Photochemistry of Linear-Shaped Phenylacetylenyl- and (Phenylacetylenyl)phenylacetylenyl-Substituted Aromatic Enediynes
作者:Yoko Sugiyama、Yoshihiro Shinohara、Atsuya Momotake、Kayori Takahashi、Yoko Kanna、Yoshinobu Nishimura、Tatsuo Arai
DOI:10.1021/jp1054827
日期:2010.10.21
constants was not observed, indicating a single emitting state in all cases. All isomers exhibited mutual cis−trans photoisomerization. The quantum yield of both trans-to-cis and cis-to-trans photoisomerization considerably decreased in 2 and 3, presumably due to an increased number of photochemical processes that yield nonreactive excited species and which result in nonradiative deactivation. Three energy
该系列线性形phenylacetylenyl-和(苯基乙炔)苯基乙炔取代的芳族烯二炔类的1 - 3合成为纯的反式和顺式异构体和它们的光化学探讨。与π电子体系的扩展,吸收光谱红移和摩尔消光系数显着增加至122000中号-1厘米-1为反式- 3。cis - 2和cis - 3的吸收光谱由两个独立的吸收带组成。分子的荧光量子产率分别为高,即使对于顺式异构(Φ ˚F= 0.39-0.61)。将每种化合物的荧光衰减分析为单指数,并且未观察到时间常数的波长依赖性,这表明在所有情况下均为单一发射状态。所有异构体均表现出相互的顺-反式光异构化。反式至顺式和顺式至反式光异构化的量子产率在2和3中均显着降低,这可能是由于产生非反应性激发物种并导致非辐射失活的光化学过程数量增加所致。在激发三重态下存在三个最小能量,其中平面构象的能量随苯基乙炔基链的延伸而降低,从而促进了非辐射过程的进行而没有构象变化。