1,10-邻菲啰啉-5,6-二酮修饰碳糊电极测定水中镉

以1,10-邻菲啰啉-5,6-二酮(phendio)修饰碳糊电极为工作电极,在0.05mol/L HAc-NaAc(pH4.74)电解液中,于-1.30V(vs.SCE)处Cd2 以Cd-1,10-邻菲啰啉-5,6-二酮络合物的形式吸附到电极上,再经过阳极溶出,从而建立了一种测定水样中痕量镉的新方法。本法于-0.69V处产生一个灵敏的溶出峰,其二阶导数峰电流与Cd2 的浓度在2.4×10-7~6.0×10-9mol/L范围内呈良好的线性关系;检出限为3.0×10-10mol/L(S/N=3)。应用本方法测定水样中的Cd2 ,结果令人满意。     

分子光谱法研究曙红Y与马来酸罗格列酮相互作用及其分析应用

在HCl-NaAc酸性缓冲介质中,曙红Y(EY)与马来酸罗格列酮(ROM)反应形成1∶1的离子缔合物,不仅引起吸收光谱(UV)的变化和EY的荧光猝灭(FS),更能导致共振瑞利散射(RRS)的显著增强,并产生新的RRS光谱。以试剂为参比,吸收光谱的最大褪色波长为510nm;荧光猝灭的激发波长λex和发射波长λem分别为521和544nm;最大共振散射波长λRRS为307nm,并在532nm处形成较强的散射峰。各方法的线性范围分别为4.98×10-7～7.5×10-6 mol/L(UV)、8.34×10-8～1.79×10-5 mol/L(FS)和4.66×10-9～1.25×10-5 mol/L(RRS),检出限分别为1.49×10-7 mol/L(UV)、2.50×10-8 mol/L(FS)和1.40×10-9 mol/L(RRS)。文中研究了吸收、荧光和共振散射的光谱特征、适宜的反应条件及影响因素,并对荧光猝灭机制及RRS的增强进行了讨论,据此建立了灵敏、简便、快速测定抗糖尿病药物马来酸罗格列酮的新方法。     

三聚氰胺基螯合树脂/碳纳米管修饰充蜡石墨电极阳极溶出伏安法测定铅和镉

采用超声法合成了三聚氰胺-甲醛-硫脲螯合树脂(MFT),基于碳纳米管优良的光电性能,制备了MFT/纳米碳管复合物修饰充蜡石墨电极(MFT/MWCNTs/WGE)。采用场发射扫描电子显微镜及电化学技术表征了该修饰电极的特性。该电极被成功地用于水溶液中重金属离子Pb(Ⅱ)和Cd(Ⅱ)的同时测定,Pb(Ⅱ)和Cd(Ⅱ)的溶出峰电流与浓度分别在3×10-8~9×10-7mol/L和5×10-8~7×10-7mol/L的浓度范围内,呈良好的线性增长关系,Pd(Ⅱ)和Cd(Ⅱ)的检测限分别为2×10-9和3×10-9mol/L(3σ)。     

山楂果和桑枝提取物中总黄酮含量的Fe(phen)2+3探针共振瑞利散射法测定

在pH值约为8.0的BR缓冲介质中,桑色素、槲皮素和芦丁等黄酮类物质能与Fe(phen)2+3反应形成离子缔合物,此时将引起共振瑞利散射(RRS)显著增强,最大RRS波长均位于310 nm. 在一定范围内散射强度(ΔI)与黄酮类物质的浓度成正比,据此可以建立用Fe(phen)2+3测定某些黄酮类物质的新RRS法. 对桑色素、槲皮素和芦丁的检出限(3σ/K)分别为1.25×10-7 mol/L(37.74 μg/L),1.80×10-7 mol/L(54.42 μg/L),2.72×10-7 mol/L(167.30 μg/L). 研究了反应的适宜条件和影响因素,考察了共存物质的影响. 结果表明,方法有较好的选择性.分别以芦丁和桑色素为对照品测定了中药材山楂果和桑枝中的总黄酮含量,对反应机理进行了初步探讨.     

CdTe量子点作为荧光探针测定水环境中微量镉离子

利用CdTe量子点(QDs)和乙二胺四乙酸(EDTA)构建的纳米探针,建立了一种能快速灵敏检测Cd2+的新方法。利用EDTA溶液与Cd2+的络合作用对QDs的表面进行化学蚀刻,在QDs表面形成了Cd2+的空腔,这些表面缺陷使得QDs荧光猝灭,而继续加入Cd2+后,新加入的Cd2+能够迅速补位空腔修复表面缺陷,使得QDs的荧光恢复。在最佳的实验条件下,当Cd2+浓度在3.3×10-9~6.7×10-6mol/L范围时,QDs恢复的荧光强度与Cd2+浓度之间呈良好的线性关系,检出限为1.0×10-9mol/L(S/N=3)。此外,相对于其他金属离子,该荧光探针对Cd2+具有高选择性,并且将其用于实际水样中Cd2+含量的检测,结果令人满意。     

盐酸吡格列酮与曙红Y相互作用的荧光和共振光散射光谱研究

在HCl-NaOAc酸性缓冲介质中,曙红Y(EY)与盐酸吡格列酮(PGH)反应形成1∶1的离子缔合物,不仅引起曙红Y的荧光猝灭(FLU),更能导致共振散射(RRS)的显著增强。荧光猝灭的激发和发射波长分别为λex=524nm和λem=544nm;最大共振散射波长为308nm,并在540nm处产生一共振峰。方法的线性范围分别为9.04×10-7～2.05×10-5mol/L(FLU)和1.6×10-7～5.1×10-6mol/L(RRS),检出限分别为1.88×10-7mol/L(FLU)和4.82×10-8mol/L(RRS)。研究了荧光和共振散射的光谱特征、适宜的反应条件及影响因素,据此建立了灵敏、简便、快速测定抗糖尿病药物盐酸吡格列酮的新方法。     

维多利亚蓝B-安乃近的共振瑞利散射光谱及应用

建立了测定安乃近的共振瑞利散射(RRS)法。在弱碱性的Tris-HCl缓冲介质中,安乃近与维多利亚蓝B的结合物使共振瑞利散射显著增强并产生新的RRS光谱,且在364nm波长处的共振散射强度△IRRS最强。安乃近的浓度在0.2×10-6~1.2×10-6mol/L范围内与△IRRS呈线性关系,相关系数为0.9987,检出限(3Sb/S)为2.6×10-8mol/L。该方法简便、快速、灵敏,用于市售安乃近药物中安乃近含量的测定,结果满意。     

镉—8—羟基喹啉络合物吸附波的研究

8-羟基喹啉(HOx)是许多金属有效的络合剂,其与金属络合物的极谱行为已有报道.镉的络合物吸附波体系已有不少报道,但镉与8-羟基喹啉络合物的极谱波尚未见报道.我们在试验中发现,镉在5×l0~（-2）mol·L~(-1)HCl-9.4×10~(-2)mol·L~(-1)HOAc-9.0×10~(-2)mol·L~(-1)NaOAc-5.O×10~（-4）mol·L~(-1)HOx溶液中,于-0.69V(vs.SCE)处出现一灵敏的络合物吸附波,峰电流与镉浓度在2.7×10~(-8)～8.9×10~(-6)mol·L~(-1)范围内呈线性关系.检测下限为1.8×1O~(-8)mol·L~(-1).用极谱直线法求得Cd(Ⅱ)与HOx络合物的络合比为1:1.本法用于河水及污水中痕量镉的测定,效果理想,回收率在95%～104%之间.     

Ru(bipy)2+3-CO2-3-SO2-3-KClO3体系化学发光法测定空气中的二氧化硫

提出了Ru(bipy) 2+ 3-CO 2- 3-SO 2- 3-KClO 3体系化学发光法测定溶液中亚硫酸盐的方法.SO 2- 3浓度与化学发光强度在1.0×10-7～1.0×10-4 mol/L 范围内成正比,检出限为8.76×10-8 mol/L,对1.0×10-4 mol/L SO2-3溶液6次测定的相对标准偏差为2.9%.该法用三乙醇胺作为吸收液,成功地用于测定空气中二氧化硫的含量,结果满意.     

磁流体动力学用于镉的溶出伏安检测

提出了一种基于磁流体动力学效应用于小体积样品中镉的测定的溶出伏安方法。在金属的溶出伏安法测定中,磁场和高浓度的Fe3 的共同作用产生的磁流体动力学效应使得更多的金属离子沉积在电极表面,使金属的溶出峰电流明显提高,极大地提高了测量的灵敏度。在对2mL样品中的Cd测定,磁场强度0.6T,Fe3 浓度为0.12mol/L,富集电位-0.8V,富集时间60s,镉的检出限为3.1×10-9mol/L,线性范围为1×10-8～1×10-6mol/L。本方法灵敏度高、重现性好,可以有效的避免传统的溶出伏安法测定中,由搅拌所产生的较大的背景电流干扰,尤其适用于小体积样品中重金属离子的溶出伏安法分析。     

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.