Cu2＋和Fe3＋与明胶的相互作用

利用荧光猝灭法, 研究了不同温度、酸度下, Cu2＋和Fe3＋与明胶的相互作用.计算了猝灭常数和结合常数.紫外光谱和显微红外光谱的测定结果表明, Cu2＋、Fe3＋与明胶分子中的酰胺键发生了作用.探讨了猝灭机理.计算出的热力学函数表明,在Cu2＋、Fe3＋与明胶的相互作用过程中熵变起主要的作用.     

Cu(phen)2+2和Cu(bpy)2+2与6-巯基嘌呤、腺嘌呤相互作用的研究

在ｐＨ为７．０的磷酸盐缓冲溶液中，用荧光光谱、紫外光谱、电化学及紫外光谱电化学等方法研究了铜配合物与６－巯基嘌呤、腺嘌呤的相互作用．结果表明，Ｃｕ（ｐｈｅｎ）２＋２和Ｃｕ（ｂｐｙ）２＋２与６－巯基嘌呤、腺嘌呤发生了相互作用，但作用程度不同．根据荧光光谱实验数据计算出Ｃｕ（ｐｈｅｎ）２＋２和Ｃｕ（ｂｐｙ）２＋２与６－巯基嘌呤、腺嘌呤的配位比均为１∶１；它们与６－巯基嘌呤作用的配位常数分别为２．２３×１０４Ｌ／ｍｏｌ和６．１１×１０４Ｌ／ｍｏｌ；与腺嘌呤作用的配位常数分别为１．９５×１０４Ｌ／ｍｏｌ和５．１２×１０４Ｌ／ｍｏｌ．电化学实验也获得了相近的结果．这为解释Ｃｕ（ｐｈｅｎ）２＋２和Ｃｕ（ｂｐｙ）２＋２与ＤＮＡ的作用机理及作用部位提供了有益的信息     

Cu（phen）^2＋3和Cu（bpy）^2＋3与6—巯基嘌呤,腺嘌呤相互作 …

在ｐＨ为７．０的磷酸盐缓冲溶液中，用荧光光谱，紫外光谱，电化学及紫外光谱电化学等方法研究了铜配合物与６－巯基嘌呤，腺嘌呤的相互作用，结果表明，Ｃｕ（ｐｈｅｎ）＾２＋２和Ｃｕ（ｂｐｙ）＾２＋３与６－巯基嘌呤，腺嘌呤发生了相互作用，但作用程度不同，根据荧光光谱实验数据计算出Ｃｕ（ｐｈｅｎ）２＋３和Ｃｕ（ｂｐｙ）＾２＋３与６－巯基嘌呤，腺嘌呤的配位比均为１：１，它们与６－巯基嘌呤作用的配位常数分别为２．     

KZnF3中Ce^3＋→Eu^2＋的能量传递

研究了ＫＺｎＦ３中Ｃｅ＾２＋和Ｅｕ＾２＋的光谱特性,在共掺Ｃｅ＾３＋和Ｅｕ＾２＋的体系中,观察到了Ｃｅ＾３＋对Ｅｕ＾２＋的能量传递过程,计算了能量传递的量子效率,探讨了能量传递机理,研究发现,Ｃｅ＾３＋的存在有利于Ｅｕ＾２＋的ｆ－ｆ跃迁线状发射。     

过渡金属离子与明胶相互作用的研究

利用荧光猝灭法,研究了pH值10.0,不同温度下,Mn^2+,Co^2+,Ni^2+,Hg^2+与明胶的相互作用。计算了猝灭常数、螯合平衡常数和结合位点数。紫外光谱和显微红外光谱的测定结果表明,Mn^2+,Co^2+,Ni^2+与明胶分子中的酰胺键发生了作用。确定了猝灭机理。计算得出的热力学函数表明,在Mn^2+,Co^2+,Ni^2+对明胶荧光的猝灭过程中,熵效应起着重要的作用。     

Ce^3＋和Eu^2＋共激活氯硅酸锌钙的光谱和敏化特性

合成了Ｃｅ＾３＋和Ｅｕ＾２＋共激活的氯硅酸锌钙「Ｃａ８Ｚｎ（ＳｉＯ４）４Ｃｌ２：Ｃｅ＾３＋，Ｅｕ＾２＋」绿色荧光粉，并报道了它们的漫反射光谱，激光发光谱及发射光谱，观测到氯硅酸锌钙中Ｃｅ＾３＋对Ｅｕ＾２＋离子发光的显著敏化现象。阐述了氯硅酸锌钙中Ｃｅ＾３＋和Ｅｕ＾２＋发光作用缘于Ｃｅ＾３＋和Ｅｕ＾２＋之间的高效无辐一传递。     

纳米ZnS与明胶蛋白质的相互作用

利用透射电子显微镜(TEM)、X射线粉末衍射(XRD)、紫外-可见吸收光谱(UV-Vis)、傅里叶变换红外光谱(FT-IR)、同步荧光和三维荧光光谱,研究了pH=7.40条件下纳米ZnS与明胶蛋白质的相互作用。FT-IR光谱表明,ZnS与明胶中酰胺基的氮和氧原子及羧基氧可能发生键合生成了水溶性ZnS/明胶纳米生物复合物;ZnS与明胶的键合对明胶分子的内源荧光有明显的猝灭作用,其猝灭机制为静态猝灭。根据修正的Scatchard方程计算了不同温度下复合物的生成常数及反应热力学参数,结果表明反应是自发进行的吸热过程,且为熵驱动。同步荧光和三维荧光光谱表明纳米ZnS引起了明胶蛋白质构象的改变。研究结果为探究此类纳米生物复合物的制备及其在生物方面的应用提供了重要信息。     

铜络合物与生物小分子次黄嘌呤相互作用的光谱电化学和荧光光谱

以光谱电化学和荧光光谱法证明了络合物Ｃｕ（ｐｈｅｎ）２２＋和Ｃｕ（ｂｐｙ）２２＋与次黄嘌呤能发生络合作用并求出它们的络合比为 １．络合常数分别为 １． ２１× １０４ Ｌ／ｍｏｌ和 ２． ３２ × １０４Ｌ／ｍｏｌ；相互作用的产物的光谱电化学性质发生了明显的变化，结合了次黄嘌呤后的 Ｃｕ（Ｐｈｅｎ）２＋－ＨＸ和Ｃｕ（ｂｐｙ）２＋－ＨＸ在空气中氧化的动力学常数明显减小．这些相互作用的定量数据为铜络合物与ＤＮＡ作用部位提供了重要信息．     

新催化动力学光度法‘花青-H_2O_2体系测定痕量铬(Ⅵ)

在六次甲基四铵－盐酸介质中, 痕量铬（Ⅵ）显著催化Ｈ２Ｏ２氧化‘花青褪色的指示反应, 催化反应的表观活化能为６．８４ ｋＪ·ｍ ｏｌ－ １, 建立了测定痕量铬（Ⅵ）的动力学分析法, 线性测定范围为０～１５０ μｇ·Ｌ－ １,检出限为０．８μｇ·Ｌ－ １。常见离子中,除Ａｌ３＋ ,Ｃｕ２＋ ,Ｆｅ３＋ ,Ｆｅ２＋ 外,其余离子不影响测定。其中Ａｌ３＋ 的干扰可用Ｆ－ 掩蔽消除, Ｃｕ２＋ ,Ｆｅ３＋ ,Ｆｅ２＋ 的干扰可用ＥＤＴＡ 掩蔽消除。本法已用于测定湖水,矿井水和电镀废水中的铬（Ⅵ）。     

BaLaB_9O_（16）中Ce~（3＋）敏化Dy~（3＋）发光的机理

在紫外光激发下，研究了ＢａＬａＢ９Ｏ（１６）中Ｄｙ（３＋）、Ｃｅ（３＋）的发光光谱、激发光谱、发光强度及荧光寿命随着组成变化的规律性．结果表明：Ｄｅ（３＋）对Ｄｙ（３＋）的发光有相当强的敏化作用，Ｃｅ（３＋）→Ｄｙ（３＋）的能量传递效率可高达９３％，能量传递的机理为电偶极－偶极相互作用的共振传递．根据３４９ｎｍ激发下Ｄｙ（３＋）发光强度与浓度的关系，证明了Ｄｙ（３＋）发光的自身浓度猝灭机理也为电偶极－偶极相互作用．     

Fluorescence quenching of anthropogenic fulvic acids by Cu(II), Fe(III) and UO(2)(2+)

The quenching of the fluorescence of three anthropogenic fulvic acids (FA) provoked by Cu(II) (pH 6.0), Fe(III) (pH 4.0) and UO₂²⁺ (pH 3.5), was analyzed by a non-linear method and by Stern-Volmer plots. The FA samples were extracted from composted sewage sludges (csFA), composted municipal wastes (mwFA) and composted livestock wastes (lsFA). Synchronous-scan fluorescence (SyF) spectra were collected as a function of metal ion concentration. Spectral data were treated by a self-modeling mixture analysis method (SIMPLISMA) to detect the SyF spectral band with the strongest quenching and to calculate the corresponding quenching profile. The analysis of these profiles by a non-linear method allowed the estimation of conditional stability constants (K) and of the percentage of non-complexing fluorophores. The same quantitative information was obtained by the modified Stern-Volmer equation taking into account the existence of fluorophores that do not participate in the complexation. Good agreement was found between the results of the two procedures. The log K calculated by the non-linear method were (standard deviation in parenthesis): csFA, Cu(II), 4.22 (5); Fe(III), 5.0 (1); UO₂²⁺, 5.2 (2); mwFA, Cu(II), 4.21 (3); Fe(III), 5.6 (2); UO₂²⁺, 4.7 (3); lsFA, Cu(II), 4.51 (8); Fe(III), 5.5 (2); UO₂²⁺, 3.6 (2).     

Effect of the pH on the complexation of Cu(II), Ni(II) and Fe(III) Ions by a vine leaf litter extract by fluorescence quenching

An extract of dead vine leaves (vitis viniferal) (VLE) was obtained by the extraction procedure for fulvic acids and its interaction (at a concentration of 25mg/L in 0.1 M KNO₃) with the Cu(II), Ni(II) and Fe(III) ions was studied in the pH range between 3 and 6. This interaction was monitored by synchronous molecular fluorescence, since bands due to the fluorescent ligands undergo quenching upon complex formation. After the chemometric isolation of the quenching profiles from the raw spectra by a self-modeling mixture analysis, SIMPLISMA, they were analyzed by two methods: (i) graphical procedures based on the Stern-Volmer model; and (ii) a non-linear least-squares procedure. For the Cu(II) and Ni(II) ions, the treatment by these two methods provided similar values both for the logarithm of the conditional stability constants (log Kc) and the percentage of fluorescent structures that do not participate in the complexation. The log Kc were (standard deviations in parenthesis): Cu(II) ion, 2.4 (3), 3.37(3), 4.4(1) and 4.92(9), respectively, for pH = 3, 4, 5 and 6; Ni(II)ion, 2.9(1), 3.3(2), and 4.09(3), respectively, for pH = 4, 5 and 6. For Fe(III) an interaction with VLE was observed, but no values for Kc could be obtained.     

金属离子对一种分子内电荷转移荧光探针与牛血清白蛋白相互作用的影响

采用荧光光谱法研究了Fe~(3+)、Cu~(2+)、Pb~(2+)三种离子对1-酮-2-(对二甲氨基苯亚甲基)-四氢萘与牛血清白蛋白相互作用的影响.三种金属离子分别存在时能增强1-酮-2-(对二甲氨基苯亚甲基)-四氢萘对牛血清白蛋白的猝灭作用及二者的结合作用,使体系的猝灭常数及结合常数增大,且影响顺序为Fe~(3+)>Cu~(2+)>Pb~(2+).实验表明金属离子对蛋白质在物质的贮存、运转、代谢等方面有重要意义.     

Synthesis and characterizations of ultra-small ZnS and Zn(1-x)Fe(x)S quantum dots in aqueous media and spectroscopic study of their interactions with bovine serum albumin

This work reports a new experimental methodology for the synthesis of ultra small zinc sulfide and iron doped zinc sulfide quantum dots in aqueous media. The nanoparticles were obtained using a simple procedure based on the precipitation of ZnS in aqueous solution in the presence of 2-mercaptoethanol as a capping agent, at room temperature. The effect of Fe(3+) ion concentration as dopant on the optical properties of ZnS was studied. The size of quantum dots was determined to be about 1nm, using scanning tunneling microscopy. The synthesized nanoparticles were characterized by X-ray diffraction, UV-Vis absorption and photoluminescence emission spectroscopies. The presence and amount of iron impurity in the structure of Zn((1-x))Fe(x)S nanocrystals were confirmed by atomic absorption spectrometry. A blue shift in band-gap of ZnS was observed upon increasing incorporation of Fe(3+) ion in the iron doped zinc sulfide quantum dots. The photoluminescence investigations showed that, in the case of iron doped ZnS nanoparticles, the emission band of pure ZnS nanoparticles at 427nm shifts to 442nm with appearance of a new sharp emission band around 532nm. The X-ray diffraction analysis indicated that the iron doped nanoparticles are crystalline, with cubic zinc blend structure, having particle diameters of 1.7±022nm. Finally, the interaction of the synthesized nanoparticles with bovine serum albumin was investigated at pH 7.2. The UV-Vis absorption and fluorescence spectroscopic methods were applied to compare the optical properties of pure and iron doped ZnS quantum dots upon interaction with BSA. It was proved that, in both cases, the fluorescence quenching of BSA by the quantum dots is mainly a result of the formation of QDs-BSA complex in solution. In the steady-state fluorescence studies, the interaction parameters including binding constants (K(a)), number of binding sites (n), quenching constants ( [Formula: see text] ), and bimolecular quenching rate constants (k(q)) were determined at three different temperatures and the results were then used to evaluate the corresponding thermodynamic parameters ΔH, ΔS and ΔG.     

A new fluorescent chemosensor for copper ions based on tripeptide glycyl-histidyl-lysine (GHK)

[structure: see text]. A new fluorescent chemosensor for Cu2+ ions was synthesized by modifying the tripeptide glycyl-histidyl-lysine (GHK) with 9-carbonylanthracene via the standard Fmoc solid-phase peptide synthesis method. While significant fluorescence quenching was observed from the molecule upon binding with Cu2+, addition of Fe2+, Co2+, Ni2+, and Zn2+ to the peptide solution caused a minimum fluorescence emission spectral change, indicating a high specificity of this chemosensor for Cu2+ ions. Effects of pH were also investigated.     

Spectrophotometric Study of Mithramycin Complexes with Cu(II), Fe(III) and Tb(III)

Abstract

The coordination of the anticancer drug mithramycin to Tb(III), Fe(III) and Cu(II) was studied in aqueous solution using absorption measurements. The stability constants were calculated from equilibrium competition experiments by means of the SQUAD program. For both first ions, the competitor was oxalic acid and for the latter the competitor was the Cu(II) ions. Cu(II) at pH 7.5, Fe(III) at pH 3.5 and Tb(III) at pH 5.5 formed respectively 1:2, 1:3 and 1:4 metal-to-ligand species.     

水溶液中对Cr~(3+)高选择性荧光化学传感器的研究

设计了一种新型的Cr3+荧光化学传感器.通过荧光光谱滴定实验研究了其对Li+,Na+,K+,Zn2+,Co2+,Ni 2+,Cu2+,Fe2+,Mn2+,Al 3+,Fe3+和Cr3+等不同金属离子的选择性识别能力,结果表明,该传感器在生理pH=7.4的HEPES中对Cr3+表现出较高的选择性,并与Cr3+形成1∶1配合物,主客体相互作用荧光猝灭的络合常数为(7.80±0.34)×103.