纳米TiO_2改性蚕丝丝素蛋白膜的研究

用溶胶凝胶法制备纳米TiO2改性再生蚕丝丝素蛋白膜.该丝素膜机械强度提高,在水中溶失率下降.UV、AFM、SEM测试的结果表明,丝素中纳米TiO2粒径约为80 nm,纳米粒子在丝素膜中分布均匀;XRD、FTIR测试结果表明,纳米TiO2的加入,可使改性丝素膜的结晶结构从SilkⅠ向SilkⅡ转化,其结晶度也随之提高;TGA测试表明改性丝素膜的热转变温度比纯丝素膜有所改变.     

PI/TiO_2纳米复合材料的耐溶剂和耐热性能研究

以可溶性聚酰亚胺PI(HQDPA DMMDA)和钛酸丁酯为原料 ,在共溶剂NMP中 ,通过溶胶 凝胶法制备出不同TiO2 含量的PI TiO2 复合膜 .采用TEM、TG DTG、DSC和溶剂抽提实验等手段表征了PI TiO2 复合膜的微结构和复合材料的耐溶剂性和耐热性等性能 .结果表明 ,TiO2 含量为 2 2 3wt%时 ,复合膜中TiO2 颗粒的平均尺寸为 1 0nm左右 .与纯PI膜相比 ,随着TiO2 含量的增加 ,PI TiO2 复合膜的耐溶剂性能显著增强 ,热稳定性明显提高 .复合材料的力学性能有所下降 .复合膜耐溶剂性和耐热性能的提高表明PI分子链与TiO2 无机网络间存在化学键联     

溶胶-凝胶法制备纳米TiO2/丝素复合膜及结构性能研究

用溶胶凝胶法制备不同比例纳米TiO₂改性再生蚕丝丝素蛋白复合膜. UV和AFM测试结果表明, 该丝素膜中纳米TiO₂均匀分散在丝素中, TiO₂粒径约为80 nm; 同时该丝素膜的结构和热性能用FTIR, XRD, EDS, TGA和DTG进行表征. XRD测试结果表明, 随着纳米TiO₂的加入, 复合丝素膜的结晶结构从Silk I向Silk II转化, 但当纳米TiO₂的加入超过一定量时, 又破坏复合丝素膜的结晶结构; FTIR和EDS测试结果表明, TiO₂与丝素形成较好的键合; TGA和DTG测试表明复合丝素膜的热转变温度相比于纯丝素膜有所提高.     

溶胶-凝胶法制备纳米TiO2/丝素复合膜及结构性能研究

用溶胶凝胶法制备不同比例纳米TiO₂改性再生蚕丝丝素蛋白复合膜. UV和AFM测试结果表明, 该丝素膜中纳米TiO₂均匀分散在丝素中, TiO₂粒径约为80 nm; 同时该丝素膜的结构和热性能用FTIR, XRD, EDS, TGA和DTG进行表征. XRD测试结果表明, 随着纳米TiO₂的加入, 复合丝素膜的结晶结构从Silk I向Silk II转化, 但当纳米TiO₂的加入超过一定量时, 又破坏复合丝素膜的结晶结构; FTIR和EDS测试结果表明, TiO₂与丝素形成较好的键合; TGA和DTG测试表明复合丝素膜的热转变温度相比于纯丝素膜有所提高.     

纳米TiO2/丝素复合膜的制备

探讨了纳米TiO2在丝素溶液中的分散条件,在此基础上制备了纳米TiO2/丝素复合膜,并用原子力显微镜(AFM)和扫描电子能谱(EDS)对复合膜进行了表征。实验结果表明,制膜方法较为合理。当以有机物A为分散剂,纳米TiO2含量为1/1000时,其以粒径50 nm左右均匀地分散于复合膜中。     

偶氮基团引发PMMA在纳米TiO2表面接枝聚合研究

采用表面接枝反应的方法,在纳米TiO2上接枝偶联剂KH-560,进而通过酯化反应引入偶氮基团引发甲基丙烯酸甲酯发生自由基聚合反应,并通过IR、SEM、TEM、DSC和TG等测试方法研究了反应条件对复合粒子结构和性能的影响.结果表明,反应约60 min时,TiO2表面的接枝率达42.9%;当搅拌速率为1.0×104 r/min时,TiO2均匀分散在PMMA基体中;TiO2粒子的加入使得PMMA的热稳定性有了明显提高.     

纳米TiO2对丝素蛋白膜构象转变的影响

采用溶胶-凝胶法制备纳米TiO2复合丝素膜,并用原子力显微镜、一维红外光谱、二维红外相关光谱对纯丝素膜及复合丝素膜进行了研究。结果表明:纳米TiO2均匀地分散在丝素膜中;纳米粒子与丝素形成了分子间氢键,导致丝素分子的重排;丝素分子链的构象发生了转变,变化顺序是无规线团先于β-折叠、α-螺旋的形成。     

TiO_2/PtO-Pt复合膜和SnO_2/PtO-Pt复合膜氢敏性能的研究

将PtO Pt纳米粒子膜与TiO2 ,SnO2 纳米粒子膜复合 ,利用PtO Pt纳米粒子膜作为插入电极和催化剂 ,设计并研制出一类新型双层结构复合膜气体传感器 .采用TEM和SEM对薄膜的显微结构进行了表征 .对空气中 4 0 %H2 的氢敏性能研究表明 :2 0 0℃时 ,TiO2 /PtO Pt复合膜对氢气的灵敏度为 70 % ,而TiO2 纳米粒子膜无响应 .10 0℃时 ,SnO2 /PtO Pt复合膜的灵敏度为 92 % ,同样条件下 ,SnO2 纳米粒子膜的灵敏度仅为 4% .说明PtO Pt纳米粒子膜的催化作用能够显著提高TiO2 和SnO2 膜的氢敏性能 .另外 ,TiO2 /PtO Pt复合膜和SnO2 /PtO Pt复合膜均对空气中H2 有很高的选择性     

壳聚糖/明胶/TiO2三元复合膜的制备与功能特性

纳米TiO2用阴离子表面改性剂SDS改性后,以溶液共混法制备了壳聚糖／明胶/TiO2复合膜,用FTIR、XRD、SEM、TEM表征了其结构与形态,并测试了其吸水率、透光率、力学性能和抑菌性能。进而探讨了复合膜中明胶和纳米TiO2含量对壳聚糖膜性能的影响。结果表明：复合膜中,壳聚糖、明胶和TiO2微粒间存在强烈的氢键相互作用,从而使明胶与壳聚糖具有良好的相容性,TiO2与壳聚糖、明胶分子间有很好的界面作用。适量TiO2的加入,可使壳聚糖／明胶共混膜的力学性能得到改善,明胶质量分数为0．30时,掺杂wTiO2为0．01、0．02的复合膜较壳聚糖／明胶共混膜的湿强及干态韧性分别提高了55．9％,40．8％和49．7％,47．9％。此外,复合膜的抑菌性能随明胶的增加而降低,但随TiO2的掺杂比的增加而增强,纳米TiO2的引入拓宽了壳聚糖和明胶两种天然高分子材料的应用范围。     

TiO2/PtO-Pt复合膜和SnO2/PtO-Pt复合膜氢敏性能的研究

将PtO-Pt纳米粒子膜与TiO2，SnO2纳米粒子膜复合，利用PtO-Pt纳米粒子膜作 为插入电极和催化剂，设计并研制出一类新型双层结构复合膜气体传感器。采用 TEM和SEM对薄膜的显微结构进行了表征，对空气中4.0H2的氢敏性能研究表明： 200℃时，TiO2/PtO-Pt复合膜对氢气的灵敏度为70％，而TiO2纳米粒子膜无响应。 100℃时，SnO2/PtO-Pt复合膜的灵敏度为92％，同样条件下，SnO2纳米粒子膜的灵 敏度仅为4％。说明PtO-Pt纳米粒子膜的催化作用能够显著提高TiO2和SnO2的膜氢 敏性能。另外，TiO2/PtO-Pt复合膜和SnO2/PtO-Pt复合膜均对空气中H2有很高的选 择性。     

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.