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Quenching of aromatic triplet by monomeric and polymeric radicals in polymer film at 77 K

Š. Chmela and P. Hrdlovič

Polymer Institute, Centre for Chemical Research, Slovak Academy of Sciences, CS-842 36 Bratislava

 

Abstract:  The quenching of triphenylene phosphorescence by monomeric, dimeric or polymeric radicals in poly(methyl methacrylate) film was investigated at 77 K. The low-molecular N-oxyl radicals (11 types) were prepared by oxidation of parent sterically hindered amines. The phosphorescence of triphenylene in solid matrix is influenced by the type of matrix, concentration of triphenylene, and traces of the solvents which have been used for the preparations of films. The values of active spheres of quenching for monomeric N-oxyl radicals were in the interval ⟨1.7 nm; 2.1 nm⟩ while no correlation between the size of active sphere and change in radical structure could be observed outside the paramagnetic centre. In a given system, the biradical exhibited quenching efficiency which was merely slightly greater than that of monoradical. As for polymeric radical, only small fraction (about 5 mole %) of the present paramagnetic centres was effective as quencher, which corresponds to molecu­lar dimensions. For quenching of triphenylene by N-oxyl radicals in film, the parameter γ=15 was determined.

Full paper in Portable Document Format: 382a199.pdf

 

Chemical Papers 38 (2) 199–215 (1984)

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