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Synthesis and Properties of Novel CdSe Nanocrystals

Author: GuoYuZuo
Tutor: SongHuiHua；GuoHaiQing
School: Hebei Normal
Course: Inorganic Chemistry
Keywords: Molecular hybrid polymer CdSe nanocrystals Sulfhydryl ethylene ketal Biocompatibility Fluorescence
CLC: TB383.1
Type: Master's thesis
Year: 2008
Downloads: 129
Quote: 1
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Abstract


Nanocrystals as a fluorescent probe of biological molecules generally need to solve the problem of the water-soluble, biocompatible and its coupling with biomolecules. Currently, multi-use Nanocrystalline via surface of an oil-soluble stabilizer replaced the organic phase obtained is converted into water-soluble and biocompatible Nanocrystals; mercapto-fatty acid, etc. have also been reported as a stabilizing agent in the aqueous solution directly synthesized water-soluble semiconductor nanocrystals, resulting semiconductor nanocrystals poor biocompatibility. In this paper, diethylene glycol, mercapto organic functional molecules stabilizer, try the one-step water-phase synthesis to meet the requirements of CdSe nanocrystals, and to explore the structural unit of the molecule to the assembly of CdSe nanocrystals hybrid polymer synthesis problems, in order to adapt to different occasions. The specific contents are as follows: (1) we have designed and synthesized a mercapto diethylene glycol, both ends respectively a mercapto group and a double bond the ethylene ketal organic functional molecule. Such organic functional molecules can be used as a stabilizer for the synthesis of CdSe nanocrystals. NMR, mass spectrometry, elemental analysis of organic functional molecules. (2) For the mercaptoacetic acid as a stabilizer with a the colloidal chemical solution to the aqueous phase synthesis of CdSe nanocrystals system, we further studied CdCl 2 / Na 2 SSeO 3 / thioglycolic acid feed ratio, nucleation temperature, curing time and other factors on the size distribution of CdSe nanocrystals luminescence properties optimized for CdSe nanocrystal synthesis conditions and explore Preparation a the CdSe nanocrystals solid powder, lay the foundation for the preparation of new functional CdSe nanocrystals. (3) mercapto-ethylene ketal as a stabilizing agent in the aqueous phase, under optimal conditions obtained by the above studies, direct synthesis of CdSe nanocrystals modified ethylene ketal. By adjusting the a CdCl 2 and Na 2 SSeO 3 feeding than, CdSe nanocrystals of different sizes. By X-ray diffraction (XRD), high resolution transmission electron microscopy (HRTEM), and UV-visible absorption spectroscopy (Uv-vis) and other means to a characterization of nano-crystalline structure, size, morphology, and its light-emitting properties of . The results show that the crystal structure of the product is better, more uniform particle size, and good fluorescence properties. Mercapto ethylene ketal and mercapto undecanoate as the stabilizer, the direct synthesis of the carboxyl group-containing ethylene ketal stabilizer modified CdSe nanocrystals in the aqueous phase. By changing the ratio of the feed ratio of different organic functional molecules can regulate the surface of the nanocrystalline, to meet the different needs of the application of the biological system. The hydroxyl and carboxyl groups on the surface of the nanocrystalline given the nature of its connection with biological molecules, and the diethylene glycol unit given its water-soluble and biocompatible. The use of high-resolution transmission electron microscopy and UV-visible - absorption spectroscopy and other means the synthesized nanocrystalline morphology, size, size distribution, and structure were characterized. Using nuclear magnetic resonance spectra (NMR), infrared spectroscopy (IR) and other methods to determine the proportion of a functional group such as a carboxyl group, a hydroxyl group; fluorescence spectrum (PL) having a good light-emitting properties that these CdSe nanocrystals. (4) to the ends of the mercapto group of diethylene glycol and a certain proportion of the mercapto group and the double bond of the ethylene ketal as stabilizer, CdC1 to 2 for the precursor of the Cd, Na 2 < / sub> SSeO 3 for the selenium source, under the optimal conditions obtained by the above studies, in the aqueous phase Direct Synthesis of CdSe nanocrystals containing a certain proportion of double bonds and a modified ethylene ketal. By measuring their NMR spectra, to determine the proportion of the CdSe nanocrystals surface functional group such as double bond, a hydroxyl group; studied this the CdSe nanocrystals assembly radical polymerizable surfactant modified homopolymerization reaction, initially synthesized soluble sexual molecules containing CdSe nanocrystals hybrid light-emitting polymer. The characterization of the size, morphology, etc. by using transmission electron microscope, an absorption spectrum, the fluorescence spectra of CdSe nanocrystals assembly and molecular hybridization the luminescence properties of the polymer by ultraviolet-visible. The results show that the hybrid assembly and molecular polymer well dispersed, the particle diameter is more uniform, good fluorescence properties. Through the study, we preliminarily with good water-soluble, biocompatible, light-emitting properties of biological molecules with novel functional coupling of CdSe nanocrystals and CdSe nanocrystals molecular hybrid polymer, which is expected as the application of biological probes tag of the biomolecule.

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