A kinetic study on singlet molecular oxygen (O2(1Δg)) generation and quenching by dihydroxynaphthalenes
作者:
Marta Luiz,
Arnaldo T. Soltermann,
Alicia Biasutti,
Norman A. Garcia,
期刊:
Canadian Journal of Chemistry
(NRC Available online 1996)
卷期:
Volume 74,
issue 1
页码: 49-54
ISSN:0008-4042
年代: 1996
DOI:10.1139/v96-006
出版商: NRC Research Press
数据来源: NRC
摘要:
A kinetic study on the aerobic (O2(1Δg)-mediated) photooxidation of a series of dihydroxynaphthalenes was carried out. Members of this family of compounds include important environmental contaminants. The interaction with O2(1Δg), determined by both time-resolved phosphorescence and static methods, yields a quenching rate constant in the range of 105–109 M−1s−1, depending on the solvent polarity, pH, and substitution pattern of the dihydroxynaphthalene. According to experimental evidence, the mechanism of the interaction seems to be mediated by an encounter complex with a considerable charge transfer component. From a mechanistic point of view this characteristic of DHN indicates a behaviour very similar to that of simple substituted phenols and dihydroxybenzenes. Quantum yields for DHN photooxidation (Φr) indicate that these substrates are excellent candidates for O2(1Δg)-mediated degradation under environment conditions. Furthermore, these compounds proved to be good self-sensitizers upon irradiation at 337 nm. Quantum yields (ΦΔ) for the production of O2(1Δg) were determined to be on the order of 0.25 in benzene.Keywords: dihydroxynaphthalenes, photooxidation, quenching, sensitization.not available
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