MECHANISM OF THE TRIPLET-STATE QUENCHING BY MOLECULAR-OXYGEN IN SOLUTION
MECHANISM OF THE TRIPLET-STATE QUENCHING BY MOLECULAR-OXYGEN IN SOLUTION
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DOI：
10.1021/j100067a006
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发表时间：
1994-04-21
影响因子：
--
通讯作者：
BRAUER, HD
中科院分区：
文献类型：
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作者：
GREWER, C;BRAUER, HD
在甲苯中测定了氧对几种取代芳烃和酮的最低激发三重态的猝灭速率常数k（q）（T），其范围为0.3 × 10（9）~ 15 × 10（9）M（-1）s（-1）。测定单线态氧（O-2（（1）Delta（g）形成的效率S-Delta，范围为0.24至1.00。结果可以用CT相互作用来解释，因为k（q）（T）和S-Delta与电子转移自由焓Δ G（el）相关，所述电子转移自由焓Δ G（el）由敏化剂和O-2的氧化还原电位计算。测定单重态和三重态通道的猝灭概率，允许计算（k（i）/k（-d））（其中i = en，能量转移，或ic，内部转化），其表现出对Δ G（el）的近似线性依赖性。在一种情况下（9-甲基咔唑），直接证据遇到复杂的系统间交叉发现和讨论方面的可逆电荷转移（CT）复杂的形成和CT复杂的系统间交叉，以获得概率的系统间交叉过程为0.27。
Rate constants k(q)(T) ranging between 0.3 X 10(9) and 15 x 10(9) M(-1) s(-1) for quenching of the lowest excited triplet state of several substituted aromatic hydrocarbons and ketones by molecular oxygen were measured in toluene. The efficiencies of singlet oxygen (O-2((1) Delta(g))) formation S-Delta were determined, ranging from 0.24 to 1.00. The results can be explained by CT interaction in that k(q)(T) and S-Delta correlate with the free enthalpy of electron transfer Delta G(el), calculated from the redox potentials of the sensitizer and O-2. Quenching probabilities for the singlet and triplet channel were determined allowing the calculation of(k(i)/k(-d)) (where i = en, energy transfer, or ic, internal conversion), which exhibit an approximately linear dependence on Delta G(el). In one case (9-methylcarbazole), direct evidence for encounter complex intersystem crossing is found and discussed in terms of reversible charge transfer (CT) complex formation and CT complex intersystem crossing to obtain a probability of the intersystem crossing process of 0.27.