurally, the molecule is formed by the union of one atom of the metal with four molecules of phthalonitrile. Copper phthalo-cyanine is typical, and has the formula... 

In the first chapter, devoted to thiazole itself, specific emphasis has been given to the structure and mechanistic aspects of the reactivity of the molecule most of the theoretical methods and physical techniques available to date have been applied in the study of thiazole and its derivatives, and the results are discussed in detail The chapter devoted to methods of synthesis is especially detailed and traces the way for the preparation of any monocyclic thiazole derivative. Three chapters concern the non-tautomeric functional derivatives, and two are devoted to amino-, hydroxy- and mercaptothiazoles these chapters constitute the core of the book. All discussion of chemical properties is complemented by tables in which all the known derivatives are inventoried and characterized by their usual physical properties. This information should be of particular value to organic chemists in identifying natural or Synthetic thiazoles. Two brief chapters concern mesoionic thiazoles and selenazoles. Finally, an important chapter is devoted to cyanine dyes derived from thiazolium salts, completing some classical reviews on the subject and discussing recent developments in the studies of the reaction mechanisms involved in their synthesis. 

The name found its origin in the fact that the first dyes known were all derived from quinoline as, for example, 2,2 -cyanine (Scheme 1). In the case of an asymmetrical or symmetrical dye involving one or two nuclei that are different from the quinoline ring, the name of the nucleus becomes the prefix in the name of the dye. So 3.3 -dimethyl-4-phenyl thiazolo cyanine is the dye of structure 1 and 3.1 -dimethyl 4-phenyl thiazolo 2 -cyanine is represented by the formula structure 2 (Scheme 2). 

Rhodacyanines possess two chromophoric systems. They are at the same time neutrocyanine derivatives, which involves position 5 of the ketomethylene, and methine cyanine, which involves position 2. Following lUPAC s standard nomenclature rules, structure 7 is named 3-ethyl-4-phenyl-2- 4-oxo-3-ethyl-5-[2-(3-ethy]-2,3-dihydro-benzo-l,3-thiazo-lylidene)ethylidene]-tetrahydro-l,3-thiazolylidene-methyl -1.3-thiazolium iodide (Scheme 5). It implies that the 4-phenyl thiazole ring having the... 

The electronic structure of a trimethine asymmetrical cyanine, controls the attack of a ketomethylene (Scheme 54). There is a condensation of the nucleophilic carbon on the electrophilic central carbon atom of the methine chain, leading to a neutrodimethine cyanine and simultaneously elimination of the more basic nucleus. 

Methylation of 2- or 4-methylquinazoline is reported to proceed with difficultyj" but 4-methylquinazoline has been quaternized with methyl iodide. The product was very hygroscopic and, although not purified, was shown to consist mostly of 1,4-dimethylquinazolinium iodide, since it gave the same cyanine dye (11) with 2-methylthio-benzthiazole metho-toluene-p-sulfonate as did l-methyl-4-methyl-thioquinazolinium iodide (of unambiguous structure) with 2-methyl-benzthiazole methiodide. ... 

Cyanine dyes have been prepared from the salts obtained by the quatemization of 4,6-dimethyl-2-phenylpyrimidine and 2-alkyl- or 2-aryl-4,6-dimethylthiopyrimidines, but there can be no ambiguity in the structure of these quaternary salts. 

Similarly, when copper(II) hexadecachlorophthalocyanine is treated with ethanol and potassium hydroxide at 145 °C for two hours and then at 160-1803C for a further two hours, a mixture of a variety of structural isomers of octachloro- and octaethoxy-substituted phthalo-cyanines is formed in 35 % yield.340... 

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... 

Carbene structure, of thiazolium salts in basic medium, 31.34 Carbocation, in thiazolium salts, 32 Carbocyanines. see Trimethine thiazolo-cyanines... 

Structural hybrid, in resonance theory. 69 Structures, of dyes, in relation with elecuo-chemical potential. 75 extreme of cyanine dyes, 69 Styryl compounds, nomenclature of, 29 Styryl dyes, in basicity scale, 71 with dialkylamino group, 77 as models in relation with pKa, 50 and role of anhvdrobases. 50 as sensitizers, in photography. 79 stereo aspect of condensation. 50 synthesis of, 49... 

Many recent stndies of NMR spectroscopy have been reported for structure elucidation of anthocyanins from many plant materials such as carrot, tart berries, boysenberries, " flowers, black soybeans, and anthocyanin and flavonol derivatives in red wine. Ginsti et al. (1998) structurally elucidated two novel diacylated anthocyanins and two monoacylated anthocyanins from radish Raphanus sativus) by one- and two-dimensional NMR. Anderson et al. (2006) applied two-dimensional NMR to characterize carboxypyranoanthocyanins. Two 3-deoxyantho-cyanins, lnteolinidin-5-glncoside, and apigeninidin-5-glucoside were identified by Swinny et al. nsing H and C NMR. 

Symmetrical cyanine dyes, because of the resonance shown in Figure 6.4 (in which the two contributing structures are exactly equivalent), are completely symmetrical molecules. X-ray crystal structure determinations and NMR spectroscopic analysis have demonstrated that the dyes are essentially planar and that the carbon-carbon bond lengths in the polymethine chain are uniform. The colour of cyanine dyes depends mainly on the nature of the terminal groups and on the length of the polymethine chain. The bathochromicity of the dyes is found to increase... 

The valence-bond (resonance) description of the triphenylmethine dye Malachite Green (125) is illustrated in Figure 6.5. Comparison with Figure 6.4 reveals their structural similarity compared with cyanine dyes. Formally, the dye contains a carbonium ion centre, as a result of a contribution from resonance form II. The molecule is stabilised by resonance that involves delocalisation of the positive charge on to the p-amino... 

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