银杏叶中α-葡萄糖苷酶抑制剂的超滤质谱筛选

采用体外酶抑制活性检测方法结合超滤质谱(UF-LC/MS)筛选方法对中药提取物中的α-葡萄糖苷酶抑制剂进行了筛选.以4-硝基苯-α-D-吡喃葡萄糖苷(PNPG)为底物,阿卡波糖为阳性对照药,对5种富含黄酮类化合物的中药提取物进行了α-葡萄糖苷酶抑制活性的初步测定.结果表明,银杏叶具有最强的α-葡萄糖苷酶抑制活性,可作为进一步复筛的对象.利用超滤质谱技术对银杏叶中潜在的α-葡萄糖苷酶抑制剂进行了筛选,从中筛选出4种潜在的α-葡萄糖苷酶抑制剂,并利用液相色谱-串联质谱技术(LC-MSn)对其结构进行了鉴定.本文结果为开发新一代安全有效的降糖药物奠定了基础.     

反离子对离子液体氯化1-(2-羟乙基)-3-十二烷基咪唑在水溶液中自组装的影响

用表面张力法和荧光探针技术分别测定了阳离子型离子液体表面活性剂氯化1-(2-羟乙基)-3-十二烷基咪唑([C2OHC12im]Cl)在无机盐(NaX,X=Cl-,Br-,I-和Na2SO4)水溶液中的自组装参数。 结果表明,反离子通过结合[C2OHC12im]+并中和其表面电荷,使[C2OHC12im]+的临界胶束浓度(CMC)和胶束平均聚集数(Nm)等自组装参数明显改变;改变幅度按照Cl-＜Br-＜I-＜SO2-4次序递增;但是反离子(Cl-、Br-和SO2-4)种类对临界胶束平均聚集数(Nm,c)和胶束微极性([I1/I3]m)的影响不甚明显;随着Br-浓度增加,lg CMC线性减小,而Nm则以幂函数形式递增。     

新型超支状液晶核酸传感器用于p53突变基因的检测

基于核酸杂交链式反应影响液晶取向的原理, 构建了一种新型的超支状液晶核酸传感器用于检测p53突变基因. 本文突破传统构建超支状分子的方式, 采用杂交链式反应方法, 以目标序列p53突变基因作为引发剂, 3种不同的发卡探针Hairpin A, Hairpin B和Hairpin C为单体, 在温和的条件下, 通过改变单体的浓度和反应时间自发杂交组装形成尺寸和分子量可控的超支状DNA(branched-like DNA, bDNA). 借助捕获探针将该超支状DNA连接到液晶传感基底表面, 观察液晶分子取向改变前后的光学信号, 实现了p53基因含249密码子突变序列的快速检测. 本方法有望为核酸诊断的发展提供一种新的方法和思路.     

氢化物发生–原子荧光光度法测定食品和食品添加剂中的砷、汞和铅

建立氢化物发生–原子荧光光度法测定食品和食品添加剂中砷、汞和铅元素的方法。对茶叶、方便面、精料与二氧化硅样品的前处理方法进行了研究,讨论了酸介质与酸度、还原剂浓度、铁氰化钾与草酸浓度等因素对样品测定的影响。当还原剂质量浓度为20 g/L、载流酸度为5%、铁氰化钾和草酸质量浓度分别为4 g/L和2 g/L时,砷、汞和铅的方法检出限分别为0.024,0.008,0.066μg/L,方法的回收率为85%~105%,测量结果的相对标准偏差分别为0.7%,0.7%,1.8%。该方法简便、快速、结果准确可靠,能满足食品和食品添加剂中砷、汞、铅的测定。     

DNA拓扑异构酶抑制剂

DNA拓扑异构酶是一种广泛存在于真核细胞和原核细胞中的重要生物酶,对DNA转录、复制、染色体分离及基因表达等过程中的DNA拓扑结构起着重要的调控作用。研究发现,与正常细胞不同,DNA拓扑异构酶在肿瘤细胞中表现出不受其他因素影响的高水平表达,而许多抗肿瘤药物的作用机制也与DNA拓扑异构酶密切相关,因此它作为抗肿瘤药物的重要靶点引起了研究者的广泛关注。本文对DNA拓扑异构酶的结构、分类及生物功能进行了简要的归纳,总结了近年来DNA拓扑异构酶抑制剂的研究进展,并重点对金属配合物作为DNA拓扑异构酶抑制剂的研究现状进行了详细的介绍。     

钴掺杂Sr1.5La0.5MnO4的合成及高温电化学性能研究

采用EDTA-柠檬酸法合成了中温固体氧化物燃料电池阴极材料Sr_1.5La_0.5Mn_1-xCo_xO₄（SLMCO_x）,并利用粉末X射线衍射（XRD）、X射线光电子能谱（XPS）以及电化学交流阻抗谱（EIS）进行表征。结果表明,该材料与Ce_0.9Gd_0.1O_1.95（CGO）在1 200℃烧结12 h不发生化学反应。随着Co掺入量的增加,氧化物中Mn³⁺和Co²⁺含量增多,晶格氧含量降低,晶格畸变率增大。交流阻抗谱（EIS）测试结果显示,钴的掺杂明显降低电极的极化电阻,其中Sr_1.5La_0.5Mn_0.7Co_0.3O₄阴极在700℃空气中的极化电阻为0.62 Ω·cm²,明显小于Sr_1.5La_0.5MnO₄阴极在750℃的极化电阻（1.5 Ω·cm²）,表明钴掺杂的Sr_1.5La_0.5Mn_1-xCo_xO₄是一种潜在的IT-SOFC阴极材料。     

基于柔性多羧酸配体H3TCOPM构筑的Co(Ⅱ)配合物的合成与结构

以三苯甲烷-4,4’,4"-三羧酸（H₃TCOPM）为主配体,以含氮二齿配体4,4’-bipyridine（4,4’-bipy）为辅助配体,与Co（NO₃）₂·6H₂O通过溶剂热反应得到了2个配位聚合物{[Co₂（α-OH-TCOPM）（OH）（H₂O）₄]·DMF}_n（1）（α-OH-H₃TCOPM=三苯甲醇-4,4’,4"-三羧酸）和{[Co₃（α-OH-TCOPM）₂（4,4’-bipy）₃（H₂O）₆]·2H₂O}_n（2）。晶体结构分析表明,配合物1为四边形的二维层状结构,而配合物2为二维网状结构。采用红外光谱、粉末X射线衍射对配合物进行了表征,用热重分析仪研究了其热稳定性。     

基于二氰根铬的一系列氰根桥联CrⅢ-CuⅡ-CrⅢ三核配合物的合成、结构与磁性

基于一系列二氰根铬与[Cu(cyclam)](ClO₄)₂反应合成了3个氰根桥联Cr^Ⅲ-Cu^Ⅱ-Cr^Ⅲ三核配合物[Cu(cyclam)][Cr(bpmb)(CN)₂]₂·4H₂O(1)(cyclam=1,4,8,11-四氮杂环十四,bpmb^2-=1,2-二(2-吡啶甲酰胺基)-4-甲基苯),[Cu(cyclam)][Cr(bpdmb)(CN)₂]₂(2)(bpdmb^2-=1,2-二(2-吡啶甲酰胺基)-4,5-二甲基苯)和[Cu(cyclam)][Cr(bpClb)(CN)₂]₂·4H₂O(3)(bpClb^2-=1,2-二(2-吡啶甲酰胺基)-4-氯苯)。单晶衍射结果表明:3个化合物是结构类似的中性三核配合物,均含有氰根桥联的Cr(Ⅲ)-CN-Cu(Ⅱ)-NC-Cr(Ⅲ)连接;磁性研究表明:氰根桥在Cr^Ⅲ和Cu^Ⅱ离子间传递弱的铁磁耦合作用,基于自旋哈密顿算符Ĥ=-2J_CrCuŜ_Cu(Ŝ_Cr1+Ŝ_Cr2)拟合得到它们的磁耦合常数分别是J_CrCu=1.53(2) cm^-1(1),0.45(1) cm^-1(2)和0.73(2) cm^-1(3)。     

Modulation of Multifunctional N,O,P Ligands for Enantioselective Copper‐Catalyzed Conjugate Addition of Diethylzinc and Trapping of the Zinc Enolate

In this work, we have successfully synthesized a new family of chiral Schiff base–phosphine ligands derived from chiral binaphthol (BINOL) and chiral primary amine. The controllable synthesis of a novel hexadentate and tetradentate N,O,P ligand that contains both axial and sp³‐central chirality from axial BINOL and sp³‐central primary amine led to the establishment of an efficient multifunctional N,O,P ligand for copper‐catalyzed conjugate addition of an organozinc reagent. In the asymmetric conjugate reaction of organozinc reagents to enones, the polymer‐like bimetallic multinuclear Cu? Zn complex constructed in situ was found to be substrate‐selective and a highly excellent catalyst for diethylzinc reagents in terms of enantioselectivity (up to >99 % ee). More importantly, the chirality matching between different chiral sources, C₂‐axial binaphthol and sp³‐central chiral phosphine, was crucial to the enantioselective induction in this reaction. The experimental results indicated that our chiral ligand (R,S,S)‐ L1 ‐ and (R,S)‐ L4 ‐based bimetallic complex catalyst system exhibited the highest catalytic performance to date in terms of enantioselectivity and conversion even in the presence of 0.005 mol % of catalyst (S/C=20 000, turnover number (TON)=17 600). We also studied the tandem silylation or acylation of enantiomerically enriched zinc enolates that formed in situ from copper‐ L4 ‐complex‐catalyzed conjugate addition, which resulted in the high‐yield synthesis of chiral silyl enol ethers and enoacetates, respectively. Furthermore, the specialized structure of the present multifunctional N,O,P ligand L1 or L4 , and the corresponding mechanistic study of the copper catalyst system were investigated by ³¹P NMR spectroscopy, circular dichroism (CD), and UV/Vis absorption.     

Color Point Tuning in Lu3−x−yMnxAl5−xSixO12:yCe3+ for White LEDs

A series of the solid‐solution phosphors Lu_3?x?yMn_xAl_5?xSi_xO₁₂:yCe³⁺ is synthesized by solid‐state reaction. The obtained phosphors possess the garnet structure and exhibit similar excitation properties as the phosphor Lu₃Al₅O₁₂:Ce³⁺, but with an effectively improved red component in the emission spectrum. This can be attributed to the energy transfer from Ce³⁺ to Mn²⁺. Our investigation reveals that electric dipole–quadrupole interactions dominate the energy‐transfer mechanism and that the critical distance determined by the spectral overlap method is about 9.21 Å. The color‐tunable emissions of the Lu_3?x?yMn_xAl_5?xSi_xO₁₂:yCe³⁺ phosphor as a function of Mn₃Al₂Si₃O₁₂ content are realized by continuously shifting the chromaticity coordinates from (0.354, 0.570) to (0.462, 0.494). They indicate that the obtained material may have potential application as a blue radiation‐converting phosphor for white LEDs with high‐quality white light.