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论文类型：期刊论文

发表时间：2011-11-18

发表刊物：JOURNAL OF ORGANIC CHEMISTRY

收录刊物：Scopus、SCIE、EI、PubMed

卷号：76

期号：22

页面范围：9294-9304

ISSN号：0022-3263

摘要：A 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 C=C 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.