Au单晶表面氟表面活性剂FSN自组装膜的电化学行为

研究Au(111)和Au(100)表面非离子型氟表面活性剂FSN自组装膜的电化学行为.电化学扫描隧道显微术和循环伏安法测试表明,在0～0.8 V电位区间,FSN自组装膜未发生氧化还原,均一性好,可稳定地存在于电极表面,并显著抑制硫酸根离子在电极表面的吸附和Au单晶表面的重构.在FSN自组装膜Au单晶电极的初始氧化阶段,Au(111)表面有少量突起,而Au(100)表面呈现台阶剧烈变化,但FSN自组装膜的吸附结构没有改变.与Au(100)表面相比,Au(111)表面形成的FSN自组装膜可更有效地抑制Au表面的氧化.     

含酰胺结构的巯基自组装膜的设计与结构表征

提出了一种简便通用的合成巯基化合物的途径，以分子中的羧基CO2H为起始基团，与2-流基乙胺的氨基选择性缩合；合成了一系列具有RC（O）NHCH2CH2SH（R分别为偶氯苯衍生物，双炔衍生物及直链烷基）结构的化合物，并用接触角测量，电化学和掠角反射红外光谱（GIR-IR）等手段对这些化合物在金表面形成的自组装单分子膜进行了表征。发现4-（N－（2‘-巯基已基））酰胺偶氮苯的自组装膜表现出良好的电活性，电化学测定表面浓度为4．21×10(－10)mol·cm(-2)．当R为烷基链时，随烷基链的增长，膜的致密度与有序度增加GIR-IR证明在自组装腹中CH3（CH2）6C（O）NHCH2CH2SH的C＝O和N－H键与Au表面平行，分子轴线与Au表面近似垂直．     

灿烂甲酚蓝在DNA修饰金电极上的电化学行为

利用自组装技术将巯基乙醇固定在金电极表面形成巯基乙醇自组装膜修饰金电极, 用乙基-(3-二甲基氨丙基)碳二亚胺盐酸盐(EDC)和N-羟基琥珀酰亚胺(NHS)为偶联试剂, 分别将鲱鱼精单链DNA(ssDNA)和双链DNA(dsDNA)固定于金电极表面形成ssDNA和dsDNA 修饰电极. 考察了灿烂甲酚蓝(BCB)在不同DNA 修饰电极上的电化学行为,结果表明, BCB 在ssDNA 和dsDNA 修饰电极上的吸附常数分别为1.67×10^4和3.22×10^4 L·mol-1, BCB 与ssDNA 主要以静电作用结合, 而与dsDNA作用存在静电和嵌插两种模式. dsDNA 对BCB 具有更高的亲和力, 使BCB 可以作为一种有效的电化学杂交指示剂.     

四氮杂杯芳烃三嗪衍生物在Au(111)表面的自组装结构的电化学STM研究

利用电化学扫描隧道显微镜和循环伏安法研究了一种新型的杂杯杂芳烃四氮杂杯芳烃三嗪衍生物在Au(111)表面的自组装结构. 高分辨的STM图像表明, 该杂杯杂芳烃可以在Au(111)表面形成长程有序的单层膜. 此外, 分子以1,3-交替构象吸附, 两个三嗪环平躺在表面, 而苯环倾斜吸附在基底上, 这是分子间与分子-基底间相互作用平衡的结果.     

细胞色素c在自组装纳米膜电极上的有效固定及直接电化学

采用自组装方法将壳聚糖-纳米金(Chi-Nano Au)修饰到金(Au)电极上,并经进一步自组装细胞色素c(Cyt c),制得自组装膜电极Cyt c/Chi-Nano Au/Au.测定了自组装膜电极的循环伏安曲线(CV)及稳定性.结果表明,利用自组装膜电极Chi-Nano Au/Au可以有效地固定Cyt c,并实现直接电子转移反应.Cyt c在0.13～0.28V(vs Ag/AgCl)之间显示一对明显的可逆氧化还原峰;峰电流与扫描速度呈现良好的线性关系,线性方程为Ipc=0.063 64+0.003 51υ,线性相关系数为r=0.997 2,这表明该电极过程受吸附控制.此外,所制备的膜电极稳定性良好.     

meso-四(对甲氧基苯基)卟啉钴在货币金属单晶表面的吸附与自组装研究

利用超高真空低温扫描隧道显微镜系统研究了meso-四对甲氧基苯基卟啉钴分子在Au(111)、Ag(111)和Cu(111)表面的吸附与自组装.该分子在金属表面可以形成两种组装结构A和B.在结构A中,分子间的相互作用主要为π-π堆叠,仅在Au(111)和Ag(111)表面被实验观察到;在结构B中,分子间的相互作用为氢键,仅在Ag(111)和Cu(111)表面被实验观察到.分子-衬底相互作用的差异所引起的分子吸附构象变化被认为是导致不同衬底上的分子形成不同组装结构的原因.研究发现在不同衬底上,分子形成自组装结构的行为存在明显差异.在相近覆盖度下,未参与组装的分子的比例在Cu(111)表面最高, Au(111)次之, Ag(111)最低.表面上参与形成两种组装结构的分子与未参与组装的分子的比例还可通过覆盖度和退火来进行调控.     

生物素衍生物自组装膜制备及其覆盖度的电化学测定

利用循环伏安法和电化学交流阻抗谱研究了MBDA/Au,MBTA/Au,TBDA/Au,TBTA/Au修饰电极以及MBDA与DT混合自组装/Au、TBTA与DT混合自组装/Au修饰电极的覆盖度。结果表明这些自组装膜在金电极表面的覆盖度均比较高,达到99%以上;对同一类修饰电极,混合自组装膜的覆盖度高于单组分自组装膜的覆盖度,混合自组装体系的覆盖度随着DT比例的增加而增加;同类物质,长链化合物在金表面的覆盖度大于短链化合物,含二硫键的化合物与金电极的键合能力比含一个巯基的化合物键合能力强。     

去甲肾上腺素在3-氨基-5-巯基-1,2,4-三唑修饰金电极上的电化学行为及研究

本文通过自组装的方法制备了3-氨基-5-巯基-1,2,4-三唑(TA)修饰金电极。X射线光电子能谱表明,3-氨基-5-巯基-1,2,4-三唑是通过形成S-Au键而组装到Au电极表面。研究了去甲肾上腺素在该自组装膜电极上的电化学行为。实验结果表明:在pH 4.5的0.1 mol/L BR缓冲溶液中,膜电极对去甲肾上腺素的电化学氧化具有明显的催化作用,其氧化峰电流与去甲肾上腺素的浓度在2.0×10-6~1.9×10-4mol/L范围内呈良好线性关系。方法检出限为4.0×10-7mol/L。     

取代苯基硫脲在Au表面的自组装

制备了对甲苯基硫脲、对氯苯基硫脲和2，4，6-三溴苯基硫脲在Au表面的自组装单分子膜（SAMs），用润湿角测量仪、椭圆偏振仪、X-射线光电子能谱仪（XPS）和原子力显微镜（AFM）对单分子膜进行了分析表征。结果表明取代苯基硫脲分子的S原子与Au形成Au-S键而诱导吸附分子形成取向排列的单分子膜。由于Au表面本身具有一定的缺陷和吸附的可逆性，使得所形成的单分子膜具有一定的缺陷。     

硒杂环化合物(4,5-苯并苤硒脑)在金表面上的自组装

为了寻求新的自组装单分子膜体系,构建新的功能膜,研究了具备平面型的大环共轭硒杂环化合物-- 4,5-苯并苤硒脑(苯并[c]硒二唑,简称苤硒脑)在金表面的自组装单分子膜.通过X射线光电子能谱(XPS)和电化学手段对其进行表征.XPS研究结果表明,自组装形成单分子膜后,苤硒脑分子中Se3d结合能从57.4 eV下降到57.1 eV;表明硒杂环化合物是通过金硒键固定在金表面上的;电化学循环伏安法实验表明,金电极表面上自组装该有机硒后, Fe(CN)63-/4-的氧化还原峰几乎完全消失;以四硼酸钠为底液,测得该化合物自组装在金表面上时,其还原电位在-0.66 V,与在溶液中用裸金电极测得的还原峰电位基本一致.     

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.