Anthraquinone Linked Anthraquinones

Compounds containing olefine links may be oxidised to 1,2-diketones, as in C4H CH CHC Hs -> C HjCO-COC H. Anthracene is readily oxidised to anthraquinone, but phenanthrene is almost unaffected. 

Polycyclic Aromatic Carbonyl Dyes. StmcturaHy, these dyes contain one or more carbonyl groups linked by a quinonoid system. They tend to be relatively large molecules built up from smaller units, typically anthraquinones. Since they are appHed to the substrate (usually cellulose) by a vatting process, the polycycHc aromatic carbonyl dyes are often called the anthraquinonoid vat dyes. 

Fig. 2 Structures of the anthraquinone-linked sensitizers. AQ is covalently attached to the 5 -end of one strand. UAQ can be placed at any position, and the attached anthraquinone intercalates in duplex DNA at the 3 -side of its linked nucleotide...

Fig. 3 Model of an end-capped anthraquinone that is covalently linked to a 5 -terminus of duplex DNA by the tether shown in Figure 2... 

Fig. 4 Schematic representation of long-distance radical cation migration in DNA. In AQ-DNA(l), irradiation of the anthraquinone group linked at the 5 -terminus leads to reaction at GG steps that are 27 A and 44 A from the site of charge injection. The amount of reaction observed at each guanine is represented approximately by the length of the solid arrow. In UAQ-DNA(2), irradiation of the anthraquinone leads to reaction at each of the eight GG steps. However, replacement of a G by 7,8-dihydro-8-oxoguanine (8-OxoG) introduces a deep trap that inhibits reaction at guanines on the same side of the DNA as the trap...

Rate constants and the products formed in the hydrolysis of Cl Reactive Red 194 (7.76) at 50 °C and pH values in the 10-12 region were determined by high-pressure liquid chromatography. In addition to the normal hydrolysis of the two reactive systems, the imino link between the triazine and benzene nuclei was also hydrolysed [67]. The heterobifunctional copper formazan dye Cl Reactive Blue 221 and two blue anthraquinone monofunctional reactive dyes of the bromamine acid type, namely the aminochlorotriazine Blue 5 and the sulphatoethylsulphone Blue 19, were compared in terms of their sensitivity to... 

Formation of C—C links in the anthraquinone molecule, especially substitutions with aryl moieties, proceed via copper-catalyzed nucleophilic exchange of halogenated anthraquinone compounds. These methods include dimerization of 1 -aminoanthraquinone. 

The anthraquinone exhibits a similar redox behavior as benzoquinone. Thus, redox luminescence switch can also be constructed with fluorophore linked to anthraquinone. For example, the luminescence of molecule 22, a ruthenium complex with an appended anthraquinone moiety, can be reversibly tuned through the interconversion between the anthraquinone and the corresponding hydroquinone.32... 

One-electron oxidation of the 5,5 -linked dihydrothymine dimer by SO/ , N/ or photoexcited anthraquinone-2-sulfonate also affords Thy together with H2Thy (Ito et al. 1999). 

Gasper SM, Schuster GB (1997) Intramolecular photoinduced electron transfer to anthraquinones linked to duplex DNA The effect of gaps and traps on long-range radical cation migration. J Am Chem Soc 119 12762-12771... 

On the basis of their chemical constitutions the anthraquinoid vat dyes may be classified in the following major groups acylaminoanthraquinones, anthraqui-noneazoles, anthrimides and other linked anthraquinones, anthrimidocarbazoles, phthaloylacridones, benzanthrone dyes, indanthrones, and other polycondensed ring systems. 

Anthrimides and Other Linked Anthraquinones. Among the anthrimides (dia-nthraquinonyl-amines), only the a,(3 derivatives have achieved limited importance as vat dyes. Coupling two anthraquinone molecules via functional derivatives of the 2-aldehyde (or 2-carboxy) group offers another type of building block for vat dyes. Such compounds, e.g., 1-aminoanthraquinones, are linked in the 2-position via an azine or oxadiazole group, and all have good fastness. 

Anthraquinone dyes have not been widely used in photography. However, Polaroid s initial color film released in 1963 used the anthraquinone cyan 53. This dye illustrates the dye-developer concept in which the control group for diffusion-transfer imaging is a pair of hydroquinone moieties. The branching of the side chain linking the control group to the chromophore is important for light stability [69],... 

These hosts include simple anion sensor systems containing urea, thiourea, amine, amide, alcohol, and pyrrole groups linked to chromophores. Chro-mophores used in this type of chromogenic anion sensors are mainly organic dyes such as azobenzene, nitrobenzene, indoaniline, and anthraquinone or... 

The mechanisms involved in dimer cleavage have been examined in simple model systems [90,261-263], including bifunctional ones in which a sensitizer (e.g. indole) is linked to the pyrimidine dimer [264, 265]. For example, the cw-head-to-head dimer of dimethylthymine (88) was cleaved efficiently upon irradiation of anthraquinone-2-sulfonate CIDNP effects observed during this reaction failed to reveal any evidence for the existence of the dimer radical cation [90]. Time-resolved... 

A relative of 12 has been prepared by Sanders, van der Plas, and coworkers [64], Triad 13 features an N,A-dimethylaniline-type donor and an anthraquinone acceptor. These moieties are linked to the ortho positions of the porphyrin aryl groups, and this leads to a folded conformation for the molecule, as determined from NMR studies. Both the free base and zinc derivatives of 13 were prepared. The folded conformation might be expected to facilitate electron transfer among the components of the triad, and while this could enhance the quantum yield of the initial charge separated state, it might unfavorably affect the yield of the final D+-P-QT state and its lifetime. Unfortunately, photochemical or spectroscopic studies were not reported. 

More recently, a new class of covalent-linked calix[4]pyrrole-anthraquinone compounds (29-31) have been introduced by Sessler s group [48], These are considered to be powerful naked eye sensors for fluoride, chloride and dihydrogen phosphate ions in dichloromethane. The most pronounced colour change was observed upon the addition of the fluoride anion into a solution of the receptor 30 in dichloromethane. The addition of bromide, iodide or nitrate anions did not lead to significant colour changes. 

Fig. 10 Two vinyl-bridged systems of Pcs linked to anthraquinone (14) [72] or a trisPc-benzene system 15 [77]...

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