伞形花内酯的荧光量子产率与电离常数

研究了伞形花内酯在不同酸度下的荧光光谱,测量了荧光量子产率和电离常数。伞形花内酯有2种荧光型体,分别存在于弱酸性和弱碱性溶液中。在pH 3～6的溶液中,伞形花内酯以中性分子型体存在,最大激发波长λex=325nm,最大发射波长λem=455nm;在pH 9～10.5的溶液中,伞形花内酯主要以阴离子型体存在,λex/λe...     

东莨菪内酯的药理活性及药代动力学研究进展

东莨菪内酯是一种香豆素类化合物,具有抗肿瘤、抗炎、降血糖、降血压、抗神经退行性疾病等多种药理活性.药代动力学方面,东莨菪内酯具有吸收快,组织分布广等特点.本文总结了近年来东莨菪内酯的药理作用及药代动力学的研究进展,以期为其深入研究和开发利用提供参考.     

荧光光谱法检测蜂蜜含量

采用荧光光谱法对蜂蜜含量进行检测,首先将蜂蜜配制成不同浓度的水溶液,然后采用稳态荧光光谱仪采集不同浓度的蜂蜜溶液的荧光光谱,通过数据处理软件分析,得到蜂蜜溶液浓度与其荧光光谱的关系。蜂蜜溶液的最佳激发波长为283nm,蜂蜜溶液最大发射波长为333nm,最大发射波长处的荧光强度与蜂蜜溶液的浓度有较好的线性关系。通过该方法得到的模型函数决定系数为0.97,预测准确率在90.4%~100.0%之间。     

应用二阶校正算法-荧光分光光度法同时测定血浆中诺氟沙星和左氧氟沙星

应用三维荧光技术,结合化学计量学中的二阶校正算法,在诺氟沙星和左氧氟沙星荧光光谱严重重叠,以及干扰物质存在下对血浆中两种喹诺酮类药物进行了同时定量分析。三维荧光激发波长范围265～510nm,发射波长范围300～650 nm。交替不对称三线性分解(AATLD)算法解析得到的诺氟沙星和左氧氟沙星的平均回收率分别为96.9%和103.9%。方法前处理简单、不需预先分离、可以快速定量分析血浆中光谱相互干扰的待测药物的含量。     

高速逆流色谱法分离制备华山参中东莨菪内酯

采用高速逆流色谱法从华山参乙醇提取液的氯仿萃取物中分离得到了一种高纯度的香豆素类化合物,东莨菪内酯．所用体系为正己烷：乙酸乙酯：甲醇：水（体积比3：5：3：5）,上相做固定相,下相做流动相．分离所得东莨菪内酯的纯度经高效液相色谱检测达到97％．该方法操作简单、方便、快捷,可用于华山参中香豆素类化合物——东莨菪内酯的分离制备．     

司帕沙星-铕荧光体系的研究及其在分析中的应用

研究了司帕沙星-铕体系的荧光光谱特性,在体系的最大激发波长(322 nm)和最大发射波长(616 nm)下,确定了铕的最佳浓度和体系的pH值.在最佳条件下,司帕沙星浓度在2～10 mg/L的范围内与体系的荧光强度呈线性关系,检测限为0.08 mg/L.对样品进行加标回收试验,回收率为96.5%～102.0%,RSD为2.5%～3.1%.利用该法测定了司帕沙星片剂中的司帕沙星含量.     

铽-环丙沙星稀土敏化荧光猝灭法测定叶酸

在pH=5.0的醋酸-醋酸钠缓冲溶液中,铽(与环丙沙星反应形成1∶2的稳定络合物,其最佳激发、发射波长分别为λex=330nm、λem=545nm。在该反应体系中加入适量叶酸溶液,铽(与环丙沙星络合物的激发、发射波长位置不变,但荧光强度下降。利用这一现象,建立了简单、快速、灵敏的测定叶酸的荧光分析方法。该方法保持了叶酸结构的完整性,叶酸浓度在22~880μg/L范围内符合线性关系;方法检出限为7.8μg/L。用于片剂及胶囊中叶酸含量的测定,结果满意。6次平行测定该方法回收率为93.7%~107.9%,相对标准偏差为0.38%~2.8%。     

水杨基荧光酮-乳化剂-羟丙基-β-环糊精荧光猝灭法测定微量铜

建立了在羟丙基-β-环糊精(HP-β-CD)和乳化剂(OP)存在下,在NaAc-HAc介质中,以水杨基荧光酮(SAF)作为荧光试剂,用荧光猝灭法测定微量铜的新方法;最大激发波长和发射波长分别为365 nm和539 nm,Cu2+含量在0~0.20μg/mL范围内符合线性关系,方法检出限为1.0μg/L。已用于人发和茶叶中铜含量的测定。     

多维数据解析联用三维荧光光谱检测污水中酚类污染物残留

应用三维荧光结合化学计量学中的二阶校正方法对城市污水中的苯酚、对苯二酚和邻苯二酚进行了定量分析研究.选用β-环糊精作为荧光增敏剂,三维荧光激发波长范围205～450 nm,发射波长范围215～320 nm.通过自加权交替三线性分解(SWATLD)解析得到的苯酚的平均回收率为95.84±0.41％,对苯二酚的平均回收率为102.31±0.44％,邻苯二酚的平均回收率为100.27±0.43％.该方法前处理简单,不需预先分离,可以快速定量分析污水中光谱相互干扰的多个待测组分的含量.     

茶多酚的三维荧光光谱特征

应用三维荧光光谱技术,研究了茶多酚溶液的三维荧光光谱特征,以及不同浓度、pH值、缓冲液、有机溶剂等因素对可见光区荧光的影响。研究表明:茶多酚溶液的三维光谱可分为三区(以激发波长/发射波长λex/λem表示):Ⅰ区:210 nm/315 nm、270 nm/315 nm;Ⅱ区:335 nm/395 nm;Ⅲ区:490 nm/515 nm。随浓度增大,茶多酚荧光的激发、发射波长逐渐红移。茶多酚浓度3 mg/mL,溶液pH 7.55条件下可灵敏检测Ⅲ区可见光区荧光;常用缓冲溶液对Ⅲ区荧光均有不同程度的增敏效果;质子化溶剂有利于Ⅲ区的荧光发射。据此可为茶多酚的快速、无损分析检测及应用开发提供新的思路。     

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.     

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.     

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.     

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.