金刚石薄膜电化学

金刚石由于其特殊的物理与化学性质,早在几百年前就吸引了人们对它的关注.化学气相沉积(chemical vapor deposition,CVD)法制备的高掺杂硼复合多晶金刚石薄膜,为金刚石薄膜在电化学中的应用开辟了新的领域.作为新型碳素电极材料,高掺杂硼复合多晶金刚石薄膜具有许多目前使用的电极材料所不可比拟的优异特性如:宽电化学势窗,低残留电流,极好的电化学稳定性以及表面不易被污染等.本文综述了高掺杂硼复合多晶金刚石薄膜电极在电化学中的几个重要应用,包括电分析、电合成及电化学法处理废水等.     

苏丹红I号在纳米金/碳球修饰硼掺杂金刚石电极上的电化学行为

采用纳米金/碳球(Au/CS)复合物修饰硼掺杂金刚石(BDD)电极,研究了苏丹红I号在Au/CS修饰BDD电极上的电化学行为,并据此建立了实际样品中的苏丹红I号的测定方法.结果表明,与裸BDD电极相比,苏丹红I号在Au/CS修饰BDD电极上的氧化峰电流由0.24μA增加到0.83μA,峰电位由0.809V负移到0.743V.在最优测试条件下,苏丹红I号浓度与其峰电流在4~100μmol/L范围内呈线性关系,线性方程为Ip=0.011 26c+0.116(R2=0.999),检出限为8.33μmol/L.采用本方法对实际样品中的苏丹红I号进行测定,测定结果及平均回收率均优于BDD电极法.     

掺硼金刚石膜/碳膜平面式复合电极的制备及电化学性能

采用微波等离子体化学气相沉积法在本征硅上制备掺硼金刚石膜/碳膜平面式复合电极,其中硅片的一面为掺硼金刚石膜,另一面为碳膜。通过SEM和拉曼光谱分析了薄膜的表面形貌和成分,掺硼金刚石膜为纳米级金刚石,碳膜表面有均匀分布的凹坑;利用四探针、循环伏安法和交流阻抗法表征电极导电性和电化学性能,随着沉积时间增加,电极方阻减小;在铁氰化钾溶液中电极发生准可逆氧化还原反应,电势差为119mV,在103Hz附近阻抗为113Ω;多巴胺的检测限为5μmol·L-1。     

硼-氮共掺杂垂直石墨烯电极的制备及其葡萄糖检测性能

采用电子辅助热丝化学气相沉积技术制备了垂直石墨烯(VG)、硼掺杂垂直石墨烯(BVG)、氮掺杂垂直石墨烯(NVG)及硼-氮共掺杂垂直石墨烯(BNVG)薄膜,采用扫描电子显微镜、透射电子显微镜、X射线光电子能谱及Raman光谱仪表征了形貌、微结构及成分,并采用电化学方法分析了其作为表皮传感电极的电化学性能。结果表明,BNVG薄膜由垂直于基片生长的二维纳米片排列成了三维多孔网结构,这些纳米片的硼和氮原子分数达到3.78%和2.75%。BNVG薄膜电极的皮肤接触电阻低至4.5 kΩ,对于葡萄糖的响应浓度范围在0.001～10 000μmol·L^-1,检测限低至0.03μmol·L^-1,具有良好的抗干扰能力及长期稳定性。     

硼-氮共掺杂垂直石墨烯电极的制备及其葡萄糖检测性能

采用电子辅助热丝化学气相沉积技术制备了垂直石墨烯(VG)、硼掺杂垂直石墨烯(BVG)、氮掺杂垂直石墨烯(NVG)及硼-氮共掺杂垂直石墨烯(BNVG)薄膜,采用扫描电子显微镜、透射电子显微镜、X射线光电子能谱及Raman光谱仪表征了形貌、微结构及成分,并采用电化学方法分析了其作为表皮传感电极的电化学性能。结果表明,BNVG薄膜由垂直于基片生长的二维纳米片排列成了三维多孔网结构,这些纳米片的硼和氮原子分数达到3.78%和2.75%。BNVG薄膜电极的皮肤接触电阻低至4.5 kΩ,对于葡萄糖的响应浓度范围在 0.001~10 000 μmol·L^-1,检测限低至 0.03 μmol·L^-1,具有良好的抗干扰能力及长期稳定性。     

三种碳基电极材料的电化学性质对比研究(英文)

对硼掺杂纳米金刚石(BDND),硼掺杂微米金刚石(BDMD)和玻碳(GC)电极的电化学性质做了对比研究.利用扫描电子显微镜表征了BDMD和BDND电极,其表面粒子大小分别为1-5μm和20-100nm.利用Raman光谱对两种金刚石薄膜的成分进行了表征,结果表明利用热丝化学气相沉积法得到了高质量的BDND和BDMD薄膜.采用0.5mol·L-1H2SO4溶液测定了三种电极的电化学窗口,BDND和BDMD电极的电化学窗口分别为3.3和3.0V,远比GC电极(2.5V)的要宽.[Fe(CN)6]3-/[Fe(CN)6]4-溶液的循环伏安和交流阻抗测定表明,在BDND、BDMD和GC电极上的峰间距(△Ep)分别为73、92和112mV,且其电子传递电阻(Ret)分别为(98±5)、(260±19)和(400±25)Ω.我们也研究了0.1mmol·L-1双酚A在三种电极上的电化学氧化行为.上述的电化学测定结果表明,两种金刚石电极均比GC电极表现出了更宽的电化学窗口、更好的电化学可逆性质、更快的电子传递速度和更高的电化学稳定性,更为重要的是与BDMD相比BDND的电化学性质有进一步的提高.     

碳薄膜电极材料在电分析化学中的应用

由于具有一系列的优点,碳材料被广泛地应用于电分析化学。新型碳电极材料的开发及其性质研究对电分析化学的发展起着重要的推动作用。最近文献报道了一些制备新型碳薄膜电极材料的方法,因为制备方法不同,这些碳薄膜材料的电化学性质如电位窗、稳定性、导电性也显著不同。人们对电位窗宽、背景电流低、稳定性高、表面不易被电极产物钝化的碳薄膜电极材料的研究非常活跃。本文综述了采用不同方法制备的一些碳薄膜电极材料如硼掺杂的金刚石薄膜、无定形碳和纳米晶体碳薄膜材料等在电分析化学中应用。     

石墨烯/类金刚石碳复合薄膜的电化学沉积及其场发射性能

采用液相电化学方法在硅基底上制备了石墨烯掺杂的类金刚石碳复合薄膜,探讨了电化学沉积复合薄膜的机理。利用扫描电子显微镜（SEM）、拉曼光谱（Raman）、透射电子显微镜（TEM）和傅里叶变换红外（FTIR）光谱技术对薄膜表面形貌和微观结构进行了分析表征。结果表明,石墨烯片均匀分散沉积在含氢类金刚石碳（a-C：H）基体中,沉积的石墨烯/类金刚石（G/a-C：H）复合薄膜表面相对均匀平整。场发射测试显示石墨烯掺杂使开启电场从4.7 V·μm^-1增加至5.8 V·μm^-1,场发射电流密度从384 μA·cm^-2显著增加至876 μA·cm^-2。     

掺硼纳米TiO2对农药毒死蜱的光催化降解作用

采用溶胶-凝胶法制备了掺杂硼的纳米TiO2,并用X射线衍射、红外光谱表征了产物的组成和结构.用制备好的掺硼纳米TiO2作为光催化剂对农药毒死蜱进行了光催化降解研究.结果表明:通过掺硼可以显著提高TiO2对毒死蜱的光催化效率.在硼掺杂量为3%,催化剂煅烧温度为500℃,煅烧时间为1 h,催化剂用量为15%时,毒死蜱的降解率最高.     

纳米硫化镉的合成及其电化学催化性能测试

采用CS2-SDS-正辛醇-水微乳体系制备了硫化镉纳米棒。利用XRD、SEM、TEM对产物进行表征，测试了其对多硫化物电极还原反应的催化性能，并与常规方法合成的大粒度CdS晶体进行对比．结果表明，纳米棒为六方型CdS晶体，直径约12nm．常规法合成的CdS为立方型晶体，平均粒度约为1μm．CdS纳米棒电极对硫化钠／多硫化钠电极反应的电催化活性明显高于大粒度CdS晶体电极．     

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.