Direct observation of delayed fluorescence from a remarkable back-isomerization in Cy5.
The direct observations of delayed fluorescence and phosphorescence from the cyanine dye Cy5 are reported. The delayed fluorescence is generated from the S(1) state of trans-Cy5 through a reserve intersystem crossing from the cis-triplet state T(1) to the trans-singlet state S(1) via thermal activation. The lowest cis-triplet state is evidenced to be involved in the formation of the isomer. The back-isomerization from cis-triplet state to trans-singlet state crossing, a remarkably back-isomerization pathway that has not been reported before, plays a significant role in this unusual delayed fluorescence.
Huang
Zhengxi
Z
State Key Laboratory of Molecular Reaction Dynamics, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100080, P. R. China.
Ji
Dongmei
D
Xia
Andong
A
Koberling
Felix
F
Patting
Matthias
M
Erdmann
Rainer
R
D002232:Carbocyanines / Q000737:chemistry*; D005456:Fluorescent Dyes / Q000737:chemistry*; D007536:Isomerism; D013050:Spectrometry, Fluorescence; D013816:Thermodynamics
D002232:Carbocyanines; D005456:Fluorescent Dyes; C085321:cyanine dye 5