Anthraquinone-modified

Salimi, A., Banks, C.E., and Compton, R.G. (2003). Ultrasonic effects on the electroreduction of oxygen at a glassy carbon anthraquinone-modified electrode. The Koutecky-Levich equation applied to insonated electrocatalytic reactions. Phys. Chem. Chem. Phys., 5, 3988-93. 

Pognon, G., T. Brousse, L. Demarconnay, D. Belanger. 2011. Performance and stability of electrochemical capacitor based on anthraquinone modified activated carbon. Journal of Power Sources 196 4117-4122. 

Algharaibeh, Z., X. R. Liu, and P. G. Pickup. 2009. An asymmetric anthraquinone-modified carbon/ruthenium oxide supercapacitor. Journal of Power Sources 187 640-643. 

Thus prepared layers have been further modified to develop electrocatalysts and sensors. Polypyridyl ruthenium-oxo complexes are of particular interest as efficient oxidants for a wide variety of organic molecules, including aromatic hydrocarbons, olefins, alcohols, and ketones. One such electrocatalyst was prepared by first electrografting bipyridine at an applied positive potential followed by treating the modified surface with [Ru tl2(DMSO)(terpyridine)] and then CFjSOjH/HjO [104]. Enhanced electrochemical activity has also been observed for the reduction of oxygen at anthraquinone-modified GC electrodes in 0.1 M KOH solution [105,... 

R.C., and Pal, R. (2013) Cyclic voltammetric investigation of caffeine at anthraquinone modified carbon paste electrode. International Journal of Electrochemistry,... 

Oxygen can be reduced to H2O2 by benzo-, naphtho-, and anthraquinone-modified electrodes [74] and by poly(violo-gen)-modified electrodes [75]. A Prussian blue-modified electrode catalyses electroreduction of O2 to H2O by the four-electron transfer reaction [76]. 

Sarapuu A, Vaik K, Schiffrin DJ, Tammeveski K. Electrochemical reduction of oxygen on anthraquinone modified glassy carbon electrodes in alkaline solution. J Electroanal Chem 2003 541 23-9. 

Yamana, K. et al., Incorporation of two anthraquinonylmethyl groups into the 2 -0-positions of oligonucleotides increased affinity and sequence specificity of anthraquinone-modified oligonucleotides in hybrid formation with DNA and RNA, Bioconjug. Chem., 7,715,1996. 

Kalinathan K, DesRoches DP, Liu X, Pickup PG (2008) Anthraquinone modified carbon fabric supercapacitors with improved energy and power densities. J Power Sources 181 182-... 

In the 1950s acid dyes were successively developed to dye nylon carpet with excellent fastness and uniform leveling. Development of polyacrylonitrile fiber stimulated the invention of anthraquinone basic dyes, modified disperse dyes in which quaternary ammonium groups are introduced. 

Anthraquinone glycosides and aglycones can be readily separated on silica layers rising moderately polar developing solvents [41 3]. The best such solvents eonsist of ethyl acetate modified to increase polarity by the addition of alcohols or water for the glycosides or changed to decrease polarity by inclusion of hydrocarbon components. 

HPLC ESI MS is also a useful tool in the analysis of non-anthraquinone red dyestuffs. The use of this technique allows the identification of carthamin as the main colour component of safflower.[34] Ten species of the genus Alkanna are extracted with hexane, and dissolved in water-methanol solution after evaporation. [47] Ammonium formate buffer (pH 3.0) was used as the mobile phase modifier. In the preparations, alkannin and many hydroxynaphthoquinones (alkannin derivatives) were identified by comparison of retention times, as mass spectra (in the NI mode) for all compounds consisted only of quasi-molecular peaks. 

Only a limited range of nitro, azo and anthraquinone disperse dyes exhibit adequate fastness to dry heat, light and weathering for application on polyester automotive fabrics. The structure of Cl Disperse Yellow 86 was modified to incorporate UV absorbers of the benzophenone, benzotriazole or oxalanilide types into the dye molecule. The derived dyes showed better fastness properties than the parent unsubstituted dye. Positioning of the photostabilising moiety within the dye molecule had little influence on the light fastness obtained, however. Built-in benzophenone residues were more effective than the other two types [177]. Nevertheless, several further monoazo and nitrodiphenylamine disperse dye... 

The selectivity was enhanced by adding small amounts of anthraquinone-2-sulfonate (A2S), which decreased the formation of deoxy by-products. Thus, by adding 260 ppm of A2S with respect to arabinonic acid the selectivity to deoxy-products decreased from 4.2 to 1.6%. A2S acted as a permanent surface modifier since the catalyst was recycled with the same selectivity without further addition of A2S. The highest selectivity to arabitol was 98.9% at 98% conversion, with a reaction rate of 73 mmol h 1 gRU 1 at 80 °C. 

ILs have been used to separate and determine the purity of anthraqui-nones. Rapid and sensitive determination of anthraquinones in Chinese herb using l-butyl-3-methylimidazolium-based IL with p-cyclodextrin (p-CD) as a modifier in CZE was provided by Qi et al. [49]. Successful separation and identification of four anthraquinones of Paedicalyx attopevensis Pierre ex Pitard extracts has been achieved. In the running electrolyte the anthraquinones may associate with the imidazolium ions or with the p-CDs. They may be entirely or partly embedded in the cavity of the p-CDs, so the association with the free imidazolium ions in the bulk solution was weak and those analytes, that were not embedded in the cavity of the p-CDs had rather stronger association with the imidazolium ions in the system. The mechanism of separation is illustrated in Figure 6.6. 

Qi, S., Cui, S., Chen, X., and Hu, Z., Rapid and sensitive determination of anthraquinones in Chinese herb using l-butyl-3-methylimidazolium-based ionic liquid with P-cyclodextrin as modifier in capillary zone electrophoresis, /. Chromatogr. A, 1059,191-198, 2004. 

Scheme 2.3. Catalytic cycle for H202 synthesis using modified anthraquinones.

---