Singlet molecular oxygen photosensitizer

Nonell, S. and Redmond, R.W., On the determination of quantum yields for singlet molecular oxygen photosensitization,/. P/zotoc/jem. Photobiol, B Biol, 22, 171, 1994. 

The basic structure of carotenoids is a conjugated polyprenoid chain. Carotenoids exert a positive impact on human welfare. They show marked singlet molecular oxygen quenching capacity [11] and they protect against photosensitized peroxidation of lipids [12],... 

Type 1 intrazeolite photooxygenation of alkenes has been also reported to give mainly allylic hydroperoxides (Scheme 42). In this process, the charge transfer band of the alkene—O2 complex within Na-Y was irradiated to form the alkene radical cation and superoxide ion. The radical ion pair in turn gives the allylic hydroperoxides via an allylic radical intermediate. On the other hand, for the Type II pathway, singlet molecular oxygen ( O2) is produced by energy transfer from the triplet excited state of a photosensitizer to 02. 

Singlet molecular oxygen (lC>2) is a very small electrophilic reagent that can produced by photosensitization and react easily with dienes and alkenes in [4 + or [2 + 2] cycloadditions or ene-reactions. In order to develop synthetic applic tions of photooxygenations, numerous studies have recently been developed wi chiral substrates and especially in the presence of chiral auxiliaries. 

Hall RD, Buettner GR, Motten AG, ChigneU CF. Near-infrared detection of singlet molecular oxygen produced by photosensitization with promazine and chlorpromazine. Photochem Photobiol 1987 46 295-300. 

Khan, A.U. (1985) Singlet molecular oxygen spectroscopy chemical and photosensitized, in Frimer, A.A. (Ed.), Singlet 02, Boca Raton, FL, CRC Press, pp. 39-79. 

One of the common uses of photosensitizers in organic reactions has been to produce singlet molecular oxygen ( 02) using various dyestuffs. As early as 1967, Leermark and James reported the use of a polymer-based carbonyl sensitizer. Although there is some reason to believe that Leermark and James photosensitizing of the reaction may have been due to the presence of the dissolved monomer, the idea still has a great deal of merit. 

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