盐酸克伦特罗与鲱鱼精DNA相互作用的研究北大核心CSCD

建立了紫外吸收光谱研究盐酸克伦特罗(CLB)与鲱鱼精DNA(hsDNA)相互作用的分析方法,初步探讨CLB与hsDNA相互作用的机理。在pH=7.00的磷酸盐缓冲溶液(PBS)中CLB与hsDNA存在相互作用。在温度为20℃时,CLB与hsDNA的结合常数K为1.23×104 L/mol,CLB与hsDNA相互作用的焓变△H=-13.67kJ/mol;熵变△S=31.67J/(mol·K),自由能△G=-22.99kJ/mol,确定了CLB与DNA的结合焓驱动占主导地位,结合方式可能为静电沟槽式结合。     

基于GSH-CdTe/CdS量子点的荧光变化研究hsDNA与盐酸洛美沙星-Cu(Ⅱ)配合物的相互作用

采用水相法合成了谷胱甘肽(GSH)修饰的CdTe/CdS量子点(GSH-CdTe/CdS QDs). 透射电子显微镜表征结果表明, GSH-CdTe/CdS QDs的粒径分布均匀, 分散性好. 在Tris-HCl(pH=7.6)缓冲液中, 由于静电引力作用, 带正电的盐酸洛美沙星(LMFH)-Cu(Ⅱ)配合物[LMFH-Cu(Ⅱ)]吸附到带负电的GSH-CdTe/CdS QDs表面形成基态复合物, 导致GSH-CdTe/CdS QDs的荧光猝灭. 随后, 向GSH-CdTe/CdS QDs-LMFH-Cu(Ⅱ)配合物体系中加入鲱鱼精DNA(hsDNA), hsDNA可诱导LMFH-Cu(Ⅱ)配合物从GSH-CdTe/CdS QDs表面脱落而嵌入到hsDNA的双螺旋结构中, 使GSH-CdTe/CdS QDs的荧光恢复. 通过对GSH-CdTe/CdS QDs荧光的可逆调控, 利用荧光光谱、 紫外-可见吸收光谱和共振瑞利散射光谱研究了hsDNA与LMFH-Cu(Ⅱ)配合物的相互作用. 通过对比GSH-CdTe/CdS QDs与LMFH相互作用的光谱性质, 讨论了GSH-CdTe/CdS QDs-LMFH-Cu(Ⅱ)-hsDNA的相互作用机理, 模拟了作用过程, 从而建立了一种研究氟诺喹酮类药物的金属配合物与核酸相互作用机制的光谱方法.     

胰蛋白酶与DNA相互作用的共振瑞利散射光谱及其分析应用研究

当胰蛋白酶与鲱鱼精DNA(hsDNA)、 鲑鱼精DNA(sDNA)以及小牛胸腺DNA(ctDNA)之间发生相互作用时,共振瑞利散射(RRS)会显著增强,并产生新的RRS光谱. 三者有近似的光谱特征,其最大RRS峰分别位于307 nm(hsDNA和sDNA体系)和290 nm处(ctDNA体系),另一散射峰位于350 nm处,其散射强度(ΔI)与DNA或者胰蛋白酶的浓度成正比,因此可用于蛋白质和DNA的相互测定. 当用胰蛋白酶测定DNA时,hsDNA,sDNA和ctDNA的检测范围分别为1.4×10^-3～2.3, 2.1×10^-3～2.5和3.5×10^-3～1.9 μg/mL(ctDNA),它们的检出限分别为0.4,0.7和1.1 ng/mL. 当用hsDNA测定胰蛋白酶时,其线性范围为0.1～30.0 μg/mL,检出限为39.0 ng/mL. 研究了最佳的反应条件、 影响因素和结合产物的化学性质,考察了胰蛋白酶与DNA的结合比,推测了它们的结合方式,并以胰蛋白酶作RRS探针,发展了一种高灵敏、 简便和快速测定痕量DNA的新方法.     

盐酸表柔比星与核酸相互作用的共振瑞利散射光谱研究及其分析应用

用共振瑞利散射光谱研究了盐酸表柔比星(EPI)与小牛胸腺DNA(ctDNA)、鲑鱼DNA(sDNA)、鲱鱼精DNA(hsDNA)和酵母RNA(yRNA)等核酸之间的相互作用. 实验表明在pH 2.0左右的酸性介质中, 表柔比星及核酸本身的共振瑞利散射(RRS)均十分微弱, 但是当它们相互作用形成结合产物时, 将导致RRS增强并出现新RRS光谱. 不同核酸与表柔比星结合产物的RRS 光谱特征略有差异, 散射增强程度则各不相同, 其相对散射强度的顺序是ctDNA≈sDNA＞hsDNA＞yRNA . 在一定范围内核酸浓度与散射强度成正比, 据此可以建立一种新的用表柔比星测定DNA的 RRS 法, 方法具有高灵敏度, 对于不同DNA 其检出限(3s)在24.0 ng/mL 至28.0 ng/mL 之间, 用于合成样品分析, 结果满意. 文中还研究了适宜的反应条件, 影响因素和结合产物的分析化学性质. 结合吸收光谱和荧光光谱特征对表柔比星与DNA 的反应机理进行了讨论.     

色氨酸-镝(Ⅲ)配合物与鲱鱼精DNA的作用方式

采用UV光谱法、荧光光谱法,在pH=7.40的缓冲溶液中确定了镝(Ⅲ)与色氨酸的结合比n_Dy(Ⅲ)∶n_Trp=1∶3,Dy(Ⅲ)(Trp)₃配合物与鲱鱼精DNA的结合比n_{Dy(Ⅲ)(Trp)3}∶n_DNA=2∶1。用双倒数法确定了结合常数K_25℃=5.75×10⁴ L·mol^-1和K_37℃=3.27×10⁴ L·mol^-1。化学热力学研究显示配合物Dy(Ⅲ)(Trp)₃与hsDNA的结合为熵和焓共同驱动。结合Scatchard法和粘度法,确定了配合物Dy(Ⅲ)(Trp)₃与hsDNA之间主要为静电作用和嵌插作用。     

盐酸平阳霉素与核酸相互作用的共振Rayleigh散射光谱及其分析应用

用共振Rayleigh散射(Resonance Rayleigh scattering, RRS)光谱结合吸收光谱和荧光光谱研究了盐酸平阳霉素(BleomycinA₅, BLMA₅)与核酸的相互作用. 在pH 2.2左右的酸性介质中, BLMA5能够与核酸结合形成复合物, 引起RRS显著增强, 并产生新的RRS光谱, 具有特征吸收波长红移和分子吸收增色效应, 能观察到BLMA₅的荧光猝灭. 不同核酸的RRS光谱特征略有差异, 最大散射波长分别位于301 nm(ctDNA和sDNA), 370 nm(hsDNA)和310 nm(RNAtypeⅢ和RNAtypeⅥ), 散射增强的程度各不相同, 其中DNA的增强程度比RNA大. 讨论了BLMA₅和核酸反应的最佳反应条件及影响因素, 并对BLMA5与核酸的结合模式、反应机理进行了讨论. 建立了一种以BLMA₅为探针用RRS法测定DNA的高灵敏度、简单、快捷的分析方法. 该方法的检出限(3σ )分别为5.7 ng·mL^-1(ctDNA), 7.4 ng·mL^-1 (sDNA), 9.2 ng·mL^-1 (hsDNA), 能用于痕量DNA的测定.     

博莱霉素铜配合物-DNA体系的共振瑞利散射及分析应用

用共振瑞利散射(resonance Rayleigh scattering,RRS)光谱和紫外吸收光谱及荧光光谱研究了博莱霉素(bleomycinA2,BLMA2)-Cu(Ⅱ)配合物的形成及其与DNA的反应.在水溶液中,BLMA2和Cu(Ⅱ)能形成1:1的配合物,产生新的吸收光谱,并能观察到BLMA2的荧光猝灭.该配合物能与DNA作用生成三元离子缔合物,引起RRS的显著增强.讨论了BLMA2-Cu(Ⅱ)配合物的形成条件及影响因素;对该配合物与DNA的结合模式和反应机理进行了讨论;探讨了博莱霉素荧光猝灭的类型,并建立了一种用BLMA2-Cu(Ⅱ)配合物作探针RRS法测定DNA的高灵敏度、简单、快捷的分析方法.该方法的检出限(3σ)分别为7.2ng·mL-1(ctDNA)、7.1ng·mL-1(sDNA)、18ng·mL-1(hsDNA),能用于痕量DNA的测定.     

Studies of Ce（Ⅲ）-ALC-F^- Interacting with Herring Sperm DNA by Electrochemical,Fluorimetric and UV-spectrophotometric Method

Ce(Ⅲ)-ALC-F^- complex can react with hsDNA to form an electrochemically non-active supermolecular complex Ce(Ⅲ)-ALC-F^--DNA in the buffer solution of (CH2)6N4(pH=4.9),which results in the decrease of the peak current of Ce(Ⅲ)-ALC-F^-.This method can be applied to determine DNA concentration.In addition,by using fluorimetric and UV-spectrophotometric methods with studies of denatured DNA and the effect of NaC1 solution,it is also found that the binding mode is intercalation.     

溶液pH对硫堇与DNA相互作用方式的影响

用电化学和光谱方法研究了溶液pH对硫堇(TH)与小牛胸腺脱氧核糖核酸(CT-DNA)相互作用方式的影响.电化学测量结果表明，在pH 7.2的磷酸盐缓冲溶液中, TH与CT-DNA之间的作用方式以嵌入结合为主，在pH 6.5的磷酸盐缓冲溶液中， TH与CT-DNA之间的作用方式既存在嵌入结合也存在静电作用.荧光光谱测量结果表明，TH与DNA结合后其荧光发生猝灭，通过Stern-Volmer方程计算得到pH 6.5时TH-DNA体系的猝灭常数高于pH 7.2时的值，表明在pH 6.5的溶液中两者相互作用更强.圆二色谱(CD)实验结果也证实了这一结论.     

鲱鱼精DNA修饰纳米金催化Fehling反应——共振散射光谱法检测痕量Hg~(2+)

用鲱鱼精DNA(hsDNA)修饰10nm的纳米金制备了Hg2+的hsDNA修饰纳米金共振散射光谱探针(AuhsDNA).在pH7.0Tris-HCl缓冲溶液中及0.017mol/LNaCl存在下,Hg2+与AuhsDNA形成稳定的Hg2+-DNA结合物,引起AuhsDNA中的纳米金析出并聚集形成纳米金簇.该溶液用150nm滤膜过滤后,滤液中过量的AuhsDNA可催化Fehling试剂-葡萄糖反应生成氧化亚铜微粒,该微粒在580nm处有一个较强的共振散射峰.随着汞离子浓度增大,形成的纳米金簇越多,滤液中AuhsDNA越少,生成的氧化亚铜微粒减少,580nm处氧化亚铜微粒的共振散射光强度线性降低,其共振散射光强度降低值ΔI580nm与汞离子浓度在1～833nmol/L范围内成线性,回归方程、相关系数、检出限分别为ΔI580nm2+Hg=0.37C+0.9,0.9990,0.3nmol/LHg2+.该法用于废水中Hg2+的检测.     

A carbanion induced synthesis of highly congested pyrazole and imidazole containing heterocycles

An efficient approach to the synthesis of highly congested di, penta and hexacyclic pyrazoles as well as imidazole fragment containing novel heterocyclic molecule has been developed through a carbanion induced transformation of suitably functionalized 2H-pyran-2-ones, benzo[h]chromene and thiochromeno[4,3-b]pyrans. Due to the presence of fluorescence, we report their prime application metal sensor as off/on switching in ferric ions.     

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.     

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%).     

Selective synthesis of 4,5-dihydroimidazo- and imidazo[1,5-a]quinoxalines via modified Pictet–Spengler reaction

An efficient tandem approach for the selective synthesis of 4,5-dihydroimidazo[1,5-a]quinoxalines 6a–g and imidazo[1,5-a]quinoxalines 7a–h by the reaction of 2-imidazolyl anilines 4a–c with aryl aldehydes 5a–k under mild reaction conditions is described. Introduction of electron releasing alkyl groups in substrates 4a–b was found to be instrumental for the success of the reaction.     

Understanding the Diels-Alder reactivity of 1,2-azaborine analogues

The Diels-Alder reactivity of 1,2-heteroborines (H₄C₄B(H)X, X?=?NH, PH, AsH; O, S, Se) has been computationally explored by means of Density Functional Theory (DFT) calculations. The influence of the HB?=?X fragment on the reactivity of the system has been quantitatively analyzed in detail by means of the so-called Activation Strain Model (ASM) of reactivity. It is found that the interaction between these species and the dienophile is significantly stronger than that computed for their all-carbon isoelectronic counterpart, benzene. In addition, the strain energy plays a key role in the observed reactivity trends. The role of the aromaticity strength of these heteroarenes on the reactivity is also assessed.     

Synthesis of N-substituted carbazolones from α-iodo enaminones via Pd(0)-catalyzed intramolecular coupling under microwave irradiation

A variety of N-aryl and N-alkyl carbazolones were conveniently achieved in good to high yields via Pd₂(dba)₃-mediated intramolecular coupling of N-substituted α-iodo enaminones under microwave irradiation. The Pd(0)-catalyzed cyclization was found to proceed favorably with the more electron-deficient phenyl ring during the reactions involving unsymmetrical N,N-diaryl α-iodo enaminones. This unique property enables the construction of carbazolone skeleton containing nitro substituted benzenoid ring.     

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.     

Synthesis of substituted 2,4,5,6-tetrahydrocyclopenta[c]pyrazoles and 2,4,5,6-tetrahydropyrrolo[3,4-c]pyrazoles by intramolecular nitrilimine cycloaddition

Both substituted 2,4,5,6-tetrahydrocyclopenta[c]pyrazoles and 2,4,5,6-tetrahydropyrrolo[3,4-c]pyrazoles have been synthesized by the 3+2 intramolecular dipolar cycloaddition of nitrilimines to alkynes. This cyclization has been extended to more versatile 3-bromo derivatives by the use of alkynylbromides as dipolarophiles.