1.Synthesis, Properties Of Trinucleus Dimethine Cyanine Dyes And Their Interaction With DNA 2.Study On A Novel No-clean Electronic Soldering Flux

This paper contains two parts:(ⅰ) Synthesis, properties of trinucleus dimethine cyanine dyes and their interaction with DNA;(ⅱ) Study on a novel no-clean electronic soldering flux.Partⅰ:Synthesis, properties of trinucleus dimethine cyanine dyes and their interaction with DNATrinucleus dimethine cyanine dyes have advantages of adjustable wavelength range. favorable fluorescence performance and good affinity for DNA. In this paper the trinucleus dimethine cyanine dyes were synthesized and their spectra properties were studied. The possibility of the dyes as the potential fluorescence probe is discussed.1. In this paper, the classification, structure features and application of flurencent dyes were presented. The structures and properties of trinucleus dimethine cyanine dyes were summarized. And the preparation and application progress of trinucleus dimethine cyanine dyes in recent years were also introduced.2. In this paper, six trinucleus dimethine cyanine dyes, four of which were novel, were synthesized. The products were identified by 1H NMR,13C NMR, IR, MS, UV-Vis spectroscopy and elemental analysis. The crystal structures and packing modes of 3f were analyzed by X-ray diffraction, which revealed molecular conformation, intra- and intermolecular interactions in solid state of the dyes. According to the irradiation time, the reaction activity for heterocyclic aromatic aldehydes was discussed. It could be found that the sequence of the reaction acitivity of heterocyclic aromatic aldehydes was:furaldehyde> 1-methylpyrrole-2-carboxaldehyde> indole-3-carboxaldehyde. The dyes absorbed in the region 397-473 nm and had molar extinction coefficients of 4.2×104-6.2×104L mol-1 cm-1 in methanol. Their fluorescence maxima, fluorescence quantum yields and Stokes shifts were located in the range of 508-559 nm,0.0027-0.0538 and 85-120 nm in methanol, respectively. Theλmax shows blue-shifted with the increase of the solvent dielectric constant, and the fluorescence quantum yields were decreased with the increase of solvent dielectric constant.3. The absorption and fluorescence properties of prepared trinucleus dimethine cyanine dyes in the DNA presence were investigated, which showed that 3b and 3d had good affinity for DNA. Significant enhancement of the fluorescence intensity was observed for dyes 3b,3d. The quantum yields of DNA-dyes 3b increased by 31.6 times compared with quantum yield of free dyes. Free dye 3d could not be detected significantly fluorescence in buffer. but DNA-dye 3d showed strong fluorescence performance and its fluorescence quantum yield is 0.0187. Therefore, dyes 3b and 3d are potential DNA fluorescent probe.Part ii:Study on a novel no-clean electronic soldering fluxSoldering flux is used to remove the oxidation from the metal and facilitate the solder and metal to be joined. With the wide use of lead free solders, it becomes more important to develop a no-clean flux for lead free solders. The paper presents the classification, composition and trend of solder flux.1. The essential ingredient of flux was studied by measuring the spreading property of 99.3Sn-0.7Cu alloy on copper substrate. The components of the flux were optimized by using the analytical method of variance in the orthogonal design. The results showed that succinic acid was the best activator while the malonic acid was the worst. It was found that triethanolamine has the greatest influence on expansion rate among high boiling point solvents while N-methyl-2-pyrrolidone has the smallest.2. The new no-clean flux in this paper could meet the requirement of 99.3Sn-0.7Cu solder, which was the most common electronic solder. The performance of the new flux on printed circuit board was satisfied. The solder joints were good and had no defects such as false welding, lack of weld and tin ball.