【作者】 郭影；

【导师】 陈接胜；

【作者基本信息】 吉林大学 ， 无机化学， 2005， 博士

【摘要】 随着微孔、介孔材料,无机-有机、无机-无机纳米复合材料研究的深入,多功能无机化合物-层状化合物的研究又成为人们关注的热点。层状化合物的结构具有特殊性,可作为制备无机-无机、无机-有机纳米复合材料的母体材料。本文选择层板带负电荷的层状硅酸盐和层板带正电荷的类水滑石型层状化合物为主体,开展了从主客体组装化学研究到新型层状化合物的合成研究,旨在制备出具有潜在应用价值的新型材料。以层板带负电荷的层状硅酸盐为主体,将修饰了偶氮苯分子的硅烷化试剂通过接枝反应组装到层间,形成了以共价键方式键合的无机-有机纳米复合材料。该复合物中无机层板的存在提高了偶氮苯分子光致各向异性的热稳定性。合成了新型含镉的层状化合物,包括镉铬型、锌镉铬型和镉铝型类水滑石结构的氢氧化物以及类水镁石结构的氢氧化镉,层间阴离子均为十二烷基硫酸根离子,这四个化合物结构有序性较好。磁性分析表明含铬型的化合物均在低温的时候显示出反铁磁性的相互作用以及零场能级分裂。以含镉的类水滑石氢氧化物为模板通过气固反应技术制备了3-5 nm尺寸的硫化物半导体纳米晶。研究表明类水滑石结构中三价金属的存在起到了控制纳米粒子尺寸的作用。这种层状化合物-纳米晶复合材料具备较好的光催化特性。以类水镁石结构的氢氧化镉为前驱体于低温水热反应条件下制备了微米棒/管,并考察了微米棒/管的形成机理和影响因素。更多还原

【Abstract】 When a guest species is encapsulated in a host, composite host-guestcompounds with unusual properties may form. Layered inorganic materials havebeen extensively considered as good hosts to incorporate functional guest specieswhich yield a variety of useful applications as catalyst, ion conductors,shape-selective adsorbents, ion exchangers, photofunctional materials, etc., andmany novel assembly structures can be tailored at the molecular level through thedesign of the host and the guest species. In this dissertation, we describe some newhost-guest systems related to layered materials.(1) A novel azobenzene derivative modified magadiite has been prepared by thereaction between the interlayer hydroxyl groups of magadiite and the azobenzenederivative using dodecyltrimethylammonium-exchanged magadiite as theintermediate. The formation of the silylated magadiite-azobenzene system wasconfirmed by X-ray diffraction, IR and MAS NMR spectroscopies. The organicgroups of the azobenzene molecules are grafted onto the interlayer surface ofmagadiite by covalent bond, affording compounds different from those derived byion exchange. The composite compound is stable in water and other commonorganic solvents. The orientation and reorientation of the azobenzene derivative inthe magadiite have been examined through observing its photoinduced anisotropybehavior. Because the azobenzene derivatives are grafted on the interlayer surface ofmagadiite, the rigid inorganic layers of pDRSiM act as a “wall”to prevent theazobenzene molecules from getting entangled with the polymer chains of PMMA. Inother words, the inorganic layers of magadiite provide a relatively free space aroundthe azobenzene groups, rendering the azobenzene free to reorient. The freeorientation of azobenzene groups leads to the faster reversal of the inducedanisotropy to isotropy. Furthermore, the photoinduced anisotropy behavior of thecomposite material can be observed even at 95 C. Our approach provides an oalternative route for the construction of new materials which can be used forreversible photoinduced anisotropy study.(2) We synthesized four types of Cd-containing LDHs compounds (CdCr-LDH,ZnCdCr-LDH, CdAl-LDH, CdDS) containing alkyl sulfate as the interlamellaranion through a coprecipitation technique. The powder X-ray diffraction patternsindicate that the as-synthesized samples exhibit high structural order. The typicaldiffraction peaks correspond to intercalated layered double hydroxides with layerseparations in good agreement with those reported previously. The UV-vis spectrareveal the existence of mononuclear state of CrIII in a nearly octahedral OH-environment within the hydroxide layer of the Cr-containing LDHs.Antiferromagnetic interactions between the CrIII centers have been observed for theas-prepared CdCr-LDH and ZnCdCr-LDH. The introduction of zinc influences theligand field of CrIII and the CrIII-CrIII interactions in the Cr-containing LDHcompound. It is found that both CdCr-LDH and ZnCdCr-LDH can be delaminatedby dispersion in formamide, leading to translucent and stable colloidal solutions.Dodecyl sulfate (DS) has been used as the anion to intercalate the layers of theseCr-containing compounds which exhibit high structural order and can be exfoliatedinto single layers in formamide solution, providing new precursors to be used inassembly chemistry.(3) Using these LDHs compounds mentioned above as precursors, for the first timewe prepared CdS nanocrystals and CdS/ZnS those are implanted and stabilized inthe layer matrices of the four types of compounds through a gas/solid reaction route.Depending on the Cd/M (M is trivalent metal) ratio in the precursor, the size of theCdS nanoparticles can be controlled and tuned. The XRD patterns of the CdM-LDHafter sulfurization reaction show three broad peaks corresponding to the (111), (220)and (311) reflections of cubic CdS, whereas the XRD patterns of the ZnCdCr-LDHafter sulfurization reaction show three broad peaks corresponding to the mixture ofcubic CdS and cubic ZnS. In contrast, the CdS nanoparticles in CdDS aftersulfurization reaction appear to be a predominant hexagonal phase contains a smallamount of cubic CdS phase. It indicates the MIII plays an important effect on theformation of the nanocrystals. It is also found that the photocatalyic performance ofthe CdAl-LDH implanted with CdS nanocrystals is distinctly superior to those ofbulk CdS and even nanosized TiO2 for the degradation of rhodamine B under UVand visible light irradiation. In principle, our preparation approach can begeneralized to extend to other nanocrystals implanted in layer matrices, and a varietyof functional composites with nanocrystals of controlled size may be prepared in asimilar way.(4) Preparation of microrods/microtubes from single metal layered hydroxides saltcompound (Cd2(OH)3(DS)·nH2O) through hydrothermal reaction.Microrods/microtubes (long: 5-30 μm; diameter: about 1-3 μm) were obtained bythe synthesis of the layered hydroxides salt compound followed by hydrothermaltreatment at 100 C for 12h. The hydrothermal temperature and the period can oinfluence the yield of the microrods/microtubes. If the hydrothermal temperature isabove 120 oC or the hydrothermal period below 4h, we can’t get themicrorods/microtubes. The hydrothermal reaction and the surfactant are更多还原