Chemiluminescence, accompanied

Zhang ZF, Cui H and Shi MJ. Chemiluminescence accompanied by the reaction of gold nanoparticles with potassium permanganate. Phys Chem Chem Phys 2006 8 1017-21. 

In contrast with the diatomic halogens, reactions of metals with O2 and other oxidants frequently involve long-lived complexes. The MO2 or MOR lifetime may be close to a rotational period and the energy disposal may depend upon collision energy and the properties of the different metal atom. Chemiluminescence accompanies many of the metal atom oxidation reactions however, the branching fraction normally is small and the chemiluminescence aspect will not be emphasized here. Velocity distributions, from molecular-beam studies, and vibrational rotational distributions, from laser-induced fluorescence studies, are available and some of the results are summarized in Table 2.16. 

Chemiluminescence accompanying thermolysis of certain acene endoperoxides has been well known for more than 40 years. Examples are the peroxides from diphenyl anthracene (39) [36], rubrene (40) [37], and l,4-dimethoxyl-9,10-diphenyl anthracene (42) [38, 39]. 

Some chemiluminescence accompanies this reaction, and emission matches the fluorescence of the isobenzofuran derivative (54), presumably excited by energy transfer or direct by CIEEL. 

RO—CF=CF2, are obtained by reaction with sodium salts of alcohols (26). An osone—TFE reaction is accompanied by chemiluminescence (27). Dimerization at 600°C gives perfluorocyclobutane, C Fg further heating gives hexafluoropropylene, CF2=CFCF2, and eventually perfluoroisobutylene, CF2=C(CF2)2 (28). Purity is deterrnined by both gas—Hquid and gas—soHd chromatography the in spectmm is complex and therefore of no value. 

Side reaction. The luminescence reaction of Cypridina luciferin catalyzed by luciferase involves a side reaction (Fig. 3.1.8). In the luminescence reaction, 85-90% of luciferin is converted into oxyluciferin and CO2 accompanied by light emission, whereas 10-15% of luciferin is converted directly into etioluciferin plus a keto-acid without light emission (Shimomura and Johnson, 1971). In the chemiluminescence reactions of Cypridina luciferin in organic solvents (such as diglyme, acetone, pyridine and DMSO), the proportion of the dark side reaction... 

Solubility and stability of coelenterazine. Coelenterazine is very poorly soluble in neutral aqueous buffer solutions, and the solutions are unstable in air. It can be easily dissolved in water in the presence of alkali, but the resulting solution is extremely unstable under aerobic conditions. Coelenterazine is soluble in methanol, and the solution is relatively stable. The stability is enhanced by the addition of a trace of HCl. A methanolic solution of coelenterazine can be stored for several days at — 20°C, and a methanolic solution containing 1-2 mM HCl can be stored for several months at — 70°C under aerobic conditions without significant oxidation. In many other organic solvents, coelenterazine is less stable, and spontaneously auto-oxidized at significant rates. In dimethylformamide and DMSO, it is rapidly decomposed accompanied by the emission of chemiluminescence. e-Coelenterazines are generally less stable than coelenterazines. 

Emission of li t accompanying the passage of an electric current through aqueous solutions and arising from chemical reactions of chemiluminescent species produced during electrolysis. 

The chemiluminescence intensity accompanying the oxidation of polymers is usually dependent on the concentration of oxygen in the surrounding atmosphere (Figures 21 and 22). This is confirmed by restricting the diffusion... 

The same may be observed with magnesium carbonate in cellulose [70] (Figure 26). The chemiluminescence intensity at a given temperature increases with pH of the sample almost linearly. As it is evidenced by DSC, the sample with pH 7.2 is the least stable. Figure 26 is also a demonstration of the much higher sensitivity of the chemiluminescence method when compared with DSC. DSC exotherms, which accompany the final stages of the cellulose decomposition... 

Numerous autoxidation reactions of aliphatic and araliphatic hydrocarbons, ketones, and esters have been found to be accompanied by chemiluminescence (for reviews see D, p. 19 14>) generally of low intensity and quantum yield. This weak chemiluminescence can be measured by means of modern equipment, especially when fluorescers are used to transform the electronic excitation energy of the triplet carbonyl compounds formed as primary reaction products. It is therefore possible to use it for analytical purposes 35>, e.g. to measure the efficiency of inhibitors as well as initiators in autoxidation of polymer hydrocarbons 14), and in mechanistic studies of radical chain reactions. 

The dismutation (disproportioning) of two free radicals is accompanied by release of a portion of reaction energy as a light quantum. As the quantum yield of such a process is extremely low, the detection of this type of chemiluminescence is technically complicated. Several compounds like lucigenin and luminol have a high quantum yield after reaction with peroxide radicals. Therefore, they are widely used for the detection of these radicals, particularly in the examination of phagocyting cells. 

Thereafter the free radicals can react with one another and with the initial molecules. The reaction LH + 02" —> 02 + LFT is not accompanied by chemiluminescence [23],... 

Another well-known CL amplifier, which is also frequently used for superoxide detection in biological systems, is luminol (5-amino-2,3-dihydro- 1,4-phthalazinedione). It has been proposed that luminol semiquinone reacts with superoxide to form the peroxide intermediate, whose decomposition is accompanied by chemiluminescence [62]. 

We should also note that there are other ways in which substances can luminesce (/.e., produce light). One of the most common nonfluorescent mechanisms is called chemiluminescence. Chemical reactions can produce light when radicals (/.e., atoms or molecules with reactive unpaired electrons) combine to form a covalent bond. Heating of molecules can also cause them to display chemiluminescence. And, of course, there are biological processes that are accompanied by chemiluminescence. The most familiar case is the luciferase reaction associated with fire flies and luminescent marine creatures. Peroxidase reactions also produce faint luminescence. 

Hi. Lysine. Gamma radiolysis of aerated aqueous solution of lysine (94) has been shown, as inferred from iodometric measurements, to give rise to hydroperoxides in a similar yield to that observed for valine and leucine. However, attempts to isolate by HPLC the peroxidic derivatives using the post-column derivatization chemiluminescence detection approach were unsuccessful. This was assumed to be due to the instability of the lysine hydroperoxides under the conditions of HPLC analysis. Indirect evidence for the OH-mediated formation of hydroperoxides was provided by the isolation of four hydroxylated derivatives of lysine as 9-fluoromethyl chloroformate (FMOC) derivatives . Interestingly, NaBILj reduction of the irradiated lysine solutions before FMOC derivatization is accompanied by a notable increase in the yields of hydroxylysine isomers. Among the latter oxidized compounds, 3-hydroxy lysine was characterized by extensive H NMR and ESI-MS measurements whereas one diastereomer of 4-hydroxylysine and the two isomeric forms of 5-hydroxylysine were identified by comparison of their HPLC features as FMOC derivatives with those of authentic samples prepared by chemical synthesis. A reasonable mechanism for the formation of the four different hydroxylysines and, therefore, of related hydroperoxides 98-100, involves initial OH-mediated hydrogen abstraction followed by O2 addition to the carbon-centered radicals 95-97 thus formed and subsequent reduction of the resulting peroxyl radicals (equation 55). 

Dufraisse has shown that the oxygen liberation from acene endo-peroxides is quite often accompanied by chemiluminescence, the spectrum of which is usually similar to the fluorescence of the corresponding hydrocarbon,271-273 although this point seems to require confirmation.274 According to Bowen,275 the most likely processes involved are... 

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