Diphenylanthracene chemiluminescence

Examples include luminescence from anthracene crystals subjected to alternating electric current (159), luminescence from electron recombination with the carbazole free radical produced by photolysis of potassium carba2ole in a fro2en glass matrix (160), reactions of free radicals with solvated electrons (155), and reduction of mtheiiium(III)tris(bipyridyl) with the hydrated electron (161). Other examples include the oxidation of aromatic radical anions with such oxidants as chlorine or ben2oyl peroxide (162,163), and the reduction of 9,10-dichloro-9,10-diphenyl-9,10-dihydroanthracene with the 9,10-diphenylanthracene radical anion (162,164). Many other examples of electron-transfer chemiluminescence have been reported (156,165). 

Similar results were obtained with the diperoxides 5 (R phenyl) and 5 a (R />-chlorophenyl) and dibenzanthrone or other fluorescers (perylene, rhodamine B, 9.10-diphenylanthracene, anthracene, fluorescein), with quantum yields of the respective chemiluminescence in the range 3.29 X 10 8.... 5.26 X 10 6. 

From all anthracene endo peroxides investigated so far (71> 1>, p. 132) the compound 7 (1.4-dimethoxy-9.10-diphenylanthracene 1.4-endoperox-ide) was found to exhibit the most efficient chemiluminescence 72> on... 

Another rather striking example demonstrates that the fluorescence efficiency of the respective dicarboxylates is not the most important factor in determining the chemiluminescence efficiencies of the hydrazides 9.10-diphenylanthracene-2.3-dicarbonic acid 25 has a fluorescence efficiency of about 0.9 (as has the parent compound 9.10-di-phenylanthracene) 94>. The corresponding hydrazide 26, however, gives a quantum yield of 48% that of luminol only (in DMSO/t-BuOK/ O2) 95) although 3-aminophtalic acid has a fluorescence efficiency of about 0.3 only. 

The main features of the chemiluminescence mechanism are exemplarily illustrated in Scheme 11 for the reaction of bis(2,4,6-trichlorophenyl)oxalate (TCPO) with hydrogen peroxide in the presence of imidazole (IMI-H) as base catalyst and the chemiluminescent activators (ACT) anthracene, 9,10-diphenylanthracene, 2,5-diphenyloxazole, perylene and rubrene. In this mechanism, the replacement of the phenolic substituents in TCPO by IMI-H constitutes the slow step, whereas the nucleophilic attack of hydrogen peroxide on the intermediary l,l -oxalyl diimidazole (ODI) is fast. This rate difference is manifested by a two-exponential behavior of the chemiluminescence kinetics. The observed dependence of the chemiexcitation yield on the electrochemical characteristics of the activator has been rationalized in terms of the intermolecular CIEEL mechanism (Scheme 12), in which the free-energy balance for the electron back-transfer (BET) determines whether the singlet-excited activator, the species responsible for the light emission, is formed ... 

While the unimolecular chemiluminescence of dioxetanones appears to fall easily within the framework of conventional dioxetane chemiluminescence, the chemiluminescence of dioxetanones in the presence of certain fluorescers falls resoundingly outside that framework. Adam et al. (1974) noted that the addition of rubrene to solutions of dimethyldioxetanone gave a yield of light twenty times that obtained when an equivalent concentration of 9,10-diphenylanthracene was added. Importantly, the apparent dissimilarity between rubrene and diphenylanthracene is inexplicable by any conventional mechanism of dioxetane decomposition. Also, significantly, Adam et al. (1974) observed an increase in the first-order decay constant of the dioxetanone with the addition of rubrene, an observation for which they did not offer an explanation. Sawaki and Ogata (1977) also observed an unusual dependence of the chemiluminescence yield on the identity of added fluorescer in the base-catalyzed decomposition of or-hydroperoxyesters, for which a dioxetanone intermediate was proposed (25). 

Cyclic peroxides may serve as a source of singlet oxygen. Wasserman et reacted 9,10-diphenylanthracene peroxide (238, conveniently prepared as in Nilsson and Kearns ) with 138 to give 140 rubrene peroxide proved to be considerably less efficient. Decomposition of anthracene peroxide alone takes another course. When 13 is treated with phthaloyl peroxide (239), 140 is isolated in 59% yield the reaction is accompanied by a weak chemiluminescence. A bright yellow chemiluminescence has been observed when a solution of 240 in 1,2,4-trichlorobenzene is treated with dibenzoyl peroxide at about 210°C. The generation of visible light from 138 under conditions where peroxides may present has been described. 

To spot the dioxetanes, monitoring the eluate by TLC, utilizing their peroxidic and/or chemiluminescent properties, is quite convenient. In most instances, a TLC plate soaked with an aqueous KI solution will do but for very resistant cases such as diadamantylidene-l,2-dioxetane (9), ferrous sulfate-ammonium thiocyanate and concentrated hydrochloric acid will not fail. In the case of detection via chemiluminescence, the TLC plate is sprayed with a 9,10-dibromoanthracene DBA) or 9,10-diphenylanthracene (DPA) solution and heated in the dark. The dioxetane spot glows bright blue. 

Most of these excitation yields have been determined by energy-transfer chemiluminescence using 9,10-diphenylanthracene (JJPA) and 9,10-dibromo-anthracene DBA) as fluorescers. 

Catalan LH, Wilson T. Electron transfer and chemiluminescence. Two inefficient systems l,4-dimethoxy-9,10-diphenylanthracene peroxide and diphenyl peroxide. J Amer Chem Soc 1989 111 2633-9. 

Chemiluminescence.—It has been suggested that problems which occur in the determination of yields of bio- and chemi-luminescence may be due to the sample cell. Errors of 25% may be caused by reflection and refraction from interfaces, and, consequently, frosted containers and point-source geometries were recommended. Several authors have concentrated on the use of sensitizers for the enhancement of chemiluminescence. The heavy-atom effect was found to operate in the energy transfer from enzyme-generated acetone to xanthene dyes. 9,10-Diphenylanthracene (9,10-DP A) has been suggested to be a poor singlet counter for chemiluminescence as some triplet states were also counted. In another report, 9,10-dibromoanthracene was found to be a more effective enhancer, when compared with 9,10-DPA, for chemiluminescence from a cyclic peroxide. Luminol chemiluminescence was employed in the analysis of Cr" ions in sea-water. Enhancement with bromide ions enabled detection limits of 3.3 X 10 m to be achieved. 

The reaction of (1) with 9,10-diphenylanthracene is chemiluminescent the diol (7) is a major product. The expected endo-peroxide has not been detected. 

Indirect (sensitized) chemiluminescence was first reported by E.A. Chandross in 1963 as a result of the reaction between oxalyl chloride and hydrogen peroxide in the presence of 9,10-diphenylanthracene (DPA), as shown in reaction [I]. The observed transient blue emission corresponds to the fluorescence of the aromatic hydrocarbon and is generated via energy transfer from an excited-state reaction intermediate ... 

Fan FRF, Mau A, Bard AJ (1985) Electrogenerated chemiluminescence, a chemiluminescent polymer based on poly(vinyl-9,10-diphenylanthracene). Chem Phy Lett 116(5) 400 04... 

A darkened room is required to observe adequately the chemiluminescence of luminol. A darkened hood that has had its window covered with butcher paper or aluminum foil also works well. Other fluorescent dyes besides those mentioned (for instance, 9,10-diphenylanthracene) can also be used for the energy-transfer experiments. The dyes selected may depend on what is immediately available. The instructor may have each student use one dye for the energy-transfer experiments, with one student making a comparison experiment without a dye. 

Santhanam KSV, Bard AJ (1965) Chemiluminescence of electrogenerated 9,10-diphenylanthracene anion radical. J Am Chem Soc 87 139-140. doi 10.1021/ ja01079a039... 

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