| Summary: | 碩士 === 國立臺灣大學 === 化學研究所 === 91 === The objective of this thesis is to use coumarin derivatives as molecular scaffold to design fluorosensors for detecting metal ions and monosaccharides based on PET (Photoinduced Electron Transfer) sensory mechanism. Evidences are also shown to reveal the origin of the fluorescence changes of these sensors.
Coumarin derivatives (1-8) containing various electron-withdrawing groups display different fluorescent intensity owing to the attenuation of PET mechanism by these substituents. Based on this concept, we designed fluorosensors, which can switch on or off PET mechanism in the presence of analytes. Iminodicarboxylic acid and 2-tolylboronic acid were chosen as the recognition units for detecting metal ions and monosaccharides in fluorosensors 9, 10 and 11, respectively. Monitoring the variation of fluorescent intensity of these fluorosensors accessed the strength of complexation between fluorosensors and analytes.
Experimental results indicate that fluorosensor 9 only selects Hg2+ and shows pronounced fluorescent enhancement either in organic solvent or water. The magnitude of the enhancement isn’t affected in the presence of other interfering metal ions. As to fluorescent sensors targeting to monosaccharides, fluorosensor 11 has broader working pH range than fluorosensor 10 in aqueous buffer. Spectroscopic results demonstrate that 10 and 11 undergo different binding mechanisms in the presence of monosaccharides.
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