白果形钨酸铅的可控合成及光致发光特性

以酒石酸钠为表面活性剂,采用直接沉淀法合成了白果形钨酸铅晶体,通过扫描电子显微镜(SEM)、X射线衍射(XRD)、能量散射仪(EDS)及荧光发射光谱(PL)对产物的结构和性质进行了表征。探讨了酒石酸钠对(004)晶面的抑制作用以及pH值和陈化温度对产物形貌的影响,结合晶体的内部结构提出了产物可能的形成机制。结果表明,陈化温度为30℃时,晶体形貌最为规整,PbWO4晶体在紫外光激发下展现出强的绿光发射,在pH=9时可达到最大的发光强度。     

乙醇/水混合溶剂体系中碳酸钙晶体晶型和取向的控制

采用（NH₄）₂CO₃分解法,制备得到了晶型和形貌可控的CaCO₃晶体。研究结果表明,乙醇/水混合溶剂、陈化时间和L-半胱氨酸自组装单层模板对CaCO₃晶体的晶型、取向和形貌都具有重要影响。无单层模板情况下,溶液中主要得到了球霰石,球霰石的形貌随陈化时间从花朵外形变为树叶形。同样的醇/水体系中,在自组装单层上却得到了取向为（104）晶面的方解石。这与水溶液中同一自组装单层上主要获得（001）结晶面的方解石有明显不同。方解石的形貌也随陈化时间变化而改变。陈化时间为3h时,得到具有孔洞结构的方解石;陈化时间为12h时,得到表面光滑的菱面体方解石。     

不同形貌TiO2的水热合成及对苯酚的降解研究

采用水热合成法, 通过对溶液的pH值、反应物配比、陈化温度及陈化时间等条件的控制, 合成出不同晶型及形貌的TiO2纳米粒子. 结果表明, 溶液的pH＝11, n(钛酸丁酯):n(三乙醇胺)＝1:2, 陈化温度为150 ℃, 陈化时间为48 h时, 能得到较规则的、长径比约为4:1的棒状TiO2. 当溶液pH<10时, 得到球形的TiO2纳米粒子; 陈化时间为24 h时, 得到纺锤形TiO2纳米晶. 以上合成的纳米粒子均为锐钛矿型, 但当溶液的pH>12时, 则得到板钛矿型TiO2粒子. 以苯酚为降解模型, 考察了不同形貌TiO2的光催化活性.     

回流法可控合成BiPO4纳米棒及其光催化性能

采用回流法合成了BiPO₄纳米棒光催化剂, 探讨了反应时间、反应物比例、pH值和反应物浓度对BiPO₄晶相结构和形貌尺寸的影响, 利用粉末X射线衍射(XRD)、透射电镜(TEM)、比表面积分析(BET)和紫外-可见漫反射光谱(UV-Vis DRS)等对产物进行了表征, 以亚甲基蓝(MB)为探针研究了其光催化活性. 反应时间和反应物浓度对产物的形貌尺寸影响较大, 反应物比例和pH值对产物晶相结构和形貌尺寸均有较大的影响, 进一步影响BiPO₄光催化剂的活性. 调控各种因素后可合成出具有单斜相独居石/六方相混晶结构的高紫外光活性BiPO₄纳米棒光催化剂.     

乙醇/水混合溶剂体系中碳酸钙晶体晶型和取向的控制

采用(NH4)2CO3分解法,制备得到了晶型和形貌可控的CaCO3晶体。研究结果表明,乙醇/水混合溶剂、陈化时间和L-半胱氨酸自组装单层模板对CaCO3晶体的晶型、取向和形貌都具有重要影响。无单层模板情况下,溶液中主要得到了球霰石,球霰石的形貌随陈化时间从花朵外形变为树叶形。同样的醇/水体系中,在自组装单层上却得到了取向为(104)晶面的方解石。这与水溶液中同一自组装单层上主要获得(001)结晶面的方解石有明显不同。方解石的形貌也随陈化时间变化而改变。陈化时间为3h时,得到具有孔洞结构的方解石;陈化时间为12 h时,得到表面光滑的菱面体方解石。     

电诱导牙釉质表面羟基磷灰石涂层形成的研究

以含Ca(NO₃)₂、NH₄H₂PO₄和NaNO₃组成的溶液作为电解液,在人牙釉质表面电诱导制备了羟基磷灰石(HA)涂层。应用X射线衍射(XRD)﹑扫描电镜(SEM)和能谱分析(EDS)对形成涂层后的牙釉质样品进行分析和表征,研究了电解液初始pH值﹑电流密度和温度的变化对涂层的组成﹑结构和形貌的影响。研究结果表明这些因素对涂层的组分(HA)没有显著影响,而对涂层中HA晶体c轴的择优取向度的影响则较显著。当控制电解液的初始pH值为6﹑电流密度为0.5 mA·cm^-2﹑温度为55 ℃的时候,涂层中HA晶体沿c轴方向择优取向生长,且择优取向度和牙釉柱的HA较为接近。     

硅酸盐对Ferrihydrite相转化为α-Fe2O3微粒形貌的调控作用

以Ferrihydrite(又称水合氧化铁hydrous iron oxide)为反应前驱物, Fe(II)为催化剂, 在微量Na₂SiO₃存在下, 控制pH＝6～9范围内合成出了亚微米级纺锤形和准立方形α-Fe₂O₃微粒. 研究了初始pH, Na₂SiO₃浓度, Ferrihydrite老化方式对相转化时间和产物形貌的影响, 利用XRD, SEM等手段对产物进行了表征. 结果表明, Na₂SiO₃对Ferriihydrite催化相转化有一定的抑制作用, 是影响其相转化过程及产物形貌的关键. 在弱碱性条件下, [Si]/[Fe^3＋]为0.01时可直接获得纺锤形(轴比≥2)或准立方形(300～400 nm) α-Fe₂O₃粒子, 并对形成机理进行了初步讨论.     

棒状氢氧化镁的合成

以氯化镁和氢氧化钠为原料合成了棒状氢氧化镁粉体。考察了氢氧化钠浓度、陈化温度、陈化时间对氢氧化镁形貌的影响。采用SEM、HRTEM、XRD、TG等对所得氢氧化镁颗粒的形貌、颗粒大小、晶习及热稳定性进行了表征。结果表明,当陈化温度为90℃时,所得棒状氢氧化镁随氢氧化钠浓度的升高及陈化时间的增加,晶形更加完整;当陈化温度在120℃时,所得氢氧化镁颗粒的形貌为片状,不能得到棒状氢氧化镁。     

反相微乳液法制备纳米Al2O3颗粒及其形成反应机理的研究

通过聚乙二醇辛基苯基醚(曲拉通X-100)/正丁醇/环己烷/水溶液形成的体系, 采用反相微乳液法合成了Al₂O₃纳米粒子. 对前驱体进行热分析(TG-DTG-DTA), 确定了合适的煅烧温度为1150 ℃. 采用X射线衍射(XRD)、透射电镜(TEM)、紫外可见分光光度法(UV-vis)分别对产物的结构、粒度和形貌进行了表征, 考察了微乳液中水与表面活性剂的物质的量之比(ω_o)、煅烧温度和煅烧时升温速率等关键因素对产物形貌和晶相的影响, 并通过分析进一步揭示了Al₂O₃纳米粒子的形成机理. 结果表明, 控制ω_o为10、煅烧温度为1150 ℃可得到分散性好、粒径分布均匀的Al₂O₃纳米粒子, 且2 ℃/min的升温速率更有利于产物向稳定的α晶相转变.     

硅酸盐对Ferrihydrite相转化为α-Fe2O3微粒形貌的调控作用

以Ferrihydrite(又称水合氧化铁hydrous iron oxide)为反应前驱物, Fe(II)为催化剂, 在微量Na₂SiO₃存在下, 控制pH＝6～9范围内合成出了亚微米级纺锤形和准立方形α-Fe₂O₃微粒. 研究了初始pH, Na₂SiO₃浓度, Ferrihydrite老化方式对相转化时间和产物形貌的影响, 利用XRD, SEM等手段对产物进行了表征. 结果表明, Na₂SiO₃对Ferriihydrite催化相转化有一定的抑制作用, 是影响其相转化过程及产物形貌的关键. 在弱碱性条件下, [Si]/[Fe^3＋]为0.01时可直接获得纺锤形(轴比≥2)或准立方形(300～400 nm) α-Fe₂O₃粒子, 并对形成机理进行了初步讨论.     

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.