β-D-核糖(RI)与一价、二价金属离子相互作用的理论研究

在HF和MP2水平用全电子(AE)和相对论有效芯势(RECP)方法研究了Ⅰa、Ⅰb、Ⅱa和Ⅱb族金属离子与β-D-核糖(RI)的相互作用.结果表明,RECP能可靠地用于重金属离子;二价金属离子(M2+)比一价金属离子(M+)更易使β-D-核糖(RI)变形;二价金属离子络合物(RI-M2+)比一价金属离子络合物(RI-M+)稳定.电荷布居分析的结果支持上述结论.     

过渡金属-二芳基希夫碱配位稳定常数的QSPR研究

金属离子与有机配体形成配合物的稳定性与金属离子的特性和有机配体的分子结构密切关系。为了探讨席夫碱与金属离子配位的稳定性规律,本文以二芳基希夫碱为模型配体化合物,选用部分过渡金属离子(Ni~(2+)、Mn~(2+)、Fe~(3+)、Cu~(2+)、Cr~(3+))为配位对象,将金属离子的特性参数和配体中取代基X的电子效应参数Hammett常数作为变量,对模型化合物与金属离子形成的配合物的稳定常数logβ_2进行定量构效关系研究,得到具有良好相关性的定量方程并通过实验验证了方程的可靠性。结果表明,金属离子的能量密度(X_P/P_(M~+))是影响配合物稳定性的主要因素;对同一金属离子,取代基的吸电子效应增强配合物的稳定性;而金属离子电荷Q和离子半径R需在一个合适的范围内,才利于配合物的稳定。     

β-D-核糖(RI)与一价、二价金属离子相互作用的理论研究

在HF和MP2水平用全电子(E)和相对论有效芯势(ECP)方法研究了Ⅰa、Ⅰb、Ⅱa和Ⅱb族金属离子与β-D-核糖(RI)的相互作用.结果表明,RECP能可靠地用于重金属离子;二价金属离子(2+)比一价金属离子(+)更易使β-D-核糖(RI)变形;二价金属离子络合物(I-M2+)比一价金属离子络合物(I-M+)稳定.电荷布居分析的结果支持上述结论.     

1,4,7-三氮杂环壬烷-N,N'',N"-三取代化合物的合成

本文报道母体化合物1,4,7-三氮杂环壬烷以及六种新的1,4,7-三氮杂环壬烷-N,N′,N″-三取代物(9～14)的合成方法,其中每个取代基的碳链均含有三个碳原子。它们都可以作为过渡金属离子Co~(2+)、Ni~(2+)、Cu~(2+)、Zn~(2+)、Co~(3+)、Fe~(3+)、Cr~(3+)的配体。     

1-(2-咪唑偶氮)-2-萘酚-4-磺酸的合成及其与钴显色反应的研究

近几年来,人们努力合成了许多试剂用于光度法测定钴,特别是偶联部分邻位含有—NH_2的吡啶偶氮类衍生物,对钴的光度法测定有较高的灵敏度和选择性,但仍然难于消除铁、铜、镍的干扰.我们合成的咪唑偶氮试剂1-(2-咪唑偶氮)-2-萘酚-4-磺酸(IANS),对其性质进行了研究,发现该试剂具有与钴显色后不被ED-TA破坏而常见其它金属离子均被破坏的特性,同时大量的EGTA、柠檬酸存在也不影响钴的显色反应,从而利用EGTA柠檬酸来有效地掩蔽和抑制具有较强络合能力的Fe~(3+)、Cu~(2+)、Ni~(2+)等金属离子,然后再用EDTA来破坏多余试剂与共存离子的有色络合物,并用EDTA在显色之前加入作为参比来消除有色背景的影响(此时钴不与试剂显色),使得方法选择性大大提高,2000倍的Fe~(3+)、Cu~(2+)、Ni~(2+)、Zn~(2+)及大量其它常见金属离子共存时不干扰测定.方法用于维生素B_(12),粗铜、铁矿、三氧化钨及合成冶金工业废水中微量钴的直接测定,结果满意.     

金属离子对4-氨基安替比林与牛血清白蛋白相互作用的影响

采用荧光法研究了金属离子Ca~(2+)、Zn~(2+)和Mg~(2+)存在下4-氨基安替比林(4-AAP)与牛血清白蛋白(BSA)的相互作用.结果表明,金属离子存在时,4-AAP对BSA的猝灭常数减小,但猝灭机制仍旧为静态猝灭,4-AAP与BSA之间的结合常数(KA)及结合位点数(n)均增大,分析认为,金属离子在二者的结合作用中起了"离子架桥"的作用.     

共沉淀分离富集偏最小二乘法在茶叶重金属测定中的应用

以铜试剂为共沉淀剂,在pH值为10.0的条件下,共沉淀分离富集茶叶中痕量金属离子Ni^(2+)、Pb^(2+)、Cd^(2+)和Cu^(2+),并分析了铜试剂与金属离子形成配合物的最佳沉淀条件.用4-(2-吡啶偶氮)间苯二酚(PAR)作为这4种重金属离子的显色剂进行分光光度测定,采用偏最小二乘-紫外可见光度法同时测定了四组分金属离子的模拟混合试样,并在茶叶中进行上述金属离子含量的测定.方法操作简便、结果可靠,对茶叶中重金属测定有一定实用价值.     

磷酸二甲酯阴离子(DMP~-)与一价、二价金属离子 相互作用的理论研究

在B3LYP、HF和MP2水平上运用全电子从头算(AE)和相对论有效实势(RECP)及6-311+G**和LanL2DZ基组计算Ⅰa、Ⅰb、Ⅱa和Ⅱb族金属离子与磷酸二甲酯阴离子(DMP-)的相互作用。 RECP用于除Li+、Be2+外所有的金属离子。 对Na+、K+、Cu+、Mg2+、Ca2+、Zn2+用AE和RECP 2种方法处理。 结果表明:RECP能可靠地用于重金属离子络合物; 二价金属离子络合物(DMP-—M2+)比一价金属离子络合物 (DMP-—M+)稳定;二价金属离子(M2+)可能比一价金属离子(M+)更易使多核苷酸折叠。     

金属离子对不同分子量腐殖酸生成三卤甲烷的影响

通过超滤手段将腐殖酸溶液分离成分子量为10K、10K-30K、30K-100K和100K的四部分。考察了金属离子K~+、Ca~(2+)、Mg~(2+)、Al~(3+)、Fe~(3+)对各分子量组分生成三卤甲烷(THMs)的影响,结果表明五种金属离子对腐殖酸各分子量组分三卤甲烷生成的影响不同。K~+使100K分子量组分生成的CHCl_3减少,Br-THMs增加;Ca~(2+)、Mg~(2+)的加入促进了分子量10K的组分生成THMs;Fe~(3+)、Al~(3+)表现出与Ca~(2+)、Mg~(2+)类似的结果。但各金属离子的加入都使得10K的分子量组分的THMs生成量降低。     

ZIF-8派生含氮多孔碳作为吸附剂固相萃取茶叶样品中6种痕量金属离子

以金属有机骨架化合物(ZIF-8)派生含氮纳米多孔碳(ZIF-8-NC)为固相萃取吸附剂,建立了火焰原子吸收光谱法测定茶叶样品中痕量Cu~(2+)、Pb~(2+)、Cd~(2+)、Cr~(3+)、Ni~(2+)、Co~(2+)的分析方法。ZIF-8-NC具有较大的比表面积(1239.8 m~2/g),既存在微孔又存在介孔,且材料表面存在可与金属离子配位的含氮基团,所以此材料对金属离子有很好的吸附性能。对影响金属离子富集效率的主要因素,如配位剂的种类、样品溶液pH值、样品体积、解吸剂种类、解吸剂体积等进行了优化。在优化条件下,6种金属离子的检出限为0.05~0.07μg/kg,线性相关系数在0.9988~0.9993范围内。各金属离子的加标回收率为76.8%~101%,RSD在5.9%~11.3%之间。本方法适用于复杂基质样品中金属离子的测定,具有操作简便、灵敏度高和环境友好的特点。     

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%.     

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.     

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.     

N-Heterocyclic carbene-palladacyclic complexes: synthesis,characterization and their applications in the C-N coupling and α-arylation of ketones using aryl chlorides

N-Heterocyclic carbene-palladacyclic complexes 3 were successfully achieved in a one-pot procedure under mild conditions. The structure of 3a was unambiguously confirmed by X-ray single crystal diffraction and it was an active catalyst in the Buchwald-Hartwig amination and α-arylation of ketones even at very low catalyst loadings (0.01?mol%).     

Iodine-mediated oxidative Pictet-Spengler reaction using terminal alkyne as the 2-oxoaldehyde surrogate for the synthesis of 1-aroyl-β-carbolines and fused-nitrogen heterocycles

An efficient iodine-mediated oxidative Pictet-Spengler reaction in dimethyl sulphoxide (DMSO) using terminal alkynes as the 2-oxoaldehyde surrogate for the synthesis of aryl (9H-pyrido[3,4-b]indol-1-yl)methanones is described. The scope of the protocol includes the total synthesis of Fascaplysin, Eudistomins Y₁ and Y₂. The methodology is extended for preparing pyrrolo[1,2-a]-quinoxaline and indolo[1,5-a]quinoxaline derivatives. The utility of 1-aroyl-β-carbolines was demonstrated by performing palladium-catalyzed β-carboline directed ortho-C(sp2)-H functionalization of the phenyl ring with thiomethyl (SMe) group using DMSO as source and for accessing 4-aryl-canthin-6-ones.     

Facile synthesis of bicyclic 1-arylpyrazol-5-ones

In this Letter, we described a facile method for constructing fused bicyclic 1-arylpyrazol-5-one ring system. We employed various methylene-containing carboxylic acids as the substrates and proved that the pyrazolone ring closure requires activated methylene group in intermediate II. Accordingly, a series of structurally diversified, fused bicyclic 1-arylpyrazol-5-ones was prepared in moderate to high yields using the requisite substrates.     

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.     

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.