一种新的褪色光度法测定Cr^3＋的方法研究

提出了一种褪色光度法测定Cr~(3+)的新方法。新的叠氮试剂3-(苯偶氮苯)-1-三氮烯苯甲酸钠(PTBAS)在NaOH-Na_2B_4O_7缓冲液中,在表面活性剂OP的存在下,与Cd~(2+)反应后形成一种橙红色的络合物。测定Cd~(2+)时,当有微量Cr~(3+)共存时,络合物吸光度值明显降低,利用这种现象可以间接测定Cr~(3+)。测得Cr~(3+)的表观摩尔吸光系数ε=1.12×10~5,线性范围为0～0.4μg·ml~(-1)。方法选择性很高,很多常见离子不干扰测定,可直接用于水样中Cr~(3+)的测定。     

掺锰五磷酸铈、铽晶体的生长及其光谱

用蒸发溶液法从磷酸溶液中首次生长出一系列Ce_xTb_(1-x)P_5O_(14):Mn晶体。它们属于单斜晶系,空间群P2_1/c。计算了晶格常数,用EPR结果确定在晶体中锰离子呈二价。测定了Ce_xTb_(1-x)P_5O_(14):Mn晶体的光谱,说明在晶体中存在着Ce~(3+)到Tb~(3+)和Mn~(2+)的能量转移。Mn~(2+)和Tb~(3+)的发射峰重叠,并使Tb~(3+)的发射峰增强。     

LiNbO_3晶体中Pr~(3+)离子的配位场能级计算

在C3v点群对称场中,运用双层点电荷配位场(DSCPCF)模型计算了LiNbO3晶体中Pr3+离子的40个配位场能级,与实验值相比,其均方根偏差为19.94 cm-1,优于文献值(44.22 cm-1).所得晶体场参数也明显好于文献值,说明双层点电荷模型能更好地拟合实验结果,对于研究C3v对称场中稀土离子的光谱特性具有非常重要的意义.     

TbP_5O_(14)中Tb~(3+)离子~5D_4,~7F_J(J=0—6)的Stark能级

本文测定了五磷酸铽单晶在77K下的偏振荧光光谱和红外吸收光谱。根据这些光谱,~5D_4,~7F多重态的能级结构以及跃迁归属已被确认。从X光结构分析的结果,该晶体中Tb~(3+)离子与八个近邻的氧原子相配位,呈稍歪扭的正方反棱柱体。换句话说,在TbP_5O_(14)中Tb_(3+)离子的局部对称性属于C_(4v)。按该对称性,利用配位场理论所做的计算与实验观察的~7F_J(J=0—6)多重态的Stark分裂得到了相当好的符合。其结果是,均方根差为8.4cm~(-1),最大偏差为17cm~(-1)。     

新型席夫碱Cr~(3+)荧光探针及其细胞成像研究

Cr~(3+)离子在脂肪、核酸、糖和蛋白质的代谢中发挥着重要作用,并且Cr~(3+)离子被认为是一种致癌物质,对人类有极大的危害.因此,通过将8-羟基喹啉醛和硫代碳酰肼反应制备出化合物L.探针L的CH_3CN/H_2O(V∶V=1∶2,Tris buffer 50 mmol/L,p H=7.3)溶液中加入Cr~(3+)离子,可以通过肉眼观察到其颜色从无色到黄色的变化和明显的荧光增强效应,这些现象表现出探针L对Cr~(3+)离子具有良好的选择性.根据Job曲线、荧光滴定、质谱和密度泛函理论(DFT)计算确定了探针L与Cr~(3+)离子形成1∶1的络合物.络合常数为1.00×10~5 L/mol,检测限为2.85×10~(-7 )mol/L.此外,生物成像实验表明,探针L可以通过荧光增强信号检测活细胞中的Cr~(3+)离子.     

d~5系C_(2h)点群强场方案和MnCl_2·2H_2O的吸收谱

利用一种处理低对称络离子吸收谱强场方案,推出d~5系C_(2h)点群不可约表示对应的能量矩阵。考虑振动电子偶合及双电子激发,解释了MnCl_2·2H_2O晶体中Mn~(2+)的复杂吸收谱。确认了Mn~(2+)络离子晶场的C_(2h)对称性。     

LiNbO3晶体中Pr3+离子的配位场能级计算

在C3v点群对称场中，运用双层点电荷配位场（DSCPCF）模型计算了LiNbO3晶体中Pr^3＋离子的40个配位场能级，与实验值相比，其均方根偏差为19．94cm^-1，优于文献值（44．22cm^-1）．所得晶体场参数也明显好于文献值，说明双层点电荷模型能更好地拟合实验结果，对于研究C3v对称场中稀土离子的光谱特性具有非常重要的意义．     

CsCdBr3晶体中Nd3+离子的晶体场能级计算

在C3v点群对称场中,运用双层点电荷和点电荷配位场模型计算了CscdBR3晶体中Nd3+离子的65个配位场能级,与实验能级值相比,它们的均方根偏差分别为29.27和36.25cm-1.结果表明:双层点电荷模型引入键电荷q是成功的,它能够更准确地反映中心离子与配体之间相互作用的真实情况,对研究C3v对称场中稀土离子的光谱特性具有非常重要的意义.     

水泥基材料铝酸三钙对不同价态金属离子的去除及其机制研究——以Zn(Ⅱ)和Cr(Ⅲ)为例

为考察水泥基材料中铝酸三钙(C_3A)稳定重金属离子的能力及其作用机制,研究了C3A对不同价态金属离子的吸附行为,并考察了溶液初始p H值对吸附效果的影响。同时,结合反应前后固体产物表征,重点讨论了C_3A对不同价态重金属离子的去除机理。结果表明,C_3A对Zn2+和Cr~(3+)的吸附动力学分别符合一级Lagergren方程(R~2=0.9714)和准二级动力学方程(R~2=0.9999),吸附等温线均符合Langmuir等温吸附模型,C_3A对Zn2+和Cr~(3+)的最大吸附量分别为13.73mmol/g和5.68mmol/g;升高p H值有利于C_3A对金属离子的吸附;C_3A对Zn~(2+)的作用机理主要为主层板阳离子交换作用,而对Cr~(3+)的去除主要依靠溶解-再沉淀作用。     

群链R3i-D4d-C2v及dN体系在C2v对称性场中的能量矩阵

R_(3i)—D_(4d)—C_(2v)是一条群链。本文讨论如何应用D_(4d)群的标准基函作为C_(2v)群的基函来写出d~N体系在C_(2v)对称性场中各配场谱项的能量矩阵H_1。H_1中的H_(el)。部分完全可以应用D_(4d)的H_1中的H_(el)。,因而简化了计算。所得能量矩阵H_1与前文列出的H_1等价。     

EPR and optical absorption studies on Cr3+ ions doped in KZnClSO4 x 3H2O single crystals

EPR and optical absorption spectra of Cr3+ ions doped in KZnClSO4 x 3H2O single crystals have been studied at room temperature. The EPR spectrum exhibits a group of three fine structure transitions characteristic of Cr3+ ions. From the observed EPR spectra, the spin-Hamiltonian parameters have been determined. The optical absorption spectrum exhibits two broad bands characteristic of Cr3+ ions in an octahedral symmetry. From the observed band positions, the crystal field parameters have been evaluated.     

Local lattice structure study of the octahedral (CrO6)9- clusters for Cr3+ ion doping in a variety of oxide crystals by simulating the corresponding EPR and optical spectra

On the basis of the 120 x 120 complete energy matrix, the local lattice structures of the octahedral (CrO6)9- clusters for Cr3+ ions doping in a variety of oxide crystals with D3d or C3v site symmetry have been studied by employing two distorted parameters, respectively. By simulating the calculated EPR and optical spectra data to the experimental results, the local lattice structure parameters are determined unambiguously. It is shown, by means of a series of calculations, that although the local lattice structures around the M (M = Al3+, Ga3+, Li+, Sc3+, etc.) ions in host crystals are obviously different, the local lattice structures of the octahedral (CrO6)9- clusters in a variety of oxide crystals doped with Cr3+ ions are similar and fluctuant in the vicinity of that of the Cr2O3. This may be ascribed to the fact that there is the similarly octahedral (CrO6)9- clusters in a variety of oxide crystals doped with Cr3+ and the Cr2O3 crystal. Our viewpoint is consistent with that of Gaudry et al. [Phys. Rev. B 2003, 67, 094108].     

d3(Re+4)和d4(Os+4)组态晶体能谱的配位场理论分析

本文根据文献[4]提出的配位场理论方法,采用SLГ_SГtτ方案,对晶体K₂PtCl₆中Re⁺⁴(5d³)和Os⁺⁴(5d⁴)离子能谱进行全分析,考虑了全部d³和d⁴组态的静电作用能,正八面体场势能和旋轨偶合作用能,计算了能级随参数变化曲线,能谱理论计算结果与文献[9-10]强场方案计算结果一致,但改正了前人对实验能谱指认不正确之处。     

水合五异硫氰铬(Ⅲ)酸钾的18-冠-6配合物的合成、性质及晶体和分子结构

在硅凝胶中培养了标题配合物的单晶,确定了它的组成,并进行了热谱、可见光谱、红外光谱及其他多项物理性质的测试和表征,其结果与单晶X射线衍射分析的结果一致。晶体学数据:分子式[K(18-冠-6)(H_2O)][K(18-冠-6)][Cr(H_2O)(NCS)_5]·H_2O,空间群C_(2h)~5—P2_1/n,a=8.592(5),b=22.976(10),c=24.372(4)A,13=96.57(4)~0,Z=4。结构用直接法解出,全矩阵最小二乘方修正,R=0.046。结果表明,铬(Ⅲ)由五个异硫氯酸根离子和一水分子配位形成一畸变八面体形的配合阴离子。一个钾离子由一个冠醚和另一水分子配位;另一钾离子由另一冠醚和一配位于铬(Ⅲ)的硫氯酸根的硫原子配位,即该N(3)-C(3)-S(3)桥连在Cr和K(2)之间;两钾离子均是7配位。第三个水分子通过氢键与阴离子的配位水分子和两个冠醚环上的醚氧原子相连。     

希土离子单硫代二苯甲酰甲烷配合物的合成及性质研究

本文合成了单硫代二苯甲酰甲烷(HTDBM)和三价希土离子及路易斯碱(Q)的Ln(TDBM)_4QH型配合物(Ln=除Ce外的La～Lu,Q=二乙基胺)。测定了它们的摩尔电导值、红外光谱,可见—紫外光谱,核磁共振谱.观察到配合物是通过硫原子、氧原子同时与Ln~(3+)离子配位.Ln-O键强于Ln-S键。在Nd~(3+)、Pr~(3+)、Ho~(3+)、Er~(3+)离子的该类配合物的可见吸收光谱中发现超灵敏跃迁现象。讨论了题述配合物作为核磁共振化学位移试剂的可能性.     

Reactions of atomic transition-metal ions with long-chain alkanes

Understanding metal ion interactions with long-chain alkanes not only is of fundamental importance in the areas of organometallic chemistry, surface chemistry, and catalysis, but also has significant implication in mass spectrometry method development for the analysis of polyethylene. Polyethylene represents one of the most challenging classes of polymers to be analyzed by mass spectrometry. In this work, reactions of several transition-metal ions including Cr+, Mn+, Fe+, Co+, Ni+, Cu+, and Ag+ with long-chain alkanes, C28H58 and C36H74, are reported. A metal powder and the nonvolatile alkane are co-deposited onto a sample target of a laser desorption/ionization (LDI) time-of-flight mass spectrometer. The metal ions generated by LDI react with the vaporized alkane during desorption. It is found that all these metal ions can form adduct ions with the long-chain alkanes. Fe+, Co+, and Ni+ produce in-source fragment ions resulting from dehydrogenation and dealkylation of the adduct ions. The post-source decay (PSD) spectra of the metal-alkane adduct ions are recorded. It is shown that PSD of Ag+ alkane adduct ions produces bare metal ions only, suggesting weak binding between this metal ion and alkane. The PSD spectra of the Fe+, Co+, and Ni+ alkane adduct ions display extensive fragmentation. Fragment ions are also observed in the PSD spectra of Cr+, Mn+, and Cu+ alkane adduct ions. The high reactivity of Fe+, Co+, and Ni+ is consistent with that observed in small alkane systems. The unusually high reactivity of Cr+, Mn+, and Cu+ is rationalized by a reaction scheme where a long-chain alkane first forms a complex with a metal ion via ion/induced dipole interactions. If sufficient internal energy is gained during the complex formation, metal ions can be inserted into C-H and C-C bonds of the alkane, followed by fragmentation. The thermal energy of the neutral alkane is believed to be the main source of the internal energy acquired in the complex. Finally, the implication of this work on mass spectrometry method development for polyethylene analysis is discussed.     

Luminescence behavior of Eu3+ doped LaF3 nanoparticles

Europium-doped LaF3 nanoparticles have been prepared by the ionic reaction in the ethanol at 60 degrees C. From the XRD pattern of nanoparticles and the emission spectra of Eu3+ ions, it has been concluded that the Eu3+ ions could easily substitute the La3+ sites and the solid solution La(1-x)Eu(x)F3 can be synthesized. Due to very low phonon energies of LaF3 matrix, the 5D1 emission of Eu3+ ions in La(1-x)Eu(x)F3 nanoparticles can be observed at room temperature when doping concentration of Eu3+ ions is lower than 30 mol%. The quenching process of 5D1 emission can be attributed to cross-relaxation. Since clusters of Eu3+ ions and resonance energy transfer only occurs within one particle due to the hindrance by the particle boundary, the concentration quenching resulted from resonance energy transfer between neighboring Eu3+ ions occurs at higher Eu3+ concentrations in the Eu3+ doped LaF3 nanoparticles.     

三重桥氧三核铬脂肪酸配合物的快原子轰击质谱研究

本文报道三重桥氧三核铬脂肪酸配合物[Cr_3(μ_3-O)(μ-OOCH)_6(H_2O)_2OOCH]和[Cr_3(μ_3-O)(μ-OOCR)_6(H_2O)_3]~+(R=CH_3,C_2H_5和C_3H_7)的快原子轰击(FAB)质谱。当桥配体为甲酸基时获得完整的配位阳离子峰(其单晶结构见文献),由于质子亲电进攻端配体甲酸基的氧,从而形成了质子化的[Cr_3(μ_3-O)(μ-OOCH)_6(H_2O)_2HCOOH]~+离子。后者可以失去CO生成[Cr_3(μ_3-O)(μ-OOCH)_6(H_2O)_3]~+,进一步的断裂和乙酸配位时的情况相同,可连续脱三个配位水,分别生成[Cr_3O(OOCR)_6(H_2O)_2]~+、[Cr_3O(OOCR)_6(H_2O)]~+和[Cr_3O(OOCR)_6]~+离子;并可进一步脱桥配基或RCO,分别生成[Cr_3O(OOCR)_5]~+、[Cr_3O(OOCR)_4]~+、[Cr_3O(OOCR)_3]~+、[Cr_3O(OOCR)_5O]~+、[Cr_3O(OOCR)_4O]~+、[Cr_3O(OOCR)_3O]~+和[Cr_3O(OOCR)_2O]~+等碎片离子。当桥配体为丙酸和丁酸时,主要观察到[Cr_3O(OOCR)_6]~+离子及其进一步断裂所形成的碎片离子,断裂过程和乙酸配位时基本相似;另外这类配合物都还形成一系列由FAB底物参与的加成离子。基于以上分析,我们提出了这类配合物可能的断裂过程,并认为随着脂肪酸碳链的增长,整个配位阳离子的稳定性下降。     

3d金属离子对H2O2氧化活性艳红的催化性能

以H2O2氧化活性艳红为研究对象,探讨了七种3d金属离子的催化性能、影响因子及其作用、氧化降解动力学和催化作用机理．通过对pH值、氧化剂用量、金属离子浓度、温度的影响研究,确定了七种3d轨道过渡金属离子的催化性能大小为：Fe^3＋〉Cu^2＋〉Co^2＋〉Mn^2＋〉Cr^3＋〉Ni^2＋〉Zn^2＋．在此基础上得到了该催化氧化反应的一级动力学模型,通过一级动力学模型求得各个金属离子的表观活化能,从活化能的大小得出受温度影响大小的顺序为：Cr^3＋〉Mn^2＋〉Co^2＋〉Cu^2＋〉Ni^2＋〉Zn^2＋〉Fe^3＋．