Photodissociation of hexaarylbiimidazole. 2. Direct and sensitized dissociation
Photodissociation of hexaarylbiimidazole. 2. Direct and sensitized dissociation
复制标题
六芳基联咪唑的光解。
DOI：
10.1021/j100180a040
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发表时间：
1992
期刊：
影响因子：
--
通讯作者：
V. Krongauz
中科院分区：
文献类型：
--
作者：
A. Liu;A. Trifunac;V. Krongauz
研究了广泛使用的光聚合引发剂2-氯六芳基联咪唑（o-Cl-HABI）在二氯甲烷溶液中，在可见光光敏染料2，5-二[（2，3，6，7-四氢-1H，5H-苯并[ij]喹嗪-1-基）亚甲基]环戊酮（JAW）存在和不存在下的光解反应.采用480 nm的激光闪光光解。在不存在JAW的情况下，o-Cl-HABI解离成三芳基咪唑基自由基（L*）。在JAW的存在下，观察到L* 形成的增加。探讨了这种解离光敏化的机理。它的结论是，这种增加发生的解离的o-Cl-HABI自由基阴离子形成的电子转移从激发单重态的JAW o-Cl-HABI。所观察到的L* 自由基的形成表现出线性依赖o-Cl-HABI浓度。由该关系式得到的电子转移速率常数等于（2.2 ± 0.4）× 10{sup 9} M{sup {minus}1} s{sup {minus}1}。JAW的激发三重态与p-Cl-HABI没有反应。参考文献22，10个无花果。
Photodissociation of a widely used photopolymerization initiator, 2-chlorohexaarylbiimidazole (o-Cl-HABI), is studied in dichloromethane solution in the absence and presence of the visible light photosensitizing dye, 2,5-bis[(2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolizin-1-yl) methylene]cyclopentanone (JAW). Laser flash photolysis at 480 nm is employed. In the absence of JAW, the o-Cl-HABI dissociates into triarylimidazolyl radicals (L*). In the presence of JAW, an increase in L* formation is observed. The mechanism of this photosensitization of dissociation is explored. It is concluded that this increase occurs by the dissociation of the o-Cl-HABI radical anion formed by electron transfer from the excited singlet state of JAW to o-Cl-HABI. The observed formation of L* radicals exhibits a linear dependence on o-Cl-HABI concentration. The rate constant of electron transfer obtained from this dependence is equal to (2.2 {plus_minus} 0.4) {times} 10{sup 9} M{sup {minus}1} s{sup {minus}1}. No reaction between the excited triplet state of JAW and p-Cl-HABI is found. 22 refs., 10 figs.