2,4-二甲基苯胺印迹电极的零流电位法制备与应用

以电聚合方式,在石墨烯修饰的铅笔芯电极表面制备出2,4-二甲基苯胺的分子印迹聚合物,以零流电位变化的最大差值为指标获得最佳电聚合参数。磷酸缓冲溶液的pH为6.47,功能单体与模板分子的配比为1∶8,电位范围为–0.8～0.8 V,聚合圈数为26,洗脱时间为5 min。与2,4-二甲基苯胺结构相近的物质如4-氯苯胺、4-氨基联苯、联苯胺、邻甲苯胺等均不干扰测定。2,4-二甲基苯胺质量浓度的对数在0.121 2～605.908μg/L范围内与零流电位线性关系良好,相关系数为0.991,检出限为0.040 6μg/L。测定结果的相对标准偏差为0.84%(n=5),平均回收率为95.59%～101.70%。该电极制备简单,灵敏度高,选择性和稳定性好,适用于实际废水中2,4-二甲基苯胺的检测。     

零流电位法对4-氨基联苯的检测

以铅笔芯电极(PGE)为工作电极,铂电极为对电极,饱和甘汞电极为参比电极,在含4. 0×10-3mol/L丙烯酸、1. 0×10-3mol/L 4-氨基联苯(4-ABP)的磷酸盐缓冲溶液(PBS,p H 7. 17)中,采用循环伏安法以0. 1 V·s-1在-1. 6～1. 6 V电位范围循环扫描16圈,经超声洗脱6 min后制得4-氨基联苯印迹聚合物修饰电极(4-ABP-MIP/PGE)。零流电位法下,在4-ABP浓度0. 005～50μmol/L范围内,4-ABP-MIP/PGE的零流电位EZCP与4-ABP浓度的对数呈线性关系,检出限为1. 07 nmol/L。将该传感器用于实际样品中4-ABP的检测,平均回收率为96. 0%～102%。     

电聚合分子印迹传感器选择性测黑茶中槲皮素的含量

以槲皮素作为模板分子,邻氨基苯酚作为功能单体,在金电极表面通过电聚合法,制备了具有选择性识别槲皮素的分子印迹传感器。采用循环伏安法、差分脉冲伏安法研究了印迹膜的性能、结构和分子印迹效应。对功能单体与模板分子的配比、洗脱时间和印迹时间等实验参数进行了优化,并与其结构相似的化合物芦丁的选择性响应进行了比较,发现该传感器对槲皮素分子具有良好的选择性。槲皮素浓度在6.0×10-6~1.0×10-4mol/L范围内与峰电流呈线性关系,线性方程为:I(μA)=27.79+9.48lgc(mol/L)(R=0.9939),检出限为2.0×10-6mol/L。用此传感器测定黑茶中槲皮素含量的结果较为满意。     

双亲聚合物分子印迹自组装胶束电化学传感器研究

结合大分子自组装和分子印迹技术制备了分子印迹聚合物胶束, 并通过电沉积将其固载到电极表面得到分子印迹电化学传感器. 首先以甲基丙烯酸二甲氨基乙酯(DMA)、丙烯酸羟乙酯(HEA)、丙烯酸二异辛酯(EHA)和苯乙烯(St)合成了共聚物poly(DMA-co-HEA-co-EHA-co-St), 在其侧链接枝上双键得到可光交联的双亲共聚物. 以水为沉淀剂诱发该双亲共聚物在含有对乙酰氨基苯酚的溶液中自组装, 得到印迹有对乙酰氨基苯酚的聚合物胶束, 利用动态激光光散射(DLS)和透射电镜(TEM)表征其尺寸和形貌. 最后通过电沉积技术诱导印迹胶束在金电极表面组装, 经紫外光辐照交联后, 洗脱模板分子形成分子印迹膜, 制备了对乙酰氨基苯酚分子印迹传感器, 通过循环伏安法、差分脉冲溶出伏安法研究此印迹传感器的性能. 实验结果表明, 该传感器对对乙酰氨基苯酚具有良好的选择性和灵敏度, 浓度响应线性范围为1×10^{-6 到4×10-3 mol/L, 检测限为3.3×10-7 mol/L.}     

基于纳米材料增效的2,6-二叔丁基对甲酚分子印迹电化学传感器的研究及应用

以2,6-二叔丁基对甲酚(BHT)为模板分子,以邻氨基苯硫酚功能化的纳米金为功能单体制备分子印迹聚合物。利用表面修饰技术,将石墨烯和所制备的分子印迹聚合物修饰至电极表面构建基于纳米材料增效的分子印迹电化学传感器。在优化条件下,该传感器的线性检测范围为5×10–6~1×10–2 mol/L,最低检测限为1.56×10–6 mol/L,5次重复测定结果的相对标准偏差为4.6%,样品加标回收率为96.5%~104.0%。该分子印迹电化学传感器能够实现对BHT的特异性识别,具有良好的重复性和稳定性,可用于实际样品检测。     

4-氨基吡啶分子模板聚合物选择性识别及结合性质的研究

以4-氨基吡啶为模板分子制备了对4-氨基吡啶具有特异选择性的模板聚合物.制得的棒状聚合物经研磨、过筛后,采用平衡结合方法评价了该模板聚合物的结合特性.Scatchard分析表明,在所研究的浓度范围内,聚合物中形成了两类不同的结合位点,这两类结合位点的离解常数采用多点结合模型计算得到的值分别为6.0μmol/L和1.2mmol/L.底物选择性表明,与其它结构相似的分子相比,该聚合物对模板分子4-氨基吡啶显示了很强的结合能力.₁HNMR研究及4-氨基吡啶共振结构分析表明,模板分子与聚合物中的结合位点之间的作用为离子作用.     

基于分子印迹电聚合膜的双酚A电化学传感器

以双酚A为模板分子,邻氨基苯硫酚为单体,采用自组装和电聚合方法,在电极表面制备了对双酚A有选择性的分子印迹聚合物膜.通过循环伏安法研究传感器对双酚A的响应特性.结果表明: 在6.0×10-7～5.5×10-5 mol/L浓度范围内峰电流值与浓度呈良好线性关系(r=0.991);检出限2.0×10-7 mol/L; 相对标准偏差<5%(n=9),达到稳定电流所用时间约2 min.此传感器具有良好的选择性、重现性及稳定性.通过交流阻抗技术和计时电流法表征了电极表面膜的电化学性质.将传感器初步用于实际样品的分析,获得了较满意的结果.     

分子印迹电化学传感器同时测定尿液中多巴胺和抗坏血酸

制备了同时检测多巴胺(DA)和抗坏血酸(AA)的分子印迹电化学传感器。该传感器以酸性铬蓝K(ACBK)为功能单体,DA/AA为模板分子,利用电化学聚合方法在电极表面合成分子印迹聚合物膜,根据DA和AA产生的氧化电流,利用差分脉冲伏安法实现DA和AA的同时测定,且DA和AA的氧化峰电位分开近300 m V。DA和AA检测限分别达6.20×10-11mol/L和1.65×10-8mol/L。传感器可应用于人尿液中DA和AA的测定。     

三聚氰胺分子印迹表面等离子体共振传感器的制备及分析应用

以合成的烯丙基-1,3,5-三嗪-2,4,6-(1H,3H,5H)三酮为功能单体,三聚氰胺为模板分子,乙二醇二甲基丙烯酸酯为交联剂,在表面等离子体共振(SPR)传感芯片上合成了分子印迹聚合物薄膜。根据印迹聚合物的朗格缪尔方程式,计算得到三聚氰胺和分子印迹聚合物之间的结合常数为1.40×10~8L/mol。此传感器显示出对模板分子三聚氰胺的高选择性,在p H=7.5的条件下,此传感器对三聚氰胺的响应最佳,线性范围为0.1-10.0 nmol/L(R=0.9991)。将此传感器用于牛奶和奶粉中三聚氰胺的检测,检出限分别为62.6 pmol/L和56.4 pmol/L(S/N=3),回收率分别为91.5%和92.0%。     

基于石墨烯增敏的甲基对硫磷分子印迹电化学传感器的研制

以甲基对硫磷为模板分子,甲基丙烯酸为功能单体,马来松香丙烯酸乙二醇酯为交联剂,在石墨烯修饰的玻碳电极表面合成分子印迹聚合物膜,制备分子印迹电化学传感器,用于检测有机磷农药甲基对硫磷。采用循环伏安法、微分脉冲伏安法、电化学交流阻抗法研究传感器的电化学特性及分析特性。结果表明,在最佳检测条件下,传感器的峰电流与甲基对硫磷浓度在1.0×10^-7～8.0×10^-5 mol/L范围内呈线性关系,线性方程为I_p(μA)=-0.65199-0.02387C(μmol/L),相关系数R²为0.9922,检出限为5.0×10^-8 mol/L(S/N=3)。构建了传感器的动力学吸附模型,测得印迹传感器的结合速率常数k=20.2758s。将此传感器用于番茄样品中甲基对硫磷的检测,加标回收率为95.0%～100.3%。     

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.