Trans to cis photoisomerization of N,N′-disubstituted indigo dyes via excited singlet states; a laser flash photolysis and steady state irradiation study
Trans to cis photoisomerization of N,N′-disubstituted indigo dyes via excited singlet states; a laser flash photolysis and steady state irradiation study
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N,N-二取代靛蓝染料通过激发单线态的反式光异构化和稳态照射研究；
DOI：
10.1139/v87-120
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发表时间：
1987
影响因子：
1.1
通讯作者：
J. Kossanyi
中科院分区：
文献类型：
--
作者：
H. Görner;J. Pouliquen;J. Kossanyi
用纳秒闪光光解和稳态测量方法研究了激发态反式-N，N‘-双酰亚胺染料(反式-1-反式-4)和刚性反式(5)和顺式(6)靛蓝类似物的弛豫路径。在液体中，1-4的反式光异构化反应是通过直接激发下的单重态机制进行的，而三重态似乎只有通过敏化反应才能达到。与1相比，室温下反式 → 顺式异构化反应的量子产率较低，这是由于导致反式基态的热激活内转换步骤。这一途径与处于激发单重态的中心双键周围的分子的荧光和扭曲竞争。增加介质的粘度减少了柔性分子的扭曲，结果是增加了最低三重态的布居。三重态瞬变的强度随介质粘度的增加而增大。
The relaxation pathways of excited trans-N,N′-diacylindigo dyes (trans-1–trans-4) and of the rigid trans (5) and cis (6) indigo analogues have been studied by nanosecond flash photolysis and steady state measurements. In fluid solution the trans to cis photoisomerization of 1–4 occurs via a singlet excited state mechanism on direct excitation, and the triplet state appears to be reached only by sensitized reaction. The lower quantum yield for trans → cis isomerization of 2–4 at room temperature, as compared to 1, is due to a thermally activated internal conversion step leading to the trans ground state. This pathway competes with fluorescence and twisting of the molecule around the central double bond in the excited singlet state. Increasing the viscosity of the medium decreases the twisting of the flexible molecules and, as a consequence, increases the population of the lowest triplet state. A triplet transient, the intensity of which increases with the viscosity of the medium, could be characterized at ...