Chemiluminescence efficiency, peroxyoxalate

Peroxyoxalate chemiluminescence is the most efficient nonenzymatic chemiluminescent reaction known. Quantum efficiencies as high as 22—27% have been reported for oxalate esters prepared from 2,4,6-trichlorophenol, 2,4-dinitrophenol, and 3-trif1uoromethy1-4-nitropheno1 (6,76,77) with the duorescers mbrene [517-51-1] (78,79) or 5,12-bis(phenylethynyl)naphthacene [18826-29-4] (79). For most reactions, however, a quantum efficiency of 4% or less is more common with many in the range of lO " to 10 ein/mol (80). The inefficiency in the chemiexcitation process undoubtedly arises from the transfer of energy of the activated peroxyoxalate to the duorescer. The inefficiency in the CIEEL sequence derives from multiple side reactions available to the reactive intermediates in competition with the excited state producing back-electron transfer process. 

The leaving group of the oxalic ester has a strong effect on the efficiency of the peroxyoxalate chemiluminescent system. The electron-attracting power of the substituents on the phenyl rings of the substituted diphenyl oxalates is important to the overall efficiency of the chemiluminescent reactions. Steric effects... 

A wide variety of different classes of fluorescent molecules has been investigated in the peroxyoxalate chemiluminescent systems. Among those screened were fluorescent dyes such as rhodamines and fluoresceins, heterocyclic compounds such as benzoxazoles and benzothiazoles, and a number of polycyclic aromatic hydrocarbons such as anthracenes, tetracenes, and perylenes. The polycyclic aromatic hydrocarbons and some of their amino derivatives appear to be the best acceptors as they combine high fluorescence efficiency with high excitation efficiency in the chemiluminescent reaction [28],... 

It must be pointed out that, despite the lack of direct experimental support for this hypothesis, the involvement of the electron transfer in luminol chemiexcitation is related to the chemiexcitation steps proposed for several highly efficient chemi- and biolu-minescent systems, such as activated peroxyoxalate chemiluminescence and the firefly luciferin/luciferase system (Section... 

Among different coumarin derivatives used, 7-Amino-4-trifluoromethylcoumarin (ATFMC) revealed the most promising characteristics as an efficient fluorescent emitter. AFTMC is used in the synthesis of a substrate for fluorimetric assay of proteolytic enzymes and for use as a laser dye. We have recently investigated the chemiluminescence reactions of some peroxyoxalate esters, hydrogen peroxide and AFTMC. In this paper we report the solvent effects on the kinetics of the chemiluminescence process of the peroxyoxalate chemiluminescence in the presence of AFTMC. 

The CDs also can be used to enhance chemiluminescence of the luminol related compounds. It was foimd that CDs were capable of increasing the light output by factors up to 300 in aqueous peroxyoxalate solution. The enhancement could be attributed to increases in reaction rate, excitation efficiency and fluorescence efficiency of the emitting species. 

Unlike the light-producing reactions described above, peroxyoxalate chemiluminescence is not well suited to aqueous conditions, due to the limited solubility and stability of the reagents in that solvent. This system has been used to detect compounds that can act as efficient fluorophores (e.g., amino-substituted polyaromatic hydrocarbons), or after derivatization of the target analytes with... 

---