HYDROXYANTHRAQUINONES AS SENSITIZERS OF SINGLET OXYGEN REACTIONS - QUANTUM YIELDS OF TRIPLET FORMATION AND SINGLET OXYGEN GENERATION IN ACETONITRILE
HYDROXYANTHRAQUINONES AS SENSITIZERS OF SINGLET OXYGEN REACTIONS - QUANTUM YIELDS OF TRIPLET FORMATION AND SINGLET OXYGEN GENERATION IN ACETONITRILE
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DOI：
10.1016/1010-6030(92)85273-w
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发表时间：
1992-12-01
影响因子：
4.3
通讯作者：
BRASLAVSKY, SE
中科院分区：
文献类型：
--
作者：
GOLLNICK, K;HELD, S;BRASLAVSKY, SE
本文研究了α-和β-羟基取代的9，10-蒽醌（1-AQ，2-AQ，1，2-AQ，1，4-AQ，1，8-AQ，2，6-AQ，3-Me-1，6，8-AQ和1，2，5，8-AQ）的电子物理性质，特别是三重态的性质。在室温乙腈中，荧光从短寿命（τ（F）小于或等于1 ns）、最低激发1（pi，pi*）态（E（S（1））在65和55 kcal mol-1之间）发生，量子产率（PHI（F）小于或等于0.025（例外是τ（F）几乎等于2ns且PHI（F）几乎等于0.1的1，4-AQ）。在甲基环己烷以及EPA中，在77 K下，AQ产生振动分辨的磷光光谱，由此确定最低三重态T1（n，pi*）的能量（E（T）= 61.6 kcal mol-1）。对于羟基-AQ，假定具有与AQ几乎相同的能量的3（n，pi*）态应该代表第二三线态T2，而最低三线态T1应该是位于T2态之下的3（pi，pi*）态。发现三重态量子产率PHI（T）以及单重态氧量子产率PHI（DELTA）取决于羟基-AQ的1（π，π *）态是否位于相应的3（n，π *）态之上或附近（PHI（T）大于或等于0.7; PHI（DELTA）小于或等于0.65）或明显低于该状态（PHI（T）小于或等于0.5; PHI（DELTA）小于或等于0.3）。这些结果是通过假设，对于具有相对高的S1水平的羟基-AQ，从S1（pi，pi*）到T2（n，pi*）的系统间交叉（随后快速内部转化为T1（pi，pi*）），除了S1（pi，pi*）-> T1（pi，pi *）跃迁之外，有效地有助于形成长寿命的T1状态来解释的。对于具有相对低的S1能级的羟基-AQs，后一个跃迁几乎完全负责T1态的形成，O-3（2）对T1态的猝灭应该是主要的，如果不是O2（1DELTAg）产生的唯一来源的话。
The photophysical properties, in particular those of the triplet states, of alpha- and beta-hydroxy-substituted 9,10-anthraquinones (1-AQ, 2-AQ, 1,2-AQ, 1,4-AQ, 1,8-AQ, 2,6-AQ, 3-Me-1,6,8-AQ and 1,2,5,8-AQ) were studied. In acetonitrile at room temperature, fluorescence occurs from the short-lived (tau(F) less-than-or-equal-equal-to 1 ns), lowest excited 1(pi, pi*) states (E(S(1)) between 65 and 55 kcal mol-1) with quantum yields (PHI(F) less-than-or-equal-to 0.025 (the exception is 1,4-AQ with tau(F) almost-equal-to 2 ns and PHI(F) almost-equal-to 0.1). In methylcyclohexane as well as in EPA at 77 K, AQ gives rise to a vibrationally resolved phosphorescence spectrum, from which the energy of the lowest triplet state T1(n, pi*) is determined (E(T) = 61.6 kcal mol-1). For the hydroxy-AQs, the 3(n, pi*) state, assumed to have almost the same energy as that of AQ, should represent the second triplet state T2, Whereas the lowest triplet state T1 should be a 3(pi, pi*) state located appreciably below the T2 state. Triplet quantum yields PHI(T) as well as singlet oxygen quantum yields PHI(DELTA) are found to depend on whether the 1(pi, pi*) state of the hydroxy-AQ is located above or close to the corresponding 3(n, pi*) state (PHI(T) greater-than-or-equal-to 0.7; PHI(DELTA) greater-than-or-equal-to 0.65) or appreciably lower than this state (PHI(T) less-than-or-equal-to 0.5; PHI(DELTA) less-than-or-equal-to 0.3). These results are interpreted by assuming that, for hydroxy-AQs with relatively high S1 levels, intersystem crossing from S1(pi, pi*) to T2(n, pi*) (followed by fast internal conversion to T1(pi, pi*)) contributes efficiently to the formation of the long-lived T1 state, in addition to the S1(pi, pi*) --> T1(pi, pi*) transition. For hydroxy-AQs with relatively low S1 levels, the latter transition is almost exclusively responsible for the formation of the T1 state, the quenching of which by O-3(2) should be the predominant, if not the only source of O2(1DELTAg) production.