Characterization of photoinduced isomerization and intersystem crossing of the cyanine dye Cy3.
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 (T1-->Tn) 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 T1-->Tn absorption of cis-Cy3 and the phosphorescence from triplet state of cis-Cy3 following a singlet excitation (S0-S1) 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.
Jia
Ke
K
The State Key Laboratory of Molecular Reaction Dynamics, and Beijing National Laboratory for Molecular Sciences (BNLMS), Institute of Chemistry, Chinese Academy of Sciences, Beijing-100080, P. R. China.
Wan
Yan
Y
Xia
Andong
A
Li
Shayu
S
Gong
Fangbin
F
Yang
Guoqiang
G
D002232:Carbocyanines / Q000737:chemistry*; D007536:Isomerism; D008027:Light; D010777:Photochemistry
D002232:Carbocyanines; C089187:cyanine dye 3