Singlet-oxygen generation

Daub, M. E., Leisman, G. B., Clark, R. A., and Bowden, E. F. (1992). Reductive detoxification as a mechanism of fungal resistance to singlet oxygen-generating photosensitizers. Proc. Natl. Acad. Sci. USA 89 9588-9592. 

This reachon, of industrial interest, utilizes singlet oxygen generated by irradiation in the presence of Rose Bengal [40]. An endoperoxide is formed as intermediate which is converted to 2-cyclopentene-l,4-diol by reduchon with thiourea. 

Rozanowska, M, Wessels, J, Boulton, M, Burke, JM, Rodgers, MA, Truscott, TG, and Sarna, T, 1998. Blue light-induced singlet oxygen generation by retinal lipofuscin in non-polar media. Free Radio Biol Med 24, 1107-1112. 

The most important application for singlet oxygen generators (SOGs), namely the anti-cancer treatment known as photodynamic therapy (PDT), is described elsewhere in this series (see Chapter 9.22). However, SOGs are also being evaluated in other areas, such as hard surface disinfectants, soaps and washing powders,73 and insecticides.74,75... 

The palladium(II) phthalocyanines are satisfactory singlet oxygen generators. Thus, f>A values for tetra-t-butylphthalocyanine ((27), with stated replacement for Mg) are 2H, 0.22 Zn, 0.34 Pd, 0.54, i.e., increasing in line with the heavy atom effect.180 For palladium(II) tetra-t-butylphthalocyanine ((27), Pd instead of Mg) in benzene at 290 K, 4>f= 0.048 and X = 0.49.180 However, palladium(II) 2,3-dihydroxy-9,16,23-tri-t-butylphthalocyanine was synthesized by a mixed condensation (1 9 mix of appropriate dinitriles) as a likely amphiphilic sensitizer, but did not show bioactivity in an enzyme assay, possibly because of aggregation.180... 

Galletero, M.S., Garcia, H. and Bourdelande, J.L. (2003). Dramatic persistence (minutes) of the triplet excited state and efficient singlet oxygen generation for C-60 incorporated in Y zeolite and MCM-41 silicate. Chem. Phys. Lett. 370, 829-833... 

Prat F, Stackow R, Bernstein R et al. (1999) Triplet-state properties and singlet oxygen generation in a homologous series of functionalized fullerene derivatives. J Phys Chem. 103 7230-7235. 

So G, Karotki A, Verma S, Pritzker K, Wilson B, Chiang LY (2006) Comparison of singlet oxygen generation efficiency between water-soluble C60-diphenylaminofluorene conjugates and molecular micelle-like FC4S. Journal of Macromolecular Science Part A-Pure and Applied Chemistry 43 1955-1963. 

Fig. 35 Molecular structures of singlet oxygen generating fluorene derivatives...

Although the above indirect method provided relatively accurate results, a new method of direct measurement of the IR phosphorescence of O2 ( A ) at 1270 nm was expected to improve the measurement [103]. The quantum yield of two-photon singlet oxygen generation, was calculated from... 

Table 6 Two-photon absorption cross sections, 32PA> and quantum yields of singlet oxygen generation, under single and two-photon excitation of 57-60 at 775 nm in ACN...

A few current examples are shown below and include unsymmetrically substituted derivatives 14227, the cationic derivative 15228, the neutral derivative 16226 and the classic anionic derivative 17229 230, (tetrabenzoporphyrinato)zinc(II) , an intermediate structure between that of porphyrins and phthalocyanines, and have also been investigated in this respect. However, its quantum yield for singlet oxygen generation (0.023) in liposomes is much lower than that of Photofrin (0.19)177. 

Detailed accounts on the photooxygenation of 1,3-diphenyl-benzo[c]furan (and other benzo [cjfurans " ) reveal a dual mechanistic process. In the high concentration region 138 reacts in its ground state with singlet oxygen (generated either by dye sensitization [Scheme 15,... 

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