荧光分析法测定银杏酚酸

根据银杏酚酸在紫外光激发下能产生荧光的性质,建立了检测银杏酚酸的荧光分光光度法.以80%乙醇80℃回流8 h提取银杏外种皮,提取液经硅胶柱层析后得酚酸样品.以白果酸为标样,激发波长345 nm、发射波长420 nm测定银杏酚酸.线性回归方程为y=2.5024x+0.4152;线性范围为0.50～100 mg/L,相关系数r=0.9922,相对标准偏差2.6%;检出限0.11 mg/L.     

柱后衍生-荧光检测高效液相色谱法快速测定鲜牛奶中链霉素残留量

牛奶样品经磷酸溶液提取，提取液用苯磺酸阳离子交换柱和C18固相萃取柱净化，链霉素残留液用甲醇从C18固相萃取柱上洗脱，经旋转蒸发器减压蒸干，残渣用0．01mol／L庚烷磺酸钠溶液溶解，用柱后衍生-高效液相色谱荧光检测器在激发波长263nm和发射波长435nm测定．方法线性范围为0.01～0．10mg／kg；在0．01～0．10mg／kg范围，三个添加水平的回收率为78．3％～80．2％，变异系数(CV)为7．4％～12．4％，方法检出限为0．005mg／kg．     

银杏酸的分光光度法测定

建立了简便、快速、准确的银杏酸含量的分光光度分析方法。银杏酸粗提物经硅胶柱色谱一次预净化处理后 ,即可在 2 4 2nm或 310nm波长处测定银杏酸。线性回归方程分别为 :A =1.5 5× 10 -4+16 .36C(R =0 .999)或A =0 .0 31+9.0 8C(R =0 .997) ,两者的线性范围均为 6 .0～ 110mg/L。在 2 4 2nm和 310nm两个波长处测定的银杏酸含量都与HPLC法测定结果接近。实验测得了各银杏酸单体的摩尔吸光系数 ,其数值相近。该法简便、快速、准确 ,线性范围宽 ,最低可测至 5 .72mg/L ,可用于银杏酸的定量分析     

流动注射在线光化学荧光法测定药物制剂中叶酸的含量

叶酸接受紫外光照后可转变成最大激发波长为274nm、最大发射波长为466nm的强荧光化合物。对光化学反应介质进行考察，发现在NaC03—NaHC03缓冲体系中所产生的光化学荧光最强，据此建立了流动注射在线光化学荧光分析法。试样在水载流的携带下与PH9．5的Na2C03—NaHC03缓冲溶液汇流后，通过一个盘绕在6—W低压汞灯上的PTFE编结式光化学反应器。在反应器中所生成的荧光化合物直接通入荧光计的流通池测定荧光强度。在最佳条件下，动态线性范围可达0．001-4mg／L，检测限为0．16μg/L，采样速率达80／h，11次测定浓度分别为0．01和0．1mg／L的叶酸标准溶液所得到的RSD分别为1．0％和0．2％。所建立的方法已成功地用于片剂中叶酸含量的测定。     

氧氟沙星在胶束体系中的荧光特性及应用

研究发现十二烷基硫酸钠胶束对氧氟沙星荧光有明显的增敏作用，据此建立了直接测定人体尿液中氧氟沙星的等波长差同步荧光光谱法（△λ=90nm）。经样品测定，其线性范围为0．12－3．6mg/L，检出限为0．12mg/L，回收率为92．2％－97．8％，相对标准偏差为1．2％－2．7％。     

Cy-5标记脱氧核糖核酸荧光毛细分析法的研究

在荧光毛细分析法（FCA）的基础上开发了一种用于DNA快速检测的DNA-FCA法。在毛细管内表面将DNA探针固定化，制成荧光毛细生物反应器（DNA-CBR）。测定时，用DNA-CBR吸入含Cy-5标记的靶DNA样品液进行杂交反应，然后在646nm激发波长、664nm发射波长下进行荧光测定；Cy-5标记的靶DNA浓度在0．1～1．0μmol／L之间线性良好（y=139．73x＋39．613，r=0．9985）；RSD〈5．5％；检出限为0．17pmol，样品用量10μL；DNA-CBR能够重复使用6次。本方法可用于靶DNA的定性和定最检测。     

核壳纳米晶二硒化镉/硫化镉的合成及荧光法测定溶菌酶

以3-巯基丙酸为修饰剂,水相合成了具有发光效率高,光稳定性强等优良特性的CdSe2／CdS核壳纳米晶,粒径约为4nm,并将其成功用于溶菌酶的测定。在pH7．4的Na2HPO4-NaH2PO4缓冲溶液中,以365nm激发,体系在642nm处的荧光强度与溶菌酶的浓度呈线性关系,线性响应范围为0．5～8．0mg／L和8.0～32mg／L;线性方程分别为△F=0．97 2．21C(mg/L)和△F=12．20 0．70C(mg／L);检出限为0．20mg／L。将该方法应用于样品的测定,结果令人满意。     

同时测定头发中铁和铝含量的褶合光谱分析法

采用褶合光谱仪双组分定量分析系统自动进行褶合变换，不经分离同时测定头发中铁和铝的含量；铁和铝的线性范围分别为0～50mg／L和0～25mg／L，检出限为0．373和1．22mg／kg最佳褶合波长范围520～700nm，铁和铝的平均回收率均为99．9％和RSD为0．27％、0．97％；准确度和精密度较好。     

四溴荧光素荧光猝灭法测定司帕沙星

基于司帕沙星能够猝灭四溴荧光素的荧光且荧光猝灭程度与司帕沙星的量成正比,建立了一种测定微量司帕沙星的方法。在pH3．5的Clark—Lubs缓冲溶液中,四溴荧光素激发波长λex=485nm、发射波长λem=545nm,司帕沙星的质量浓度在0～2．0mg／L范围内符合比耳定律,方法检出限为42．7μg/L。已用于片剂及胶囊中司帕沙星的测定。6次平行测定回收率为93．8％～104．3％,相对标准偏差为1．1％～2．8％。     

液膜分离富集二甲氧基羟基苯基荧光酮荧光猝灭法测定微量钼的研究

研究了在pH5．0～6．4的HAC-NaAC缓冲介质中和CTMAB存在下,Mo(Ⅳ)对二甲氧基羟基苯基荧光酮(DMH-PF)的荧光猝灭效应,建立了荧光猝灭法测定微量Mo(Ⅳ)的新体系,DMH-PF最大激发波长为λex=514nm、最大发射波长为λem=547nm,DMH-PF与Mo(Ⅵ）形成1：2配合物使荧光猝灭,荧光猝灭量与Mo(Ⅵ)在0～0．072mg／L范围内呈线性关系,方法的检出限为0．0022mg／L,体系稳定,灵敏度高,采用液膜分离富集钼,可应用于合金钢和石墨中微量钼的测定。     

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.