2-羟基-3-(三乙胺基)丙基十烷基硫醚修饰电极测定痕量金

研究了 2 羟基 3 (三乙胺基 )丙基十烷基硫醚 (HTPSD)修饰玻碳电极测定金的伏安特性及分析条件。在 0 .2mol·L- 1KCl HCl缓冲溶液中 (pH 1) ,金 (Ⅲ )被富集到电极表面 ,然后介质交换到 0 .2mol·L- 1KCl HCl空白溶液中 (pH 1)进行阴极溶出伏安测定 ,金 (Ⅲ )浓度在 2× 10 - 81× 10 - 6mol·L- 1范围内呈线性关系。检出限为 1× 10 - 8mol·L- 1。相对标准偏差小于 6 2 % ,一般常见离子不干扰。     

流动注射不可逆双安培法测定二苯胺磺酸盐

通过配合0.5mol·L-1硫酸溶液中二苯胺磺酸根在一支铂电极上的氧化和0.05mol·L-1硫酸溶液中高锰酸根在另一支铂电极上的还原,构建了类似可逆电对的双安培检测体系,在两铂电极间电位差为OV时,实现了流动注射不可逆双安培法测定二苯胺磺酸盐。二苯胺磺酸盐溶液和高锰酸钾溶液被隔离在两个用盐桥相连的电极室中,以避免两者发生化学均相反应。在试验条件下,回路电流与二苯胺磺酸根的浓度在2.0×10-6-2.0×10-4mol·L-1范围内呈线性关系,检出限为7.0×10-7mol·L-1(S／N=3)。连续11次测定1.0×10-5mol·L-1二苯胺磺酸钠,电流值的RSD为0.52％。方法简单快速,可用于工业产品中二苯胺磺酸盐的测定。     

钴氢氧化物修饰玻碳电极的镀膜/循环伏安法制备及其电化学行为

采用一种新方法镀膜 /循环伏安法成功制备了钴氢氧化物修饰玻碳电极 .考察了影响钴氢氧化物膜电催化活性的因素 ,确定最佳富集时间为 2min ,最佳活性单元浓度为 9 90× 10 -4mol·L-1.讨论了成膜过程及机理 .膜氧化峰电流 (i0pa)与扫描速率 (v <0 60V·s-1)成正比 ,具有表面吸附反应特征 ,表面覆盖量约相当于 0 5个单层的氧化还原活性物质 .制得的钴氢氧化物膜修饰电极具有相当的稳定性 ,并对H2 O2 氧化表现出较高的电催化活性 .线性回归方程为 :Δipa( μA) =-2 10 3 6+2 3 72 0× 10 4CH2 O2 (mol·L-1) (R =0 9990 ,n =18) ,线性范围为 :1 43× 10 -5～ 1 80× 10 -2 mol·L-1,检出限为 :9 5 9× 10 -6mol·L-1( 3S/k) .     

硒代胱氨酸修饰银电极及应用研究

介绍了硒代胱氨酸修饰银电极的制备及其电化学特性 ,并将该修饰电极用于痕量金属离子的分析。研究结果表明 ,此修饰电极具有良好的电化学性质和化学、机械和电化学的稳定性 ,在测定Pb2 + 时 ,检出限可达到 1.0× 10 - 11mol·L- 1,线性范围在 2 .0× 10 - 10 ～ 4 .0× 10 - 11mol·L- 1,同时对于其他金属离子 (Cd2 + ,Cu2 + ,Zn2 + )的分析中也获得较满意的结果     

钆对Tb3+-2,3-吡啶二羧酸体系荧光的增敏及其分析应用

研究了Tb3 + Gd3 + 2 ,3 吡啶二羧酸体系的荧光特性。结果表明 ,钆对该体系中Tb3 +的特征荧光有显著增敏作用 ,当钆浓度为 4 .0× 10 - 4mol·L- 1,pH为 8.0 ,2 ,3 吡啶二羧酸浓度为3.5× 10 - 4mol·L- 1时 ,体系荧光强度最大。该体系用于稀土样品中痕量Tb3 + 的测定 ,铽浓度在 1× 10 - 9～ 2× 10 - 7mol·L- 1范围内与荧光强度呈线性关系 ,检出限为 5× 10 - 10 mol·L- 1。     

单扫示波极谱法同时测定钴与镍

在 pH 9.70的Na2 CO3 NaHCO3、亚硝基红盐和氯代十四烷基吡啶体系中 ,镍和钴均有灵敏的络合物吸附波 ,其二阶导数峰电位分别为 - 0 .6 4V (vs .SCE) (镍 )和 - 0 .80V (vs .SCE)(钴 ) ,电流峰高与浓度在 3.4× 10 - 9～ 3.74× 10 - 6 mol·L- 1(镍 )和 7.0× 10 - 11～ 6 .0× 10 - 6 mol·L- 1(钴 )范围内呈线性关系 ,检出限分别为 2 .4× 10 - 9mol·L- 1(14 1ng·L- 1镍 )和 3.2× 10 - 11mol·L- 1(1.9ng·L- 1钴 )。方法应用于水样和生物样品中微量钴和镍的测定 ,结果满意     

肌红蛋白在磷脂-月桂酸修饰的玻碳电极上的电化学行为及其分析应用

报道了肌红蛋白(Mb)在磷脂、月桂酸修饰的玻碳电极上的电化学行为 ,在 +0.2～ -0.7V(vs.Ag/AgCl)电位范围内 ,于pH6.0的0.01mol·L-1的KH2PO4、Na2HPO4底液中 ,肌红蛋白产生不可逆的还原电流峰 ;还原峰电流与肌红蛋白浓度在2.25×10-8 ～1.40×10-6 mol·L-1 范围内呈良好线性关系 ;线性回归方程为Ip(μA)=-0.01419 +0.2382cMb(10 -7mol·L -1) ,线性回归系数r(10)为0.998 ,检出限为1.20×10 -8mol·L -1,该电极可作为检测肌红蛋白的新型的高灵敏度电化学生物传感器。     

锑(Ⅲ)-钛铁试剂-溴化十六烷基三甲胺体系极谱络合吸附波研究

在 0 .0 4mol·L- 1磷酸中 ,锑 (Ⅲ ) 钛铁试剂 (Tiron) 溴化十六烷基三甲胺体系产生灵敏的极谱络合吸附波。峰电位为 - 0 .4 4V(vs .SCE) ,二阶导数峰高与锑 (Ⅲ )浓度在 8.2× 10 - 10 ～ 2 .0× 10 - 6mol·L- 1范围内呈线性关系 ,检出限达 4× 10 - 10 mol·L- 1。研究了极谱波的性质及电极反应机理。方法应用于三氧化二砷及铜合金中微量锑的直接测定 ,结果满意     

痕量雌二醇的吸附方波伏安法检测

本文报道一种简便、快速、灵敏检测痕量雌激素的吸附溶出方波伏安法。该法先将雌二醇在玻碳电极上吸附富集一定时间 ,然后以方波伏安溶出法检测其氧化电流。介质为含有 8× 1 0 - 5mol· L- 1溴化十六烷基三甲铵 ( CTAB)的 0 .1 mol· L- 1磷酸盐缓冲溶液 ( p H=1 0 .0 )。该法检出限为 5× 1 0 - 8mol· L- 1,线性范围为 5 .2× 1 0 - 7～ 5× 1 0 - 5mol· L- 1。研究了雌二醇的电极反应机理     

二次微分简易示波伏安法直接测定酒样中半胱氨酸

在 0 .2mol·L- 1NaOH支持电解质溶液中 ,半胱氨酸在二次微分简易示波伏安图阴极支- 0 .4 9V(vs .SCE)处产生一灵敏的峰 ,研究了半胱氨酸在此底液中的示波伏安行为 ,并据上述示波特性建立了二次微分简易示波伏安法直接测定酒中半胱氨酸含量的新方法。校正曲线的线性范围为 3.0× 10 - 6 ～ 5 .0× 10 - 5mol·L- 1,相关系数为 0 .9995 ,检出限为 1× 10 - 6 mol·L- 1,对 1.0×10 - 5mol·L- 1半胱氨酸进行 6次测定的RSD为 1.8%。利用此法测定了啤酒、黄酒及加饭酒中半胱氨酸的含量 ,样品的回收率分别为 94 .2 %、10 1.6 %和 10 2 .2 %。方法具有仪器装置简单、经济 ,方法简便快速、无需通氮除氧以及对样品进行前处理的优点     

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.     

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.     

Facile synthesis of bicyclic 1-arylpyrazol-5-ones

In this Letter, we described a facile method for constructing fused bicyclic 1-arylpyrazol-5-one ring system. We employed various methylene-containing carboxylic acids as the substrates and proved that the pyrazolone ring closure requires activated methylene group in intermediate II. Accordingly, a series of structurally diversified, fused bicyclic 1-arylpyrazol-5-ones was prepared in moderate to high yields using the requisite substrates.     

A carbanion induced synthesis of highly congested pyrazole and imidazole containing heterocycles

An efficient approach to the synthesis of highly congested di, penta and hexacyclic pyrazoles as well as imidazole fragment containing novel heterocyclic molecule has been developed through a carbanion induced transformation of suitably functionalized 2H-pyran-2-ones, benzo[h]chromene and thiochromeno[4,3-b]pyrans. Due to the presence of fluorescence, we report their prime application metal sensor as off/on switching in ferric ions.     

Synthesis of pyrrolo[1,2-a]pyrazines and pyrazino[1,2-a]indoles by Curtius reaction in Morita-Baylis-Hillman derivatives

Synthesis of substituted pyrrolo[1,2-a]pyrazines and pyrazino[1,2-a]indoles from the Morita-Baylis-Hillman derivatives of acrylates via saponification followed by Curtius reaction is described.     

正丁胺对激光染料荧光谱影响的研究

用正丁胺作为碳源,采用射频辉光放电制备碳膜,选用激光染料R6G和聚乙二醇混合液作为蒸气源,采用单源热蒸发,在蒸发室与染料同时沉积得到混合膜,用拉曼光谱和红外光谱分析了碳膜的结构和键合方式,分析表明:碳膜中存在胺基团和氢原子.混合膜的荧光谱测量结果表明,认为正丁胺对染料荧光谱的影响是因为胺基和氢原子的存在.     

Selective synthesis of 4,5-dihydroimidazo- and imidazo[1,5-a]quinoxalines via modified Pictet–Spengler reaction

An efficient tandem approach for the selective synthesis of 4,5-dihydroimidazo[1,5-a]quinoxalines 6a–g and imidazo[1,5-a]quinoxalines 7a–h by the reaction of 2-imidazolyl anilines 4a–c with aryl aldehydes 5a–k under mild reaction conditions is described. Introduction of electron releasing alkyl groups in substrates 4a–b was found to be instrumental for the success of the reaction.     

Understanding the Diels-Alder reactivity of 1,2-azaborine analogues

The Diels-Alder reactivity of 1,2-heteroborines (H₄C₄B(H)X, X?=?NH, PH, AsH; O, S, Se) has been computationally explored by means of Density Functional Theory (DFT) calculations. The influence of the HB?=?X fragment on the reactivity of the system has been quantitatively analyzed in detail by means of the so-called Activation Strain Model (ASM) of reactivity. It is found that the interaction between these species and the dienophile is significantly stronger than that computed for their all-carbon isoelectronic counterpart, benzene. In addition, the strain energy plays a key role in the observed reactivity trends. The role of the aromaticity strength of these heteroarenes on the reactivity is also assessed.