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Colorimetric and Ratiometric Fluorescent Chemosensor Based on Diketopyrrolopyrrole for Selective Detection of Thiols: An Experimental and Theoretical Study
journal contribution
posted on 2011-11-18, 00:00 authored by Ling Deng, Wenting Wu, Huimin Guo, Jianzhang Zhao, Shaomin Ji, Xin Zhang, Xiaolin Yuan, Chunlei ZhangA colorimetric and ratiometric fluorescent thiol probe
was devised
with diketopyrrolopyrrole (DPP) fluorophore. The probe gives absorption
and emission at 523 and 666 nm, respectively. In the presence of thiols,
such as cysteine, the absorption and emission band shifted to 479
and 540 nm, respectively. Correspondingly, the color of the probe
solution changed from purple to yellow, and the fluorescence changed
from red to yellow. The emission intensity at 540 nm was enhanced
by 140-fold. The Stokes shift of probe 1 (107 nm) is
much larger than the unsubstituted DPP fluorophore (56 nm). Mass spectral
analysis demonstrated that besides the expected Michael addition of
thiols to the CC bonds, the CN groups of the malonitrile moieties
also react with thiols to form 4,5-dihydrothiazole structure. Probe 1 was used for fluorescence imaging of intracellular thiols.
In the presence of thiols, both the green and red channel of the microscopy
are active. With removal of the intracellular thiols, signal can only
be detected through the red channel; thus, ratiometric bioimaging
of intracellular thiols was achieved. The ratiometric response of
probe 1 was rationalized by DFT calculations. Our complementary
experimental and theoretical studies will be useful for design of
ratiometric/colorimetric molecular probes.