磁性二氧化硅复合纳米粒子的合成及其与青铜器的相互作用研究

采用反相微乳液法, 合成了以PVP分散的磁性Fe₃O₄纳米粒子为核、SiO₂为壳并复合有荧光标记物钌联吡啶的核壳型复合功能纳米粒子. 在对该功能型二氧化硅复合纳米粒子进行TEM、荧光特性和磁性等特性表征的基础上, 重点研究了水溶性高聚物PVP溶液对Fe₃O₄纳米粒子的分散性, 并将其均匀的包入SiO₂壳中, 基于此研究了该功能型二氧化硅复合纳米粒子与青铜器之间的相互作用、以功能型复合纳米粒子为材料对青铜器腐蚀机理进行了在线、无损、实时监测以及将复合纳米材料从被分析体系中无损去除的方法, 发展了适合于去除吸附于青铜器文物表面的功能型纳米粒子的新方法. 这一研究结果为以该纳米粒子为基质构建适合于青铜器表面成分分析的纳米传感器奠定了基础.     

基于能量转移的稀土上转换发光复合体系检测过氧亚硝酸根

采用热分解法制备得到核壳双层结构的稀土上转换发光纳米粒子(UCNP)。通过表面活性剂的软模板法制备了SiO₂包覆的蛋黄-壳(yolk-shell)结构稀土纳米粒子YSUCNP,介孔SiO₂包裹层赋予稀土纳米粒子YSUCNP亲水性。利用荧光探针NOF2功能化稀土纳米粒子YSUCNP,得到具有过氧亚硝酸根(ONOO-)响应能力的复合检测体系YSUCNP-NOF2。该体系能够在纯水体系中实现发光能量转移的ONOO-上转换发光检测。利用稀土上转换纳米材料的近红外激发优势,在细胞层次实现了ONOO-的上转换发光成像检测。     

振荡剪切流场下PS/PVME/SiO2复合物的相行为

利用光学显微镜-剪切台联用系统研究了振荡剪切流场下聚苯乙烯（PS）/聚甲基乙烯基醚（PVME）/二氧化硅（SiO₂）纳米粒子复合物的热力学稳定性. 结果表明,小振幅振荡剪切可导致PS/PVME共混物出现类似在稳态流场下的剪切诱导相容及剪切诱导相分离现象. 共混体系存在临界振荡频率ω_c,当振荡频率低于ω_c时,发生剪切诱导相分离（SID）行为,反之发生剪切诱导相容（SIM）行为. SiO₂纳米粒子的加入使复合体系的相容性提高. 存在一个临界SiO₂纳米粒子含量φ_c,当SiO₂纳米粒子含量高于φ_c时,复合体系中不存在临界振荡频率ω_c,低振荡频率下的剪切诱导相分离得到抑制. 此外,复合体系的上述行为与升温速率和共混物组成密切相关.     

SiO2@Fe2O3核-壳结构催化剂的制备及表征

采用优化的Stöber法制备了平均粒径为230 nm的单分散球形SiO₂颗粒,并以此为内核,通过水解沉积法制备了不同壳层厚度的核-壳结构SiO₂@Fe₂O₃催化剂。采用扫描电子显微镜(SEM)、透射电子显微镜(TEM)、N₂物理吸附和X射线衍射分析(XRD)等手段对催化剂进行表征,探讨了不同制备条件对SiO₂@Fe₂O₃催化剂形貌的影响。结果表明,通过水解沉积法制备的SiO₂@Fe₂O₃催化剂具有明显的核-壳结构,并且保持了原始SiO₂核的球形形貌,Fe₂O₃纳米粒子通过-OH的氢键作用连接在SiO₂表面,形成了2~10 nm厚的Fe₂O₃均匀连续包覆层。     

基于姜黄素负载的上转换纳米传感体系测定生物样品中的铜离子

通过高温共沉淀法制备了发光效率高、形貌规则、粒径均一的上转换纳米粒子；采用反相微乳法合成二氧化硅壳层(SiO₂)，实现上转换纳米粒子从油相到水相的转移；将介孔二氧化硅壳层(mSiO₂)包覆在上转换纳米粒子表面，荧光响应分子姜黄素被负载在m SiO₂的孔道中。基于荧光共振能量转移的原理，构建“Turn on”纳米传感体系，并用于Cu²⁺的检测，检测线性范围为10～50μmol/L，检出限为0.5μmol/L。本方法可实现大鼠血清样品中Cu²⁺的检测。     

在无机SiO2纳米粒子存在下的苯丙乳液共聚合

研究了在无机SiO₂纳米粒子存在下的苯丙乳液共聚合.选择了能使苯丙乳液稳定存在的乳化剂体系,研究了温度和SiO₂的加入对聚合过程转化率的影响,结果表明,SiO₂的加入对聚合过程有阻聚作用,使单体的转化率降低.SEM照片证明SiO₂粒子已经进入苯丙乳液粒子中,而且SiO₂的加入对乳液制成的膜断面形态有一定影响.实验发现在无机SiO₂纳米粒子存在下,苯丙乳液共聚合时有较多残渣出现,对此通过改进乳液聚合进行了有效地改善.同时对制成的复合材料进行了力学性能和热学性能的测定.     

新型核壳结构纳米催化剂的三效催化活性及热稳定性

从Pd纳米粒子出发制备了具有核壳结构的新型纳米Pd@SiO₂/Ce_0.4Zr_0.6O₂三效催化剂及作为参比的Pd/Ce_0.4Zr_0.6O₂催化剂, 采用X射线衍射、 透射电子显微镜、 氢气程序升温还原和氮气低温吸附-脱附等技术对催化剂的物化性质进行了表征, 研究了Pd@SiO₂/Ce_0.4Zr_0.6O₂和Pd/Ce_0.4Zr_0.6O₂催化剂的三效反应催化活性和热稳定性. 结果表明, SiO₂壳层可以抑制Pd粒子的团聚, 同时还能抑制Pd物种的再分散, 减少Pd的流失. 具有核壳结构的纳米Pd@SiO₂/Ce_0.4Zr_0.6O₂催化剂具有更好的三效催化活性和更高的热稳定性.     

介孔结构增强的Fe3O4超粒子@介孔SiO2的光热性能

采用湿化学法制备了多功能Fe₃O₄超粒子@介孔SiO₂复合材料.该纳米复合材料具有超顺磁性,在商用磁铁下可实现快速富集、分离.SiO₂的包覆增强了Fe₃O₄超粒子在近红外光区的吸收,提高了其光热性能;介孔结构的构建提高了近红外光的利用率,进一步提升了纳米复合物的光热性能,且介孔SiO₂的壳层越厚,光热性能越优.细胞实验结果表明,Fe₃O₄超粒子@介孔SiO₂在近红外光照射下具有较高的癌细胞杀伤能力.     

类蛋结构的可磁分离光催化剂纳米球的制备及催化性能

通过反胶束和静电自组装方法制备了一种类蛋结构的可磁分离光催化剂纳米材料SiO₂@NiFe₂O₄@TiO₂(TSN), 这种光催化剂对甲基橙废水有较好的降解效果, 并显示出了超顺磁性, 通过外加磁场方便地实现催化剂在水中的分离与回收. 该光催化剂纳米球的X射线衍射, TEM和FTIR结果表明, 铁酸镍纳米粒子被包裹在SiO₂内, 形成SiO₂@NiFe₂O₄(SN)纳米球载体, 纳米TiO₂颗粒组装在SN表面, 形成TiO₂光催化壳层. 利用甲基橙的降解考察了光催化剂纳米球的活性, 结果表明, 在NiFe₂O₄和TiO₂之间包覆一层无定形的SiO₂可以显著提高光催化剂纳米球TSN的催化活性.     

基于氧化石墨烯信号放大的化学发光法联合检测甲胎蛋白和癌胚抗原

提出了一种基于信号放大技术的流动注射化学发光免疫传感器, 用于联合检测人血清中甲胎蛋白(AFP)和癌胚抗原(CEA)的含量. 该传感器首先用表面接枝羧基的氧化石墨烯来吸附固定辣根过氧化物酶(HRP)标记的二抗, 制得信号放大型免疫探针. 然后用合成的磁性介孔材料Fe₃O₄/SiO₂来吸附固定AFP和CEA的单克隆抗体, 用磁铁将其吸附在两个检测池内壁. 当待检样品和信号放大型免疫探针陆续注射进入相应检测池, 发生夹心式免疫反应, 形成的免疫复合物被磁条吸附在检测池内壁. 随后加入鲁米诺和H₂O₂发光底物, 与酶标记物发生酶促增强的化学发光反应, 并通过控制设在两个管路上的开关来控制鲁米诺和H₂O₂的流通, 相继检测两个检测池中的化学发光信号, 从而实现两种待测物的同时检测.     

二氧化碳和丙烯直接合成甲基丙烯酸的NiPMo/TiO2催化剂的研究

用溶胶-凝胶法以磷钼酸(MPA)的镍盐溶液水解钛酸四丁酯制备了NiPMo/TiO2催化剂.使用ICP、 XRD、 TG-DTA、 IR、 TPD-MS和微反应技术研究了催化剂的化学组成、热稳定性、化学吸附性质和催化反应性能.杂多钼酸盐与TiO2通过O2-在TiO2表面发生了键合.在623 K下,杂多阴离子仍保持原有的Keggin结构.CO2在Lewis酸位Ni(Ⅱ)和Lewis碱位Ni-O-Mo的桥氧协同作用下生成CO2卧式吸附态Ni(Ⅱ)←O-(CO)←(O--Ni).丙烯有多种吸附态在催化剂上吸附.在563 K、 1 MPa和空速1500 h-1的反应条件下,丙烯的摩尔转化率为3.2%,产物MAA选择性为95%.     

Toward new camptothecins. Part 6: Synthesis of crucial ketones and their use in Friedländer reaction

In the context of the preparation of camptothecin and luotonin A analogs, the synthesis of some key keto-precursors and their use in Friedländer condensation are described. This paper also focuses on the stability of these keto intermediates and emphasizes the major differences between indolizinones and pyrroloquinazolinones series. Noteworthy is also the report of some original structures isolated as by-products of some experiments.     

CoFe2O4自形成磁性液体场致结构化对磁化的影响

The Langevin paramagnetic theory can’t describe the relation between magnetization of ferrofluids and applied magnetic field. The structuralization of ferrofluids, which is considered the main influence factor of the magnetization, is regarded. The part of magnetization works is deposited when the structure is forming. This action influences the magnetization of ferrofluids directly or indirectly. On the base of the “compressing” model, the Langevin function that usually describes the magnetization of ferrofluid is modified, and a well-fitted curve is obtained. An equation of the relation between the equivalent volume fraction after being “compressed” and the intensity of magnetic field is discovered, which approximately describes the process of magnetization. The relation between the approximate initial susceptibility and the volume fraction can be obtained from modified formula.     

Highly regioselective Buchwald–Hartwig amination at C-2 of 2,4-dichloropyridine enabling a novel approach to 2,4-bisanilinopyridine (BAPyd) libraries

The highly regioselective Buchwald–Hartwig amination at C-2 of the cheap and readily accessible reagent, 2,4-dichloropyridine with a range of anilines and heterocyclic amines is described. This new methodology is robust and provides a facile access to 4-chloro-N-phenylpyridin-2-amines on 0.25 mol scale. These intermediates undergo a further Buchwald–Hartwig amination at higher temperature to enable rapid exploration of the chemical space at C-4 and to provide a library of 2,4-bisaminopyridines.     

KMnO4-mediated oxidative CN bond cleavage of tertiary amines: Synthesis of amides and sulfonamides

KMnO₄-mediated oxidative CN bond cleavage of tertiary amines producing secondary amine was introduced, which was trapped by electrophiles (acyl chloride and sulfonyl chloride) to form amides and sulfonamides. The reaction could take place at mild condition, tolerating a wide range of function groups and affording products in moderate to excellent yields.     

Chemistry of heterocyclic compounds at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences, over 50 years (Review)

The review contains a concise historical account and information on the most significant researches undertaken by the staff at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences on the Chemistry of Heterocyclic Compounds. Dedicated to Academician of the Russian Academy of Sciences B. A. Trofimov on his 70th jubilee. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1443–1502, October, 2008.     

Sulfur-directed metal-free and regiospecific methyl C(sp3)–H imidation of thioanisoles

Regiospecific and direct imidation of the methyl C(sp³)–H bond of thioanisoles is realized under mild and metal-free conditions with N-fluorobis(benzenesulfonyl)imide as an oxidant and nitrogen source. Proposed mechanism suggests that thionium ion intermediates and a Pummerer-type reaction are involved. The imidation has advantages such as high step-economy, excellent functionality tolerance, and regiospecificity, giving structurally diverse imidation products.     

Selective syntheses of 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones via temperature-dependent Rh(II)-carbenoid-mediated 2H-azirine-ring expansion

The Rh(II)-catalyzed reaction of 2-carbonyl-substituted 2H-azirines with ethyl 2-cyano-2-diazoacetate or 2-diazo-3,3,3-trifluoropropionate provides an easy access to 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones. These compounds can be selectively prepared from the same starting material using temperature as the only varied parameter. The 2-azabuta-1,3-diene intermediate, a common precursor for both heterocyclic products, isomerizes into 2H-1,3-oxazine under kinetic control, while 1H-pyrrol-3(2H)-one is the sole product of the reaction at elevated temperatures. According to DFT-calculations a one-atom oxazine ring contraction involving ring-opening to a 2-azabuta-1,3-diene intermediate, followed by a 1,5- and 1,2-prototropic shift leads to the consecutive formation of imidoylketene and azomethine ylide, which then further undergo cyclization to the pyrrole derivative.     

Synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives

Different approaches for the synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives from simple amino acids have been investigated. A library of 33 precursors for the preparation of N-hydroxy pyrazinones was obtained in moderate to good yields.