锇胺分子氢配合物的研究进展

由于锇胺分子氢配合物中有特殊的键M(η2 H2 )和特殊的配体 分子氢的存在 ,故而具有丰富的取代化学和特殊的光谱性质。在无机化学、配位化学、生物、医药等方面都有极为广阔的应用前景。本文就此进行了简要的回顾与展望     

以锇的分子氢配合物作~1HNMR探针研究抗癌金属化合物与脱氧鸟苷酸的配位作用

锇的分子氢配合物[trans-en_2Os(η-H_2)]~(2+)(en,乙二胺)是一种新的生物分子~1H NMR识别探针.本文首次以该探针研究了抗癌金属化合物二氯二茂钛、二氯二乙基锡、二乙基邻菲咯啉二氯合锡及顺铂与脱氧鸟苷酸(dGMP)在接近生理条件下重水溶液中的配位作用.结果表明,前三者主要与dGMP的磷酸氧发生强的配位作用,而顺铂主要与dGMP的碱基N(7)发生配位作用.     

用锇胺分子氢探针以竞争模式研究金属抗癌剂与核苷酸的作用

早期的工作表明很多亲核试剂可以置换trans-[en₂Os(η²-H₂)D₂O]²⁺(称其为探针)中的D₂O,导致其特征H₂的¹H NMR负区化学位移发生变化. 如果亲核试剂与探针的键合常数可以测得, 则它与其他金属离子的键合常数也可方便地求出. 运用此探针以竞争模式系统研究了Cp₂TiCl₂, R₂SnCl₂, 抗癌药物顺铂等与dGMP之间的作用, 详细诠释了它们的竞争键合、组分变化、键合常数之间的定量关系, 论述了不同药剂与dGMP结合的差异. 结果表明, 在探针与dGMP的体系中加入药物后, 药物和探针对dGMP的咪唑氮N₇和磷酸氧两个位点进行竞争结合. 对于Cp₂TiCl₂, Ti与磷酸氧、咪唑氮均有明显的结合; 而(CH₃)₂SnCl₂与dGMP的磷酸氧有明显键合, 与咪唑氮则甚少结合. 探针与N₇的键合将导致它对同一dGMP分子上磷酸氧的键合能力减弱. 研究这些抗肿瘤金属络合物与单核苷酸、尤其是DNA的基本单元dGMP之间的作用, 对于阐明络合物与DNA键合模式是重要的. 预期这一结论同样适用于其他金属络合物与核苷酸的键合.     

DNA与金属锇配合物相互作用的表面电化学研究

采用自己建立的DNA表面电化学研究微量方法, 研究了单双链DNA与两种锇配合物(联吡啶锇和二氯菲咯啉锇)的相互作用. 研究发现, 两种锇配合物都是通过静电作用与DNA结合, 其作用方式不受溶液离子强度的影响. 并计算得到了联吡啶锇和二氯菲咯啉锇与dsDNA和ssDNA相互作用的多个热力学和动力学参数, 如结合常数K_3＋或K_2＋, 结合常数比K_3＋/K_2＋, 离子强度为零时的极限比 , 结合自由能ΔG_b, 解离速度常数k, 结合位点数s.     

多吡啶钌配合物作为DNA结构探针的研究

本文对多吡啶钌配合物作为DNA荧光或结构探针的研究背景、研究技术及其特点、钌配合物与DNA的键合模式及其结合力大小的影响因素、钌配合物与DNA键合的异构选择性及不同键合速率、非放射性核酸标记及DNA分子光开关等方面进行了简要述评     

单核锇配合物的合成、晶体结构及其与DNA的作用

使用溶剂热合成法,以p-bitmb配体(1,4-二(1-咪唑基-亚甲基)-2,3,5,6-四甲基苯)与[(η6-cymene)Os(μ-Cl)Cl]2或[(η6-bip)Os(μ-Cl)Cl]2为原料,合成了2种单核芳基锇配合物,并利用核磁、质谱、元素分析和X射线单晶衍射等手段对配合物进行了表征。配合物1属于单斜晶系,P21/c空间群,为一个单核锇的结构。中心锇原子与2个配体p-bitmb上的氮原子以及氯原子进行配位,2个配体的另一个咪唑基团通过一个亚甲基碳原子进行连接形成咪唑嗡离子,形成一个类似"碗"状的结构。一个氯离子通过氢键装载在结构的空腔内。利用核磁共振氢谱研究了结构中亚甲基的来源,并研究了配合物在缓冲溶液中的稳定性。用紫外吸收光谱、圆二色谱以及粘度法研究了配合物与DNA的相互作用,结果表明,配合物中的亚甲基来自于溶剂二氯甲烷。配合物以嵌入的方式与CT-DNA相互作用,结合常数分别为3.222×10~4 L·mol-1 (1)和1.53×10~4 L·mol-1 (2),同时配合物会减弱DNA的碱基堆积作用并可以使DNA发生解旋。     

三甲基胺氧化物希土配合物的振动光谱和配位结构研究

用三甲基胺氧化物(TMAO)与希土高氯酸盐和硝酸盐反应，制得了组成为：［Ln(TMAO)₆］(ClO₄)₃和［Ln(TMAO)₃(NO₃)］(NO₃)₂, (Ln=La、Nd、Sm、Gd)的配合物。用摩尔电导、IR、Raman光谱结合GF矩阵力常数及INDO分子轨道计算对其配位结构进行了研究。     

三吡啶胺和四齿链酚胺配体与Cu(Ⅱ)配位性质及其配合物催化酯水解研究

运用pH电位滴定法,在25±0.1℃ T,I=0.1(KNO₃)条件下,研究了Cu(Ⅱ)与三吡啶胺(L¹)和队(2'-羟基苄基)-二乙二胺(HL²)的配位行为。结果表明,L¹以二齿的形式和Cu(Ⅱ)形成稳定的2:1(L:M)配合物。其配位水分子的离解常数pKa为7.54.对于HL²,三个氮原子和酚氧负离子与Cu(Ⅱ)配位,酚羟基离解常数pKa为4.44.在25±0.1℃,I=0.1(KNO相似文献   

以不同铕配合物为探针分子的温敏漆制备及性能

以氧化铕(Eu_2O_3)、甲基丙烯酸(MAA)、水杨酸(HSal)、肉桂酸(HCA)和菲咯啉(Phen)为原料制备了Eu(MAA)3Phen、Eu(Sal)_3Phen和Eu(CA)_3Phen探针分子,并将不同探针分子分别加到甲基丙烯酸甲酯(MMA)中,在过氧化苯甲酰(BPO)引发下聚合,制得一系列温敏漆样品。采用红外光谱仪、荧光光谱仪和扫描电子显微镜对探针分子的结构、发光性能、形貌和温敏漆的温度猝灭性能进行了表征,研究了不同配体对探针分子发光性能和温敏漆温度猝灭性能的影响。结果表明,探针分子Eu(MAA)3Phen的荧光强度明显高于Eu(Sal)_3Phen和Eu(CA)_3Phen,相应的3种温敏漆Eu(MAA)3Phen/PMMA、Eu(CA)_3Phen/PMMA和Eu(Sal)_3Phen/PMMA均有良好的温度猝灭特性,但是对比发现在55~65℃范围内Eu(MAA)3Phen/PMMA和Eu(CA)_3Phen/PMMA温敏漆的灵敏度较高,而在35~45℃范围内Eu(Sal)_3Phen/PMMA温敏漆的灵敏度较高,可见不同的温敏漆适用于不同的温度范围。     

以不同铕配合物为探针分子的温敏漆制备及性能

以氧化铕（Eu₂O₃）、甲基丙烯酸（MAA）、水杨酸（HSal）、肉桂酸（HCA）和菲咯啉（Phen）为原料制备了Eu（MAA）₃Phen、Eu（Sal）₃Phen和Eu（CA）₃Phen探针分子,并将不同探针分子分别加到甲基丙烯酸甲酯（MMA）中,在过氧化苯甲酰（BPO）引发下聚合,制得一系列温敏漆样品。采用红外光谱仪、荧光光谱仪和扫描电子显微镜对探针分子的结构、发光性能、形貌和温敏漆的温度猝灭性能进行了表征,研究了不同配体对探针分子发光性能和温敏漆温度猝灭性能的影响。结果表明,探针分子Eu（MAA）₃Phen的荧光强度明显高于Eu（Sal）₃Phen和Eu（CA）₃Phen,相应的3种温敏漆Eu（MAA）₃Phen/PMMA、Eu（CA）₃Phen/PMMA和Eu（Sal）₃Phen/PMMA均有良好的温度猝灭特性,但是对比发现在55~65℃范围内Eu（MAA）₃Phen/PMMA和Eu（CA）₃Phen/PMMA温敏漆的灵敏度较高,而在35~45℃范围内Eu（Sal）₃Phen/PMMA温敏漆的灵敏度较高,可见不同的温敏漆适用于不同的温度范围。     

Study on the interactions between anti-tumor metal complexes and mononucleotides using trans-[en2Os(η2-H2)(CF3SO3)](CF3SO3) as a 1H NMR probe in a competitive mode

The interaction of several anti-tumor metal complexes with dGMP have been investigated using trans-[en2Os(η2-H2)]2+ as a 1H NMR probe in a competitive mode. Me2SnCl2, Bu2SnCl2, Et2Sn(phen)Cl2 and Et2SnCl2 can bind to dGMP mainly via phosphate; Cp2TiCl2 binds to dGMP mainly via phosphate and N7. The binding constant for (CH3)2SnCl2 binding to phosphate of dGMP exceeds 2.71×104. The binding constant for Cp2TiCl2 to phosphate is even greater than that of Sn(IV). Cis-platin has high affinity for both N7 and phosphate, but mainly for N7. Binding of the probe to N7 of dGMP reduces the binding affinity for phosphate of the same dGMP molecule by a factor of 5 to 6. Much the same factor is expected to apply to other metals containing agents interacting with dGMP.     

Determination of nucleic acids using calcein-neodymium complex as a fluorescence probe.

A novel fluorometric method has been developed for rapid determination of DNA and RNA with calcein-neodymium complex as a fluorescence probe. The method is based on the fluorescence enhancement of calcein-Nd(III) complex in the presence of DNA or RNA, with maximum excitation and emission wavelength at 489 nm and 514 nm, respectively. Under optimal conditions, the calibration graphs are linear over the range 0.5 - 3.0 microg/ml for both DNA and yeast RNA, 0.4 - 2.0 microg/ml for fish sperm DNA (FS DNA) and 0 - 3.0 microg/ml for calf thymus DNA (CT DNA). The corresponding detection limits are 15.1 ng/ml for DNA, 21.2 ng/ml for yeast RNA, 10.5 ng/ml for FS DNA and 8.9 ng/ml for CT DNA. The interaction mechanism for the binding of calcein-Nd(III) complex to DNA is also studied. The results of absorption spectra, fluorescence polarization measurements and thermal denaturation experiments, suggested that the interaction between calcein-Nd(III) complex and DNA is an electrostatic interaction.     

Perturbed angular correlation study using147Nd as a probe

The time integral pertturbed angular correlation (TIPAC) technique is employed to study PAC parameters in aqueous solutions of biomolecules Bovine Serum Albumin (BSA), lysozyme and ethylenediaminetetraacetic acid disodium salt (EDTA), using radioactive¹⁴⁷Nd as a probe. The attenuation coefficient (G₂₂) is found to decrease with increasing concentration of BSA The effect of attenuation is more pronounced for protein molecules BSA and lysozyme than in the case of EDTA. The relaxation constant (₂) increases with increasing concentration of the solution as well as with the increasing size of the solute molecule.     

Microtiter plate assay for phosphate using a europium-tetracycline complex as a sensitive luminescent probe

A new luminescent europium probe is presented for the determination of phosphate (P) in microtiter plate format. The assay is based on the quenching of the luminescence of the europium-tetracycline (EuTc) 1:1 complex by phosphate using a reagent concentration of 20.8 μmol/L. The probe is excited at 400 nm and displays a large Stokes’ shift of 210 nm. The emission maximum is located at 616 nm. The system works best at neutral pH 7 and is therefore suitable for phosphate determination in biological and biochemical systems. The linear range of the calibration plot is from 5 × 10⁻⁶ mol/L to 7.5 × 10⁻⁴ mol/L of phosphate, and the limit of detection is 3 μmol/L.     

Detection of DNA hybridization by various spectroscopic methods using the copper tetraphenylporphyrin complex as a probe

We are presenting new and highly sensitive hybridization assays. They are based on various spectroscopic methods including resonance light scattering, circular dichroism, ultraviolet spectra and fluorescence spectra, as well as atomic force microscopy, and relies on the interaction of the Cu(II), Ni(II), Mg(II), Co(II), Cd(II), and Zn(II) complexes, respectively, of tetraphenylporphyrin (TPP) with double-strand DNA (dsDNA) and single strand DNA (ssDNA). The interaction results in amplified resonance light scattering (RLS) signals and enables the detection of hybridization without the need for labeling DNA. The RLS signals are strongest in case of the Cu (II)-TPP complex which therefore was selected as the probe. The technique is simple, robust, accurate, and can be completed in less than one hour.

Electrochemistry of complex formation of carbaryl with ds-DNA using [Ru(bpy)2dppz]2+ as probe

An electrochemical competition method was used to study the interaction of carbaryl with natural double-stranded DNA (ds-DNA). Layer-by-layer films of negatively charged natural ds-DNA and polycationic poly (diallyldimethylammonium chloride) were assembled on the surface of a glassy carbon electrode. The DNA intercalator [Ru(bpy)₂(dppz)]²⁺ (bpy?=?2, 2′-bipyridine, dppz?=?dipyrido [3, 2-a: 2′,3′-c] phenazine) was chosen as an electrochemical probe. Tripropylamine was used as an electron donor to chemically amplify the oxidation current of the probe. In order to examine the effects of substituting group on the binding interaction of carbaryl with DNA, the interaction of naphthalene or α-naphthol with DNA was also studied by square wave voltammetry (SWV). The values of binding constant K _b of the three compounds to DNA are determined, which fall in the range of (0.2?×?10⁵) to (1.3?×?10⁵)?M^?1. The correlation suggests that the functional groups may play an important role in the DNA/analyte competition binding interaction. We demonstrated that it is conducive to the combination of small molecules and DNA when the functional groups are hydrophobic and have the lone-pair electrons as the electron donor. Furthermore, UV-absorption and fluorescence intensity of Ru-dppz decreases in the presence of carbaryl. These characteristics strongly support the intercalation of carbaryl into double-stranded DNA.     

Interaction of m-nitrophenylfluorone-Mo(VI) complex as a probe with human serum albumin: a fluorescence quenching study

In this paper, the binding characteristics of human serum albumin (HSA) and m-nitrophenylfluorone (m-NPF)-molybdenum (Mo(VI)) complex have been studied by fluorophotometry. The binding constants are measured at different temperature. Based on the theory of Forster energy transfer, the binding distance and the energy transfer efficiency between m-nitrophenylfluorone-Mo(VI) complex and protein are obtained. According to the thermodynamic parameters, the main sort of binding force can be judged. The results indicate that HSA and m-NPF-Mo(VI) complex have strong interactions. The mechanism of quenching belongs to static quenching and the main sort of binding force is electrostatic gravitation.     

Kinetic approach for the purification of nucleotides with magnetic separation

The isolation of β‐nicotinamide adenine dinucleotide is of great importance since it is widely used in different scientific and technologic fields such as biofuel cells, sensor technology, and hydrogen production. In order to isolate β‐nicotinamide adenine dinucleotide, first 3‐aminophenyboronic acid functionalized magnetic nanoparticles were prepared to serve as a magnetic solid support and subsequently they were used for reversible adsorption/desorption of β‐nicotinamide adenine dinucleotide in a batch fashion. The loading capacity of the 3‐aminophenyboronic acid functionalized nanoparticles for β‐nicotinamide adenine dinucleotide adsorption was 13.0 μmol/g. Adsorption kinetic and isotherm studies showed that the adsorption process followed a pseudo‐second‐order kinetic model and the experimental data can be represented using Langmuir isotherm model. The 3‐aminophenyboronic acid functionalized magnetic nanoparticles were proposed as an alternative support for the β‐nicotinamide adenine dinucleotide purification. The results elucidated the significance of magnetic separation as a fast, relatively simple, and low‐cost technique. Furthermore, the magnetic supports can be reused at least five times for purification processes.     

Spectrofluorometric determination of trace amounts of coenzyme II using norfioxacin-terbium complex as a fluorescent probe.

When terbium ion (Tb3+)-norfloxacin (NFLX) complex is issued a fluorescent probe, in a buffer solution of pH = 7.6, NADP can remarkably enhance the fluorescence intensity of the Tb3+ -NFLX complex at lambda = 545 nm. The enhanced fluorescence intensity of Tb3+ is in proportion to the concentration of NADP. The dynamic range for the determination of NADP is 1.11 x 10(-7) - 6.16 x 10(-5) mol l(-1), with a detection limit of 4.31 x 10(-8) mol l(-1). This method is simple, practical and relatively free of interference from coexisting substances, so it can be successfully applied to determination of NADP in synthetic water samples.     

NMR diffusion spectroscopy as a measure of host-guest complex association constants and as a probe of complex size

The complexes of cyclohexylacetic acid and cholic acid with beta-cyclodextrin were studied by NMR diffusion coefficient measurements. The diffusion coefficient of the 1:1 cyclohexylacetic acid/beta-cyclodextrin complex, K(a) = 1800 +/- 100 M(-1), is slightly slower (3.23 +/- 0.07 x 10(-6) cm(2) s(-1)) than that of beta-cyclodextrin (3.29 +/- 0.07 x 10(-6) cm(2) s(-1)). The diffusion coefficient of the 1:1 cholic acid/beta-cyclodextrin complex, K(a) = 5900 +/- 800 M(-1), is significantly slower (2.93 +/- 0.07 x 10(-6) cm(2) s(-1)) than that of beta-cyclodextrin. The results indicate that caution should be exercised when studying host-guest complexation by the so-called 'single point' technique. A novel data treatment is introduced which takes into account the diffusion behavior of all of the species when determining K(a). Experimentally determined diffusion coefficients of complexes are also a useful probe of the size of host-guest complexes.