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     

线性扫描伏安法同时测定铬、镉、铜

在苯胲类试剂-乙醇-醋酸铵体系中，Cr(Ⅵ)、Cd^2 、Cu^2 都能产生灵敏的阴极络合吸附波。Cr(Ⅵ)的二次导数峰电位在-0．92V(vs．SCE)处，在0．0017～0．67μg／mL范围内与峰电流成正比；Cu^2 的峰电位在-0．21V(vs．SCE)处，在0．0083～5．8μg／mL范围内与峰电流成正比；Cd^2 的峰电位在-0．70V(vs．SCE)处，线性范围为0．0017～0．117μg／mL。这一方法为工业废水中重金属的同时测定提供了可靠、灵敏的检测方法。     

Vibrational and electronic studies on interactions of Cu (II) with protic amides: Structural aspects of biological importance

Raman, IR and UV–Vis–NIR experiments of formamide (FA), N-methylformamide (NMF) and their solutions with copper perchlorate at different compositions were carried out. The downshift of the ν_CO mode and the upshift of the νCN vibration have been observed for both amides and suggest that an ionic structure is stabilized by Cu (II). The quantitative Raman study at the νCN region reveals that six FA molecules are coordinated to Cu (II) while four NMF molecules are around the metal ion. The data are complemented by information at the region characteristic of the metal–ligand vibrations, which evidences coordination through the O atom. The spectral changes observed at the ν_CN region have been then combined to the electronic data and show that [Cu(FA)₆]²⁺ and [Cu(NMF)₄]²⁺ are described as distorted octahedral and square planar complexes.     

Protocol for Extraction and Determination of Cr(VI) in Solid Materials with a High Cr(III)/Cr(VI) Ratio Using EDDS as a Leaching Agent for Cr(VI) and a Masking Agent for Cr(III)

A sensitive and selective protocol for the extraction of all forms of Cr(VI) from solid materials followed by determination by catalytic adsorptive stripping voltammetry has been elaborated. Cr(VI) was leached to a solution with 0.2 mol L^?1 (NH₄)₂SO₄/NH₄OH+0.1 mol L^?1 EDDS (pH 9.5) and simultaneously Cr(III) was transferred to a nonactive electrochemical complex with EDDS. The method allows for Cr(VI) determination in solid samples containing even a 1000–2000 fold excess of extractable Cr(III) without its noticeable influence. The effects of several experimental variables such as the composition and pH of the extractant, the time and temperature of the solid sample mixing with the extractant were studied. At the optimized conditions more than 95% of total Cr(VI) recoveries from solid samples were achieved. The validation of the proposed procedure was carried out by Cr(VI) determination in certified reference material CRM 019 Ash, spiked and unspiked with Cr(III), and by comparing the obtained results with those obtained using other common extraction procedures.     

石墨炉原子吸收光谱法测定土壤中可交换态Cr(Ⅲ)和Cr(Ⅵ)

提出了流动注射离子交换石墨炉原子吸收光谱法测定土壤中可交换态Cr(Ⅲ）和Cr(Ⅵ）的分析方法，优化了提取方法、分离富集条件和流路参数等。分析速度为20样/h，Cr(Ⅲ）和Cr(Ⅵ）的检出限（3σ）分别为24pg和4.0pg，相对标准偏差（n=10)分别为4.7%和5.9%。     

Transition metal complexes of N,N-dimethylthreonine: Stability and UV/Vis spectra

Summary Acidity (dehydronation) constants of N,N-dimethylthreonine (DMT) and stability constants of its complexes with Cu⁺², Ni⁺², and Co⁺² were determined in aqueous solution by means of potentiometric titration. UV/Vis spectra were also taken during the titration. It is suggested thatDMT acts as a bidentate ligand toward copper(II) by engaging either (a) amino and carboxyl groups (in [Cu(DMT)] and [Cu(DMT)₂]), or, (b) upon dehydronation, amino and hydroxyl groups (in [Cu(DMT)H_–1], [Cu(DMT)₂H_–1], and [Cu(DMT)₂H_–2]). It is suggested that the coordination in threoninato andallo-threoninato complexes is similar to that described under (a).Based upon Master of Science thesis submitted to the University of Zagreb, Croatia byB. Blagovi     

脯氨酸与Cu、Cu~+和Cu~(2+)配位体系的计算研究

运用M06-2X和ωB97XD方法分别在6-311++G(2d,p)和TZVP基组水平上,对脯氨酸(Pro)的15种构象与Cu、Cu+和Cu2+形成的多种配合物的几何结构、能量学特征、振动光谱和电子结构等进行计算研究.四种水平得到20种[Pro-Cu]、16种[Pro-Cu]+和16种[Pro-Cu]2+稳定结构.[Pro-Cu]和[Pro-Cu]+体系中出现12种Pro构象,而[Pro-Cu]2+体系中出现11种Pro构象,三种体系中最稳定的结构都不是由能量最低的Pro构象生成的.在结构CI3、CI4、CII7和CII8中,Pro的羧基氢转移到亚氨基氮形成两性离子与Cu双配位结合.[Pro-Cu]0/1+/2+体系四种水平计算相对能差范围逐渐增加,结合能分别在-60.0--5.0 kJ·mol-1、-340.0--170.0 kJ·mol-1和-1100.0--860.0 kJ·mol-1范围,配位体系中Pro的变形能逐渐增加.N―H和O―H键伸缩振动频率普遍发生红移,配位体系中部分电荷从Pro转移到Cu上,在[Pro-Cu]2+体系中单配位结构中电荷转移最多,约为单位负电荷.     

Direct Determination of Cu2+ Based on the Electrochemical Catalytic Reaction of Fe3+/Cu2+

Copper ion (Cu²⁺) is one of the heavy metal ions which has been considered as a severe pollutant affecting the environment and human health. Therefore, it is necessary to detect Cu²⁺ sensitively and conveniently in food and drinks. However, the gold standard method that inductively coupled plasma mass spectrometry (ICP‐MS) is expensive equipment required and time‐consuming. In this work, a highly sensitive and facile electrochemical method was studied to directly determine the concentration of Cu²⁺ without cumbersome modification on the surface of glassy carbon electrode (GCE). In the presence of ferric ion (Fe³⁺), Cu²⁺ could play a role of catalyst in the detection system, and the electrochemical signal of differential pulse voltammetry (DPV) response to Cu²⁺ could be amplified obviously. Under the optimal conditions, a good linear relationship was obtained in the range of 1 nM to 5 μM with a detection limit of 57.5 pM (S/N=3) were obtained. Besides, the proposed method has good applicability for the detection of Cu²⁺ in tap water. Furthermore, the copper complex was detected and the results were indicated the proposed method was effective and sensitive.     

Equilibrium and spectral studies of putrescine complexes with copper(II)

Summary It has been found that in the putrescine-copper system several types of complex compounds (MHL,ML,ML ₂,ML ₂OH) are formed. In thepH range of 7–9, despite a multiple excess of ligand, a precipitation occurs. When adenosine is introduced to the system, the ability to observe the complexation reaction in solution is largely increased, because the additional ligand prevents precipitation. On the basis of computer analysis of potentiometric titration data the stability constants of the compounds have been determined. The coordination mode of the complexes is discussed.

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Gleichgewichte und spektroskopische Untersuchungen an Putrescin-Komplexen mit Kupfer(II)

Zusammenfassung Es wurde festgestellt, daß sich im Putrescin-Kupfer System einige Typen von Komplexen bilden (MHL,ML,ML ₂ andML ₂OH). ImpH-Bereich von 7–9 tritt trotz eines mehrfachen Ligandenüberschusses ein Niederschlag auf. Bei Einführung von Adenosin in das System wird die Beobachtbarkeit der Komplexreaktion verbessert, da der zusätzliche Ligand die Niederschlagsbildung verhindert. Mittels Computeranalyse der potentiometrischen Titrationsdaten wurden die Stabilitätskonstanten der Verbindungen ermittelt. Die Art der Komplexierung wird ebenfalls diskutiert.

     

Simultaneous removal of Cu2+ and Cr3+ ions from aqueous solution based on Complexation with Eriochrome cyanine‐R and derivative spectrophotometric method

TiO₂ nanoparticles deposited on activated carbon (TiO₂–NP–AC) was prepared and characterized by XRD and SEM analysis. Subsequently, simultaneous ultrasound‐assisted adsorption of Cu²⁺ and Cr³⁺ ions onto TiO₂‐NPs‐AC after complexation via eriochrome cyanine R (ECR) has been investigated with UV–Vis and FAA spectrophotometer. Spectra overlapping of the ECR‐Cu and ECR‐Cr complex was resolve by derivative spectrophotometric technique. The effects of various parameters such as initial Cu²⁺ (A) and Cr³⁺ (B) ions concentrations, TiO₂‐NPs‐AC mass (C), sonication time (D) and pH (E) on the removal percentage were investigated and optimized by central composite design (CCD). The optimize conditions were set as: 4.21 min, 0.019 mg, 20.02 and 13.22 mg L^?1 and 6.63 for sonication time, TiO₂–NP–AC mass, initial Cr³⁺ and Cu²⁺ ions concentration and pH, respectively. The experimental equilibrium data fitting to Langmuir, Freundlich, Temkin and Dubinin–Radushkevich models show that the Langmuir model is a good and suitable model for evaluation and the actual behavior of adsorption process and maximum adsorption capacity of 105.26 and 93.46 mg g^?1 were obtained for Cu²⁺ and Cr³⁺ ions, respectively. Kinetic evaluation of experimental data showed that the adsorption processes followed well pseudo second order and intraparticle diffusion models.     

Catalase and Peroxidase Activity of Cu2+ Complexes

The relation between the structure of Cu²⁺ complexes and their catalytic activity in the decomposition of H₂O₂ can be used as a “molecular probe”, since it allows the deduction of the number of coordinated ligand groups in a Cu²⁺ complex from its catalytic activity. Since only coordinated ligand groups are oxidized by H₂O₂, further information about the coordination sphere of the metal ion can be obtained from the oxidation of certain parts of a ligand, which can be followed spectrophotometrically. The Cu²⁺ complexes of amides, polyamino acids, nucleotides, RNA, and native and denatured DNA have been investigated in this way. Kinetic studies provide an insight into the mechanisms of catalase and peroxidase reactions.     

A Logic Fluorescent Chemosensor Based on Eu3+ Functionalized Cd-MOFs for Sensing Fe3+ and Cu2+ Synchronously

One of the most critical and yet unsolved issues is the effective monitoring of multiple heavy metal ions in complex systems through their specific function in fluorescence detection. In this work, luminescence-active cadmium base metal-organic frameworks (Cd-MOFs) based on the planar and rigid π-conjugated structure ligand benzo-(1,2;3,4;5,6)-tris (thiophene-2’-carboxylic acid) (H₃BTTC) was chosen. A series of sensing experiments demonstrated that the Cd-MOFs exhibits selective and sensitive response for Fe³⁺ and Eu³⁺ through fluorescence “turn off” and “antenna effect” respectively. In addition, the encapsulation of Eu³⁺ inside the Cd-MOFs (Eu³⁺@Cd-MOFs) led to an excellent probe with dual emission. To this end, a programmable fluorescence platform was developed to detect Fe³⁺ and Cu²⁺, in which the emission peaks of both the ligand and Eu³⁺ are completely quenched by Fe³⁺. The ratiometric detection of Cu²⁺ leads to a decrease in Eu³⁺ emission, while the ligand emission remains stable. To demonstrate the strategy, the fluorescence (Output) of Cd-MOFs, Eu³⁺@Cd-MOFs, and the analytes (Eu³⁺, Fe³⁺, and Cu²⁺, input) achieved elementary Boolean logic operations (OR, NOR, AND) and they constitute a logic fluorescent chemosensor to analyze Fe³⁺ and Cu²⁺ synchronously.     

Synthesis,characterization and applications of schiff base chemosensor for determination of Cu2+ ions

A novel thiazole-based Schiffbase chemosensor SB1 with N- and O- donor atoms was synthesized and characterized by different techniques (UV–vis, ¹³C NMR, ¹H NMR, and FT-IR analysis). The chemosensor SB1 was used for the determination of Cu²⁺ ions in various samples. The significant spectral changes in absorption spectra of chemosensor SB1 at 220 and 416 nm and the color change from light yellow to yellowish-brown indicate high selectivity and sensitivity towards Cu²⁺ ions as compared to other cations (Na⁺, K⁺, Ag⁺, Zn²⁺, Ni²⁺, Pb²⁺, Mn²⁺, Mg²⁺, Co²⁺, Cd²⁺, Sn²⁺, Hg²⁺, Cr³⁺, Fe^3+, and Al³⁺). The sensing mechanism of SB1 was investigated through various techniques such as FT-IR, UV–vis and ¹H NMR titration experiment and further confirmed by DFT computational studies. The 2:1 binding mode between SB1 and Cu²⁺ ions was confirmed by Job‘s plot using UV–vis spectrophotometry. The limit of detection (LOD) and limit of quantification (LOQ) were found to be 0.015 and 0.0471 µg mL^?1, respectively. The percent recovery of Cu²⁺ from various environmental samples was found to be 95.00–103.33% at various levels. These obtained results demonstrate that chemosensor SB1 is a cost-effective, facile, selective, sensitive, and colorimetric sensing platform to detect trace amounts of Cu²⁺ ions in variousenvironmental and agricultural samples.     

Selective recognition of Fe3+ and Cr3+ in aqueous medium via fluorescence quenching of graphene quantum dots

Graphene quantum dots (GQDs) have been prepared from graphene oxide (GO) and characterized by standard analytical techniques. The size of the prepared GQDs ranges from 2-10?nm. Aqueous dispersion of GQDs exhibited excitation-dependent emission behavior. Emission intensity of the aqueous dispersion found stable for the examined duration of about four months. GQDs exhibited selective recognition of Fe³⁺ and Cr³⁺ out of various common ions such as alkali, alkaline-earth and transition metal ions in aqueous medium through fluorescence quenching. The lower limit of detection of Fe³⁺ is 1?µM and that of Cr³⁺ is 4?µM.     

Synthesis,crystal and spectroscopic characterization of [RuHCl(CO)(PPh3)2(pyrazine)]

The reaction of [RuHCl(CO)(PPh₃)₃] with pyrazine has been examined and a ruthenium(II) complex – [RuHCl(CO)(PPh₃)₂(C₄H₄N₂)] -- has been obtained. The compound has been studied by IR, UV–Vis spectroscopy, and X-ray crystallography. The molecular orbital diagram of the complex has been calculated with density functional theory (DFT). The spin-allowed singlet--singlet electronic transitions of the complex have been calculated with the time-dependent DFT method, and the UV–Vis spectrum of the compound has been discussed on this basis.     

Synthesis,Crystal Structure,and Spectroscopic Characterization of Na5[NiO2][CO3], containing the Linear [NiO2]3– Group with Monovalent Nickel

For the first time ruby‐red single crystals and powder samples of Na₅[NiO₂][CO₃] were obtained via a redox reaction between nickel metal and CdO in the presence of Na₂O and Na₂CO₃ (molar ratios of CdO : Na₂O : Na₂CO₃ equal 1 : 3 : 2). The crystal structure has been refined from single crystal X‐ray diffraction data at 170 K (tetragonal, P4/mmm, a = 462.7(1) pm, c = 830.5(2) pm) and at 293 K (a = 462.35(7) pm, c = 830.9(1) pm). Na₅[NiO₂][CO₃] is the first example of an alkaline‐rich transition metal oxide with two different oxoanions, [NiO₂]^3– and [CO₃]^2–, coexisting in one compound. The electronic spectrum of Na₅[NiO₂][CO₃] has been measured between 4000 and 25000 cm^–1. Two d‐d‐transitions of the linear [NiO₂]^3– complex (d⁹) are observed at 5870 cm^–1 and 11850 cm^–1 and analysed using the angular overlap model. MIR and FIR spectra give evidence for the [CO₃]^2– anion present in the structure.     

Chemical and electrochemical synthesis,structure, photoluminescent properties,and biological activity of 4-methyl-N-[2-[(Z)-2-(2-pyridyl)alkyliminomethyl]phenyl]benzenesulfamide zinc(II) complexes

A series of Zn(II) complexes of the tridentate azomethine ligands, condensation products of 2-(N-tosylamino)benzaldehyde and 2-aminoalkylpyridines, were synthesized by chemical and electrochemical methods. All compounds were characterized on the basis of C, H, N elemental analysis, Fourier-transform infrared, ¹H nuclear magnetic resonance, UV–Vis, and photoluminescence studies. The local atomic structures of complexes were determined from analysis of extended X-ray absorption fine structure and X-ray absorption near-edge structure of Zn K-edges. The molecular structure of chloro-{4-methyl-N-[2-[(Z)-2-pyridyl)ethyliminomethyl]phenyl]benzenesulfamide}zinc(II) was determined by X-ray single-crystal diffraction. The fluorescence spectra show that these complexes in dimethyl sulfoxide solutions at room temperature emit bright blue luminescence at 435–461 nm with fluorescence quantum yields in the range of 0.20–0.31. The assignment and the nature of the bands in experimental UV–Vis spectra of complexes were analyzed using time-dependent density functional theory calculations B3LYP/6-31G(d). The azomethines and complexes of zinc have been screened for their antibacterial, protistocidal, and fungistatic activities against Penicillium italicum, Colpoda steinii, Escherichia coli 078, and Staphylococcus aureus P-209, and the results are compared with the activity of furazolidone, chloroquine, and Fundazol.     

Synthesis and Characterization of Copper Hexathiometadiphosphate Cu2P2S6

Copper hexathiometadiphosphate, Cu₂P₂S₆, was synthesized and characterized. Brick‐red copper hexathiometadiphosphate Cu₂P₂S₆ crystallizes in the tetragonal space group P4₂/mnm (no. 136) with a = b = 5.2565(7), c = 15.066(3) Å and V = 416.3(1) ų in a novel structure type. This is the first hexathiometadiphosphate, whose crystal structure is based on a slightly distorted cubic closest packing of sulfur atoms. 1/3 of the tetrahedral voids are occupied by Cu and P in an ordered fashion, thus resulting in a layered structure. The structural motif of layers composed of corner‐sharing CuS₄ tetrahedra (comparable to red HgI₂) that are separated by [P₂S₆]^2– anions orientated perpendicular to these layers, is rarely found in solid state chemistry. The compound is diamagnetic and shows negligible electronic conductivity. Electronic structure calculations and UV/Vis measurements point to a bandgap in the visible range and explain the red color of the compound. Additionally, the oxidation state +1 for Cu was confirmed by the electronic structure calculations. The thermal properties of Cu₂P₂S₆ were investigated by DTA.