【作者】 陈悦；

【导师】 裘式纶；

【作者基本信息】 吉林大学 ， 无机化学， 2005， 博士

【摘要】 本论文以分子筛规则的孔道为主体,通过吸附、结晶包覆、修饰等组装方法,对具有光学活性的客体材料进行组装,并对其光学性质进行了系统的研究。采用单晶硅片作硅源,在r 体系中合成了高质量的毫米级MFI 大单晶,以此MFI 大单晶为主体材料,用PVD 方法制备了MB/MFI 复合物,激光光致发光具有窄化发光特性,使得分子筛单晶主体材料,新型功能材料、光电微器件领域得到了拓展。MB/MFI 复合物中,MB 分子呈现单分散且具有高度取向采用单晶硅片为基质,水热合成了具有高度取向的silicalite-1 分子筛膜,通过对不同单晶硅片与silicalite-1 生成的模型进行分子动力学模拟计算,得到了与实验结果相符的理论计算结果。以此膜为主体,采用PVD 方法制备了具有一定的发光特性的PNA/silicalite-1 膜复合材料。推动了分子筛主体材料向可实用方向发展的进程。采用结晶包覆的方法将功能性染料掺杂到不同形貌不同孔径的介孔分子筛中,介孔的形貌包括粉体、纤维、以及膜,考察了不同形貌的介孔材料/染料复合物的光学性质。介孔材料/染料复合物具有很强的光致发光特性,与染料分子在溶剂中的发光性质不同。为避免结晶包覆法对掺杂后的染料的光学性质的影响,采用共价结合的方式,将多种染料组装在用硅烷偶联剂修饰后的介孔分子筛孔壁上,体现了单分散状态的染料分子与硅烷偶联剂相互作用后的光学特性:光致发光波长与染料液相单分散状态相比有较大的红移,且具有激光发光特性。介孔分子筛的孔道是良好的光学谐振腔,只有在谐振腔内完成振荡周期的才可以发光。采用新型简便的合成纤维方法一电纺丝方法,制备了具有良好光学性质的掺杂染料的介孔二氧化硅纤维。由于静电场作用,染料分子染料分子的分子内电荷转移(TICT)趋势增强,在激光的激发下,染料在介孔纤维内部形成光学谐振腔内,产生驻波,产生放大的自发发射(ASE),即激光窄化现象。更多还原

【Abstract】 Recently, the research of molecular sieves and porous materials are focus not only on adsorption, separation, ion-exchange and catalysis, but also on the preparation and development of the host materials for optical or optoelectronic molecules. however, the application of such functional materials, especially micro-devices, are based on handful morphology, higher quality membrane, and lager size of zeolites crystals, which are very different to achieve. In our research work, narrowlined emission spectrum of the MB/MFI composite was demonstrated. By physical vapor deposition (PVD) method, p-nitro aniline (PNA) was encapsulated in the pores of high-oriented silicalite-1 film, and fluorescence of the PNA/silicalite-1 film was observed. Laser dye coumarin derivative has been successfully incorporated into mesoporous powder, fiber, and film by one-pot method. The channels of mesoporous silica can be modified with organic functional groups and post-grafted organic dyes. Through electrospining technique, the mesoporous fibers which doped with coumarin 151 are obtained. High-quality MFI large single crystals can be used as host material which were synthesized using monocrystallion silicon slice as silicon source, and methylene blue (MB) are used as guest molecular. Narrow linewidth action was achieved in the MB/MFI composite which obtained by physical vapor deposition (PVD). The emission spectrum final luminescence spectrum full width at half-maximum is about 2nm. High oriented siicalite-1 film was prepared by in situ crystallization onto MSS support. The MSS with (111) was most suitable for the preparation of silicalite-1 film, and it was shown from XRD patterns that the crystallographic b-axis of MFI crystals was perpendicular to the MSS surface. The experimental results also got theoretical support from molecular mechanics, according to the structure of MSS surface and silicalite-1 framework. PNA encapsulated silicalite-1 film composites were prepared by PVD. The results of UV and XPS showed that the PNA molecule were encapsulated into the channels of the silicalite-1 zeolite on film, and the composite showed strong fluorescence under 488nm laser. For many applications, the mesoporous materials should be controlled not only on the nanometer scale of the pore structure but also on the micrometer scale of the morphology. A diversity of mesoporous silica with defined morphology, like films, spheres, fibers or tubules, can be used as good host material. Dye molecule –coumarin 151 has been successfully incorporated into mesoporous powder, fiber, and film by one-pot methods. In the preparation process, add organic chromophores to the synthesis mixtures, the template was supermolecule which formed by interaction between structure-directing agent and dye molecules. This procedure results in a uniform dispersion of the dyes in the mesoporous host, and keep the well-ordered porous properties. In UV and PL spectra, significant blue shift can be observed. The difference that exist in the UV and PL bands implied that the nearest-neighbor structure around dye molecules was not so simple as the cluster structure of solvate in the solution if compared with solvents. The polarity of the local environment surrounding the dye molecules has been changed because of interaction between dye molecules and structure-directing agent through the inter-molecular force such as electrostatic force and van der waals force. The wall surface of mesoporous silica can be modified with proper organicfunctional groups and provide accessibility for anchoring other substrates. The encapsulation of guest molecules in these hosts leads to composite materials with novel properties, which enable possible applications as materials for catalysis, adsorption, and electronic devices. Firstly, the template of the msoporous material must be removed. There are three method: calcination, extraction, and microwave digestion. Microwave digestion can fast and completely remove the template and can keep rich surface silanol groups. Rhodamine B and coumarin 4 have been encapsulated in the channels of rodlike SBA-15 with NH2 group. The composite of Rh B/Rsba-15 can be observed blue shift in UV and PL spectra because of the dye mono-disperse in the channels of SBA-15. But red-shift can be observed in the Coumarin 4/Rsba-15 composite, when pumped with 355nm laser, there are wide fluorescence band at lower intensity, increasing the laser intensity, narrowed emission band can be showed. The line structure of laser emission spectrum is determined by the cavity geometry, since the cavity permits only certain fields or eigen modes to oscillate. It is possible to calculate the wavelength spacing of the modes using the formula ?λ≈λ2 ?2nL, assuming a Fabry-Perot geometry for the laser cavity. The match between the calculated mode separation and the measured one is satisfactory. The smaller length of the composite can obtain wider output lasing mode. Among generating 1D nanostructures methods, electrospinning seems to provide the simplest approach to nanofibers with both solid and hollow interiors. When a high voltage is applied, the pendent drop of polymer solution at the nozzle of the spinneret will become highly electrified. The electrified jet undergoes a stretching and whipping process, leading to the formation of a long and thin thread. As the liquid jet is continuously elongated and the solvent is evaporated, its diameter can be greatly reduced to nanometers. Through this method, the nanofibers can be obtained which have mesosporous structure and doped with coumarin 151. Lasing from the electrospinning nanofibers can be observed, when the mesoporous structure fibers iiiwere pumped by the third harmonic light of a Q-switched Nd:YAG laser (355nm, ~5ns pulse width, 10Hz). Coumarin dyes are considered to form a different class of compounds able to give ion-radical pair (ICT formation) or twisted intramolecular charge transfer (TICT) excited states with highly specific solute-solvent interaction. In the preparative process, there are not only polar solvent-EtOH but also HCl in the sample solution. Under laser intense fast pulse excitation, the number density of the excited molecules existing in the TICT conformation could become quite large and serve to produce high gain which could then lead to superradiance from the TICT conformation. The dye molecules are sited into the channels of mseoporous fibers which can be used as microresonator, and the laser emission spectra are determined by cavity geometry.更多还原