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Organic Dye Design, Synthesis And Photochemical Sensing Applications

Posted on:2008-08-16Degree:DoctorType:Dissertation
Country:ChinaCandidate:Y F ChengFull Text:PDF
GTID:1118360215484416Subject:Inorganic Chemistry
Abstract/Summary:PDF Full Text Request
Fluorescent and colorimetric chemosensors in selectively recognizing ions and molecules are of great interest in supramolecular chemistry. The advantages of fluorescence chemosensors are high selectivity, sensitivity and simplicity. Colorimetric sensors are popular due to their capability to detect analyte by the naked eye without resorting to any expensive instruments. In this thesis, a series of new fluorescent and colorimetric chemosensors were synthesized and investigated for their applications in the detection of Hg2+ and anions. The details are as follows:1. Four 8-hydroxyquinoline benzoate derivatives with diverse azo substituents 1-4 (see Fig. A1) were synthesized by diazo-reaction of 2-methyl-8-hydroxyquinoline with various arylamines, followed by esterification with benzoyl chloride. All the products allowed selective responding to Hg2+, which was confirmed by Uv-vis absorption spectra. Different spectral changes were observed for these compounds with electron-donating substituent (bathochromic shift) or electron-withdrawing substituent (hypsochromic shift). Particularly, obvious color change was found for 5-(4-dimethylaminophenylazo) -2-methylquinolin-8-yl benzoate (3) in the presence of Hg2+, which made it possible for distinguishing Hg2+ from other metal ions by naked eye.2. Three rhodamine B derivatives 1-3 (see Fig. A2) were synthesized and studied as turn-on fluorescent chemosensors for Hg2+. When Hg2+ was added, the solution of these compounds turned from colorless to red, corresponding to apparent fluorescent change from colorless to red-orange with excitation wavelength at 365 nm. Especially, a rhodamine B derivative with quinoline group (1) displayed highly selectivity for Hg2+ over other metal ions, which made it possible for distinguishing Hg2+ from other metal ions by naked eye.3. Three 8-hydroxyquinoline azo derivatives 1-3 (see Fig. A3) with diverse conjugated structures were synthesized and studied to chromogenically detect anions. All these dyes allowed detection for fluoride anion in CH3CN via instance deprotonation of compounds, which was confirmed by UV-vis absorption and H NMR spectra. The chromogenic responding ability increases as the substituent changes from phenyl to naphthyl or anthryl. This phenomenon is likely to be related to the enhancement of intramolecular charge transfer (ICT) induced by extension of conjugated structure. 4. Four hemicyanine derivatives 1-4 (see Fig. A4) with diverse conjugated structures were synthesized and studied to chromogenically detect anions. All these dyes allowed detection for anions such as F- and AcO- in CH3CN, which is likely to be related to the enhancement of intramolecular charge transfer (ICT) induced by instance deprotonation of compounds. In addition, a chalcone derivative was synthesized as fluorescent and colorimetric chemosensor for anions such as F- and AcO-.5. Mesoporous SQ/SBA-15 on the basis of the interaction of squaraine dye and mercaptol was designed and synthesized. This chemodosimeter system displayed highly selectivity for Hg2+ over other metal ions, corresponding to apparent color change from colorless to blue, which made it possible for distinguishing Hg2+ from other metal ions by naked eye. Moreover, SQ/SBA-15 could adsorb and separate Hg2+ from solution. This route based on guest-induced dye release methods might be of interest as a new route for the design of new and improved regenerative sensor molecules.
Keywords/Search Tags:Colorimetric chemosensors, Hg2+, anion
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