噻吩醛缩合苯二胺有机敏化剂及其敏化二氧化钛光催化研究

【作者】 甄远；

【导师】 张逢星；

【作者基本信息】 西北大学 ， 材料化学， 2011， 硕士

【摘要】 锐钛矿型二氧化钛可用于太阳能电池、光催化制氢和光催化有机化合物降解等领域而备受人们的关注。人们为提高其光电转化率,采取的措施之一是对其进行有机染料敏化,将吸收光由紫外区引入可见光区。研究表明,具有大π共轭体系芳香类为母体的有机化合物可能成为一类有效的二氧化钛敏化染料。噻吩作为吡啶和苯的等π电子体,具有较为稳定的五元杂硫原子芳香环结构特点,可以和有机胺通过缩合反应,形成具有大π共轭体系的有机染料分子。因此,设计合成新的噻吩缩胺化合物及其敏化二氧化钛光催化研究具有重要的理论意义和实际价值。本论文正是基于这一出发点,主要完成了如下工作：1.分别以邻苯二胺、对苯二胺与2-噻吩甲醛进行缩合反应,制备了1-（2-噻吩亚甲基）-2-（2-噻吩基）苯并咪唑（L1）和2-噻吩甲醛缩对苯二胺双Schiff碱（L2）。在制备1-（2-噻吩亚甲基）-2-（2-噻吩基）苯并咪唑过程中对传统制备方法进行了改进,用稀土盐取代了传统制备方法中所使用的氧化剂作为催化剂,使得合成反应容易得到的目标产物唯一,基本不会出现其他的反应副产物。2.采用合成得到的两种有机敏化剂对纳米TiO₂进行表面修饰,以敏化二氧化钛为光催化剂、以4-NP为氧化底物,在300m紫外光下研究了光催化降解效果,发现底物与纳米TiO2比例为20μmol:1g时光催化效果最佳。3.应用多种方法如一般制备法,模板法,水热法等制备了不同金属中心的配合物：L12CoCl2、L12NiCl2（一般合成法）,L12CdCl2（模板法）和L12MnCl2（水热法）。对所得配合物通过元素分析,红外分析、固体荧光分析和TG-DSC进行表征；还获得了配合物的单晶,进行了它们的单晶衍射结构。结果表明,这些配合物均具有配位数位4的结构单元,呈畸变的四面体结构,晶体结构中存在不同的氢键扩展结构。综上,论文设计合成了两种新的噻吩醛缩胺有机化合物,并在配体L1的合成方法上有一定的创新和突破,对苯并咪唑类化合物的合成具有重要的意义。两个有机化合物敏化的二氧化钛均具有光催化降解有机化合物功能,可发展成为有机物废水处理新材料。更多还原

【Abstract】 Anatase titanium dioxide has been drawn a great attention from researchers and chemists for its application to solar batteries, photocatalytic hydrogen evolution and photocatalytic degradation of organic compounds. In order to raise the photoelectric converting rate, one of measures taken is to sensitize organic dyes with the shift of light-absorption from ultraviolet region to visible region. Previous studies showed that an aromatic organic compound in structure of extended Pi-conjugated system can act as a kind of sensitizing dye for titanium dioxide. Tiophene, an isoelectronic species of naphthyridine and benzene, is constructed with relatively stable five-membered aromatic ring of sulphur atoms, and can react with organic amine through condensation reaction to produce organic dye molecules with extended Pi-conjugated structure. Therefore, it is of great theoretical and practical significance to create new thiosemiamic complexes and to research its application to sensitization of titanium dioxide, based on which the current study is conducted. The following goals are to be achieved:1.Firstly, the thiophene compounds of 1-(2-thenylidene)-2-(2-thienyl) benzoglioxaline and 2-thiophene carboxaldehyde and contracted p-phenylenediamine bis-schiff base are made by the method of condensation reaction with o-phenylenediamine, ursol, and 2-thiophenealdehyde. Secondly, the current experiment tends to improve the traditional way of preparation of thiophene compounds. That is, rare-earth salt serves as a substitution for oxidation catalyst in the traditional methods, which helps to obtain the single compound easily without any other byproducts of reaction.2. Different amount of organic compounds L1, L2 are used to modify the surface of Nanometer TiO2. Then, various modified Nanometer TiO2s are added into the photocatalytic degradation reaction of 4-NP when it is exposed to the 300mm UV-light. Afterwards, the effect of photocatalytic degradation is tested and a conclusion is reached that the best effect can be achieved when the rate of two organic compounds to Nanometer TiO2 is 20μmol:1g.3. Multiple methods are used in current experiment to produce composition with various metal cores, such as common synthesis method, template method, and hydrothermal method. Specifically, common synthesis method is applied in the production of L12CoCl2 and L12NiCl2; template method is used to produce L12CdCl2; lastly, the hydrothermal method is employed when it comes to the production of L12MnCl2. However, only the composition of Cd ionic complex is successful in the template experiment. Subsequently, four compositions are examined with elementary analysis, infrared analysis, and TG-DSC. By single crystal diffraction, it is revealed that the coordination number of four compositions is 4 and all of their structure is distorted tetrahedral structure with various extended hydrogen bond. At last, the solid fluorescence analysis is performed to investigate photoluminescent properties of these compositions.The present study has applied various ways to synthesize chemical compositions. Thus, it sheds new light on traditional synthetic methods of the ligand L1, and is of great significance for the synthesis of benzimidazoles compositions. Both of sensitized titanium dioxides can perform the function of photocatalytic degradation, and thus are the new materials to dispose waste water.更多还原