Oxygen singlet form

If singlet oxygen is formed by an energy transfer reaction from excited diphenylanthracene to oxygen, the quantum yield of which is the quantum yields of endoperoxide formation are given by... 

If a large amount of the toxic substance is present, then the detoxication processes present are overwhelmed. Excess super oxide is produced, reduced GSH and NADPH are depleted, and hydroxyl radicals and singlet oxygen are formed. This is the condition known as oxidative stress (see also below this chapter). As well as causing lipid peroxidation, ROS will also cause DNA damage and damage to proteins. 

Paramagnetic molecules K)a and 2NO are very efficient quenchers of singlet and triplet states. Oxygen may form CT complex and lead to peroxide formation in the triplet state. Paramagnetic ions of the transition series and lanthanides also quench the triplet states. 

Anthracene and its 9,10-disubstituted derivatives add singlet oxygen to form the 9,10-endoperoxide,825-827 but strong directing effect is displayed by substituents in the 1,4 positions 827... 

Regardless of whether singlet oxygen is formed chemically or photochem-ically, it gives similar products in reactions with alkenes. 

It should be noted that for aqueous systems a suitable dye was not easily found, since many water-soluble dyes apparently undergo a photoreaction in the presence of triplet oxygen, which is photochemically transformed into its reactive singlet form due to sensibilization by the dye [41]. After degassing with argon, good results for aqueous systems have been achieved with Orange I [42]. 

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