新型含磷酰基的脂溶性自由基捕捉剂的合成及其ESR研究

超氧阴离子自由基的研究最近得到了广泛的关注, 这主要是因为超氧阴离子自由基及由其诱导产生的各种活性氧(HOO @, HO @和H2O2)与许多病理过程有关, 如发炎 [1]、缺血再灌综合症 [2]、 DNA损伤 [3]和神经死亡疾病 [4]等.     

模板技术制备单块介孔分子筛

模板技术与溶胶-凝胶过程结合是合成介孔分子筛的有效方法. 模板通常采用表面活性剂在一定条件下自组装形成超分子结构, 在不同条件下, 此超分子结构具有不同聚集形态, 合成出的介孔分子筛也具有不同的孔道排列方式 [1~4]. 溶胶-凝胶过程是通过硅源体的水解缩合并缓慢蒸发除去溶剂实现的. 此过程及产物受体系的pH值影响很大. 在碱性体系中制备的介孔材料通常为粉末状, 不利于实际应用, 因此人们更加重视合成具有规则外形的介孔材料 [5]. 目前报道大多是在酸性体系中制备不同形状的介孔材料 [6~12]. 有关合成单块介孔分子筛的报道较少 [13]. 最近, 王策等 [14,15]改进了通常的溶胶-凝胶过程, 预先将溶胶中的有机溶剂通过萃取加以除去, 然后实现凝胶过程. 结果表明, 采用改进的溶胶-凝胶技术能显著地加快凝胶过程, 从而制备出任意形状和尺寸的氧化物单块, 并有无裂纹、透明性好等特点. 所以, 采用改进的溶胶-凝胶技术能高效地制备出高质量的氧化物单块.      

吸附转移溶出伏安法测定氟罗沙星注射液含量

氟罗沙星 (ｆｌｅｒｏｘａｃｉｎ ,ＦＬＲＸ)是一种抗菌谱广 ,杀菌力强的三氟喹诺酮类抗菌药[1] 。ＦＬＲＸ含量的测定方式主要有ＨＰＬＣ法[2 ,3] 、紫外分光光度法[3,4 ] 和荧光分光光度法[5] 。本文研究ＦＬＲＸ在不同支持电解质中的电化学行为 ,发现其在石墨电极表面有很强的吸附性 ,在一定的电位下富集几分钟 ,电极冲洗后在底液中扫描 ,仍有很大的峰电流。在此基础上建立了吸附转移溶出伏安法(ＡｄＴＳＶ) [6 ] 测定ＦＬＲＸ。方法的线性范围为 4～42 μｇ/ｍｌ,用于ＦＬＲＸ葡萄糖注射液中ＦＬＲＸ含量的测定 ,比其他方法灵敏、准确、…     

单柱离子色谱法同时分离分析9种多价金属阳离子的研究

近年来 ,对生物样品中的重金属和过渡金属离子的分析已引起人们的关注 .目前 ,对这些离子的分析方法主要有分光光度法 [1] 、原子吸收法 (AAS) [2 ] 、原子发射法 (AES) [3 ] 和高频电感偶合等离子体发射光谱 -质谱 (ICP- MS) [4 ] 等 .这些方法或操作步骤冗长费时 ,需要多种化     

原位氧化还原沉淀水热合成法制备LixMn2O4尖晶石

Li xMn2O4尖晶石是新一代的锂离子二次电池正极材料 [1], 其合成方法对材料的电化学性质影响很大[2].常规合成大多采用高温固相反应法, 此法具有反应温度高, 反应时间长, 容易产生缺陷和产物不纯净等缺点, 导致所合成的锂离子二次电池正极材料的性能较差. 目前用水热合成法制备电池正极材料Li xMn2O4尖晶石尚未见文献报道. 本文在常规水热合成法的基础上采用原位氧化还原沉淀水热合成法 [3]制备前驱物, 该法合成条件更温和, 而且使材料的综合性能得到了改善和提高.      

醇-水混合溶剂中双亲水嵌段共聚物对CaCO3粒子形貌的调控

合成形态、大小及结构受到人为调控的无机材料是现代材料科学的一个重要研究方向, 通过生物模拟方法可望实现各类有机添加剂及模板对无机物形貌与结构的有效调控[1,2]. 近年来, 一类新型的无机晶体生长调控剂--双亲水嵌段共聚物[3]已成功地用于多种无机粒子形貌的有效调控. 双亲水嵌段共聚物由2个与无机表面亲和作用不同的亲水链段构成, 在其水溶液中, 已实现了具有一系列特殊形貌的碳酸钙[4~6]、磷酸钙[7]及硫酸钡[8]粒子的生物模拟合成. 人们已陆续报道了在多种有机添加剂及模板作用下典型的生物矿物CaCO3的生物模拟合成[9,10]. 我们曾系统地研究了水溶液中双亲水嵌段共聚物对CaCO3粒子形貌的调控作用[6],最近又在双亲水嵌段共聚物-表面活性剂混合溶液中合成出具有新颖形貌(如空壳状等)的CaCO3粒子[11]. 本文考察了醇-水混合溶剂中双亲水嵌段共聚物对CaCO3粒子形貌的调控作用, 初步揭示了溶剂特性对该调控作用的显著影响.     

一种测定高浓度臭氧的新方法

测定空气中臭氧浓度的方法很多,常用的有直接紫外分光光度法[1]、间接紫外分光光度法[2]、碘量法[3]、电化学法[4]以及可见光度法等[5].但是上述方法大多仅适用于低浓度臭氧(<10 mg·m-3)的测定,可用于高浓度臭氧(>1 000 mg·m-3)测定的仅有直接紫外分光光度法和碘量法,但经比较发现两种方法的测定结果存在一定差异.     

十八烷基三甲基溴化铵-十四烷基溴化吡啶协同增敏邻二氮菲间接光度法测定药品中安乃近

正安乃近属于吡唑酮类解热镇痛药物,临床上广泛用于感冒、头痛、发热、肌肉关节痛、牙痛、痛经、风湿及类风湿关节痛等的治疗。目前,安乃近的测定方法主要有碘量法[1]、高效液相色谱法[2-3]、电化学分析法[4]、分光光度法[5]、红外光谱法[6]、荧光分析法[7]和化学发光法[8-9]等。碘量法操作较为繁琐和费时,紫外-分光光度法操作简便,但灵敏度较低。基于Fe3+的显色反应采用可见分光光度法测定安     

羧基化碳纳米管修饰的安培型葡萄糖传感器测定血液中葡萄糖

在临床医学、生物过程、食品工业中葡萄糖的分析测定一直都占有重要地位。葡萄糖的测定以分光光度法[1]和酶电极法[2]为主。光度法的灵敏度和准确度低,选择性差。第一代酶电极通常采用分子氧作为电子媒介体,但此法背景电流大,易受环境中分子氧浓度的影响。逐渐发展起来的第二代     

流动注射-化学发光法测定药物中异丙肾上腺素

异丙肾上腺素属于儿茶酚胺类药物,临床广泛用于支气管哮喘、心脏骤停、房室阻滞以及抗休克等方面的治疗.测定异丙肾上腺素的分析方法文献报道主要有高效液相色谱法[1,2]、荧光法[3]、分光光度法[4,5]和核磁共振波谱法[6]等.     

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%.     

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.     

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.     

N-Heterocyclic carbene-palladacyclic complexes: synthesis,characterization and their applications in the C-N coupling and α-arylation of ketones using aryl chlorides

N-Heterocyclic carbene-palladacyclic complexes 3 were successfully achieved in a one-pot procedure under mild conditions. The structure of 3a was unambiguously confirmed by X-ray single crystal diffraction and it was an active catalyst in the Buchwald-Hartwig amination and α-arylation of ketones even at very low catalyst loadings (0.01?mol%).     

Iodine-mediated oxidative Pictet-Spengler reaction using terminal alkyne as the 2-oxoaldehyde surrogate for the synthesis of 1-aroyl-β-carbolines and fused-nitrogen heterocycles

An efficient iodine-mediated oxidative Pictet-Spengler reaction in dimethyl sulphoxide (DMSO) using terminal alkynes as the 2-oxoaldehyde surrogate for the synthesis of aryl (9H-pyrido[3,4-b]indol-1-yl)methanones is described. The scope of the protocol includes the total synthesis of Fascaplysin, Eudistomins Y₁ and Y₂. The methodology is extended for preparing pyrrolo[1,2-a]-quinoxaline and indolo[1,5-a]quinoxaline derivatives. The utility of 1-aroyl-β-carbolines was demonstrated by performing palladium-catalyzed β-carboline directed ortho-C(sp2)-H functionalization of the phenyl ring with thiomethyl (SMe) group using DMSO as source and for accessing 4-aryl-canthin-6-ones.     

Facile synthesis of bicyclic 1-arylpyrazol-5-ones

In this Letter, we described a facile method for constructing fused bicyclic 1-arylpyrazol-5-one ring system. We employed various methylene-containing carboxylic acids as the substrates and proved that the pyrazolone ring closure requires activated methylene group in intermediate II. Accordingly, a series of structurally diversified, fused bicyclic 1-arylpyrazol-5-ones was prepared in moderate to high yields using the requisite substrates.     

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.