DL-赖氨酸-β-环糊精/碳纳米管修饰电极的制备与应用研究

对DL-赖氨酸-β-环糊精/碳纳米管修饰金电极的制备与应用进行了研究,建立了一种新的测定DL-赖氨酸的电化学分析方法。用循环伏安法研究了该修饰电极的选择性和灵敏度以及DL-赖氨酸在修饰电极上的氧化还原特性,结果表明该修饰电极对DL-赖氨酸具有显著的催化还原和选择作用。在pH=5.6的磷酸盐缓冲溶液中,还原峰电流与DL-赖氨酸浓度在5~100mg/L范围内呈良好的线性关系,最低检出限为0.1mg/L。方法操作简便,可用于药剂中DL-赖氨酸含量的测定。     

氯过氧化物酶-聚L-赖氨酸/GC电极的电化学特性

应用电化学方法在玻碳电极上修饰聚L-赖氨酸膜,以1-乙基-(3-二甲基氨基丙基)碳二亚胺盐酸盐做交联剂,固定氯过氧化物酶.修饰电极的循环伏安曲线呈现一对可逆的氧化还原峰,表明聚L-赖氨酸能够很好地促进氯过氧化物酶在电极表面的直接电子传递,这是一个受吸附控制并伴随有质子转移的准可逆电子传递过程.该电极有很好的稳定性,并能显著地电催化氧的电化学还原反应.     

刀豆球蛋白层层自组装双酶电极对芳香胺物质的检测

基于生物识别组装方法将辣根过氧化物酶(HRP)和葡萄糖氧化酶(Gox)固定在金电极表面制备了HRP/Gox双酶多层膜电极.HRP/Gox双酶电极通过Gox催化氧化葡萄糖"原位"产生过氧化氢的方式分析检测芳香胺物质.探讨了葡萄糖浓度和酶组装层数对双酶电极电流响应的影响.在优化条件下,制备的双酶电极在p-苯二胺的浓度为7.6 ～53.2 μmol/L时有良好的线性响应,灵敏度为146.04 mA·L/mol.常见的干扰物葡萄糖和抗坏血酸对该双酶电极无干扰.     

纳米聚苯胺修饰石墨电极的葡萄糖双酶传感器

用循环伏安法在石墨电极上制得纳米纤维聚苯胺, 并在其上固定葡萄糖氧化酶(GOD)和辣根过氧化物酶(HRP)制备葡萄糖双酶传感器. 用交流阻抗、SEM等技术对其进行表征; 考察了各种因素对双酶电极响应电流的影响以及双酶电极的稳定性. 该传感器对葡萄糖响应电流的测定在0.05 V(vs SCE)下进行, 有效避免了电活性物质的影响, 线性响应范围为0.05-2.0 mmol·L-1.     

动物组织切片L-赖氨酸电极研究

本文首次使用鸡肾组织切片作为L-赖氨酸氧化酶的来源并与氧电极偶合制作成测定L-赖氨酸的组织电极。该电极在5.0×10~(-5)～7.0×10~(-3)mol/L浓度范围内电极输出讯号与L-赖氨酸的浓度呈线性关系。电极响应时间为5～8min。除L-亮氨酸外,其它17种氨基酸均无明显干扰。电极寿命可达14天。实验并发现维生素B_2对L-赖氨酸氧化酶有较大的激活作用。     

传感器与反胶束和酶敏感膜

用传感技术研究了反胶束对酶的构象的影响 .用测定葡萄糖氧化酶 (GOD)酶膜电极响应电流的方法 ,讨论磺基琥珀酸双 2 乙基己基酯钠盐 (AOT)反胶束包埋酶对GOD构象和催化活性的影响 ,GOD/AOT的比值减小而响应电流大大增加 ,意味着大大增加了酶的催化活性和酶构象的稳定性 .     

聚L-赖氨酸修饰电极循环伏安法测定药剂中的多巴胺

用循环伏安法制备了聚L-赖氨酸修饰玻碳电极,研究多巴胺在聚L-赖氨酸修饰电极上的电化学行为,建立了循环伏安法测定多巴胺的新方法。实验结果表明,在pH7.0的磷酸盐缓冲溶液中,扫描速率为150mV/s,循环扫描电位在-0.3~0.6V时,多巴胺在聚L-赖氨酸修饰玻碳电极上出现一对灵敏的氧化还原峰,峰电位分别为Epa=0.175V,Epc=0.146V(相对饱和甘汞电极);测定多巴胺的线性范围为1.0×10-3~1.0×10-5mol/L和1.0×10-5~8.0×10-9mol/L,方法检出限1.0×10-9mol/L。用于药剂中多巴胺的测定。     

黄嘌呤和尿酸在修饰电极上的电化学行为及测定研究

用循环伏安法制备了银掺杂聚L-赖氨酸修饰玻碳电极,并对修饰电极表面进行了表征,研究了黄嘌呤和尿酸在该修饰电极上的电化学行为,建立了循环伏安法和示差脉冲伏安法同时测定黄嘌呤和尿酸的新方法。研究表明,修饰电极对尿酸和黄嘌呤的氧化具有较好的电催化活性,在pH 3.0磷酸盐缓冲溶液中,黄嘌呤和尿酸在银掺杂聚L-赖氨酸修饰电极上的氧化峰电位分别为0.980和0.600 V,两者的峰电位差达0.380 V。在最优实验条件下,用差分脉冲伏安法同时测定黄嘌呤和尿酸的线性范围为1.0×10-6~2.5×10-4mol/L,检出限为5.0×10-7mol/L。用于人尿样中黄嘌呤和尿酸的测定,获得满意结果。     

氢氧化镍薄膜修饰玻碳电极的制备及其对L-赖氨酸氧化的电催化活性

采用恒电位沉积方法将氢氧化镍沉积到玻碳电极表面,得到稳定性高、催化活性好的氢氧化镍薄膜修饰玻碳电极;分析了影响薄膜形成过程的关键因素,确定了最佳薄膜制备方案;与此同时,将薄膜修饰玻碳电极用于生物样品L-赖氨酸的氧化测定,并探讨了其催化作用机理.结果表明,所制备的氢氧化镍薄膜修饰玻碳电极表面发生电化学反应[Ni(OH)2→NiOOH],从而促进电极表面的电子转移,实现对L-赖氨酸的电催化作用.当L-赖氨酸的浓度在1.0×10-4～4.0×10-7 mol/L范围内时,相应氧化峰电流与浓度呈线性关系,检出限达4.0×10-7 mol/L;据此可方便地制备稳定性好且灵敏度高的电流型传感器.     

葡萄糖酶电极测定环糊精聚合物中的环糊精单元

用多巴胺电氧化聚合物膜将葡萄糖氧化酶固定在铅笔电极上,制得简易的葡萄糖酶电极.用自制的葡萄糖酶电极对自制环糊精聚合物中环糊精单元进行定量检测.研究了自制的葡萄糖酶电极的检测范围和稳定性.结果表明环糊精聚合物中环糊精单元质量与葡萄糖酶电极响应电流间存在很好的线性关系,且酶电极稳定性好,可以多次反复使用,连续使用30天,响应电流只减弱7%.与用Sulfate-Phenol比色法测得的环糊精聚合物中环糊精单元结果相比,两者相对偏差在8%以内.     

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.     

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.     

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.     

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.