光谱法研究牛血清白蛋白与磷钼酸的相互作用

运用UV-Vis光谱、荧光光谱、同步荧光光谱、FT-IR光谱等手段,研究了在模拟人体生理条件下,牛血清白蛋白(BSA)与磷钼酸的相互作用。UV-Vis光谱显示,加入磷钼酸后,BSA的紫外吸收降低且吸收峰红移,表明磷钼酸与BSA形成了复合物;荧光猝灭光谱显示磷钼酸对BSA有荧光猝灭作用,且其荧光猝灭机理符合静态机制,磷钼酸与BSA结合的结合常数为:Ks=2.539×104L·mol-1;探针实验表明磷钼酸与BSA在结合位点I发生结合;Fster偶极-偶极非辐射能量转移机理确定了磷钼酸在BSA中与第214位色氨酸残基之间的距离r=1.93nm;FT-IR光谱显示磷钼酸诱导BSA的二级结构发生了变化,α-螺旋含量降低。     

极谱催化波测定多晶硅中的磷

多晶硅中的杂质通常用光谱分析法来测定,但测磷的灵敏度不够高。近来人们用间接法,先使磷酸根与钼酸铵生成磷钼杂多酸,再用乙酸正丁酯萃取此杂多酸,使其与砷、硅等分离,然后用光谱法测定钼以间接测定磷,这样提高了测定灵敏度。我们考虑到钼在苦杏仁酸存在下的极谱催化波十分灵敏,因此将有机相中的磷钼杂多酸反萃于氨溶液中,加入硫酸、苦杏仁酸和氯酸钠,极谱测钼的催化波,从而间接测定磷。实验结果表明催化波法可测至0.005微克磷/11毫升,能满足一般多晶硅分析的要求。     

铅—锶—偶氮氯膦Ⅲ体系极谱吸附波的研究及应用

在NaNO_2底液中,Pb~(2+)与偶氮氯磷Ⅲ形成2:1的络合物,于-0.60 V(vs.SCE)处产生一与Pb~(2+)浓度有关的极谱吸附波。加入Sr~(2+)后,形成铅-锶-偶氮氯膦Ⅲ三元异双核络合物,其极谱波灵敏度增加、稳定性更好,峰电位负移至-0.61 V。利用此波建立了测定痕量铅的极谱吸附波分析法,用以测定蕃茄叶标样(美国NBS,SRM-1573)中痕量铅,结果良好。还研究了此络合物组成及极谱波性质。     

1,4-二巯基苏糖醇的间接极谱法研究

1,4—二巯基苏糖醇(简称DTT)是一种生化物质,常用于蛋白质的分离、测定和生理作用的研究等方面[1,2]在生物医学上有重要的作用。曾百肇等人研究了DTT在氯乙酸介质中极谱波的性质[3],本文用单扫描示波极谱法研究了DTT与磷钼黄的还原产物在滴汞电极上产生的极谱波,建立了一种简单、快速、可靠的测定DTT的极谱分析法,该法线性范围宽、灵敏度高、再现性好,具有一定的应用价值。1　实验部分1.1　仪器与试剂JP—2型示波极谱仪(成都仪器厂);PAR—174极谱分析仪;PAR—303静汞电极(美国PAR公司);pHS—2型酸度计。1,4—二巯基苏糖醇(GR进口…     

极谱法测定毒死蜱等有机磷农药残留

建立了测定毒死蜱、辛硫磷、乐果、水胺硫磷和三唑磷5种常见有机磷农药残留的极谱分析新方法。优化实验条件下,毒死蜱浓度在0.0192~24.0μg/mL范围内与峰电流成线性关系,检出限为0.012μg/mL,回收率在90.36%~103.3%范围。其它有机磷农药的线性范围分别为:辛硫磷0.016~25.2μg/mL,乐果13.41~33.52μg/mL,水胺硫磷为17.42~34.84μg/mL,三唑磷为0.0110~21.2μg/mL。用极谱法研究了毒死蜱的电化学行为,证明了电极反应物为水杨基荧光酮,极谱波为不可逆还原吸附波。     

在2,4,5-三氯酚存在时皮蝇磷的极谱测定法

皮蝇磷是一种防治牲畜体内外寄生虫的特效药物,还可作农药和家用卫生品使用。文献中,用色谱法,分光光度法和薄层色谱-比色法等测定皮蝇磷在各种情况下的浓度已有许多报导。作者在1964年首先用极谱法研究了皮蝇磷的测定法。由于2、4、5-三氯酚是合成皮蝇磷时需要过量加入的一种基本原料,合成后虽经分离回收,有时仍难免有少量三氯酚混     

催化动力学极谱法测定痕量钯的研究

研究了催化动力学极谱法测定痕量钯的方法，在盐酸介质中，钯催化次磷酸钠与钼酸铵反应生成磷钼蓝，用氨－氯化铵缓冲液调节溶液ｐＨ值为９．２６可抑制催化反应条件，并在单扫描示波极谱仪上于－１．２４Ｖ（ｖｓ．ＳＣＥ）产生一灵敏极谱波，导数波高与钯０．０５～１．０ｎｇ．ｍｌ＾－１呈线性关系，检出限为０．０３ｎｇ．ｍｌ＾－１，研究了极谱波性质及机理，证明其为吸附波，方法用于合成样及电镀废液中的钯测定，结果满意。     

交流示波极谱漓定法测定砷(Ⅴ)及其在炼焦气脱硫砷碱液中的应用

高鸿等用铅标准溶液作滴定剂进行示波极谱滴定,成功地测定了铬酸根,钼酸根,钨酸根和磷酸根等阴离子。我们尝试在微酸性溶液中用生成焦砷酸铅的反应,进行示波极谱滴定测定砷(V)。应用在炼焦气脱硫砷碱液中砷的测定亦得到满意的结果。实验部分试剂和仪器 0.1919N铅标准溶液,0.03274N砷标准溶液:分别采用硝酸铅和砷酸钠配制,用常规方     

极谱法在环境分析中的应用

<正> 随着科学技术的发展,对极谱法提出了进一步的要求,快速、高灵敏度和高分辨率的极谱方法诸如溶出伏安法、催化极谱法、示波极谱、交流极谱、方波极谱和脉冲极谱法等相继问世。极谱法用于环境样品分析广泛采用了新技术,某些元素的伏安法或与脉冲极谱相结合的方法其灵敏度可与无火焰原子吸收光谱法比美。极谱法设备简单,价格低廉,加之方法在不断改进,因而在成份复杂的环境样品分析中得到日趋广泛的研究和应用。     

单扫描示波极谱法测定人发中磷

用极谱法直接测人发中磷的方法至今未见报道。本文在文献[1]工作基础上,对其测定条件进行了探讨和改进,并应用于人发中磷的直接测定,获满意结果。磷和钼在酸性条件及抗坏血酸的催化作用下,迅速形成具有电活性的二元磷钼杂多酸,此杂多酸在氨性缓冲溶液介质中(pH 9.5～10.4)产生灵敏的吸附还原波,磷与该波在0.03～15μg/10ml范围内呈线性关系。本法操作简便、快速灵敏。     

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.     

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.     

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.     

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.