Complex Formation of Rhenium (V) with Benzimidazole in Acidic Media

Rhenium(V) complexes of 1H-benzimidazole (L), isolated from acidic media: (HL)₂[ReOX₅]·(H₂O) _n and [ReOL _x X _y (H₂O) _z ](H₂O) _n (HL and L are protonated and deprotonated forms of benzimidazole; X = Cl^-, Br^-) were studied by means of IR spectroscopy, ¹H NMR spectroscopy, and thermal analysis.     

酸性条件下纯硅六方介孔分子筛的合成(Ⅱ)合成温度、时间的影响及其与碱性合成的比较

本文以十六烷基三甲基溴化铵为模板剂,正硅酸乙酯为硅源,考察了反应温度和时间对酸性条件下合成纯硅六方介孔分子筛的影响,并与碱性合成路径相比较。结果表明,由于无机物种与表面活性剂之间的相互作用不同,六方介孔分子筛的酸性合成经历了与碱性合成完全不同的机理。对要到性合成来说,由于六方结构的形成取决于稳定的模板胶束的存在,并不特别依赖于硅物种的缩合,故高温、长反应时间等有利于缩合的因素对提高产品质量几乎没有促进作用,较高的反应温度甚至起反作用。因此,酸性合成宜采用室温条件。     

Rearrangements of Neoclovene Epoxides in Acidic Media

Rearrangements of neoclovene epoxides in the presence of a solid superacid ZrO₂/SO₄ ^{2 -} and in formic acid were investigated. In the latter case a ketone was obtained with a previously unknown carbon skeleton. The most probable pathway of its formation was derived from calculations by molecular mechanics and quantum-chemical methods.     

硬模板法高温水热合成微孔-介孔二氧化硅及掺铝介孔二氧化硅

摘要 采用高温水热合成的方法有利于得到具备高水热稳定性的介孔二氧化硅.本研究中,我们利用α-亚麻酸在加热条件下通过胶束内聚合转化为能够耐受高温水热环境的介观模板,利用此硬模板在高温水热条件下直接合成了微孔-介孔二氧化硅及掺铝介孔二氧化硅.采用了不同的表征手段如X射线衍射（XRD）,氮气吸附,透射电镜等手段对材料进行了表征. 实验结果表明,制得的材料在沸水中处理5天后,仍能保持670m2 g-1的比表面积.透射电镜结果和NLDFT孔径分析结果显示,材料同时具备介孔和微孔结构.29Si MAS NMR谱图显示,完全缩聚的Q4型硅为材料中主要的硅组分,这解释了材料的高水热稳定性.     

偶氮染料在酸性介质中的电还原性质

研究了4个偶氮染料在酸性介质中的电还原性质。偶氮基在酸性介质中的还原均为不可逆四电子一步全还原。邻、对位上有吸电子基(如—CO_2Bu-n)的偶氮基较间位有吸电子基时更易被还原。分子中同时含有偶氮基和硝基时,偶氮基先被还原。     

Rearrangements of Epoxides of Some Acyclic Terpenoids in Acidic Media

2,3-Epoxygeraniol undergoes dissimilar rearrangements in contact with liquid superacids at low temperature or on solid superacids at room temperature due to different location of the arising cationic center depending on the superacid character. 2,3-Epoxynerol, 6,7-epoxycitronellol, and 6,7-geranyl acetate on ZrO₂SO₄ ^{2 -} afford the corresponding ketones via epoxy ring opening followed by 1,2-hydride shift. With 6,7-geranyl acetate 7-oxanobornane formed as a minor product. The mode of generation of the cationic center (either the olefin protonation or the epoxy ring opening) affects the rearrangement direction at similar conditions.     

Fabrication of Porous Silica Microspheres Under the Assistance of Solid Template

Spherical porous silica microparticles were synthesized by a sol-gel process in the presence of porous CaCO₃ particles, followed by removal of the carbonate templates. The resulting silica particles had very high porosity and wide pore size distribution, whose surface area and pore volume reached up to 367.3 m²/g and 0.72 mL/g, respectively. With a larger amount of the tetraethyl orthosilicate used, hollow silica microspheres were further obtained. Characterization was made to confirm the chemical and physical structures and purity of the silica microspheres. Spontaneous deposition of tetramethyl rhodamine isothiocyanate labeled dextran into the microspheres was also observed due to the charge attraction.     

混合模板法制备螺旋纳米结构二氧化硅

用凝胶剂高氯酸环（L-11-（N-甲基咪唑）十一烷基天冬酰胺-L-苯丙酰胺）（11mim ClO4）和十六烷基三甲基氯化铵（CTAC）作模板剂,经溶胶-凝胶过程,制备纳米结构二氧化硅．使用冷场发射扫描电镜（FESEM）,表征了多种反应条件下样品的形貌和表面结构．结果表明,通过调节CTAC和凝胶剂的质量比,可以得到螺旋介孔二氧化硅纳米纤维,其长度为数百纳米,孔径为3．0nm．     

Formation of Water-Soluble Dye-Doped Silica Particles

Formation mechanism of dye-doped silica particles less than 1 µm in diameters by the Stöber method was investigated. With increasing the content of dyes such as water-soluble porphyrin (TTMAPP) and laser dye (Nile blue), these dye-doped silica particles showed the similar tendency to the following characters: (1) Particle size increased, passed through the maximum at the dye content corresponds to the isoelectric point, and then followed by decrease; (2) Ratio of dimer and monomer of the incorporated dye decreased. In aqueous solution positively charged dyes showed good affinity with negatively charged SiO₂ primary particles from the early stage of the formation. Zeta potential of doped-silica particles was measured against nominal dye content: from non-doped to highly doped particles, their surface charge changed from negative to positive. The similar influence caused by positively charged dyes on the particle formation was also observed by Ca²⁺ doping.     

Formation of Hierarchical Pore Structure in Silica Gel

By inducing a phase separation parallel to the sol-gel transition of alkoxy-derived silicate systems, gels with well-defined macroporous structure can be prepared. Depending on the post-gelation treatment such as aging and solvent exchange, the final pore structure in the nanometer range of dried and heat-treated gels exhibits a considerable variation. With an aim of completely controlling the hierarchical pore structure in the discrete size ranges of nanometers and micrometers, systematic experimental studies have been performed. The macroporous nature of the wet gels allows an efficient solvent exchange process compared with conventional gels only with mesopores. In addition, the surface chemistry of the wet gel skeleton affects the mesopore formation process by the solvent exchange to a great extent. The median size of mesopores larger than 5 nm can be controlled by adjusting the basic solvent exchange conditions such as pH value, temperature and bath ratio for any kind of macroporous silica gel. On the other hand, the control of pore volume independent of the mesopore size is possible only in the system incorporated with the micelle-forming surfactant. Some examples of the effects of controlled mesopores on the analytical performance of monolithic-type chromatographic columns are also presented.     

新型球形纳米空心SiO2的模板合成方法研究

以纳米碳酸钙颗粒为新颖的无机模板剂,硅酸钠为无机硅源,通过溶胶-凝胶法形成CaCO3／SiO2的核壳结构;随后通过高温煅烧、酸溶和干燥处理,合成出了具有高比表面积的球形纳米空心二氧化硅粒子．然后,分别采用TEM,SEM,EDS,XRD,FTIR和TG等测试手段对样品进行了分析和表征,并考察了不同合成条件,如反应温度、反应pH值、煅烧温度和包覆反应时SiO2／CaCO3的配比对纳米空心二氧化硅粒子的比表面积变化．实验结果表明：较高的反应温度如60～80℃,pn值9左右、SiO2包覆量为碳酸钙质量的10％,以及煅烧温度为700℃,有利于形成空心形貌较好、比表面较大的球形纳米空心二氧化硅。     

新型球形纳米空心SiO2的模板合成方法研究

以纳米碳酸钙颗粒为新颖的无机模板剂, 硅酸钠为无机硅源, 通过溶胶-凝胶法形成CaCO₃/SiO₂的核壳结构; 随后通过高温煅烧、酸溶和干燥处理, 合成出了具有高比表面积的球形纳米空心二氧化硅粒子. 然后, 分别采用TEM, SEM, EDS, XRD, FTIR和TG等测试手段对样品进行了分析和表征, 并考察了不同合成条件, 如反应温度、反应pH值、煅烧温度和包覆反应时SiO₂/CaCO₃的配比对纳米空心二氧化硅粒子的比表面积变化. 实验结果表明: 较高的反应温度如60～80 ℃, pH值9左右、SiO₂包覆量为碳酸钙质量的10%, 以及煅烧温度为700 ℃, 有利于形成空心形貌较好、比表面较大的球形纳米空心二氧化硅.     

DNA模板诱导针状CdS纳米粒子的形成

利用生物分子作为模板合成无机纳米粒子 ,可以精确地控制生成粒子的结构、大小、形状等 ,这方面的工作已经引起了研究者的广泛关注[1].目前 ,已经对许多生物分子作为无机纳米粒子合成模板剂的可行性进行了探索 .Ｍａｎｎ等[2 ]利用蛋白质作为模板合成ＣｄＳ纳米粒子 ;Ｗａｎｇ等[3]利用哺乳类眼睛晶状体管蛋白作为模板合成纳米尺寸的ＣｄＳ粒子 ;Ｂｒａｕｎ等[4 ]将寡聚核苷酸连接在两个金电极之间 ,用ＤＮＡ分子作为模板生长出长 1 2 μｍ、直径 1 0 0ｎｍ的银纳米线 ;Ｓｈｅｎｔｏｎ等[5 ]用烟草斑纹病毒的蛋白外壳作模板剂诱导生成无机 …     

有机官能化MSU-x孔分子筛的界面特征

MSU- x是自 M41S系列介孔分子筛问世以来所合成的另一类新型介孔分子筛材料 ,它具有三维立体交叉排列的 " worm- like"孔道结构特征及采用中性模板剂、廉价无毒等诸多合成优点 [1～ 4],有着潜在的应用价值 .为了改善纯硅的介孔材料的表面和孔道性质 ,扩大其应用领域 ,除了在骨架引入金属离子或在其孔道中负载催化活性物质外 ,对介孔材料进行有机官能化制备无机-有机杂化材料改善其骨架和孔道性质是当前研究的热点之一 [5].正是由于活性有机基团的存在 ,使得这些材料可直接用于催化反应 ,或作为中间介质成为其它络合离子的主体 .由于有机基…     

Inhibition of Scale Formation Using Silica Nanoparticle

Because of the wide use of water injection for enhanced oil recovery in the oil fields in order to displace oil into the production well, many reservoirs experience scale deposition problems. Scale formation can cause the production path to be blocked and also cause significant reduction in productivity. One of the most common methods for preventing or lowering the amount of scale formation is applying the scale inhibitors. In this work, silica nanoparticles are used as a scale inhibitor. Conductivity is used as a property of the fluid to show the amount of ion in the solution, leading us to predict the amount of scale formed in the solution. An optimum amount of silica nanoparticles could reduce the rate of conductivity decreasing the solution and consequently lowering the scale deposition, which is the aim of this challenging subject in the oil industry.