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。     

Zn2+,Cu2+及Ni2+对二甲双胍的配合作用及降血糖活性研究

二甲双胍盐酸盐、硝酸盐及与Zn²⁺, Cu²⁺, Ni²⁺三种金属离子配合物的结构特点、电荷分布和二甲双胍配合物对四氧嘧啶糖尿病小鼠血糖影响的研究表明:Zn²⁺配合物表现为较为少见的单齿配位,而Cu²⁺, Ni²⁺配合物表现为双齿配位.进一步电荷分布计算发现,与端基N原子相比,二甲双胍的桥基N原子具有较高的负电荷.三种金属离子配合物对四氧嘧啶糖尿病小鼠血糖的影响研究显示,桥基N配位掩蔽后,二甲双胍的降血糖功能丧失.说明桥基N对二甲双胍的降血糖作用具有重要意义.     

溶液中杯[4]芳烃双冠-6与Cs~+配位化学研究

研究了溶液中杯[4]芳烃双冠-6(BisC₆)与Cs⁺配位行为.常温下,BisC₆/NPME(邻硝基苯甲醚)体系单级萃铯百分率达99.36%,模拟料液中,Cs⁺/Na⁺和Cs⁺/K²⁺分离系数分别为3.92×10⁴和2.21×10⁴.局域结构模型实验表明,配合物分子中可能存在水或(和)硝酸(根).ESI-MS谱表明,NPME体系中,铯离子与BisC₆同时形成1:1(单核)和2:1(双核)的配合物,并且存在[BisC₆·H₂O],[BisC₆·Cs⁺]⁺,[BisC₆·2Cs⁺·H₂O]₂+和[BisC₆·2Cs₁₀⁺·No₁₀^-3]10⁺等多种配合物分子.EXAFS实验表明,溶液中铯离子的配位数为7,形成7个氧配位的稳定结构,ADF计算验证了EXAFS实验结果.     

4-(4-羧基苯氧基)间苯二甲酸构筑的过渡金属配位聚合物: 合成、 晶体结构、 荧光传感与光催化

采用水热法合成了4个配位聚合物[Zn(Hcpoia)(2,2'-bpy)·H₂O]_n(1)和[M(Hcpoia)(phen)]_n·nH₂O[M=Zn(2), Mn(3), Co(4); H₃cpoia=4-(4-羧基苯氧基)间苯二甲酸; 2,2'-bpy=2,2'-联吡啶; phen=1,10-邻菲罗啉], 利用X射线单晶衍射分析确定了配合物的晶体结构. 配合物1为一维链状结构, 中心Zn ²⁺离子的配位环境为[ZnO₄N₂]扭曲的八面体构型, 配体Hcpoia ^2-以μ₁∶η ¹η ⁰和μ₁∶η ¹η ¹配位模式桥连相邻的Zn ²⁺离子. 配合物2和4的结构与配合物1类似, 是由配体Hcpoia ^2-以μ₁∶η ¹η ⁰和μ₁∶η ¹η ¹配位模式联接[MO₄N₂]结构单元而形成的一维链状结构. 配合物1, 2和4中均存在分子间氢键(O—H…O), 氢键的存在使一维链连接形成二维超分子结构. 配合物3为二维网状结构, Mn ²⁺离子的配位环境为[MnO₄N₂]扭曲的八面体构型, 配体Hcpoia ^2-以μ₂∶η ¹η ¹配位模式桥连相邻Mn ²⁺离子形成[Mn₂COO₂]结构单元, 该结构单元被Hcpoia ^2-连接形成二维结构. 在4个配合物中, 2,2'-bpy和phen配体均以端基的形式与金属离子螯合配位. 研究了水溶液中抗生素分子和Fe ³⁺离子对配合物1与荧光强度的影响, 实验结果表明, 甲硝唑、 Fe ³⁺离子对配合物1有荧光猝灭作用, 并进一步考察了甲硝唑浓度和Fe ³⁺离子浓度对配合物1荧光强度的影响. 基于荧光猝灭机理, 配合物1可以用作荧光传感器检测水溶液中的甲硝唑和Fe ³⁺离子. 研究了配合物4对罗丹明B(RhB)的催化降解性能, 发现在氙灯照射和H₂O₂存在条件下, 配合物4对RhB具有较好的光催化降解作用.     

基于3-乙基-1-(2-噻吩基)咪唑鎓的环金属钌配合物的合成及其对Hg2+的识别

以3?乙基?1?(2?噻吩基)咪唑鎓(L)和2,2'?联吡啶(bpy)为配体,合成了一个新的环金属钌配合物[Ru(L)(bpy)₂]⁺(1),并通过NMR和HRMS谱表征了该配合物。用紫外可见吸收光谱实验研究了该配合物对常见金属离子的识别作用,发现在CH₃CN/HEPES中,仅Hg²⁺的加入使配合物溶液的最大吸收峰由546 nm蓝移至448 nm,溶液由紫红色变为黄色。通过吸收光谱及质谱分析,推测Hg²⁺与配合物1的作用机理可能是Hg²⁺与硫作用引起Ru—C配位向Ru—S配位模式转化。     

吡唑-吡啶铕配合物的合成、结构及荧光效应

以硝酸铕为金属源,2,6-二-[3-(5-苯基-1-氢-吡唑基)]吡啶(L)为配体,在水热反应条件下合成了一种新型配合物Eu(L)(MeOH)(NO₃)₃。 通过元素分析、红外光谱、热重分析、X射线粉末衍射以及X射线单晶衍射方法对该配合物进行了表征。 结构分析表明,配合物的中心金属为九配位,每个中心金属铕原子与L配体中的3个N原子和硝酸根离子和配位甲醇分子上的6个氧原子配位,形成轻微扭曲的三帽三角棱柱体的空间构型。 荧光性能研究发现,该配合物对金属离子铜和镍有较强的荧光猝灭效应。即使在其它竞争金属离子的存在下,配合物仍然可以选择性地检测Cu²⁺,但对选择性的检测Ni²⁺有一定影响。     

基于香豆素与胍的荧光探针的合成及对Co2+、Fe3+的识别研究(英文)

本论文设计合成了基于1,3-二氨基胍盐酸盐、氨基胍盐酸盐的新型香豆素类荧光探针L1、L2。通过紫外-可见、荧光光谱的变化研究探针L1、L2对金属离子的识别效应。利用Job’s plot曲线确定探针L1与Co²⁺形成了1∶2的配合物,探针L2和Fe³⁺形成了3∶1的配合物,且表现为明显的荧光增强。探针L1对Co²⁺的检出限可达到10^-6mol/L,探针L2对Fe³⁺的检出限可达到10^-7mol/L。两种高灵敏度荧光探针有望应用于生物和环境监测领域。     

吸收光谱法研究新型双钼配合物{Mo[S2CN(C2H5)2 4}{MOCl6)}的结构

双钼配合物〔Mo(DTC)₄〕〔MoCl₆〕(其中DTC=S₂CN(C₂H₅)₂)由于它在一个分子中同时包含两个处于不同配位环境中的、表观氧化态都是正五价的钼,即:一个Mo⁵⁺与四个DTC配体构成配位阳离子〔Mo(DTC)₄〕⁺;另一个Mo⁵⁺与氯离子配体构成配位阴离子〔MoCl₆〕^-而独具特色。本文首次发表了它的红外和紫外-可见吸收光谱数据,并通过初步的光谱分析,确定了上述配合物的结构特征。     

烯醇-酮互变异构型亚胺衍生物对Co2+的高选择性识别

设计合成了新型烯醇-酮互变异构型亚胺衍生物R, 考察了受体R对18种阳离子的紫外光谱及裸眼识别性能. 结果表明, 该受体对Co²⁺, Fe²⁺和Ni²⁺表现出良好的紫外光谱识别能力, 且可实现对Co²⁺相对明显的裸眼单一识别. Job曲线表明, 受体R与Co²⁺形成了1:1型金属配合物, 且检出限可达4.14×10^-7 mol/L. 制备了受体R裸眼比色识别试纸; 根据理论计算及核磁滴定实验结果阐述了Co²⁺离子识别过程中烯醇-酮互变异构机理.     

配合物[Eu(4-MOBA)3(terpy)(H2O)]2的合成、表征、热分解机理及性质

合成了一个新的配合物[Eu(4-MOBA)₃(terpy)(H₂O)]₂ (4-MOBA:4-甲氧基苯甲酸根, terpy:2, 2':6', 2"-三联吡啶)。采用傅里叶变换红外(FTIR)光谱、元素分析和X射线粉末衍射(XRD)技术对标题配合物进行了表征,用X射线单晶衍射仪测定了配合物的晶体结构,在配合物中每个Eu³⁺离子与一个三联吡啶分子、一个水分子和三个羧酸分子结合,配位数为9,羧酸基团的配位模式包含三种:双齿螯合,桥连双齿,单齿。根据热重-差示扫描量热/傅里叶变换红外(TG-DSC/FTIR)联用技术,研究了配合物的热分解机理。配合物的发射光谱显示出Eu³⁺离子的特征荧光发射,表明三联吡啶和4-甲氧基苯甲酸在该体系中可作为敏化集团。另外,文中还讨论了配合物对白色念珠菌和大肠杆菌的抑菌活性。     

铝,镁,锌—氟哌酸配合物的荧光特性及其脂溶性研究

探讨了介质ＰＨ值及Ａｌ＾３－，Ｍｇ＾２＋，Ｚｎ＾２＋离子对喹诺酮类药物氟哌酸荧光特性的影响。发现铝，镁及锌离子在不同ＰＨ值条件下与氟哌酸形成配合物而增强荧光，据此建立了用铝离子增强荧光测定氟哌酸含量的新方法。     

Theoretical investigation of electron paramagnetic resonance spectra and local structure distortion for Mn2+ ions in CaCO3:Mn2+ system: a simple model for Mn2+ ions in a trigonal ligand field

This paper reports on a novel application of a ligand field model for the detection of the local molecular structure of a coordination complex. By diagonalizing the complete energy matrices of the electron-electron repulsion, the ligand field and the spin-orbit coupling for the d5 configuration ion in a trigonal ligand field, the local distortion structure of the (MnO6)10- coordination complex for Mn2+ ions doped into CaCO3, have been investigated. Both the second-order zero-field splitting parameter b(0)2 and the fourth-order zero-field splitting parameter b(0)4 are taken simultaneously in the structural investigation. From the electron paramagnetic resonance (EPR) calculations, the local structure distortion, DeltaR=-0.169 A to -0.156 A, Deltatheta=0.996 degrees to 1.035 degrees for Mn2+ ions in calcite single crystal, DeltaR=-0.185 A to -0.171 A, Deltatheta=3.139 degrees to 3.184 degrees for Mn2+ ions in travertines, and DeltaR=-0.149 A to -0.102 A, Deltatheta=0.791 degrees to 3.927 degrees for Mn2+ ions in shells are determined, respectively. These results elucidate a microscopic origin of various ligand field parameters which are usually used empirically for the interpretation of EPR and optical absorption experiments. It is found that the theoretical results of the EPR and optical absorption spectra for Mn2+ ions in CaCO3 are in good agreement with the experimental findings. Moreover, to understand the detailed physical and chemical properties of the doped CaCO3, the theoretical values of the fourth-order zero-field splitting parameters b(0)4 for Mn2+ ions in travertines and shells are reported first.     

Theoretical study of local structure for Ni2+ ions at tetragonal sites in K2ZnF4:Ni2+ system

A theoretical method for studying the local lattice structure of Ni2+ ions in (NiF6)(4-) coordination complex is presented. Using the ligand-field model, the formulas relating the microscopic spin Hamiltonian parameters with the crystal structure parameters are derived. Based on the theoretical formulas, the 45 x 45 complete energy matrices for d8 (d2) configuration ions in a tetragonal ligand-field are constructed. By diagonalizing the complete energy matrices, the local distortion structure parameters (R perpendicular and R || ) of Ni2+ ions in K2ZnF4:Ni2+ system have been investigated. The theoretical results are accorded well with the experimental values. Moreover, to understand the detailed physical and chemical properties of the fluoroperovskite crystals, the theoretical values of the g factor of K2ZnF4:Ni2+ system at 78 and 290 K are reported first.     

Simultaneous determination of Cu2+, Zn2+, Cd2+, Hg2+ and Pb2+ by using second-derivative spectrophotometry method

A new method of simultaneous determination of Cu2+, Zn2+, Cd2+, Hg2+ and Pb2+ is proposed here by using the second-derivative spectrophotometry method. In pH=10.35 Borax-NaOH buffer, using meso-tetra (3-methoxyl-4-hydroxylphenyl) porphyrin ([T-(3-MO-4-HP)P]) as chromomeric reagent, micelle solution was formed after Tween-80 surfactant was added into the solution containing Cu2+, Zn2+, Cd2+, Hg2+ and Pb2+ ions. The original absorption spectrum of the above complexes was obtained after heating in the boiling water for 25 min. The second-derivative absorption peaks of five metal-porphyrin complexes can be separated from the original absorption spectrum by using chemometric tool. In this way, Cu2+, Zn2+, Cd2+, Hg2+ and Pb2+ ions can be determined simultaneously. Under the optimal conditions, the linear ranges of the calibration curve were 0-0.60, 0-0.60, 0-0.40, 0-0.80 and 0-0.48 μg mL(-1) for Cu2+, Zn2+, Cd2+, Hg2+ and Pb2+, respectively. The molar absorptivity of these color systems were 1.38×10(5), 1.01×10(5), 3.24×10(5), 1.07×10(5) and 1.29×10(5)Lmol(-1)cm(-1). The method developed in this paper has advantages in selectivity, sensitivity, operation and can effectively resolve spectra overlapping problem. This method has been applied to determine the real samples with satisfactory results.     

Crystal structures of the NO and N2O4 sorption complexes of fully dehydrated fully Cd2+-exchanged zeolite X (FAU): coordination of neutral NO and N2O4 to Cd2+

The structures of the nitric oxide and dinitrogen tetroxide sorption complexes of dehydrated fully Cd2+-exchanged zeolite X (FAU) have been determined using single-crystal X-ray diffraction in the cubic space group Fdm at 21(1) degrees C. Ion exchange was accomplished by allowing an aqueous stream 0.05 M in Cd2+ to flow past each crystal for 5 days. Each crystal was then dehydrated at 500 degrees C and 2 x 10(-6) Torr for 2 days, followed by exposure to 100 Torr of zeolitically dry NO or NO2/N2O4 gas. The structures were determined in these atmospheres. The unit cell constants at 21(1) degrees C are 24.877(2) A for the dark-yellow NO complex, |Cd46(NO)16|[Si100Al92O384]-FAU, and 24.735(2) A for the black N2O4 complex, |Cd46(N2O4)25.5|[Si100Al92O384]-FAU. The structure of the NO complex was refined to R1 = 0.072 and wR2 = 0.134. In this structure, Cd2+ ions occupy four crystallographic sites. Fifteen Cd2+ ions occupy site I (at the centers of the double 6-rings (D6Rs)), and one occupies site I' (in the sodalite cavity opposite a D6R). The remaining 30 Cd2+ ions occupy two different sites II (near 6-rings in the supercages): 16 coordinate to nitric oxide molecules and 14 do not. Sixteen NO molecules lie in the supercage where each interacts weakly with a Cd2+ ion: Cd-N = 2.57(22) A. The observed N-O bond distance is 1.28(25) A and Cd-N-O is 118(10) degrees. The structure of the N2O4 complex was refined to R1 = 0.084 and wR2 = 0.216. In this structure, Cd2+ ions occupy only three crystallographic sites. The 16 D6Rs per unit cell are filled with 11.5 Cd2+ ions at site I and 9 Cd2+ ions at site I': 11.5 + 9/2 = 16. The remaining 25.5 Cd2+ ions occupy site II where each coordinates at 2.43(8) A to a nitrogen atom of a N2O4 molecule. At the coordinating nitrogen atom, O-N-O is 147(10) degrees and the N-O bond lengths are 1.07(9) and 1.23(10) A. At the second nitrogen atom, O-N-O is 140(10) degrees, and the N-O bond lengths are 1.03(13) and 1.42(12) A. The imprecisely determined N-N bond length, 2.74(17) A, appears to be very much lengthened by coordination to Cd2+. The Cd-N-N angle is 144(10) degrees. This appears to be the first crystallographic report of the coordination of N2O4 to a cation.     

Single and double pH-driven Cu2+ translocation with molecular rearrangement in alkyne-functionalized polyamino polyamido ligands

A new series of ligands, containing one (L1H(2)-L4H(2)) or two (L5H(4)-L6H(4)) 1,4,8,11-tetraaza-5,7-dione units and functionalized with a propargyl group on the C atom between the C=O moieties, has been synthesized. Protonation constants for the ligands and formation constants of their Cu(2+) complexes have been determined in water, and the coordination geometry of the complexes existing at various pH values has been investigated by coupled pH-metric and spectrophotometric titrations. Ligands capable of simple uptake of Cu(2+) with the formation of neutral, square-planar complexes containing the -2-charged diamino-diimido donor sets and ligands containing further coordinating groups (quinoline or pyridine) capable of single and double cation translocation have been investigated. The role of the substituents on the amino groups and the structural role played by the propargyl group have been examined as regards Cu(2+) complexation and translocation. In the double-translocating ligand L6H(4), when the two Cu(2+) ions move inside the diamino-diamido donor set, the slim propargyl group allows an unprecedented folding of the whole ligand with apical coordination of one pyridine to form a five-coordinate, square-pyramidal Cu(2+) ion. The crystal and molecular structures of this unusual [L6Cu(2)] complex have been determined by X-ray diffraction. Finally, oxidation of Cu(2+) to Cu(3+) has been studied by cyclic voltammetry in water, which revealed that the redox reaction occurs only when the copper cation is within the diamino-diimido compartment. Moreover, both functionalization of the primary amines with bulky substituents and apical coordination of Cu(2+) make access to the 3+ oxidation state more difficult and disrupt the reversibility of the electrochemical process.     

Selective detection of Zn2+ and Cd2+ ions in water using a host-guest complex between chromone and Q[7]

In this paper, the host-guest interaction of cucurbit[7]uril (Q[7]) and chromone (CMO) has been developed as a fluorescent probe for the highly selective detection of Zn²⁺ and Cd²⁺ in water based on a chelation-enhanced fluorescence (CHEF) mechanism. There was a good linear relationship between the fluorescence intensity of the CMO@Q[7] probe and the concentration of Zn²⁺ or Cd²⁺ in the range of 0–3.0 × 10^–5 mol/L and the detection limit for Zn²⁺ and Cd²⁺ was found to be 2.03 × 10^–6 mol/L and 1.89 × 10^–6 mol/L, respectively. The X-ray crystal structure indicated that different coordination fashions were triggered by Zn²⁺ and Cd²⁺ in the CMO@Q[7] complexes, respectively. However, both metal ions coordinated with the carbonyl oxygen of CMO, which was encapsulated in the cavity of Q[7], thus leading to the enhancement of recognition fluorescence emission of CMO.     

Electrostatic versus nonelectrostatic effects in DNA sequence discrimination by divalent ions Mg2+ and Mn2+

Mg2+ and Mn2+ ions are critical to the functioning of phosphoryl transfer enzymes, such as restriction endonucleases. Although these ions play similar roles in the chemical steps, they govern substrate specificity via modulating sequence discrimination by up to a factor of 10(5) with Mg2+ and only up to a factor of 10 with Mn2+. To explain whether such diversity originates in fundamental differences in the electronic structures of the nucleobase-hydrated-metal ion complexes, structures and interaction energies were determined at the density functional (DFT) and second-order M?ller-Plesset (MP2) levels of theory. Although both metal ions favor identical binding sites, Mn2+ complexes exhibit greater distortions from the ideal octahedral geometry and larger variability than the corresponding Mg2+ systems. In inner-shell complexes, with direct contact between the metal and the nucleobase, Mg2+ is preferred over Mn2+ in the gas phase, due primarily to nonelectrostatic effects. The interaction energies of the two metal ions are more similar in the outer-shell complexes, likely due to reduced charge transfer between the hydrated metal ion and the base moieties. Inclusion of solvation effects can amplify the relative nucleobase preferences of Mg2+ and Mn2+, indicating that bulk hydration modulates the balance between electrostatic and nonelectrostatic terms. In most cases, the base substitutions in solution are facilitated more by Mn2+ than by Mg2+. Electrostatic properties of the environment were demonstrated to have a major influence on the nucleobase preferences of the two metal ions. Overall, quantum chemical calculations suggest that the contrasting selectivity of Mg2+ and Mn2+ cofactors toward nucleobases derives from the larger flexibility of the Mn2+ complexes accompanied by the excessive polarization and charge-transfer effects as well as less favorable solvation.     

Theoretical study of hydrated Be2+ ions

Hydrated Be²⁺ ions [Be(H₂O)_n]²⁺, n = 1−4 and 6, were examined theoretically. The structure of the hydrated ions was determined and the hydration energy estimated with and without electron correlation. The bond between the Be²⁺ ion and the oxygen of water is very strong and has the nature of a dative bond. The non-additivity of the binding energy is so profound that without taking it into account the structure and dynamics of Be²⁺ ions cannot be explained. The hydration number in water is found to be 4. The fifth and sixth water molecules prefer forming the second coordination shell to the Be²⁺ ion. The result is in agreement with X-ray analysis of the aqueous solution, but not with a recent molecular dynamics simulation. In addition, the harmonic vibrational frequencies for the complexes are evaluated and compared with some experiments.     

La3Ni2O6: a new double T'-type nickelate with infinite Ni1+/2+O2 layers

New mixed-valent, Ni1+/Ni2+, metastable nickelate, La3Ni2O6, was synthesized by low-temperature reduction of La3Ni2O7 with CaH2. The crystal structure of La3Ni2O6 (space group: I4/mmm, a = 3.9686(1) A and c = 19.3154(6) A) was determined from powder neutron diffraction data by Rietveld analysis. The structure can be described as an intergrowth of LaO2 fluorite and double infinite layer (LaNiO2)2 blocks and represents the n = 2 homologue of the T'-type series Lan+1NinO2n+2. Such double T'-type structural arrangement has never been observed before. The 3d9/3d8 electronic configuration of Ni1+/Ni2+ and the presence of NiO2 infinite layers resemble electronic and structural features of the superconducting cuprates. X-ray absorption spectroscopy supports the 1+/2+ oxidation state and planar coordination of Ni in agreement with the structure determination.