磁场效应下分子发光行为的研究：Ⅱ.磁场效应—偏振—共振同步荧光法

本文叙述了新建立的磁场效应－偏振－共振同步荧光法。利用偏振技术抑制掉溶剂散射光的９９％，利用ＭＦＥｓ抑制熔剂９８％的散射光波动。将偏振、ＭＦＥｓ技术与共振同步荧光法结合为一体时，其检测限分别为０．０６８ｎｇ／ｍｌ，０．０５ｎｇ／ｍｌ。优于一般的△λ值较小（０－５ｎｍ）的同步荧光法和偏振－同步荧光法。     

磁效应—偏振—共振同步荧光法同时测定痕量Qu,蒽,Bei

偏振－同步荧光法能有效地抑制同步扫描过程中散射光总水平的影响，外加磁场效应能有效地抑制散射光的波动。二者结合起来用于同时测定Ｑｕ、蒽、Ｂｅｉ，Ｂｅｉ检测限改善近６７倍，该法相对标准偏差小于２．７％。     

偏振-导数-同步荧光法同时测定痕量芴、苊、蒽、苝

本文采取偏振-导数-同步扫描联用技术同时测定痕量的芴、苊、蒽和多环芳烃。实验结果表明,多种荧光分析技术联用可以弥补单独应用其中一种或两种技术的不足,扬长避短,大大改善此类化合物的检测限。该方法同时测定上述四种组份,检测限依次为0.089、2.4、0.045、0.0096 ng/mL,相对标准偏差不大于 5％。     

高效液相色谱分离偏振同步荧光同时检测环境样品中的茐、苊、 、苯并[a]荧蒽

以高效液相色谱（ＨＰＬＣ）为分离手段，偏振同步荧光法为检测手段，实现了环境样 品中茐、苊、　、苯并[a]荧蒽（Ｂ［ａ］Ａ）的同时检测。所建方法对茐、苊、　、Ｂ[a]Ａ的检测限分 别为 ０．０３９，０．０４６，０．０１６和 ０．０４２（ｍｇ／Ｌ）。该法用于大气、海洋沉积物中的茐、苊、　、Ｂ[a] Ａ的同时测定，结果满意。     

痕量芴、苊、蒽和(艹北)的同时偏振-同步荧光分析

本文建立了痕量芴、苊、蒽和(艹北)的同时偏振-同步荧光分析法.该法能有效地抑制同步扫描过程中散射光的影响,从而提高测定的灵敏度.芴、苊、蒽和(艹北)的检测限分别为(ng/mL):1.1、10.0、1.8、0.26,相对标准偏差不大于4.2％.     

偏振—导数—同步荧光法同时测定痕量芴,苊,蒽,北

本文采取偏振－导数－同步扫描联用技术同时测定痕量的芴、苊、恩和北多环芳烃。实验结果表明，多种荧光分析技术联用可以弥补单独应用其中一种或两种技术的不足，扬长避短，大大改善此类化合物的检测限。该方法同时测定上述四种组份，检测限依次为０．０８９、２．４、０．０４５、０．００９６ｎｇ／ｍＬ，相对标准偏差不大于５％。     

二阶导数-同步荧光法同时测定微量维生素B_1,B_2和烟酰胺

建立了二阶导数-同步荧光法同时测定微量维生素B1,B2和烟酰胺含量的方法.在最佳实验条件下,维生素B1,B2和烟酰胺的检测限分别为2.1,2.6,和2.8 ng/mL,相对标准偏差为1.5%～4.9%,加标回收率为92%～105%.该方法可用于样品中微量维生素的测定.     

荧光偏振发射平台法及其应用

本文从原理上叙述荧光偏振发射平台法,并用荧光单体-单体混合物及单体-聚合物体系进行验证试验。前者如荧光黄-罗丹明S(或四碘荧光素、或罗丹明B),后者如罗丹明6G-罗丹明6G聚合物体系,结果满意。     

动力学荧光法测定药物、水果、蔬菜中的维生素C

提出了动力学荧光法测定维生素C的新方法。该法基于脱氢抗坏血酸(DAsA)对还原型罗丹明B在钒(Ⅴ)催化下自动氧化的活化作用。在pH为3.7的HAc-NaAc缓冲溶液中,还原型罗丹明B在钒(Ⅴ)催化下的氧化反应速度与DAsA的浓度成正比,采用固定时间法,测定在λ_(ex)=554 nm,λ_(em)=580 nm时的荧光强度。DAsA的线性范围为0～4.0×10~(-7)mol/L, 检测限4.0×10~(-9)mol/L。用该法测定药物、水果、蔬菜中维生素C含量,回收率在93%～108%之间。     

导数-可变角同步荧光法用于1-萘酚和2-萘酚的同时测定

同步扫描和导数光谱法是两类很有用的荧光分析新技术。固定波长或恒能量同步荧光法和导数技术的结合可进一步提高光谱分辨率和排除基体干扰。本文将导数技术和可变角同步荧光法结合起来,用于1-萘酚和2-萘酚的同时分析,效果良好。研究表明,导数-可变角同步荧光法可望发展为荧光分析复杂样品的新技术。     

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.