磁性γ-Fe2O3/BiOCl/BiVO4复合材料的制备及其光催化性能研究

采用γ-Fe2O3掺杂对Bi OCl/Bi VO4进行改性。通过超声-水热法合成出粒径在1.5~2.0μm、表面附着Bi OCl纳米片和球形颗粒γ-Fe2O3的Bi VO4微米块状磁性γ-Fe2O3/Bi OCl/Bi VO4复合光催化剂。结合XRD、SEM、UV-Vis DRS等表征手段对复合材料的组成、形貌、光学性质进行表征,通过光催化降解若丹明B溶液对其光催化性能进行评价。结果表明,使用过的15%γ-Fe2O3/Bi OCl/Bi VO4复合光催化剂可以通过外磁场作用很容易地与反应溶液分离,且仍具有较高的可见光催化活性和稳定性,其重复使用4次后,对若丹明B的降解率和光催化剂的回收率变化不明显,仍达到88.6%和90.3%。     

Pd/BiOCl高效室温催化甲醛产氢性能研究

利用浸渍-还原法制备Bi OCl纳米片负载的钯纳米颗粒催化剂(Pd/Bi OCl),对室温催化氧化HCHO产氢性能进行了研究,并与纯Pd纳米颗粒催化效果进行了对比.研究结果表明,Pd/Bi OCl催化剂在有效降低贵金属Pd用量情况下(仅为2%wt),仍表现出比纯Pd纳米颗粒更高的催化HCHO产氢的性能.此外,通过进一步优化甲醛浓度、氢氧化钠浓度、氧气浓度和反应温度等参数,Pd/Bi OCl催化氧化HCHO产氢速率最高可达到200 m L/(min*gcatalyst).进一步研究结果表明,Pd/Bi OCl催化HCHO产氢反应的活化能仅为15.2 k J/mol,远低于无催化剂条件下甲醛产氢的活化能65 k J/mol.     

异质结构AgCl/Bi2WO6微米球制备、表征及其光催化性能

首先利用水热法制备了由纳米片组装的粒径为1.5–2μm的Bi2WO6微球,然后在微球表面沉积了不同含量的AgCl (5 wt%,10wt%,20wt%,30wt%),制备了异质结构AgCl/Bi2WO6微球光催化剂.利用X射线粉末衍射、扫描电镜、透射电镜、红外光谱、紫外-可见漫反射吸收等手段对所制的光催化剂进行表征,并以紫外光和可见光分别为光源,罗丹明B为降解对象测试了其光催化活性,考察复合不同含量的AgCl对Bi2WO6光催化剂的性能影响.结果表明,沉积AgCl对Bi2WO6的晶体结构、表面性能和光吸收性能没有产生明显影响,但大幅度提高了Bi2WO6的紫外和可见光催化活性.当复合20wt%AgCl时, AgCl/Bi2WO6光催化活性最佳,紫外光下比纯Bi2WO6提高了2.2倍,可见光下提高了1倍.这主要是由于形成的AgCl/Bi2WO6异质结能有效抑制光生电子和空穴的复合,从而提了其光催化性能.     

异质结构AgCl/Bi_2WO_6微米球制备、表征及其光催化性能（英文）

首先利用水热法制备了由纳米片组装的粒径为1.5–2μm的Bi2WO6微球,然后在微球表面沉积了不同含量的AgC l(5 wt%,10 wt%,20 wt%,30 wt%),制备了异质结构Ag Cl/Bi2WO6微球光催化剂.利用X射线粉末衍射、扫描电镜、透射电镜、红外光谱、紫外-可见漫反射吸收等手段对所制的光催化剂进行表征,并以紫外光和可见光分别为光源,罗丹明B为降解对象测试了其光催化活性,考察复合不同含量的AgC l对Bi2WO6光催化剂的性能影响.结果表明,沉积AgC l对Bi2WO6的晶体结构、表面性能和光吸收性能没有产生明显影响,但大幅度提高了Bi2WO6的紫外和可见光催化活性.当复合20 wt%Ag Cl时,AgC l/Bi2WO6光催化活性最佳,紫外光下比纯Bi2WO6提高了2.2倍,可见光下提高了1倍.这主要是由于形成的Ag Cl/Bi2WO6异质结能有效抑制光生电子和空穴的复合,从而提了其光催化性能.     

BiOCl/NaBiO_3复合材料的原位合成及光催化性能

利用HCl与Na Bi O3反应原位制备了结构可控的Bi OCl/Na Bi O3复合光催化材料.通过X射线粉末衍射(XRD)、紫外-可见漫反射光谱(UV-Vis-DRS)和扫描电子显微镜(SEM)等技术对其晶相组成、光吸收特性和表面形貌进行了表征,并评价了样品在可见光和紫外光下的光催化性能.结果表明,尽管Bi OCl几乎没有可见光活性,但27.4%Bi OCl/Na Bi O3在可见光下却表现出明显高于纯Bi OCl和Na Bi O3的光催化活性.由于紫外光照可以有效激发Bi OCl,所有组成的复合Bi OCl/Na Bi O3都显示出高于纯Bi OCl和Na Bi O3的光催化活性,其中47.6%Bi OCl/Na Bi O3具有最大光催化活性.研究了加入不同活性物种的捕获剂对光催化效率的影响,结合荧光实验结果和样品能带结构推测了复合材料光催化过程中光生载流子的传输行为.结果表明,Bi OCl/Na Bi O3催化活性增强主要归结于2种材料之间形成了有效的异质结构,其内建电场能够促进光生载流子的传输和分离;羟基自由基在光催化降解过程中是主要的活性物种.     

CQDs/TNS复合光催化剂的制备及其可见光催化活性

以明胶为原料用水热法一步合成了碳量子点(CQDs),经过聚乙二醇表面修饰后,在乙醇溶液中与二氧化钛纳米片(TNS)复合形成了碳量子点高分散负载的CQDs/TNS复合光催化剂.对复合光催化剂进行了XRD、FT-IR、HRTEM和XPS表征,结果表明合成的碳量子点的平均粒径为4nm且具有较好的荧光性能.与纯TNS相比,CQDs/TNS复合光催化剂在可见光下对罗丹明B表现出很好的光催化降解活性.当CQDs/TNS复合光催化剂中CQDs含量为7.5%时光催化活性最好,并且在3次循环降解后活性仍保持不变.其优异的光催化活性来自于碳量子点的独特上转换荧光性能和二氧化钛纳米片高活性{001}晶面的共同作用.     

原位合成具有高可见光催化活性的C_3N_4/CdS纳米复合材料（英文）

以硫氰酸铵和氯化镉为原料,采用无模板混合高温煅烧法一步合成氮化碳/硫化镉纳米晶(C3N4/Cd S)的复合半导体材料.采用X射线衍射、傅立叶变换红外光谱和透射电镜等技术对其结构和形貌进行了表征.以有机污染物罗丹明B(Rh B)为模拟污染物对复合催化剂的可见光催化活性进行测试.结果表明,C3N4/Cd S复合材料中Cd S以六方相纳米晶的形式均匀分散;Cd S的复合基本不改变C3N4主体结构及聚合度;与纯C3N4相比,复合材料在可见区的光吸收能力有所增强.合适的能带匹配有利于光生载流子的迁移,抑制了其复合速率.在可见光照射下,复合半导体能够更加快速的降解有机污染物,且保持很好的稳定性.     

Bi_2MoO_6/BiVO_4异质结的水热合成和可见光催化活性(英文)

采用一步水热法制备Bi2MoO6/BiVO4复合光催化剂.利用X射线衍射(XRD)、场发射扫描电子显微镜(FESEM)、高分辨透射电子显微镜(HRTEM)等手段对其晶体结构和微观结构进行了表征.结果表明,Bi2MoO6纳米粒子沉积在BiVO4纳米片表面从而形成异质结结构.紫外-可见漫反射光谱(UV-Vis DRS)表明所制备的Bi2MoO6/BiVO4异质结较纯相Bi2MoO6和BiVO4对可见光吸收更强.由于形成异质结结构及其光吸收性能使Bi2MoO6/BiVO4光催化活性有较大提高.可见光下(λ420 nm)光催化降解罗丹明B(RhB)实验结果表明,Bi2MoO6/BiVO4光催化活性较纯相Bi2MoO6和BiVO4高.Bi2MoO6/BiVO4样品光催化性能提高的原因是Bi2MoO6和BiVO4形成异质结,从而有效抑制光生电子-空穴对的复合,增大了可见光吸收范围及比表面积.     

复合光催化剂CNNS/CdS QDs的一步法合成及催化性能研究

利用尿素与2,4,6-三氨基嘧啶共聚煅烧制备层状氮化碳纳米片(CNNS),以CNNS作为复合材料的基底,采用简单的一步反应法(溶剂热法)合成CNNS/CdS QDs复合光催化剂并进行表征,同时研究其在可见光下对罗丹明B的催化性能。实验结果表明:一步法制备CNNS/CdS QDs复合材料的方法简单高效,制备的CNNS/CdS QDs的复合材料没有改变氮化碳纳米片原有的结构构型。当CNNS的理论质量分数为42%时,CNNS/CdS QDs复合材料的复合效果和光催化性能最佳。     

阳离子淀粉与硫化镉复合膜对染料的选择性光降解

对复杂污染物进行有效分离,实现资源化再利用具有重要的现实意义.光催化具有氧化性强的特点,但降解不具有选择性,很难实现资源化.本文针对混合染料废水,选用对不同染料具有不同吸附能力的阳离子改性淀粉(St-CTA)作为光催化剂Cd S的载体,采用原位生成法制成复合膜(Cd S/St-CTA),详细考察了Cd S/St-CTA在茜素绿(AG25)、甲基橙(MO)和罗丹明B (Rh B)单组分与二元染料组分溶液中的吸附降解行为.Cd S/St-CTA在AG25/Rh B和MO/Rh B混合溶液中分别对AG25和MO具有良好的选择性降解作用,而对Rh B没有去除效果.这是由于St-CTA载体对不同染料具有不同的吸附性能所造成的. Cd S/St-CTA的选择降解性能不受Cl~-、SO_4~(2-)和CO_3~(2-)等共存阴离子及p H的影响.此外,使用后的Cd S/St-CTA不需要脱附或其他再生处理,便可应用于下一次降解处理,循环5次后仍能保持原有的降解效率,证明Cd S/St-CTA具有稳定的回收再利用性能.本文提出的载体负载光催化剂"选择吸附富集-选择光降解"这一策略,具有良好的普适性,对处理不同污染物均具有一定的参考价值.     

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.