甲基紫6B与核酸作用的共振光散射光谱及其分析应用

将三苯甲烷类碱性染料甲基紫6B用于核酸的共振光散射测定。在pH10.8的缓冲液中 ,核酸的加入导致甲基紫6B在386nm处共振光散射的增强 ,其强度与核酸的质量浓度呈线性关系 ,据此建立了一种测定核酸的共振光散射法。fsDNA与 yRNA的线性范围分别为0.083～1.0mg·L -1和0.076～0.8mg·L -1,检出限分别为82.6和75.3μg·L -1。将该法用于混合样品中核酸的测定 ,结果令人满意。     

甲基紫6B共振光散射法测定脱氧核糖核酸

基于甲基紫6B与脱氧核糖核酸在酸性条件下共振光散射的增强效应,建立了测定DNA的共振光散射法。在pH值为2．0～3．0的三羟甲基氨基甲烷一盐酸缓冲溶液中,甲基紫6B与fsDNA、ctDNA分子作用后共振光散射增强,其强度增加值与DNA的浓度呈线性关系,线性范围分别为0～1．0、0～1．5mg／L,相关系数分别为0．9993、0．9997,检出限分别为15．3、12．2ug／L,用于DNA合成样品的测定,测定结果的精密度、准确度较高。     

La-phen-邻苯二甲酸混配化合物与DNA作用的共振光散射光谱及分析应用

本文研究了镧的混配物LaL1L2·3H2O(L1为邻苯二甲酸,L2为邻菲咯啉)与DNA作用的共振光散射光谱。加入DNA后,在pH6.5～7.5的范围内,LaL1L2·3H2O在DNA分子表面发生长距离自组装,在470nm处产生了增强的共振光散射峰,其发光强度与DNA的浓度成线性关系。该方法的线性范围为23～1870ng·mL-1,检出限(3σ)为23ng·mL-1,可用于测定纳克级的DNA。     

两性离子表面活性剂作为共振光散射探针测定脱氧核糖核酸

将两性离子表面活性剂用于DNA的共振光散射测定。在pH值为7．96～9．40较宽的范围内,DNA与椰油酰胺丙基-2-羟基-3-磺基丙基甜菜碱(HSB)在392nm处有稳定的共振光散射增强,其强度与DNA浓度呈线性关系,建立了一种测定DNA的新方法。线性范围为0．02—4．25mg／L;检出限达1．5μg／L。该法简便、快速,用于合成样品中DNA的测定,重现性好,结果满意。同时探讨了有关机理。     

花菁-脱氧核糖核酸的共振光散射光谱及其分析应用

研究了一种苯并噻唑阳离子花菁与脱氧核糖核酸(DNA)作用的共振光散射光谱,在pH 6.0的六次甲基四胺-HCl缓冲介质中,痕量DNA的加入使花菁在590nm的共振光散射强度显著增强。在最佳实验条件下,增强的共振光散射强度与DNA浓度具有良好的线性关系,据此建立了一种测定DNA的共振光散射光谱法。方法的线性范围为:小牛胸腺DNA(CT DNA),0～20μg/mL,鱼精子DNA(FS DNA),0～15μg/mL;检出限分别为0.005μg/mL和0.008μg/mL。该方法已用于合成样品中DNA的测定。     

溴代十六烷基三甲基铵敏化吡罗红B-核酸作用的共振光散射增强法测定核酸

基于表面活性剂溴代十六烷基三甲基铵（CTMAB）对吡罗红B-核酸作用的共振光散射增强效应有敏化作用,建立了一种高灵敏测定核酸的新方法。在pH7．4时,吡罗红B在328nm处的共振光散射的增强与核酸浓度有良好的线性关系。在最佳实验条件下,对小牛胸腺DNA（ct-DNA）、鲱鱼精DNA（fs-DNA）、酵母RNA（yeast—RNA）测定的线性范围分别为0．0～1．2mg／L、0．0～0．8mg／L和0．04～1．4mg／L。检出限分别为6．1μg／L、11．2μg／L和8．6μg／L。该法简便、快捷、重现性好,对合成样品进行了测定,结果令人满意。     

天青Ⅰ共振光散射法测定DNA

基于脱氧核糖核酸(DNA)对混合有机染料天青Ⅰ的共振光散射增强效应,拟定了一种测定DNA的共振光散射法。在pH9.5～10.5的范围内,天青Ⅰ在299、355、400、570、630nm附近均有较弱的共振光散射信号,随着DNA的加入,共振光散射信号大大增强。在355nm处,其散射光增强强度与DNA质量浓度呈线性关系。其线性回归方程为ΔI=-96.62 606.6ρ,线性范围为0 20～0.60μg mL,相关系数r=0.9998,检出限为11.2μg L。该方法可应用于合成样品中DNA的测定。     

CTMAB与DNA相互作用的共振光散射研究及其应用

应用共振光散射(resonance light scattering,RLS)光谱法对十六烷基三甲基溴化胺(CTMAB)与小牛胸腺DNA(ct DNA)相互作用进行了研究,并研究了该体系的最佳反应条件.发现CTMAB可提高ct DNA的RLS信号.采用该方法对合成样品进行了分析测定,回收率和RSD分别为94.8%~97.3%和1.1%~2.5%,检出限为9.3μg/L.     

十六烷基溴化吡啶与脱氧核糖核酸作用的共振光散射光谱及其分析应用

在碱性条件下，十六烷基溴化吡啶(CPB)与脱氧核糖核酸(DNA)共存时，体系产生较强的共振光散射，其强度与DNA浓度呈线性关系，据此提出了基于阳离子表面活性剂的共振光散射法定量测定DNA。在最佳实验条件下，测得小牛胸腺DNA(ctDNA)和鱼精子DNA(fsDNA)的线性范围分别为0．2-2．0mg／L和0．2—1．25mg／L，检出限分别为0．07mg／L和0．05mg／L。该方法已应用于合成样品及实际样品中DNA含量的测定。     

DNA对Ru(bpy)_2(dppx)~(2+)-SDS体系共振光散射的猝灭作用及其应用

研究了Ru(bpy)2(dppx)2+-SDS-DNA(bpy=2,2′-联吡啶,dppx=7,8-二甲基-吡啶并[3,2-a:2′,3′-c]吩嗪)体系的共振光散射光谱。结果表明,在阴离子表面活性剂十二烷基硫酸钠(SDS)预胶束聚集体存在下,Ru(bpy)2(dppx)2+-SDS体系具有很强的共振光散射,DNA的加入使其共振散射光猝灭。探讨了反应机理。基于DNA对Ru(bpy)2(dppx)2+-SDS体系共振光散射的猝灭作用,建立了共振光散射法测定DNA的新方法。在最佳实验条件下,体系在393nm处的共振光散射猝灭程度与DNA的浓度呈线性关系,线性范围为0.01～1.2mg/L,检出限为1.5μg/L。     

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%.     

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.     

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.     

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.     

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.