Characterization of photoinduced isomerization and intersystem crossing of the cyanine dye Cy3
Characterization of photoinduced isomerization and intersystem crossing of the cyanine dye Cy3
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DOI：
10.1021/jp067843i
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发表时间：
2007-03-08
影响因子：
2.9
通讯作者：
Yang, Guoqiang
中科院分区：
文献类型：
--
作者：
Jia, Ke;Wan, Yan;Yang, Guoqiang
用激光闪光光解法测定了菁染料Cy_3的几个重要的物理化学性质。利用重原子效应和氧诱导三重态->三重态能量转移区分了Cy 3的三重态吸收和光致异构化。此外，还分别用三重态-三重态能量转移法和比较光光度法测量了Cy 3的三重态消光系数和量子产率。发现trans-Cy 3的三重态->三重态（T-1 -> T-n）吸收与cis-Cy 3的基态吸收有很大的重叠。与在Cy 5中发生的不同，我们没有观察到顺式-Cy 3的三重态T-1 -> T-n吸收和在反式-Cy 3的单重激发（S-0-S-1）之后来自顺式-Cy 3的三重态的磷光，表明在Cy 3中激发时不存在作为异构化中间体的最低顺式-三重态。本文报道的Cy 3的详细光谱有助于我们解释菁染料复杂的化学物理。
Several important photophysical properties of the cyanine dye Cy3 have been determined by laser flash photolysis. The triplet-state absorption and photoisomerization of Cy3 are distinguished by using the heavy-atom effects and oxygen-induced triplet -> triplet energy transfer. Furthermore, the triplet-state extinction coefficient and quantum yield of Cy3 are also measured via triplet-triplet energy-transfer method and comparative actinometry, respectively. It is found that the triplet -> triplet (T-1 -> T-n) absorptions of trans-Cy3 largely overlap the ground-state absorption of cis-Cy3. Unlike what occurred in Cy5, we have not observed the triplet-state T-1 -> T-n absorption of cis-Cy3 and the phosphorescence from triplet state of cis-Cy3 following a singlet excitation (S-0-S-1) of trans-Cy3, indicating the absence of a lowest cis-triplet state as an isomerization intermediate upon excitation in Cy3. The detailed spectra of Cy3 reported in this paper could help us interpret the complicated photophysics of cyanine dyes.