琼脂糖水凝胶固定化血红素蛋白质的电化学研究

利用琼脂糖（agarose）水凝胶将肌红蛋白（Mb）、血红蛋白（Hb）、辣根过氧化物酶（HRP）和过氧化氢酶（Cat）4种血红素蛋白质固定在裂解石墨电极表面,形成稳定的血红素蛋白质-agarose膜修饰电极。在agarose膜中,Mb、Hb、HRP和Cat直接与电极传递电子。4种血红素蛋白质的式电势都随溶液pH的增加而负移且呈线性关系,表明电子传递过程伴随着质子转移。     

过氧化氢酶在琼脂糖膜中的电化学研究

用琼脂糖(Agarose)将过氧化氢酶(Cat)固定在热裂解石墨电极表面,制备了Cat-agarose膜修饰电极。包埋在琼脂糖中的过氧化氢酶可以与电极直接传递电子,在pH6．0的磷酸缓冲溶液中可得一对可逆的过氧化氢酶辅基血红素Fe(Ⅲ)／Fe(Ⅱ)氧化还原峰,式电势为-0．343V(vs．SCE)。其式电势随溶液的pH值增加而负移且呈线性关系,直线斜率为-36．8mV／pH,说明过氧化氢酶的电子传递过程伴随有质子的转移。紫外可见光谱、红外光谱表明,在琼脂糖膜中过氧化氢酶的构象保持不变。并研究了过氧化氢酶修饰电极对氧气、过氧化氢、一氧化氮的电催化性质。在16．5～278／μmol／L的范围内,催化电流与过氧化氢浓度呈线性关系;在2．75～20．76mmol／L的范围内,催化电流与亚硝酸根浓度呈线性关系。     

琼脂糖膜固载肌红蛋白催化还原过氧化物的研究

用琼脂糖(agarose)将肌红蛋白(Mb)固定在玻碳电极(GCE)表面,制备了Mb-Agarose膜修饰电极。在水-乙醇混合溶液中,包埋在Agarose中的Mb与电极发生直接电子传递,并且能催化还原H2O2、过氧化丁酮、氢过氧化叔丁基、氢过氧化异丙基苯等过氧化物和NO。Mb-Agarose膜修饰电极具有较好的稳定性和重现性,可用于上述过氧化物和亚硝酸盐的定量检测。     

血红素-琼脂糖修饰电极的电化学和电催化性质研究

用循环伏安法研究了血红素-琼脂糖凝胶修饰电极在水和有机溶剂/水混合溶液中的电化学和催化还原过氧化物的性质。包埋在琼脂糖水凝胶膜中的血红素能与电极之间直接传递电子,且具有过氧化物模拟酶的特性,能快速地催化还原过氧化物,可用于这些物质的定量检测。     

OPD-H2O2-HRP伏安酶联免疫分析体系酶催化反应的研究

应用电化学分析、高效液相色谱、紫外-可见光谱、红外光谱和核磁共振等技术对邻苯二胺(OPD)-H2O2-辣根过氧化物酶(HRP)伏安酶联免疫分析体系的酶催化反应进行了详细深入的研究.用化学方法制得了HRP酶催化H2O2氧化OPD的产物纯品.伏安法和高效液相色谱实验说明,在所选择的酶催化反应条件下,酶催化反应只生成一种产物;经紫外-可见光谱,红外光谱和13C核磁共振谱鉴定,产物为2,3-二氨基吩嗪.写出了酶催化反应过程,同时对酶催化反应产物的电极还原过程也进行了研究.     

石墨烯-铁卟啉复合材料的制备及其H2O2传感器应用研究

本文通过π-π非共价键的方式合成了具有仿生功能的石墨烯-铁卟啉复合材料,并将其修饰在玻碳电极上,制备成一种新型的无酶H2O2传感器。利用傅里叶变换红外(FT-IR)光谱、紫外-可见吸收光谱(UV-Vis)及电化学阻抗谱(EIS)对合成材料进行了表征,并研究了该传感器对H2O2的电催化还原性能。实验结果表明,该传感器对H2O2具有较好的催化还原效果,能够在-0.24V电位下对H2O2进行测定;其对H2O2的线性检测范围为5.0×10-7～1.975×10-4 mol/L,检测限为4.1×10-7 mol/L。     

电沉积普鲁士蓝/壳聚糖修饰金电极的电化学研究

应用控制电位电解法在金电极上进行了普鲁士蓝(PB)/壳聚糖(CS)修饰膜的电沉积。在pH2、溶液组成为2.5 mmol/L FeCl3 2.5 mmol/L K3[Fe(CN)6] 0.01%CS 0.01 mol/L HCl和0.1 mol/L KCl的溶液中,于0.4 V(vs.SCE)电沉积300 s,获得性能理想的沉积膜。对修饰膜进行了红外和显微表征,结果表明,PB和CS同时沉积在电极上,且膜结构较纯PB沉积膜粗糙,修饰量大,具有更强的空间结构性。研究了PB/CS/金修饰电极(PB/CS/Au/CME)的电化学行为,该电极在中性(pH7.0~8.0)条件下性能比纯PB修饰膜更稳定,具有良好的电化学活性和对H2O2的电催化性能。氧化峰电流与H2O2浓度在1×10-6~5×10-3mol/L范围内呈良好线性关系,为研制基于酶催化反应的电化学生物传感器奠定了良好基础。     

水-乙醇溶液中肌红蛋白在琼脂糖膜中的氧化还原和电催化

用琼脂糖(Agarose)将肌红蛋白(Mb)固定在玻碳电极(GCE)表面,制备了Mb-Agrose膜修饰电极。在乙醇亲水性有机溶剂与水的混合溶液中,包埋在Agrose中的Mb可以与电极发生直接电子传递。紫外可见光谱表明水-乙醇溶液中琼脂糖膜中的肌红蛋白的构象保持不变。Mb-Agrose膜能快速地催化氯代乙烷(六氯乙烷、五氯乙烷和四氯乙烷等)脱氯,具有较好的稳定性和重现性,可用于这些物质的定量检测。     

间苯二胺的电化学及紫外-可见薄层光谱电化学研究

研究了间苯二胺(MPD)在金电极和SnO₂;F膜电极上的循环伏安行为及在SnO₂;F膜电极上的紫外-可见薄层光谱电化学性质.获得了间苯二胺在SnO₂;F膜电极上电氧化的薄层恒电势电解-吸收光谱图,采用双对数法对紫外-可见薄层光谱电化学数据进行了处理.研究了间苯二胺的光谱及电化学性质,求得了间苯二胺的动力学修饰式量电位E⁰和αn等热力学参数.     

血红蛋白和SiO2凝胶层层组装膜在碳纳米管/金纳米粒子修饰电极界面上的直接电化学及电催化研究

以SiO2凝胶膜和蛋白质交互组装法固定血红蛋白(Hb), 对其进行了电化学和电催化研究. 首先制备碳纳米管/金纳米粒子复合材料修饰的MWNTs-Au/GC电极, 为防止蛋白质在电极表面流失, 将Hb和自制的SiO2凝胶膜交替滴涂到电极表面, 得到SiO2/Hb层层组装膜修饰电极, 即{SiO2/Hb}n/MWNTs-Au/GC电极, n=2为优化层数. Hb在{SiO2/Hb}2/MWNTs-Au/GC电极上仍能保持其特有的生物活性, 并能与电极进行稳定快速的电子直接转移, 同时表现出过氧化物酶特性, 对H2O2具有良好的生物电催化还原能力.     

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%.     

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.     

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.     

Copper catalyzed/mediated synthetic methodology for ebselen and related isoselenazolones

Scope of the copper catalyzed/mediated selenium-nitrogen coupling reaction has been studied for the synthesis of isoselenazolones. It is noticed that the 2-chloro, 2-bromo-, and 2-iodo-aryl amides substrates can be exploited in the selenium-nitrogen coupling reaction by employing 25-100 mol % of CuI/1,10-phenanthroline (L) and potassium carbonate as a base in DMF. Furthermore, electron rich 2-chloro-arylamides also underwent selenium-nitrogen coupling reaction to give biologically important selenium-nitrogen heterocycles. Also, copper-catalyzed selenium-nitrogen coupling reaction has been meticulously applied for the synthesis of diaryl diselenides having methoxy, amine, and amide functionality from respective aryl iodides in the presence of stoichiometric amount of succinimide as an external Se-N coupling partner.     

Knoevenagel condensation catalyzed by novel Nmm-based ionic liquids in water

A series of novel N-methyl morpholine (Nmm) based ionic liquids with 1,2-propanediol group were synthesized and used as catalysts for Knoevenagel condensation at room temperature in water. Under the effect of the catalyst, various aldehydes or aliphatic ketones could react with a wide range of activated methylene compounds well, including malononitrile, alkyl cyanoacetate, cyanoacetamide, β-diketone, barbituric acid, 2-arylacetonitrile and thiazolidinedione. Furthermore, most of the products could be separated just by filtrating and washing with water. Additionally, the catalyst is recyclable and applicable for the large-scale synthesis.     

Construction of polyheterocyclic spirotetrahydrothiophene derivatives via sulfa-Michael/aldol cascade reaction

A series of polyheterocyclic spirotetrahydrothiophene derivatives were obtained in moderate to excellent yields via a catalyst-free sulfa-Michael/aldol cascade reaction of chalcones 1 and commercially available 1,4-dithiane-2,5-diol 2 under mild conditions. We also present the first asymmetric sulfa-Michael/aldol cascade reaction of chalcones 1 and commercially available 1,4-dithiane-2,5-diol 2 with moderate to good enantioselectivities catalyzed by readily available chiral phase-transfer catalysts (PTCs).     

Suzuki-Miyaura reactions of the soluble guanylate cyclase inhibitor NS2028: a non-product specific route to C-8 substituted analogues

Both soluble guanylate cyclase (sGC) inhibitors ODQ 1 and NS2028 2 are synthesized via improved protocols. In the former case treating 3,4-dihydroquinoxalin-2(1H)-one oxime 8, which can be prepared in two steps from 1,2-benzenediamine, with 1,1′-carbonyldiimidazole (CDI) gives the dihydro-ODQ 10 that in the presence of KMnO₄ oxidises to give ODQ 1 in an overall yield of 46% starting from 1,2-benzenediamine. In the latter case, the synthesis affords NS2028 2 from 2-amino-4-bromophenol 3 in three steps with an overall yield of 85% and avoids the need for chromatography. Furthermore, Suzuki-Miyaura reaction conditions are described that enable the preparation of 8-aryl and 8-heteroaryl derivatives of NS2028 directly from NS2028 2. Finally, demethylation of the 8-(methoxyphenyl) substituted analogues afforded the 8-(hydroxyphenyl) derivatives 40-42. All new products are fully characterised.