Dissertation > Mathematical sciences and chemical > Chemistry > Analytical Chemistry > Instrument analysis ( physics and physical chemistry ) > Photochemical analysis ( spectral analysis method)

Design and Assemblying of Fluorescent Receptors for Molecular Recognition and Chemosensing

Author SunXiangYing
Tutor JiangYunBao
School Xiamen University
Course Analytical Chemistry
Keywords Internal conversion Intramolecular charge transfer Electron transfer N- substituent effect Self-assembled monolayer Interface fluorescence Fluorescence Sensing Molecular Recognition Cu2 Sugar Solvent effect Fluorescence quenching Boric acid.
CLC O657.3
Type PhD thesis
Year 2003
Downloads 836
Quotes 2
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This thesis is divided into five chapters. The first chapter is an introduction, describes the molecular recognition and fluorescence sensing achieved in the field of the latest research results and trends. Include: (1) identification of metal ion sensing system; (2) sugar recognition mechanism and fluorescent acceptor molecule design; (3) excited state non-radiative internal conversion of research progress; (4) self-assembled film build, type its application. Review of molecular recognition and fluorescence sensing system design ideas as well as receptor molecules SAMs latest research, the presentation of papers on the basis of vision. Chapter II, based on excited state non-radiative internal conversion (IC) design principles of fluorescent molecules and build on environmentally sensitive medium such as solvent polarity identification system. Recent studies suggest that 1-N, N-dimethylamino-naphthalene (DMAN) and fluorescence quantum yield of fluorescence lifetime decreases with decreasing polarity of the solvent and reduce the phenomenon is caused by IC, IC adjacent to the occurrence of The excited state S 1 , S 2 energy difference between relevant. Alter the emission characteristics of the charge transfer state S 1 of energy, can be modulated IC's happening. Which were designed and synthesized in chapter 1 - naphthyl amine substituted on the nitrogen with different electron donating group push 1 - naphthyl amine derivative, by varying the substituents on nitrogen atom electron donating ability of adjusting the pressing electron donating amine, thereby regulating emitting state S 1 Energy and regulation of IC occurred; simultaneously by changing the water - organic solvent to adjust the mixing ratio of solvent polarity, further control IC process. First synthesized 1 - naphthylamine sodium diacetate (NADA), with two carboxymethyl (-CH 2 CO 2 Na) Alternative DMAN molecule two methyl and by varying the water and an organic solvent (methanol, ethanol, n-propanol, isopropanol and acetonitrile) to adjust the ratio of solvent polarity. NADA investigated in various polar solvents fluorescence spectra, fluorescence intensity and found NADA fluorescence quantum yield increased with increasing solvent polarity decreases. Compared with the Chinese abstract DMAN, electron donating ability of the two amino groups is less than a methyl group substituted such that the conversion process NADA intensified within the molecule. In this study, based on the DMAN in a CH: one by one by methoxy methyl phthalate CCHZCOZCH3) replaces synthesized N-methyl-N-methoxy-methyl-1 Cai phthalocyanine amine (MMAN) and N, N a two (methoxy-methyl phthalate) a one Cai amine (DCAN), detailed study of the substituents push / pull electronic capabilities and Solvent Effects of internal conversion. Ller equation based on W will launch seven state energy fluorescent molecules in the oxidation potential of the electron donor is associated to better explain the experimental results. AMI also calculated using molecular structure parameters, discussed the relationship between structure and properties. Experimental results show that the 1-amino nitrogen atom amine Cai by introducing electron donating ability than a methyl substituent improved energy emission state, the IC process is easy to happen. Therefore, by changing the electron donor / acceptor giving / receiving electronic capabilities and solvent polarity to control the occurrence of IC, IC-based principles for the establishment of a new foundation for identifying the sensing means. Known amino acid with copper and other metal ions to form stable complexes and will therefore modified to completion methyl 1 - CAI amine nitrogen atom of the molecule. Synthesis of N-(l an Chua) amino acid gamma AA), 1 a CAI amine sodium diacetate sleepy ADA), N a (a one Cai Ji Bu N ', N' twelve shuttle methyl ethylenediamine sleepy cEA), conceived with the metal ion coordinated way to change the Cai amine nitrogen atom of the amine molecule electron density method regulated charge-transfer (CT) state energy emission and the corresponding IC process, and accordingly establish identification and fluorescent metal ions Sensing new model. The first chapter examines the metal ions Cu2, co2, NiZ ten and znZ right NAA fluorescence spectra, and found that the metal ions in an aqueous solution containing 30% ethanol for NAA in the fluorescence quenching effect of different levels, from the absorption spectra, chopped off temperature effect and fluorescence lifetime measurement results suggest that metal ions on NAA fluorescence quenching effect of the static quenching of the metal ions and NAA formed stable complexes and the fluorescence quenching. Cu2 quenching of the fluorescence of NAA much higher than other similar structure of the metal ions and metal ions can not and NAA complexing constant coincide. Further experiments showed that the observed may in fact be a static quenching through \coordination between the role and ligand components suitable redox capability matching, which gives a high selectivity for Cu2 method whereby NAA established fluorescence sensing system for Cu2. Similar experimental phenomena occur in NADA molecules. As compared with NAA on NADA metal ions have a stronger coordination ability, so the metal ions C ore on the fluorescence quenching constant NADA greater. Experiments show that the formation of Cu2 with NADA 1:1 complexes, complex structure determined by X-diffraction results. Cu2, C a, Ni2 other metal ions with ethylenediamine ligand constant approximate and amino acid ligand constant. It was found that these metal ions on the N-(1-Cai Ji Bu ethylenediamine visit EDA) fluorescence quenching constant basically in the same order of magnitude, and well below cu2 for NAA fluorescence quenching constant. This phenomenon is due to a stronger NEDA terminal amine electron-donating ability, thereby terminating the aromatic amine by electron transfer to the metal ions as a result of the fluorescence quenching. Based on this view, the design of the N-1-Chua an N ', N'-methyl-ethylenediamine trapped twelve shuttle cEA), in the introduction NEDA Carboxymethyl-terminal amine end to reduce the charge on the nitrogen atom of the amine density, so that electron-donating ability decreased, so Cai amine electron transfer to the metal ions to occur, while enhancing phosphors with metal ions and coordination ability. Experiments show that metal ions on the fluorescence quenching NCEA level far greater than NADE fluorescence quenching, but CuZ ten identified poor selectivity, which may be due to Cai distance amines with metal ions and electron transfer quenching role of The deviations due. To improve cu2 identify selective, with CTAB surfactant sensitizing effect, making the building fluorescent Cu2 sensor system can be measured as low as 1.48oxlo one, moFL the eu,. Sugar in the organism play an important role in metabolism. Therefore, the accurate detection of an aqueous solution of some important sugar (fructose, lactose, glucose and GAN) is a biomedical research important content. Based on the specific binding of boric acid on the role of sugar in sugar boric acid receptor sensitivity can create highly selective carbohydrate recognition system. ?

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