锰(Ⅱ)-邻菲罗啉络合物的电化学行为及应用

在pH 9.5的氨水-氯化铵缓冲溶液中,锰(Ⅱ)与邻菲罗啉反应生成组成比为1:1稳定且电活性的锰(Ⅱ)-邻菲罗啉络合物.采用线性扫描极谱法和循环伏安法研究了锰(Ⅱ)-邻菲罗啉络合物的电化学行为,提出了茶叶中锰含量的测定方法.对测定条件,包括支持电解质、缓冲溶液的浓度、反应介质的酸度、以及增敏剂的选择等,作了试验并予以优化,并探讨了锰(Ⅱ)-邻菲罗啉络合物极谱峰的电化学性质及电极反应机理.在优化的条件下,还原峰峰电流与锰(Ⅱ)浓度在6.3×10-8～8.0 ×10-7mol·L-1范围内呈线性关系,检出限(3S/N)为2.0×10-8mol·L-1.此法用于茶叶样品分析,加标回收率在97.8%～102.1%之间.     

鲁米诺-过硫酸钠体系后化学发光法测定银

邻菲罗啉存在下,银对鲁米诺-Na2S2O8体系的后化学发光具有增敏作用,建立了流动注射后化学发光测定银的新方法.在优化实验条件下,该法测定银的线性范围为1.0×10-9～4.0×10-7 mol/L,线性相关系数为0.9987(n =7),检出限为3.53×10-10mol/L(n=11),对1.0×10-7 mol/...     

盐酸去氯羟嗪和盐酸氯丙那林的毛细管电泳-电致化学发光法同时测定

基于盐酸去氯羟嗪和盐酸氯丙那林都能增强联吡啶钌的电致化学发光信号,建立了一种分离检测海珠喘息定片中盐酸去氯羟嗪和盐酸氯丙那林的毛细管电泳-电致化学发光新方法.考察了联吡啶钌浓度、检测电位、磷酸盐缓冲液(PBS)浓度及其pH值、进样电压和进样时间等实验条件对分离、检测体系的影响.在优化的实验条件下,海珠喘息定片中的盐酸去氯羟嗪和盐酸氯丙那林在4 min内可实现分离检测.其线性范围均为5×107～1 × 10-5mol/L(相关系数分别为0.998 4和0.999 0),检出限分别为1.05×10-7mol/L和6.98×10-8mol/L(S/N=3).     

毛细管电泳-间接电化学发光法对茶叶中百草枯农药残留的检测

基于农药百草枯对钌联吡啶-三丙胺(TPA)体系的电化学发光具有显著的抑制作用,建立了毛细管电泳-间接电化学发光检测茶叶中残留农药百草枯的新方法.讨论了初始电位、钌联吡啶和TPA浓度、进样电压、进样时间、运行缓冲溶液的浓度与pH值等条件对百草枯检测灵敏度的影响.确定最佳实验条件为1.20 V初始电压、0.7 mmol/L钌联吡啶、0.6 mmol/L TPA、9 kV进样电压、9 s进样时间、35 mmol/L磷酸盐(pH 8.5)为运行缓冲溶液.在优化实验条件下,百草枯浓度在5×10~(-7) 5×10~(-5)mol/L范围内呈良好线性(相关系数为0.994 5),检出限为9.4×10~(-8) mol/L.对5×10~(-5) mol/L百草枯标准溶液连续测定5次,相对峰高与迁移时间的相对标准偏差分别为3.7%和2.1%.该方法对2.0×10~(-6)、1.0×10~(-5) mol/L百草枯标样的萃取回收率分别为74%和83%,相对标准偏差分别为15%、4.2%(n=5).     

毛细管电泳-电致化学发光法测定维C银翘片中的马来酸氯苯那敏

基于马来酸氯苯那敏增强联吡啶钌的电致化学发光信号,建立了一种分离检测维C银翘片中马来酸氯苯那敏的毛细管电泳-电致化学发光新方法.考察了联吡啶钌浓度、检测电位、磷酸盐缓冲液浓度和pH、进样电压和进样时间等实验条件对分离、检测体系的影响. 在优化实验条件下,维C银翘片中的马来酸氯苯那敏在3 min内可实现分离检测,其线性范围为5.0×10-7～1.0×10-4 mol/L(相关系数0.9994),检出限为5.1×10-8 mol/L(S/N=3).本法可用于维C银翘片中马来酸氯苯那敏的质量检测.     

毛细管电泳联用电致化学发光法测定胶囊剂中的马来酸依那普利

本文基于马来酸依那普利能够增敏三联吡啶钌的电化学发光,建立了毛细管电泳-电化学发光法测定马来酸依那普利的新方法.考察并优化了检测电位,缓冲溶液的浓度和pH等影响因素.在优化的实验条件下,马来酸依那普利的线性范围为3.0×10-6～5.0×10-4mol/L:检出限(S/N=3)为6.5×10-7mol/L;迁移时间和峰高的相对标准偏差分别为0.9%和4.3%(10-5mol/L,n=5).本法用于胶囊剂中马来酸依那普利含量的测定,回收率为94.0%～102.6%.     

Silica sol/Nano-Au/PVA/L-cysteine修饰金电极电致化学发光测定甲氧氯普胺的研究

在甲氧氯普胺对联吡啶钌具有较好电化学发光增敏效果的基础上,制备出Silica sol/Nano-Au/PVA/L-cysteine修饰金电极,并通过电致化学发光法,考察了联吡啶钌及联吡啶钌-甲氧氯普胺体系在此电极上的电化学及电化学发光行为。该修饰电极对联吡啶钌-甲氧氯普胺体系有良好的电致化学发光响应特性;在最优条件下,在1.0×10-7~1.0×10-4mol/L范围内甲氧氯普胺浓度与其对应的电化学发光强度值线性关系良好,检出限(S/N=3)为1.40×10-9mol/L;通过平行测定1.0×10-5mol/L甲氧氯普胺溶液8次,发光强度值相对偏差(RSD)为1.8%,样品回收率在98.3%~104.4%之间,RSD为2.3%(n=5)。     

电泳中介微分析法测定铁(Ⅱ)和铜(Ⅱ)

利用电泳中介微分析通过与邻菲罗啉的络合反应完成了对Fe2+与Cu2+的同时测定。在压差作用下,淌度较小的邻菲罗啉在金属离子区带之前首先进样,加高电压后,两区带电泳在磷酸缓冲液中 (pH=4. 5)混合、反应形成络合物并实现电泳分离。研究了缓冲液pH、试剂和样品区带长度对分离效果的影响。对于Fe2+与Cu2+两离子,方法的检出限(S/N=3)分别为 1. 6和 11μmol/L;线性范围分别为 5. 0×10-6 ~3. 0×10-4 mol/L(r=0. 9979)和 8. 0×10-5 ~3. 0×10-4 mol/L(r=0. 9996)。采用标准矿样验证了测定Fe2+的可行性。     

毛细管电泳电化学发光法分离检测西咪替丁

建立了以三联吡啶钌为发光体系的毛细管电泳电化学发光(CE-ECL)检测系统,并应用于分离和测定西咪替丁片剂中西咪替丁的含量。考察了检测电位,三联吡啶钌(Ru(bpy)32+)的溶液浓度,缓冲液的pH和溶液浓度,分离电压、进样电压与进样时间等因素对分离检测的影响。结果表明:在检测电位1.18V,Ru(bpy)32+溶液浓度为5 mmol/L,磷酸盐缓冲液(PBS)25 mmol/L(pH 7.8),进样时间10 s,进样电位10 kV,运行电位15 kV下,测得西咪替丁线性范围为2.8×10-6~4.0×10-4mol/L,检出限为1.2×10-7mol/L(S/N=3)。对1.0×10-5mol/L的西咪替丁标准溶液连续测定5次,电化学发光强度和迁移时间的RSD分别为3.9%和1.5%。方法已应用于西咪替丁片剂中西咪替丁含量的测定。     

毛细管电泳安培法测定田基黄中的芦丁与槲皮素

建立了毛细管电泳电化学分离检测田基黄中生物活性成分芦丁和槲皮素的方法。考察了检测电极电位、缓冲液浓度、pH、运行电压和进样时间对分离的影响。以40 cm长,50μm内径的石英毛细管作为分离通道,运行缓冲液为25 mmol/L硼砂(pH 9.2)溶液,分离电压12 kV,0.3 mm直径的铂圆盘电极为检测电极,检测电位1.00 V(vs.Ag/AgCl),芦丁和槲皮素在10 min内得到良好分离。在上述实验条件下,芦丁和槲皮素分别在8.2×10-6~5.2×10-4mol/L与6.8×10-6~7.2×10-4mol/L范围内与峰面积呈良好线性关系,检出限分别为9.0×10-7mol/L(S/N=3)和4.7×10-7mol/L(S/N=3)。方法已应用于田基黄药材提取物成分分析。     

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.