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Preparation Of Ferrocene Functionalized Order Mesoporous Materials And Its Catalytic Activity

Posted on:2012-06-12Degree:DoctorType:Dissertation
Country:ChinaCandidate:T M ZhangFull Text:PDF
GTID:1111330368989823Subject:Applied Chemistry
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Periodic mesoporous organosilicas (PMOs), integrating the organic and inorganic domain in molecular lever in the network of pore wall, possess many unique properties. First the organic moiety uniformly distributed in the mesoporous framework, without blocking the pore, which accelerate the diffusion of guest molecules. Second, the organic moiety in the framework of the material could change the surface hydrophilicity/hydrophobicity, mechanical and hydrothermal stability of the PMOs. Finally, the functionality of the material can be changed easily by using the precursor with different organic moiety. Due to the unique properties, PMO materials are considered as highly promising candidates for a series of technical applications, for example, in the areas of catalysis, adsorption, chromatography and nanoelectronics etc. As for the functionality and application of the PMOs can be widen by using different organic moiety in the precursor, the choice of the functional organic moiety is very important.Ferrocene, reported half a century ago, is a useful organometallic compound. The stability of the ferrocenyl group in aqueous, aerobic media, the accessibility of a large variety of derivatives, and its unique electrochemical properties have made ferrocene and its derivatives very popular molecules for catalysts, sensors and biological applications. So, ferrocene moiety was selected as the functional moiety, and introduced it into the framework of PMOs.In the paper, we synthesized a new precursor named 1,1'-bis[(2-(triethoxylsilyl)- ethyl)ferrocene (BTEF), by using vinyl trichlorosilane, cyclopentadiene and anhydrous ferrous chloride as the main original reagents. Furthermore, we prepared a serious new ferrocene-containing ordered mesoporous materials through co-condensation of 1,1'-bis[2-(triethoxylsilyl)ethyl]ferrocene (BTEF) and tetraethyl orthosilicate (TEOS) under basic or acid conditions using supramolecular templates of cationic surfactant or non-ionic surfactant as structure directing agents. We evaluated the catalytic property of the prepared materials in the reaction of benzene hydroxylation to phenol and phenol hydroxylation to catechol and p-Hydroquinone.The paper mainly divided into three parts:first, the synthesis of the BTEF; second, the preparation and characterization the ferrocene-containing ordered mesoporous materials by using BTEF as precursor; finally, ferrocene modified glassy carbon modified electrode was prepared and characterized by cyclic voltammetry.In chapter 2, we described the synthesis process of BTEF in detail. Due to the reagents used in the reaction is sensitive to water, so all the procedures were conducted under nitrogen atmosphere. First, vinyl trichlorosilane react with HBr through anti-Markovnikov addition by the initiation of benzoyl peroxide. Then the product alcoholysize with alcohol to obtain (2-bromoethyl)triethoxysilane. After that, (2-bromoethyl)triethoxysilane react with sodium cyclopentadienide to obtain (2-(cyclopenta-1,3-dienyl)ethyl)triethoxysilane. Finally, the BTEF was prepared by reacting with anhydrous ferrous chloride. The BTEF and the intermediate products were confirmed by NMR, FT-IR and UV etc.In chapter 3, ferrocene-containing MCM-41-type ordered mesoporous materials synthesized by co-condensation of 1,1'-bis[(2-(triethoxylsilyl)ethyl)ferro-cene (BTEF) and tetraethyl orthosilicate (TEOS) under basic conditions using supramolecular templates of cetyltrimethyl-ammonium bromide (CTAB) as structure directing agents. The synthesis parameters such as temperature, contents of surfactant, water and alcohol have been systematically investigated. The results of N2 sorption, XRD and TEM indicate the formation of the 2D hexagonally ordered mesoporous materials. Furthermore the evidences from FT-IR, UV-Vis DRS,13C CP-MAS NMR,29Si MAS NMR and elemental analysis confirmed the ferrocene moiety was incorporated in the mesoporous material through covalent bonding. In the reaction of benzene hydroxylation to phenol, the prepared mesoporous organosilica material showed as high catalytic activity as its homogeneous analogy.In chapter 4, ferrocene-containing ordered mesoporous materials were prepared by the use of quaternary ammonium surfactants CnH2n+1(CH3)3NBr and organic additives during the hydrothermal synthesis process. The characterization results showed all the materials exhibit an ordered two-dimensional hexagonal pore structure with pore diameter from 2.04 nm to 4.01 nm. It was found that the pore diameter of the materials was strongly dependent on the surfactant chain length and the content of the organic additives. The Fourier transform infrared spectra revealed that the organic bridge is preserved during the hydrothermal synthesis and subsequent extraction procedure.In chapter 5, Ferrocene-bridged mesoporous organosilicas with large pore size were prepared by evaporation-induced self-assembly of 1,1'-bis[(2-(triethoxylsilyl)ethyl)ferrocene and tetraethyl orthosilicate by using polymer Pluronic P123 as a template under acid conditions. The prepared materials were characterized by N2 sorption, XRD and TEM, and the results showed all the materials exhibited highly ordered 2D hexagonal pore structure, thick pore wall and large pore size. The FT-IR revealed that the organic bridge was preserved during the material synthesis and subsequent extraction procedure. In the reaction of phenol hydroxylation, the prepared mesoporous organosilica material showed as high catalytic activity as its homogeneous analogy.In chapter 6, Ferrocene modified glassy carbon (GC) electrode was prepared BTEF via one pot sol-gel method. The electrochemical behavior of the modified electrode was characterized by cyclic voltammetry in aqueous solutions. The results showed that the obtained electrode had a pair of reversible redox peaks ascribed to Fc/Fc+. The modified electrode was placed in air for 15 days, only 16.41% of responds decreased. In the oxidation of ascorbic acid, the modified electrode showed excellent electrocatalytic response.
Keywords/Search Tags:PMOs, ferrocene, phenol, hybrid material, modified electrode
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