多壁碳纳米管修饰碳黑微电极同时测定多巴胺和抗坏血酸

制备了多壁碳纳米管修饰碳黑微电极,研究了多巴胺(DA)和抗坏血酸(AA)在该修饰电极上的电化学行为.实验表明,在pH 7.0的PBS缓冲溶液中,该修饰电极对DA和从均具有显著的催化氧化作用,AA与DA的氧化电位分别为30 mV和280 mV(vs.SCE).利用二次导数线性扫描伏安法测定,DA与AA的线性范围分别为6.0×10-9～2.0×10-4 mol/L和2.0×10-7～1.0×10-3mol/L,检出限为2.0×10-9mol/L 和1.0×10-7mol/L.方法已用于人工合成样品的分析.     

多巴胺和抗坏血酸在十六烷基三甲基溴化铵/碳纳米管电极上的检测

研究了十六烷基三甲基溴化铵(CTMAB)/多壁碳纳米管修饰玻碳电极的制备以及多巴胺和抗坏血酸在该修饰电极上的电化学行为。在CTMAB和多壁碳纳米管的协同作用下,该修饰电极对多巴胺和抗坏血酸均具有显著的催化氧化作用,多巴胺和抗坏血酸的氧化峰电位分别为223mV和15mV,实现了在抗坏血酸共存时测定多巴胺。在pH7.0的磷酸盐缓冲溶液中,多巴胺和抗坏血酸的线性范围分别为2.0×10-6～2.0×10-3mol/L和4.0×10-5～1.0×10-2mol/L,检出限分别为6.0×10-7mol/L和1.0×10-5mol/L。     

芦丁修饰电极研究多巴胺的电化学响应

通过循环伏安法(CV)制备了芦丁修饰电极,研究多巴胺(DA)在修饰电极上的电化学行为.结果表明,芦丁修饰膜对DA的氧化有明显的催化作用,并且可以消除抗坏血酸(AA)对DA测定的干扰.DA的浓度在1.0×10-7～9.5×10-6 mol/L范围内与其氧化峰电流呈线性关系,相关系数为0.9996,检出限为1.0×10-8 mol/L.将该修饰电极用于注射液样品中DA的测定,结果表明该修饰电极可用于实际样品分析.     

聚对氨基苯磺酸/氧化石墨烯修饰电极同时测定多巴胺和抗坏血酸

用循环伏安法制备了聚对氨基苯磺酸/氧化石墨烯修饰玻碳电极(PABSA/GO/GCE),研究了多巴胺(DA)和抗坏血酸(AA)在该修饰电极上的电化学行为,并建立了同时测定多巴胺和抗坏血酸电化学分析新方法,相对于裸玻碳电极,该电极测定DA和AA的峰电流明显增加。实验结果表明:在实验条件下,DA测定的线性范围为0.50～300μmol/L;检出限为5.0μmol/L。AA测定的线性范围是0.10～2.4 mmol/L,检出限为0.50μmol/L。     

电聚合o-ImBPTPPMn(Ⅲ)Cl膜修饰玻碳电极同时测定抗坏血酸和多巴胺

用循环伏安法在强酸性水溶液中制备出氯化5-邻[4-(1-咪唑基)丁氧基]苯基-10,15,20-三苯基卟啉锰聚合膜修饰玻碳电极。该电极具有良好的电化学活性,对抗坏血酸(AA)及多巴胺(DA)有明显的催化作用,而且在同一缓冲溶液中用微分脉冲伏安法扫描二者峰电位差达240mV,此时已达到完全分离。将该电极应用于DA和AA的同时测定,其线性范围分别为2.0×10-6~1.0×10-4mol/L和6.5×10-7~2.6×10-5mol/L;检出限分别为1.0μmol/L和0.39μmol/L。二者在微分脉冲伏安法扫描时各有独立的电流响应峰,互不干扰。该电极重现性和稳定性好,在空气中放置3个月以上经处理后电化学活性无下降趋势。     

纳米金双巯基修饰金电极差分脉冲伏安法测定多巴胺和抗坏血酸

在裸金电极上自组装4,4-二甲基联苯硫醇(MTP)膜(MTP/AuSAMs),再电还原氯金酸溶液修饰纳米金,得纳米金双巯基修饰金电极(NG/MTP/Au).研究了多巴胺(DA)和抗坏血酸(AA)在NG/MTP/Au上的电化学行为,发现该修饰电极对DA、AA的氧化具有良好的电催化作用,多巴胺(DA)和抗坏血酸(AA)的氧化峰电位差达到155mV,可以实现对此二组分混合溶液的选择性测定.差分脉冲法测得的峰电流与DA、AA浓度分别在5.0×10-7～1×10-4mol.L-1和3.5×10-6～1.0×10-3mol.L-1范围内呈线性关系,检测限(3σ)分别为1.5×10-7mol.L-1和1.2×10-6mol.L-1,相关系数0.998.     

柠檬酸修饰电极对抗坏血酸、多巴胺和尿酸的同时检测

研究柠檬酸(CA)修饰玻碳电极(CA/GC)在抗坏血酸(AA)、多巴胺(DA)和尿酸(UA)混合体系中的循环伏安(CV)行为.结果表明,AA、DA和UA在CA/GC电极上氧化峰电流增大,且三者氧化峰电位明显分离(ΔEp(DA,AA)=170 mV,ΔEp(DA,UA)=130 mV,ΔEp(AA,UA)=300 mV).据此,可同时检测AA、DA和UA.在优化的实验条件下,AA、DA和UA的氧化峰电流与其浓度分别在2.0×10-6～1.5×10-3mol.L-1,6.0×10-7～1.0×10-3mol.L-1和6.0×10-7～1.0×10-3mol.L-1范围内呈线性关系.该电极重现性好,可用于盐酸多巴胺针剂DA、VC片剂AA及人体尿液UA的测定.     

聚三聚氰胺-石墨烯复合膜修饰电极对多巴胺与尿酸的同时测定

采用循环伏安法制备了聚三聚氰胺-石墨烯复合膜修饰电极(poly-(MA)-ERGO/GCE)。研究了抗坏血酸(AA)、尿酸(UA)和多巴胺(DA)在该修饰电极上的电化学行为。结果表明,该修饰电极对AA、UA和DA均有良好的电化学响应,且三者的氧化峰在该修饰电极上可完全分离。据此建立了在大量AA存在下同时测定UA和DA的新方法。在优化条件下,微分脉冲伏安法(DPV)测定UA和DA的线性范围均为1.0×10~(-8)~5.0×10-6mol·L~(-1),检出限(3sb)均为5.0×10~(-9)mol·L~(-1)。     

新型平板碳电极的研制与应用

研制了一种新型平板碳电极,用K3Fe(CN)6对电极的性能进行了简单的研究。将该电极用于神经递质多巴胺(DA)的测定,发现在pH 7.0的磷酸盐缓冲介质(PBS)中,多巴胺在该电极上产生一灵敏的氧化峰,峰电流与DA浓度在6.0×10-8~1.0×10-3mol/L范围内呈良好的线性关系,检出限(3σ)为2.0×10-8mol/L。方法可用于人工合成样品的分析。     

镍纳米粒子-离子液体修饰碳糊电极的制备及其对多巴胺的测定

制备了镍纳米粒子-离子液体修饰电极,在0.1 mol/L磷酸缓冲溶液(pH 6.0)中研究了多巴胺(DA)在修饰电极上的电化学行为.与裸电极相比,DA在该修饰电极上的氧化还原电位明显降低,氧化还原反应的峰电流明显增大,DA的峰电流与其浓度在2.0×10~(-8) ～1.0×10~(-4) mol/L范围内呈良好的线性关系,检出限为6.5×10~(-9) mol/L.该修饰电极对抗坏血酸具有明显的抗干扰能力.     

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.     

α-Amino acid derived enaminones and their application in the synthesis of N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates and other heterocycles

A new and simple synthesis of novel N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates, which exist in equilibrium with their 4-oxo tautomers, has been developed in two steps starting from N-protected α-amino acids. The key intermediates are enaminones, which can also be isolated, characterized, and used for the construction of other functionalized heterocycles, before they spontaneously decompose to pyrrole products. 4-Hydroxypyrroles are prone to partial aerial oxidation but can be efficiently alkylated or reduced to stable polysubstituted pyrrolidine derivatives.     

Specific intramolecular aromatic CH insertion of diazosulfonamides

The chemoselectivity in the intramolecular CH insertion of various diazosulfonamides has been experimentally studied. The results reveal that the aliphatic 1,4-, 1,5-, or 1,6-C(sp³)?H insertions of diazosulfonamides are not accessible, while the aromatic 1,5-C(sp²)?H insertion can be realized specifically by adjusting the diazo-adjacent group. In addition, the general chemoselectivities in the intramolecular CH insertions of diazosulfonyl compounds are summarized. Generally, diazosulfones undergo both aromatic 1,5-C(sp²)?H and aliphatic 1,5- and 1,6-C(sp³)?H insertions, while diazosulfonates undergo aliphatic 1,5- and 1,6-C(sp³)?H insertions. However, diazosulfonamides only undergo aromatic 1,5-C(sp²)?H insertion.     

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.     

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.     

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.     

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.     

N-Heterocyclic carbene-palladacyclic complexes: synthesis,characterization and their applications in the C-N coupling and α-arylation of ketones using aryl chlorides

N-Heterocyclic carbene-palladacyclic complexes 3 were successfully achieved in a one-pot procedure under mild conditions. The structure of 3a was unambiguously confirmed by X-ray single crystal diffraction and it was an active catalyst in the Buchwald-Hartwig amination and α-arylation of ketones even at very low catalyst loadings (0.01?mol%).     

Iodine-mediated oxidative Pictet-Spengler reaction using terminal alkyne as the 2-oxoaldehyde surrogate for the synthesis of 1-aroyl-β-carbolines and fused-nitrogen heterocycles

An efficient iodine-mediated oxidative Pictet-Spengler reaction in dimethyl sulphoxide (DMSO) using terminal alkynes as the 2-oxoaldehyde surrogate for the synthesis of aryl (9H-pyrido[3,4-b]indol-1-yl)methanones is described. The scope of the protocol includes the total synthesis of Fascaplysin, Eudistomins Y₁ and Y₂. The methodology is extended for preparing pyrrolo[1,2-a]-quinoxaline and indolo[1,5-a]quinoxaline derivatives. The utility of 1-aroyl-β-carbolines was demonstrated by performing palladium-catalyzed β-carboline directed ortho-C(sp2)-H functionalization of the phenyl ring with thiomethyl (SMe) group using DMSO as source and for accessing 4-aryl-canthin-6-ones.