荷移光度法测定依诺沙星

依诺沙星与茜素红在水-乙醇介质中发生电荷转移反应,其中依诺沙星是电子给予体,茜素红是电子接受体,依据此荷移反应建立了一种快速测定依诺沙星的荷移分光光度法.荷移络合物在 546 nm 波长处有最大吸收,表观摩尔吸光率为 8.04×103L·mol-1·cm-1,相关系数为0.999 9.该络合物的组成为 1:1,表观稳定常数为 2.84×104.依诺沙星的质量浓度在 0～40 mg·L-1范围内服从比耳定律.当依诺沙星的质量浓度为 20 mg·L-1时,测定结果的相对标准偏差(n=6)为 1.2%,回收率在 99%以上.测定了依诺沙星制剂中有效成分的含量,与文献[1]方法结果基本吻合.     

衍生化分光光度法测定依诺沙星和诺氟沙星

碱性介质中,依诺沙星和诺氟沙星均能与1,2-萘醌-4-磺酸钠(NQS)发生反应而生成橙红色的物质,并使最大吸收波长发生大幅度的红移。据此建立了测定这两种药物的分光光度新方法。依诺沙星和诺氟沙星的浓度分别在0.8~16 mg.L-1和0.9~18 mg.L-1范围内符合比耳定律;衍生物在454 nm和462 nm波长处的表观摩尔吸光系数分别为1.86×104L.mol-1.cm-1和1.93×104L.mol-1.cm-1;两种药物的检出限分别为0.13 mg.L-1和0.19 mg.L-1。该方法已成功用于药物制剂中依诺沙星和诺氟沙星含量的测定。其回收率为96.63%~99.55%,相对标准偏差为0.56%~0.89%。     

铽-依诺沙星络合物与辅酶Ⅱ(NADP)的相互作用研究及其分析应用

实验发现,在pH=7.80最佳酸度下,辅酶Ⅱ(NADP)能使依诺沙星-Tb3 位于545 nm处的特征荧光强度显著增强。根据这一性质,以依诺沙星-Tb3 作为荧光探针,建立了一种利用荧光光谱测量NADP的新方法,线性范围为6.66×10-7~3.33×10-5mol.L-1,检出限为5.60×10-8mol.L-1。该法灵敏度高,选择性好,干扰少,操作简单,用于合成样中NADP的测定,结果满意。     

铽-依诺沙星-邻菲啰啉络合物荧光猝灭法测定ATP

研究了铽-依诺沙星(enx)-邻菲啰啉(phen)络合物作为荧光探针,荧光猝灭法测定三磷酸腺苷二钠(ATP)的新方法。试验结果表明,在pH 6.7乙酸-乙酸钠缓冲溶液中,eλx=340 nm,eλm=545 nm时,荧光强度的减小值与ATP的浓度在0.1~10.0 mg.L-1范围内呈线性关系,检出限为0.02 mg.L-1。该体系直接用于三磷酸腺苷二钠片剂中ATP含量的测定,标准加入回收率为98.4%~104.0%,相对标准偏差为2.34%。     

铽-沙拉沙星荧光光度法测定沙拉沙星含量

在pH 5.9醋酸-醋酸钠缓冲溶液中,Tb3+与沙拉沙星反应形成1:2的稳定络合物,发出Tb3+特征荧光.Tb3+在激发波长335 nm,发射波长545 nm处的特征荧光强度与沙拉沙星含量成正比,沙拉沙星溶液浓度在0.05～0.65 mg/L范围内符合线性关系,方法检出限为0.72μg/L.该方法用于片剂中盐酸沙拉沙星含量的测定,6次平行测定该方法回收率为94.8%～104.3%,相对标准偏差为1.5%～3.8%.     

流动注射-鲁米诺-铁氰化钾反应体系化学发光法测定依诺沙星

试验发现依诺沙星对鲁米诺与铁氰化钾之间的化学发光反应具有显著的增敏作用,而且当依诺沙星浓度在2.0×10-8～2.0×10-5mol·L-1范围内,与相应的化学发光增强信号值(△I)之间呈线性关系,其检出限(3S)为5.7×10-9mol·L-1,取1.0 × 10-6mol·L-1依诺沙星按试验方法测定11次,算得其相对标准偏差为1.75%.结合应用流动注射技术,提出了流动注射-化学发光法(FI-CL)测定药片中依诺沙星的方法,应用此方法分析了3个依诺沙星片剂试样,所测得的结果与其标示值相符.按标准加入法作了回收率试验,所得结果在96.7%～103.0%之间.     

基于银纳米粒子的荧光增强法测定依诺沙星

以NaBH4为还原剂,聚乙烯吡咯烷酮为稳定剂,室温下制备了银纳米粒子(AgNPs),用荧光、紫外光谱等进行表征。依诺沙星与聚乙烯吡咯烷酮纳米银相互作用后,使AgNPs荧光增强,由此建立测定依诺沙星的新方法。在最佳实验条件下,体系的荧光强度之比(F/F_0)与依诺沙星浓度呈良好线性关系,线性范围为1.0×10~(-7)~1.0×10~(-5) mol/L,检出限为8.0×10~(-8) mol/L。该方法用于实际样品中依诺沙星含量的测定,回收率为94.5%~99.8%。     

铽-洛美沙星体系的荧光性质研究及应用

在pH 6.0~6.5的乙酸-乙酸钠缓冲溶液中,铽(Ⅲ)与洛美沙星生成具有荧光特性的络合物,其激发波长在330 nm处,发射波长在546 nm处,相对荧光强度与洛美沙星质量浓度之间,在0.01~0.43 mg.L-1范围内呈线性关系,检出限为0.001 mg.L-1。方法应用于洛美沙星胶囊中含量的测定,测得回收率在96.5%~102.0%之间,测定结果的相对标准偏差(n=5)在1.5%~2.1%之间。     

荧光光度法快速测定辛硫磷残留量

在pH 6.6的磷酸二氢钾-磷酸氢二钠缓冲溶液中,达旦黄(TY)与一定浓度的吐温-80发生荧光增强反应,当在该体系中加入辛硫磷农药后,在激发波长412 nm,发射波长460 nm处荧光强度明显降低,且降低程度与辛硫磷的加入量呈线性关系,方法的线性范围在0.72 mg.L-1以内,检出限(3S/N)为0.031 mg.L-1。据此建立了测定辛硫磷残留量的方法,该方法用于小米和土壤中辛硫磷残留测定,两者的平均回收率依次为93.5%和97.7%,测定值的相对标准偏差(n=5)分别为1.7%和2.6%。     

同步扫描-双波长荧光分光光度法同时测定三种儿茶酚胺类神经递质

提出了用同步扫描-双波长荧光分光光度法同时测定肾上腺素(EP)、去甲肾上腺素素(NEP)和多巴胺(DA)3种儿茶酚胺类神经递质.试验表明:荧光检测宜选定发射波长(λen)与激发波长(λex)的波长差为70 nm(△λ=λem-λex)的条件下进行同步扫描.在λem为385.0 nm时DA的荧光信号不受EP和NEP的干扰,而EP和NEP相互的干扰,采用双波长荧光检测模式可消除.选择测定NEP的波长对为470.0 nm(λem,1)和531.8 nm(λem,2),测定EP的波长对为500.0 nm(λ'em,1)和445.6 nm(λ'em,2).测得荧光强度与3种儿茶酚胺浓度在320 μg·L-1(EP),640 μg·L-1(NEP)及160μg·L-1(DA)内呈线性关系,检出限(3σ/k)依次为0.20,0.97,0.73 μg·L-1.     

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%.     

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.     

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.     

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.