微/纳米ZnO绒球的制备及其在自然光下催化降解有机染料性能

以谷氨酸氟硼酸(GluBF₄)离子液体水溶液为反应介质,以物质的量比为1:6的二水合醋酸锌[Zn(Ac)₂·2H₂O]和氢氧化钠为原料,室温下制备前驱体,再微波辅助加热制备了纳米氧化锌粉体,获得了纳米结构微米尺寸纳米ZnO绒球.利用场发射扫描电镜(FESEM)、X射线衍射(XRD)、比表面(BET)、能量色散谱(EDS)等对产物进行了表征.所得产物为六方晶系纤锌矿结构,粉体粒径20.4 nm,绒球比表面积为28.3 m²·g^-1,产物纯度较高,收率95.3%.同时探讨了纳米ZnO绒球生成的可能机理.该纳米材料在日光下显示较高的光催化活性和稳定性.分别配制浓度为10 mg·L^-1的100 mL甲基橙(MO)和甲基紫(MV)水溶液, 30 mg纳米氧化锌为光催化降解催化剂,太阳光激发下5 h脱色率分别达到74.3%和96.9%;溶液总有机碳(TOC)含量随光降解的进行缓慢下降;光催化剂重复利用5次,催化剂形貌不变、颜色不变,质量基本未发生变化.     

花形ZnO纳米片微球的合成、表征及光催化性能

以ZnCl2和尿素为原料,采用水热法合成了由纳米片组成的花形微球碱式碳酸锌前驱体,然后在300℃下煅烧0.5 h得到了形貌一致的ZnO产物。采用XRD、FTIR、TG、SEM、TEM、XPS对其进行表征,结果表明产物为六方纤维矿结构ZnO;组成3D花型微球的纳米片构筑单元厚度为10 nm,表面呈孔装结构,比表面积为72 m2.g-1。分别以花形ZnO纳米片、单分散ZnO纳米片和商用ZnO纳米颗粒为光催化剂,通过降解罗丹明B(Rh B)进行了光催化活性研究。结果表明,与商用ZnO纳米颗粒相比,水热法制备的花形ZnO纳米片显示了更好的光催化活性,可能是由于花形ZnO纳米片微球有较高的比表面积和3D花形形貌所致。     

真空冷冻干燥制备高比表面积纳米氧化铝

采用真空冷冻干燥技术结合反相微乳液法, 于环己烷/聚乙二醇辛基苯基醚(曲拉通X-100)-十六烷基三甲基溴化铵(CTAB)/正丁醇/水溶液体系中, 合成了纳米Al2O3粉体. 采用扫描电子显微镜(SEM)、透射电子显微镜(TEM)、X射线衍射(XRD)及比表面积与孔隙度分析仪对产物的形貌、结构、比表面积、孔容与孔径进行了表征. 经过煅烧, 该纳米Al2O3比表面积约550.0 m2·g-1(随反应参数不同而变化), 属γ-Al2O3晶型, 粒径均匀, 颗粒直径小于10.0 nm. 考察了不同的干燥方式(电热鼓风干燥、普通真空干燥、真空冷冻干燥)以及真空冷冻干燥过程中主要参数对产物比表面积、孔容、平均孔径等物理性质的影响. 结果表明, 采用真空冷冻干燥法制备的纳米Al2O3的比表面积和孔容远高于采用另外两种干燥方式制备的纳米Al2O3. 采用真空冷冻干燥法制备纳米Al2O3时, 降温速率、预冻时间、冻干时间等参数对最终制备的产物比表面积与孔结构有显著影响.     

不同形貌PbS 纳米粒子形成机理的探讨

采用聚乙二醇辛基苯基醚(OP)/正戊醇/环己烷/水溶液所形成的W/O型微乳液中的水核作软模板,合成了不同形貌如球形、立方体形、纺锤形、梭形和棒形的PbS纳米粒子。运用透射电子显微镜(TEM)对产物的形貌进行了表征。考察了W/O型微乳液中水与表面活性剂的物质的量的比(ω0)、反应物浓度和陈化时间等条件对产物形貌的影响。对不同形貌PbS纳米粒子的形成机理进行了探讨。     

ZnO纳米环的可控合成

以六次甲基四胺(Hexamethylenetetramine, C6H12N4)和水合硝酸锌[Zn(NO3)2·2H2O]为原料, 表面活性剂聚丙烯酰胺-氯化二烯丙基二甲基铵[poly(acrylamide-co-diallyldimethylammonium chloride, 缩写为PAM-CTAC]为形貌控制剂, 采用液相沉淀法合成了ZnO纳米环. 产物的结构与形貌经X射线粉末衍射(XRD)和扫描电子显微镜(SEM)表征. 研究了不同实验条件(如表面活性剂的浓度、反应物浓度、反应温度和反应时间等)对产物形貌与尺寸的影响. 讨论了PAM-CTAC作用下ZnO纳米环可能的形成机理. 结果表明, 合成产物为六方Wurtzite型结构的ZnO纳米环, 环内径约为220 nm, 壁厚约为70 nm. 反应物浓度、反应温度对ZnO纳米环的形成以及纳米环的尺寸都有一定的影响, 但起关键作用的是PAM-CTAC. 通过改变PAM-CTAC的浓度, 能有效地实现ZnO纳米环的可控合成. 室温荧光光谱显示, ZnO纳米环的紫外发射峰具有较窄的半高宽(FWHM)(约7 nm), 表明合成产物具有较窄的尺寸分布.     

反相微乳液法制备纳米氧化铝

采用由环己烷、聚乙二醇辛基苯基醚(TritonX-100)、正丁醇与水溶液构成的反相微乳液体系, 合成了纳米Al2O3粉体. 采用X射线衍射、扫描电子显微镜、透射电子显微镜、比表面积分析仪等表征手段, 分别对产物的结构、形貌、比表面积和孔容进行了表征, 该纳米Al2O3比表面积约450 m2·g-1(随反应参数不同发生变化), 均属γ-Al2O3, 粒径均匀, 颗粒直径小于10 nm. 考察了微乳液体系中水与表面活性剂的物质的量之比r0、表面活性剂与助表面活性剂的体积比φ、焙烧温度等关键因素对产物比表面积等物理性质的影响. 结果表明, 当r0=20, φ=0.5, 焙烧温度为500 ℃时, 可以得到大比表面积、高孔容、分散性好及粒径分布均匀的γ-Al2O3粉体.     

超声化学法制备SrF2纳米片自组装微球

通过简单的超声化学方法制备了SrF2纳米片自组装微球.合成的产物通过粉末X射线衍射仪、场发射扫描电子显微镜、透射电子显微镜进行了表征和分析.结果表明这些微球是由规则、有序的纳米片组成.而这些纳米片互相垂直连接组装成微球.研究还发现反应物的浓度.配位剂和pH值对产物的形貌和尺寸有着重要的作用.     

聚乙烯吡咯烷酮碱性水溶液中金纳米花的简易合成

以聚乙烯吡咯烷酮(PVP)兼作保护剂和还原剂在碱性水溶液中直接还原HAuCl₄制备出了60-80 nm的三维(3D)金纳米花. 产物的透射电子显微镜(TEM)和扫描电子显微镜(SEM)图像显示, 金纳米花表面布满10-15 nm左右的纳米触角, X射线衍射(XRD)表征揭示产物为金的面心立方晶体, 选区电子衍射(SAED)花样说明金纳米花为多晶结构. 金纳米花的生长经历了三个关键步骤, 即初级纳米晶聚集成多脚状纳米粒子, 随后在合适的PVP/HAuCl₄浓度比及NaOH浓度下, 多脚状纳米粒子进一步聚集形成疏松的花状粒子, 最终经过Ostwald熟化形成致密的花状产物. 一定HAuCl₄浓度下PVP/HAuCl₄浓度比和NaOH浓度对产物的形貌影响显著, 因此通过同时调控合适的PVP/HAuCl₄浓度比和NaOH浓度, 就能得到适应各种应用需求的尺度可控和纳米触角形貌可控的金纳米花.     

W/O型微乳液中不同形貌PbS纳米粒子的制备及其形成机理的探讨

用聚乙二醇辛基苯基醚(OP)/异辛醇/环己烷/水溶液所形成的微乳液体系控制合成出了PbS纳米粒子，考察了微乳液中水与表面活性剂的物质的量的比(ω₀)、反应物浓度及浓度比、陈化时间等条件对产物形貌的影响。采用透射电子显微镜(TEM)、X-射线衍射(XRD)分别对产物的结构、粒度和形貌进行了表征。结果表明，在微乳液体系中，控制不同的实验条件，可以成功地合成球形、梭形、针状和棒状的PbS纳米粒子，并且粒径分布集中，无团聚现象。论文还对不同形貌PbS纳米粒子的形成机理进行了探讨。     

咪唑类离子液体辅助水热法合成棒状微/纳米ZnO晶体

以醋酸锌和氢氧化钠为原料, 以水和含不同长度烷基链的咪唑类氯盐离子液体的混合物作为反应介质, 采用水热法合成出不同形貌的微/纳米ZnO晶体, 用扫描电子显微镜(SEM)和X射线衍射仪(XRD)对合成的ZnO晶体进行表征. 研究了烷基链长度、 离子液体用量、 反应时间以及反应温度对形成棒状ZnO晶体形貌的影响. 实验结果表明, 所制备的棒状ZnO晶体样品均为六方晶系结构. 在棒状ZnO晶体的制备过程中, 控制反应温度, 选择不同的离子液体及其用量十分重要.     

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%.     

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.     

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.     

A general and convenient synthesis of 4-(tosylmethyl)semicarbazones and their use in amidoalkylation of hydrogen,heteroatom, and carbon nucleophiles

A general synthesis of previously unknown semicarbazone-based α-amidoalkylating reagents, 4-(tosylmethyl)semicarbazones, has been developed. The synthesis involved three-component condensation of semicarbazones of aliphatic or aromatic aldehydes with the same or other aldehydes and p-toluenesulfinic acid. The scope and limitations of this reaction were investigated. The compounds obtained were demonstrated to be an efficient α-(4-semicarbazono)alkylating agents. They were reacted with H- (sodium borohydride), O- (sodium methylate), S- (sodium phenylthiolate), N- (pyrrolidine, sodium succinimide), P- (trialkyl phosphites), and C-nucleophiles (sodium diethyl malonate) to give the corresponding products of the tosyl group substitution, 4-substituted semicarbazones, including analogues of nitrofurazone. Among the prepared compounds tested in vitro for antibacterial and antifungal activity, three nitrofuryl-containing semicarbazones exhibited high biological activities with minimum inhibitory concentration (MIC) values of 8–32 μg/mL.     

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.     

Synthesis of novel chiral bidentate hydroxyalkyl-N-heterocyclic carbene ligands and their application in palladium-catalyzed Mizoroki–Heck couplings and asymmetric addition of diethylzinc to benzaldehyde

A small library of new chiral bidentate hydroxyalkyl-imidazolium salts 1 is conveniently synthesized on multi-gram scale from inexpensive and commercially available chiral pool amino acids. The corresponding carbenes, generated by deprotonation of imidazolium salts 1, in combination with palladium(II) chloride were tested in the Mizoroki–Heck coupling reaction. The most significant results in terms of yields and reactivities were achieved with low catalyst loading. The catalytic activities of these imidazolium salts were also investigated in the asymmetric addition of diethylzinc to benzaldehyde. The use of MgO nanoparticles as an additive in conjunction with these ligands played a crucial role in increasing the efficiency of these reactions.