溶胶-凝胶法热解石墨电极传感器制备及其在电致化学发光中的应用

依据多壁碳纳米管(MWNT)导电性优良和纳米银(nano-Ag)电催化特性,以硅溶胶(silica sol)为成膜剂,在助膜剂聚乙烯醇(PVA)协同作用下,以溶胶-凝胶法实现了对MWNT、nano-Ag及Ru(bpy)_3~(2+)在热解石墨电极表面的固载修饰,制备出MWNT/nano-Ag/silica sol/PVA/Ru(bpy)_3~(2+)修饰热解石墨电极,并依据苦参碱(MT)对Ru(bpy)_3~(2+)增敏作用,建立了电致化学发光法对苦参碱的测定方法。结果表明,苦参碱浓度在2. 04×10~(-7)～1. 02×10~(-4)mol/L范围内与Ru(bpy)_3~(2+)-MT体系ECL强度呈良好线性关系(R~2=0. 998),检出限(S/N=3)为2. 96×10~(-9)mol/L,连续平行测定1. 02×10~(-5)mol/L苦参碱溶液5次,ECL强度的相对标准偏差(RSD)为1. 3%,体系稳定性及重现性良好; 3组样品平均加标回收率为97. 7%～103. 9%。     

氮掺杂石墨烯量子点/Ru(bpy)_3~(2+)体系电致化学发光法检测邻苯二酚

采用简单的方法合成了氮掺杂石墨烯量子点(NG QDs),并分别用荧光光谱仪和透射电子显微镜进行了表征。研究了NG QDs对Ru(bpy)_3~(2+)电致化学发光(ECL)体系的增敏作用。实验优化了体系pH、Ru(bpy)_3~(2+)用量、NG QDs用量以及扫速等条件。在最优条件下,根据邻苯二酚对NG QDs/Ru(bpy)_3~(2+)耦合ECL体系信号的猝灭作用,建立了测定邻苯二酚的新方法。邻苯二酚浓度(1.0×10~(-8)～1.0×10~(-5) mol/L)的对数值与ECL信号强度差之间呈线性关系,检测限低至5.0×10~(-9) mol/L,而且选择性和重现性好,实际样品检测结果令人满意。     

硫化镉量子点对三联吡啶钌电化学发光的增敏作用及用于邻苯二酚的检测

研究了CdS量子点(CdS QDs)对三联吡啶钌(Ru(bpy)_3~(2+))电致化学发光(ECL)信号的作用,发现CdS QDs对Ru(bpy)_3~(2+)的ECL信号有良好的增敏作用,基于此建立了高灵敏的CdS QDs/Ru(bpy)_3~(2+)ECL体系。探讨了该体系的ECL机理,考察了CdS QDs的浓度、缓冲溶液p H值、扫描速率等实验参数对ECL信号的影响,优化了体系的ECL条件。基于邻苯二酚对该体系ECL信号的抑制作用,建立了邻苯二酚的ECL检测方法。在1.0×10~(-8)~1.0×10~(-5)mol/L范围内,邻苯二酚的浓度与ECL信号的变化值呈良好的线性关系,检出限(S/N=3)为5.5 nmol/L,将本方法用于茶叶中邻苯二酚的检测,结果令人满意。     

Nano-Au/Silica sol/PVP修饰金电极上电化学发光测定盐酸硫必利

采用溶胶-凝胶法制备了Nano-Au/Silica sol/PVP修饰金电极,并基于盐酸硫必利对联吡啶钌(Ru(bpy)2+3)在该修饰电极上弱电化学发光具有较强的增敏作用,建立了电化学发光检测盐酸硫必利的新方法。在最佳实验条件下,盐酸硫必利浓度在1.0×10-7~1.0×0-4 mol/L范围内与相对发光强度呈线性关系(r2=0.9978),检出限(S/N=3)为6.7×10-10 mol/L。连续平行测定1.0×10-5 mol/L盐酸硫必利溶液10次,发光强度的相对标准偏差(RSD)为1.78%。对样品进行回收率试验,其回收率在97.7%~103.9%之间,RSD为2.62%。该方法具有较高的选择性和灵敏度,样品处理简单快速,用于盐酸硫必利的测定,结果满意。     

Ru(bpy)_3~(2+)体系电化学发光法测定盐酸左氧氟沙星

基于盐酸左氧氟沙星对联吡啶钌(Ru(bpy)2+3)的电化学发光信号有较强的增敏作用,建立了一种检测盐酸左氧氟沙星的电化学发光分析新方法。结果表明,在0.1mol/L NaHPO4-KH2PO4介质中,以恒电位电解,Ru(bpy)2+3的浓度为1.0×10-5g/mL时,盐酸左氧氟沙星对Ru(bpy)2+3电化学发光信号的增敏效果最好。在此条件下,测定盐酸左氧氟沙星的线性范围为6~400×10-9g/mL,检出限为5.0×10-9g/mL,对8.0×10-9 g/mL盐酸左氟沙星平行测次11次,相对标准偏差(RSD)为1.9%。该方法已应用于人体尿样中盐酸左氧氟沙星的测定,并且用此方法对盐酸左氧氟沙星的国产及进口片剂进行了体外溶出度的测定。     

取代基对胺化合物联吡啶钌电致化学光影响的研究

研究了苦豆子中主要生物碱槐定碱、苦参碱,以及神经兴奋药物甲基安非他命 、安非他命等化合物,在碱性联吡啶钌[Ru(bpy)_3~(2+)]水溶液（pH 9.0）中的电 致化学发光（ECL）行为。在玻碳电极上,生物碱中的氨基氮于+1.30 V（vs. Ag/AgCl）左右被氧化为氮正自由基离子,该自由基离子与Ru(bpy)_3~(2+)反应生 成激发态的Ru(bpy)_3~(2+*)而发光。研究比较了取代基性质、氨基氮周围的三维 空间结构对各生物碱ECL的影响,并结合生物碱氨基氮的电离势和键角的计算,对 这些影响进行了解释。     

取代基对胺化合物联吡啶钌电致化学光影响的研究

研究了苦豆子中主要生物碱槐定碱、苦参碱，以及神经兴奋药物甲基安非他命 、安非他命等化合物，在碱性联吡啶钌[Ru(bpy)_3~(2+)]水溶液（pH 9.0）中的电 致化学发光（ECL）行为。在玻碳电极上，生物碱中的氨基氮于+1.30 V（vs. Ag/AgCl）左右被氧化为氮正自由基离子，该自由基离子与Ru(bpy)_3~(2+)反应生 成激发态的Ru(bpy)_3~(2+*)而发光。研究比较了取代基性质、氨基氮周围的三维 空间结构对各生物碱ECL的影响，并结合生物碱氨基氮的电离势和键角的计算，对 这些影响进行了解释。     

基于环境污染物对DNA损伤筛查的电化学发光传感器的构建

在本文中,进一步发展了以二联吡啶二吡啶并[3,2-a:2',3'-c]吩嗪钌([Ru(bpy)_2dppz]~(2+))为电化学发光指示剂的DNA损伤传感器。将通过S-Au键组装在金电极表面的双链DNA浸泡在[Ru(bpy)_2dppz]~(2+)溶液中,利用[Ru(bpy)_2dppz]~(2+)是双链DNA分子"光开关"的特性,得到[Ru(bpy)_2dppz]~(2+)/DNA/Au电化学发光传感器,并优化了[Ru(bpy)_2dppz]~(2+)的浸泡时间,浸泡浓度等实验条件。发现在含有[Ru(bpy)_2dppz]~(2+)的底液中测定其电化学发光强度值比不含[Ru(bpy)_2dppz]~(2+)的底液中增强了6倍左右。此外将此传感器经全氟辛酸磺酸、五溴联苯醚、氧化苯乙烯等物质温浴后,其电化学发光强度显著降低,说明该传感器可用于环境污染物对DNA损伤的筛查测定。     

Ru~(3+)增敏的化学发光新体系测定呋塞米的研究

Ru~(3+)存在下,呋塞米能够大幅度增强三(1,10-菲咯啉)钌(Ⅱ)(Ru(phen)_3~(2+))-Ce(Ⅳ)体系的化学发光,且当体系中Ru~(3+)的浓度从0增至15μmol/L时,呋塞米对体系发光的增强值提高1个数量级,基于此,建立了高灵敏测定呋塞米的Ru(phen)_3~(2+)-Ce(Ⅳ)-Ru~(3+)体系化学发光方法。在优化实验条件下,该法测定呋塞米的线性范围为5. 0×10~(-9)~2. 0×10~(-6)mol/L,检出限为3. 8×10~(-9)mol/L。方法具有较高的分析灵敏度,将其应用于呋塞米片剂和呋塞米注射液的分析,结果满意。结合紫外光谱的研究结果,对化学发光反应机理进行了探讨。     

基于Ce（Ⅳ）-Ru（bpy）_3（2＋）化学发光体系测定盐酸雷诺嗪

在0.12mol·L~（-1）硫酸介质中,由1.0×10~（-3）mol·L~（-1）硫酸铈溶液与2.0×10~（-4）mol·L~（-1）Ru（bpy）_3~（2＋）溶液反应产生的化学发光强度因盐酸雷诺嗪的存在而明显增强。试验表明：盐酸雷诺嗪的质量浓度在0.1～2.0mg·L~（-1）及2.0～10.0mg·L~（-...     

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.     

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.     

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.     

Microwave-assisted copper-catalyzed stereoselective ring expansion of three-membered heterocycles with α-diazo-β-dicarbonyl compounds

Microwave-assisted copper-catalyzed ring expansions of three-membered heterocycles with α-diazo-β-dicarbonyl compounds were investigated. Thiiranes generated 3-acyl-5,6-dihydro-1,4-oxathiines in the presence of copper sulfate and trans-3-acyl-5,6-dihydro-1,4-oxathiines as stereospecific products for 1,2-disubstituted cis-thiiranes through an intramolecular S_N2 process. Oxiranes gave rise to 2-acyl-5,6-dihydro-1,4-dioxines under the catalysis of copper hexafluoroacetylacetonate and cis-3-acyl-5,6-dihydro-1,4-dioxines as stereospecific products for 1,2-disubstituted cis-oxiranes via an intimate ion-pair mechanism. The current method provides a direct and simple strategy in efficient preparation of 3-acyl-5,6-dihydro-1,4-oxathiines and 2-acyl-5,6-dihydro-1,4-dioxines, important agents in medicinal and agricultural chemistry, from readily available thiiranes and oxiranes, respectively.     

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.