Mechanistic studies on the photodegradation of 2,5-dialkyloxyl-substituted para-phenylenevinylene oligomers by singlet oxygen

被引:9
作者
Burrows, Hugh D. [1 ]
Narwark, Oliver [2 ]
Peetz, Ralf [2 ]
Thorn-Csanyi, Emma [2 ]
Monkman, Andrew P. [3 ]
Hamblett, Ian [4 ]
Navaratnam, Suppiah [5 ]
机构
[1] Univ Coimbra, Dept Quim, P-304535 Coimbra, Portugal
[2] Univ Hamburg, Inst Tech & Makromol Chem, D-20146 Hamburg, Germany
[3] Univ Durham, Dept Phys, Organ Electroact Mat Res Grp, Durham DH1 3LE, England
[4] Christie Hosp NHS Trust, PICR, Dept Radiochem Targeting & Imaging, Manchester M20 9BX, Lancs, England
[5] Univ Salford, Biosci Res Inst, Salford M4 4WT, Lancs, England
关键词
LIGHT-EMITTING-DIODES; VINYLENE PV OLIGOMERS; PULSE-RADIOLYSIS; TRIPLET-STATE; SPECTROSCOPIC CHARACTERIZATION; PHOTOPHYSICAL PROPERTIES; REACTIVE INTERMEDIATE; CONJUGATED POLYMERS; ABSORPTION-SPECTRA; HOMOLOGOUS SERIES;
D O I
10.1039/c0pp00053a
中图分类号
Q5 [生物化学]; Q7 [分子生物学];
学科分类号
071010 ; 081704 ;
摘要
Time-dependent UV/visible absorption changes are observed on photolysis of aerated solutions of monodisperse, vinyl end-capped 2,5-diheptyloxyl substituted PV-oligomers (OPV, n = 1, 2, 3). In all cases, photolysis occurs in at least two distinct stages. Evidence for the intermediacy of singlet oxygen comes from pulse radiolysis and time-resolved luminescence studies, which confirm formation of the OPV triplet state and its quenching by molecular oxygen to produce singlet oxygen. The subsequent reaction with oligomers is observed directly by time-resolved phosphorescence and indirectly through product identification. The results strongly suggest that the reaction between singlet oxygen and OPV proceeds via cycloaddition, leading to bond scission and aldehyde group formation. The reactivity of vinylene linkages is greater than of vinyl end groups. Consequently, the photostability decreases as the chain length is extended. Implications on the oxidative degradation of poly(p-phenylenevinylene)s in optoelectronic devices, and of competing singlet oxygen and superoxide radical anion degradation pathways, are discussed.
引用
收藏
页码:942 / 948
页数:7
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