同多钨酸-阿米卡星相互作用的共振瑞利散射光谱及其分析应用

在pH值为0.65～1.10的HCl-NaAc缓冲溶液中,同多钨酸(IPT)与阿米卡星(AMK)形成离子缔合物,能引起共振瑞利散射(RRS)显著增强,并产生新的RRS光谱,其最大散射峰位于340 nm,AMK质量浓度在1.0×10-9～8.0×10-8 g/mL范围内与散射增强程度呈线性关系. 建立了测定AMK的RRS新方法,检出限(3σ)为0.4×10-9 g/mL. 考察了体系的RRS和吸收光谱特征,优化了测定条件,考察了常见共存物质的干扰,方法具有良好的选择性. 用于人血清中AMK的测定,结果满意. 讨论了离子缔合反应和RRS增强机理.     

硫酸耐而蓝-肝素体系的共振瑞利散射光谱及其分析应用

提出了共振瑞利散射法(RRS)测定肝素的新方法.在pH为5.7～7.5的B-R缓冲溶液中,硫酸耐而蓝与肝素结合生成离子缔合物,使溶液共振瑞利散射(RRS)增强,其最大散射峰位于738 nm,另在536、 395、 305 nm有3个较弱的散射峰.肝素的质量浓度在0.01～0.5 mg/L范围内,与RRS强度有良好的线性关系,对肝素的检出限(3σ)达0.42 μg/L.研究了适宜的反应条件和影响因素,该方法用于肝素钠注射液的测定,回收率为98.6%～102.5%.     

苯唑西林与维多利亚蓝B的共振瑞利散射光谱及应用

在pH 9.54时,苯唑西林的水解产物与维多利亚蓝B形成紫红色的离子缔合物,使体系的共振瑞利散射(RRS)急剧增强并产生新的RRS光谱,在最大散射波长366 nm处,苯唑西林的浓度在0~6.0μg/mL范围内与散射强度(△IRRS)成良好的线性关系,据此建立了测定苯唑西林的共振瑞利散射法,检出限为0.039μg/mL。该方法可用于苯唑西林药物及人体尿液中苯唑西林含量的测定。     

甲基蓝与血红蛋白相互作用的共振瑞利散射光谱研究及小分子的影响

在弱酸性条件下,甲基蓝(MB)可以通过静电和疏水作用聚集到血红蛋白(Hb)上并形成离子缔合物,不仅使得吸收光谱发生变化,而且使得共振瑞利散射增强。据此发展了一种测定Hb的RRS便捷方法,其线性范围和检出限分别为0.2~20μg/mL和0.012μg/mL。与RRS法相比,分光光度法的线性范围和检出限分别为8~60μg/mL和0.688μg/mL(344 nm),5~60μg/mL和0.398μg/mL(408 nm)。此RRS法可用于尿样中Hb的痕量检测。实验考察了体系的吸收、散射光谱性质和最佳聚合条件,并在最佳条件下研究了分析参数及作用机理。并初步讨论了有机小分子对体系的影响,结果表明分子间氢键是主要作用力不容忽视。     

固绿FCF共振瑞利散射法测定食品中的Al(Ⅲ)

在酸性Tris-HCl缓冲介质中,溴化十六烷基三甲基铵(CTMAB)增敏固绿FCF,与Al(Ⅲ)结合生成三元络合物使共振瑞利散射(RRS)显著增强并产生新的RRS光谱,其最大共振瑞利散射峰位于330 nm,RRS增强程度(△IRRS)与Al(Ⅲ)的质量浓度在0.02～0.49 mg/L成正比,方法有很高的灵敏度,检出限是0.0096 mg/L.方法用于面制食品中Al(Ⅲ)的测定,结果满意.     

α1受体阻滞剂类药物与某些同多酸根的共振瑞利散射光谱及其分析应用

在酸性介质中,钼酸根、钨酸根等同多酸根与盐酸哌唑嗪(PRH)和甲磺酸多沙唑嗪(Dox)等α1受体阻滞剂反应形成离子缔合物时,会导致体系的共振瑞利散射(RRS)显著增强并出现新的RRS光谱,最大散射峰分别位于367 nm(钼酸根体系)和290 nm(钨酸根体系)。 PRH和Dox与同多酸根的反应产物具有相似的RRS光谱特征。 其反应的适宜酸度分别为pH值2.1～2.3(钼酸根-PRH体系)和pH值3.1～3.3(钨酸根-PRH体系)。 在一定浓度范围内,不同的反应体系RRS强度增强程度与药物浓度成正比,均可用于痕量药物的测定。 反应具有很高的灵敏度,不同同多酸对PRH的检出限(3σ/s)分别为4.76 μg/L(钼酸根-PRH体系)和9.88 μg/L(钨酸根-PRH体系)。 方法也具有较好的选择性,用于片剂和人尿液中的α1受体阻滞剂的测定,结果满意。 此外,本文还应用计算化学软件Gaussview3.07和Gaussian03W,采用密度泛函法,在B3LYP/6-31G基组水平上计算了盐酸哌唑嗪的电荷分布,对反应机理和RRS增强的原因进行了讨论。     

痕量铜蓝蛋白的免疫纳米金催化-氧化亚铜微粒共振散射光谱分析

用15 nm的纳米金标记羊抗人铜蓝蛋白抗体(GCP)可获得铜蓝蛋白(CP)纳米金探针(AuGCP). 在pH 7.8柠檬酸-磷酸氢二钠缓冲溶液中, CP与AuGCP发生特异性结合生成胶体金免疫复合物. 离心分离后, 离心液中的AuGCP可作为酒石酸铜(C4H4O6Cu)-葡萄糖反应体系的催化剂, 生成的Cu2O微粒在620 nm处有一共振散射峰. 在选定条件下, 620 nm处共振散射信号降低值△I620 nm与铜蓝蛋白浓度cCP在0.18～45 ng/mL范围内存在良好线性关系, 回归方程为 ΔI620 nm＝2.27cCP＋5.05, 相关系数为0.9940, 检出限为0.14 ng/mL. 该法用于人血清中铜蓝蛋白的检测, 结果满意.     

曲利本蓝共振瑞利散射法测定苹果中钙北大核心CSCD

采用曲利本蓝共振瑞利散射法测定苹果中钙的含量。在pH 6.50的三羟甲基氨基甲烷-盐酸缓冲溶液中,曲利本蓝与钙(Ⅱ)及阳离子表面活性剂十六烷基三甲基溴化铵反应生成一种三元离子缔合物,使体系的共振瑞利散射(RRS)信号显著增强,最大共振瑞利散射峰位于波长348nm处。优化的试验条件如下:(1) pH 6.50的三羟甲基氨基甲烷-盐酸缓冲溶液的用量为2.00mL;(2)1.0×10^(-4) mol·L^(-1)曲利本蓝溶液的用量为2.50mL;(3) 4.00×102 mg·L^(-1)十六烷基三甲基溴化铵溶液的用量为0.40 mL;(4)反应时间为25 min。钙的质量浓度在0.007 0～0.080 0mg·L^(-1)内与体系的RRS增强程度(ΔIRRS)呈线性关系,检出限(3s/k)为0.001 3mg·L^(-1)。方法用于苹果样品的分析,加标回收率为98.3%～102%,测定值的相对标准偏差(n=6)为1.8%～2.3%。     

硫酸皮肤素的共振瑞利散射法测定

研究了硫酸皮肤素对十六烷基三甲基溴化铵(CTMAB)发生缔合反应的条件、共振瑞利散射特征.结果表明,在pH 5.8的BR缓冲溶液中,硫酸皮肤素能与CTMAB形成离子缔合物,使共振瑞利散射RRS急剧增强并产生新的RRS光谱.硫酸皮肤素浓度在0.04～4.0μg/mL之间与散射强度呈线性关系,方法检出限(3σ)为13 ng/mL,并以CTMAB体系为例研究了共存物质的影响,表明方法选择性好.     

镉(Ⅱ)-邻菲罗啉-曙红Y体系的共振光散射光谱研究及应用

在pH=4.5的HAc-NaAc介质中,Cd2+,phen及EY三者能通过静电引力和疏水作用力生成三元离子缔合物[Cd(phen)3]EY,其共振瑞利散射和共振非线性散射显著增强,最大的光谱散射波长分别位于RRS(375nm),SOS(732nm)及FDS(372nm)处.其散射增强程度(ΔI)与Cd2+浓度在一定范围内呈良好的线性关系,检出限分别为0.16(RRS),0.28(SOS)和0.10μg/L(FDS).采用分子荧光光谱和紫外-可见吸收光谱、透射电镜对该缔合物的共振瑞利散射及共振非线性散射光谱进行了详细研究,并对共振增强原因及反应机理进行了探讨.在优化的实验条件下,该方法用于环境水样中Cd2+的检测与国标方法无显著性差异,效果令人满意.     

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.     

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.     

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.     

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.     

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.     

Microwave-assisted copper-catalyzed stereoselective ring expansion of three-membered heterocycles with α-diazo-β-dicarbonyl compounds

Microwave-assisted copper-catalyzed ring expansions of three-membered heterocycles with α-diazo-β-dicarbonyl compounds were investigated. Thiiranes generated 3-acyl-5,6-dihydro-1,4-oxathiines in the presence of copper sulfate and trans-3-acyl-5,6-dihydro-1,4-oxathiines as stereospecific products for 1,2-disubstituted cis-thiiranes through an intramolecular S_N2 process. Oxiranes gave rise to 2-acyl-5,6-dihydro-1,4-dioxines under the catalysis of copper hexafluoroacetylacetonate and cis-3-acyl-5,6-dihydro-1,4-dioxines as stereospecific products for 1,2-disubstituted cis-oxiranes via an intimate ion-pair mechanism. The current method provides a direct and simple strategy in efficient preparation of 3-acyl-5,6-dihydro-1,4-oxathiines and 2-acyl-5,6-dihydro-1,4-dioxines, important agents in medicinal and agricultural chemistry, from readily available thiiranes and oxiranes, respectively.     

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.     

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.