1,8-Acridinedione dyes

The sequential electron-proton-electron transfer mechanism is in agreement with the experimental observation by Ohno et al. [141]. The mechanism was confirmed by Selvaraju and Ramamurthy [142] from photophysical and photochemical study of a NADH model compound, 1,8-acridinedione dyes in micelles. 

SEE 01] Selvaraju C., Sivakumar A., Rammamurthy P., Excited state reactions of acridinedione dyes with onium salts mechanistic details , Journal of Photochemistry and Photobiology A Chemistry, vol. 138, no. 3, pp. 213-226, 2001. 

The oxidative degradations of binuclear azaarenes (quinoline, isoquinoline, and benzodrazines) by hydroxyl and sulfate radicals and halogen radicals have been studied under both photochemical and dark-reaction conditions. A shift from oxidation of the benzene moiety to the pyridine moiety was observed in the quinoline and isoquinoline systems upon changing the reaction from the dark to photochemical conditions. The results were interpreted using frontier-orbital calculations. The reaction of OH with the dye 3,3,6,6-tetramethyl-3,4,6,7,9,10-hexahydro-(l,8)(2//,5//)-acridinedione has been studied, and the transient absorption bands assigned in neutral solution.The redox potential (and also the pA a of the transient species) was determined. Hydroxyl radicals have been found to react with thioanisole via both electron transfer to give radical cations (73%) and OH-adduct formation (23%). The bimolec-ular rate constant was determined (3.5 x lO lmoU s ). " ... 

A wide assortment of additional electron-transfer PSs for diaryliodonium salts have been described in the journal and patent literature. These include ketocoumarins [FOU 88], 9,10-phenanthraquinone [BAU 86], Mannich bases [DE 88b], 1,3-indanediones [TEH 13], benzoquinonylsulfanyl derivatives [SUG 03], acridinediones [SEE 01] and dimethylaminobenzylidine derivatives [ICH 87], In addition, the use of dyes such as eosine and Rhodamine [DE 88a, DE 89] have been employed to provide photosensitization in the visible region of the spectrum. A particularly interesting system devised by Yagci et al. [AYD 08] is the dithienothiophene, 48, used with diphenyliodonium hexaflurophosphate to carry out the cationic photopolymerizations of cyclohexene oxide, 3,4-epoxycyclohexylmethyl 3, 4 -epoxycyclohexane carboxylate, N-vinyl carbazole, n-butyl vinyl ether and styrene. These investigators have further applied this system to the preparation of metallic silver-filled epoxy nanocomposites [YAG 11]. 

---