Photochemical synthesis of pentacene and its derivatives
Photochemical synthesis of pentacene and its derivatives
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DOI：
10.1002/chem.200500564
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发表时间：
2005-10-21
影响因子：
4.3
通讯作者：
Ono, N
中科院分区：
文献类型：
--
作者：
Yamada, H;Yamashita, Y;Ono, N
制备了并五苯的新型α-二酮前体6，13-二氢-6，13-乙并五苯-15，16-二酮，并通过前体在甲苯中的光解成功转化为并五苯，产率为74%：在Ar气氛下用460 nm的光照射二酮的甲苯溶液，导致溶液在几分钟内从黄色变为荧光橙粉色，之后，出现紫色沉淀。35分钟后，溶液变为无色，过滤紫色沉淀，得到并五苯，产率74%。相比之下，在氧气存在下，溶液的颜色从黄色变为浅黄色。并且仅定量获得并五苯的6，13-内过氧化物。通过观察前体在460 nm处的n-pi* 吸收的衰减来测量光解时的反应速率，并且发现在存在和不存在氧的情况下是相似的。因此，α-二酮前体的光反应似乎经由单重激发态发生。由于在Ar气氛下的纳秒瞬态吸收测量中，在前体的光解时观察到并五苯的T-T吸收，并五苯的激发三重态通过敏化产生单线态氧，并且它与基态并五苯反应，得到6，13-内过氧化物。沉积在玻璃上的α-二酮也被成功地转化为并五苯薄膜。此外，还制备了2，8-和2，9-二溴并五苯和2，6-三蒽烯的混合物的二酮前体，并进行了它们的光转换。
A novel alpha-diketone precursor of pentacene, 6,13-dihydro-6,13-ethanopentacene-15,16-dione, was prepared and converted successfully to pentacene in 74% yield by photolysis of the precursor in toluene: Irradiation of the diketone solution in toluene with light of 460 nm under an Ar atmosphere caused the solution to change from yellow to fluorescent orange-pink within a few minutes, after which, purple precipitates appeared. After 35 min, the solution changed to colorless and the purple precipitates were filtered to give pentacene in 74% yield. By contrast, in the presence of oxygen, the color of the solution changed from yellow to pale yellow., and only 6,13-endoperoxide of pentacene was quantitatively obtained. The rate of the reaction upon photolysis was measured by observing the decay of n-pi* absorption of the precursor at 460 nm, and was found to be similar in both the presence and absence of oxygen. Therefore, the photoreaction of the alpha-diketone precursor seemed to occur via the singlet excited state. Because the T-T absorption of pentacene was observed upon photolysis of the precursor in the nanosecond transient absorption measurement under an Ar atmosphere, the excited triplet state of the pentacene generated singlet oxygen by sensitization, and it reacted with the ground-state pentacene to give the 6,13-endoperoxide. The alpha-diketone deposited on glass was also converted successfully to pentacene film by photoirradiation. In addition, diketone precursors of a mixture of 2,8- and 2,9-di-bromopentacene and 2,6-trianthrylene were also prepared and their photoconversion was performed.