Different binding thermodynamics of Ni2+, Cu2+, and Zn2+ to bacitracin A1 determined by capillary electrophoresis

Thermodynamics of the binding of Ni(2+), Cu(2+) and Zn(2+) to bacitracin A(1) was studied by capillary electrophoresis measuring the peptide effective mobility at different pH in the presence of increasing concentration of the three ligands. The affinity follows the order Ni(2+) > Cu(2+) > Zn(2+), with association constant values of (2.3 +/- 0.1)x10(4), (4.9 +/- 0.2)x10(3), and (1.5 +/- 0.1)x10(3) M(-1), respectively. The only model able to rationalize mobility data implies that metal ion binds to the P(0) peptide form. Moreover, mobility values indicated a change of bacitracin A(1) acidic properties on Ni(2+) and Cu(2+) binding, with a shift of the pK(a) of N-terminal Ile-1 from 7.6 to about 5 and of the pK(a) of the delta-amino group of D-Orn-7 from 9.7 to about 7. Even though on Zn(2+) binding a shift of the N-terminal Ile-1 pK(a) was observed, restrictions in the pH range suitable for investigation, due to precipitation phenomena, did not allow establish if the shift of D-Orn-7 lateral chain pK(a) also occurred. Nonetheless, if present, the shift should be limited to the 7.8-9.7 range. Mobility data indicated that the Stokes radius of the complexes is ca. 3 A lower than that of the free peptide. The present results indicate that metal-ion binding to bacitracin A(1) is more complex than previously assumed.     

Das erste Alkali-Erdalkalimetall-Oxoniccolat(II,III): NaBa2Ni22+Ni3+O6

The First Alkalinc Alkaline Earth Oxoniccolate(II,III): NaBa₂Ni₂²⁺Ni³⁺O₆ Single crystals of NaBa₂Ni₂²⁺Ni³⁺O₆ were prepared by solid state reaction. X-ray investigations led to orthorhombic symmetry, space group D-Fmmm; a = 8.310; b = 11.220; c = 14.397 Å; Z = 8. Na⁺ is coordinated by six O^2? in form of a trigonal prism and the two Ba²⁺ point positions show different coordination numbers C.N. = 6 + 4 and 8. The Ni²⁺ /Ni³⁺ ions are in square planar polygons, six of them are forming a so far unknown closed macro polyhedra.     

2-Pyridylaldehydebenzoylhydrazone derivatives as highly selective precolumn chelating reagents for nickel (II) ion in kinetic differentiation mode high-performance liquid chromatography

2-Pyridylaldehydearoylhydrazones have been examined as reagents for precolumn derivatization of metal ions in the HPLC-spectrophotometry system. With the simplest analog, 2-pyridylaldehydebenzoylhydrazone (PAB), among 11 metal ions only Ni(II) ion gives the peak while the other metal chelates seem to be dissociated on an HPLC column where no added PAB is present in the eluent solutions. All other PAB analogs exhibit the peak for Ni(II) ion as well as Co(III) ion. In one reagent system, V(V) and Fe(II) chelates also appear in the chromatograms. It has been stressed that the selectivity principle is the kinetic differentiation (KD) towards metal chelates associated with the HPLC processes. The specificity for Ni(II) ion is in close relation to a key structure of the ligand molecules which provides an N,N,O coplanar coordination environment to form two five-membered chelate rings. An extremely selective and sensitive KD-HPLC method for the quantitation of Ni(II) ion at the ultra-trace levels was assessed; the detection limit (3 _Blank) for Ni(II) ion was down to 5.34 × 10^–9 mol l^–1 (31.5 pg in a 100 l injection) and the excellent applicability was checked using coal fly ash samples.     

A Self-Formed Stable PbI2/NiOx Interface with Increased Ni3+ Centers for Perovskite Photovoltaics

Nickel oxide (NiO_x) is a promising hole transport material (HTM) for perovskite photovoltaics owing to its chemical stability and low cost. However, most NiO_x based solar cells deliver relatively weak performance because of its insufficient electrical property and interfacial contact. In this work, a self-formed PbI₂/NiO_x interface was developed to stabilize the Ni³⁺ centers, which was beneficial for electrical transport and band alignment in perovskite solar cells. Combined with ultraviolet ozone treatment ( UVO ) and sequential deposition, the density of Ni³⁺ centers was greatly increased and could be stabilized by the PbI₂ interface. These merits contributed coordinately to the fast hole extraction and low energy loss across the PbI₂/NiO_x interface, yielding power conversion efficiencies (PCEs) of over 19 %.     

超分子化合物[Ni(C_6H_4O_2N)_2·(H_2O)_4]_n的水热合成及晶体结构

用皮考林酸和六水合氯化镍反应制备了一种三维氢键超分子配合物,经X射线衍射分析确定了单晶结构.该晶体属单斜晶系,P21/m空间群,晶胞参数为:a=0.976 0(2)nm,b=0.522 54(10)nm,c=1.450 1(3)nm,Mr=374.98,α=90.08(3)°,β=90.08(3)°,γ=90°,V=0.739 63(3)nm3,Z=2,ρ=1.684 g/cm3,F(000)=388,μ=1.357 mm-1,R=0.039 0,wR=0.090 8.共收集2 656个衍射数据,其中1 569个为独立衍射点(Rint=0.033 2),可观测点数1 382个(I>2σ(I)).结果表明,在组成该超分子体系的基本结构单元[N i(C6H4O2N)2.(H2O)4]中,N i(Ⅱ)离子形成六配位的稍拉长的八面体构型,配合物单元之间通过氢键相互连接,形成了无限延伸的具有网状结构的三维超分子体系.     

An Effective Pd–Ni2P/C Anode Catalyst for Direct Formic Acid Fuel Cells

The direct formic acid fuel cell is an emerging energy conversion device for which palladium is considered as the state‐of‐the‐art anode catalyst. In this communication, we show that the activity and stability of palladium for formic acid oxidation can be significantly enhanced using nickel phosphide (Ni₂P) nanoparticles as a cocatalyst. X‐ray photoelectron spectroscopy (XPS) reveals a strong electronic interaction between Ni₂P and Pd. A direct formic acid fuel cell incorporating the best Pd–Ni₂P anode catalyst exhibits a power density of 550 mW cm^?2, which is 3.5 times of that of an analogous device using a commercial Pd anode catalyst.     

Ni2（OEt）2／SiO2催化二氧化碳与丙烯直接合成甲基丙烯酸的研究

 采用表面改性法制备了负载型Ni2（OEt）2／SiO2双核金属乙氧基配合物催化剂，利用示差量热、红外光谱和微反技术对催化剂的表面结构、热稳定性、化学吸附性质和催化活性进行了研究．结果表明，负载型双核金属乙氧基配合物Ni2（OEt）2／SiO2中的Ni2＋与载体SiO2表面的O2－以双齿配位形式键合；二氧化碳在催化剂表面存在桥式吸附态和碳酸单乙酯基物种两种吸附态，丙烯则只有一种分子吸附态；在适宜的反应条件下，二氧化碳和丙烯在Ni2（OEt）2／SiO2催化剂上的反应产物主要是甲基丙烯酸．根据实验结果，提出了二氧化碳和丙烯在Ni2（OEt）2／SiO2催化剂表面的反应机理，反应物分子共吸附于催化剂表面同一活性单元上，羧酸根和丙烯解离吸附态的形成是反应顺利进行的关键步骤．     

Monodisperse Sandwich‐Like Coupled Quasi‐Graphene Sheets Encapsulating Ni2P Nanoparticles for Enhanced Lithium‐Ion Batteries

In this report, sandwiched Ni₂P nanoparticles encapsulated by graphene sheets are first synthesized by directly encapsulating functional units in graphene sheets instead of fabricating separate graphene sheets and then immobilizing the functional components onto the generated surfaces. In this strategy, we use low‐cost, sustainable and environmentally friendly glucose as a carbon source and NiNH₄PO₄ ? H₂O nanosheets as sacrificial templates. This unique structure obtained here cannot only prevent the nanoparticles from aggregation or loss but also enhance the electronic conductivity compared to the independent nanoparticles. Furthermore, the novel sandwich‐like Ni₂P/C can be applied in plenty of fields, especially in electrical energy storage. In this paper, a series of electrochemical tests of the sandwich‐like Ni₂P/C are carried out, which demonstrate the excellent cyclic stability and rate capacity for lithium‐ion batteries.     

一种2-乙酰基吡嗪-罗丹明B衍生物的合成及其对Ni~(2+)的识别

分子光谱法具有灵敏度高、操作简单等优点,发展简便、快捷、对镍离子(Ni~(2+))具有高度选择性的探针具有非常重要的意义。本文以金属离子诱导罗丹明酰胺衍生物反应开环的策略,设计并合成了对Ni~(2+)检测具有单一选择性识别的紫外吸收探针。同时,该探针可对水溶液中的Ni~(2+)实现"裸眼"识别。此外,该探针对Ni~(2+)具有较高的灵敏度,其对水溶液中Ni~(2+)的检测限为0.5μmol/L,表明该探针可用于Ni~(2+)的检测分析。     

硫脲基红麻纤维的制备及其对Ni2+、Cr3+、Mn2+的吸附性

红麻纤维是自然界广泛存在的一类天然高分子化合物 ,分子链由葡萄糖单体通过 β -1 ,4糖苷键连接而成 ,其中含有多个羟基 ,具有一定的反应活性。选取链上的羟基为接枝点 ,经过高分子接枝反应 ,把具有较强配位与螯合能力的基团引入链中 ,从而得到对金属离子具有吸附功能的改性纤维[1,2 ] 。我们选取豫南大别山区盛产的红麻纤维为母体 ,对链上羟基活化而引入硫脲功能基 ,并测试了硫脲基红麻纤维对Ｎｉ2 +、Ｃｒ3+、Ｍｎ2 +的吸附性能 ,探讨了温度、时间等因素对吸附性能的影响。1　实验部分1 .1　仪器与试剂ＷＦＸ -1Ｆ2Ｂ2　原子吸收分光光度…     

Effects of Different Solvent Characteristics on the Proton-Ligand and Ni2+-, Sm3+-, AND Yb3+- Ligand Formation Constants of 5,5-Dimethyl-Cyclohexane-2-(2-Hydroxyphenyl)Hydrazono- 1,3-Dione (DCPHD) in Various Mixed Aqueous Solvents-(II)

Complex equilibria of DCPHD with proton and Ni²⁺, Sm³⁺, and Yb³⁺ ions has been measured in various mixed aqueous solvents, viz: isopropanol-water, acetone-water, ethanol-water, and methanol-water. Based on potentiometric equilibrium measurements of hydrogen ion concentration at 30°C, ionic strenght 0.10 M (KNO₃) and in the above various mixed aqueous solvents, the values of the protonation constants of DCPHD and the stability constants of DCPHD with Ni²⁺, Sm³⁺, and Yb³⁺ have been evaluated. The variation of protonation and stability constants with the inverse of dielectric constant or mole fraction of the solvent was studied. Application of Fuoss expression and consideration of electrosatic and non-electrostatic effects are made to explain the values of the constants.     

Characterization of Ni(II) complexes of Schiff bases of amino acids and (S)-N-(2-benzoylphenyl)-1-benzylpyrrolidine-2-carboxamide using ion trap and QqTOF electrospray ionization tandem mass spectrometry

This work demonstrates the application of electrospray ionization mass spectrometry (ESI-MS) using two different mass analyzers, ion trap and hybrid quadrupole time-of-flight (QqTOF) mass analyzer, for the structural characterization of Ni(II) complexes of Schiff bases of (S)-N-(2-benzoylphenyl)-1-benzylpyrrolidine-2-carboxamide with different amino acids. ESI enables the determination of molecular weight on the basis of rather simple positive-ion ESI mass spectra containing only protonated molecules and adducts with sodium or potassium ions. Fragmentation patterns are characterized by tandem mass spectrometric experiments, where both tandem mass analyzers provide complementary information. QqTOF data are used for the determination of elemental composition of individual ions due to mass accuracies always better than 3 ppm with the external calibration, while multistage tandem mass spectra obtained by the ion trap are suitable for studying the fragmentation paths. The novel aspect of our approach is the combination of mass accuracies and relative abundances of all isotopic peaks in isotopic clusters providing more powerful data for the structural characterization of organometallic compounds containing polyisotopic elements. The benefit of relative and absolute mean mass accuracies is demonstrated on the example of studied Ni(II) complexes. Copyright (c) 2008 John Wiley & Sons, Ltd.     

Novel nanostructured dendrimer based on 1,3-bis(4,6-dichloro-1,3,5-triazine-2-yl)urea as an excellent adsorbent for Pb2+, Ni2+, Co2+ and Zn2+ metal ions

Human health is seriously harmed by the consumption of poor-quality water. Due to high toxicity and water solubility, heavy metals are present in wastewater discharged from numerous industries. In the environmental realm, metal-containing water must be treated before being released. A dendrimer is a superior adsorbent for the removal of heavy metal ions due to its nanostructure and hydrophilic end group. In this work, a novel triazine-based hydroxy-terminated dendrimer up to generation three is designed employing a carbamide core. The dendrimer's structure was explored using FT-IR and ¹H NMR studies. Full generation dendrimers UG1.0, UG2.0, and UG3.0 were utilized as an adsorbent for Pb²⁺, Ni²⁺, Co²⁺ and Zn²⁺ metal ion removal from water in a series of tests. The ability of dendrimers to uptake Pb²⁺, Ni²⁺, Co²⁺ and Zn²⁺ metal ions was investigated under various pH, time interval and dendrimer generation parameters. The presence of metal in the dendrimer was confirmed by FT-IR studies of dendrimer-metal complexes. The overall results show that Pb²⁺, Ni²⁺, Co²⁺ and Zn²⁺ metal ions uptake increases with the generation, time, and pH.     

Unraveling Ultrafast Photoinduced Proton Transfer Dynamics in a Fluorescent Protein Biosensor for Ca2+ Imaging

Imaging Ca²⁺ dynamics in living systems holds great potential to advance neuroscience and cellular biology. G‐GECO1.1 is an intensiometric fluorescent protein Ca²⁺ biosensor with a Thr‐Tyr‐Gly chromophore. The protonated chromophore emits green upon photoexcitation via excited‐state proton transfer (ESPT). Upon Ca²⁺ binding, a significant population of the chromophores becomes deprotonated. It remains elusive how the chromophore structurally evolves prior to and during ESPT, and how it is affected by Ca²⁺. We use femtosecond stimulated Raman spectroscopy to dissect ESPT in both the Ca²⁺‐free and bound states. The protein chromophores exhibit a sub‐200 fs vibrational frequency shift due to coherent small‐scale proton motions. After wavepackets move out of the Franck–Condon region, ESPT gets faster in the Ca²⁺‐bound protein, indicative of the formation of a more hydrophilic environment. These results reveal the governing structure–function relationship of Ca²⁺‐sensing protein biosensors.     

Ni2＋的引入对离子液体烷基化催化性能的影响

Thealkylationofisobutanewithbuteneisanim portantprocessforthe productionofhigh qualitypetroleum .In placeofconcentratedsulfuricacid ,Et3NHCl/AlCl3ionicliquidhasbeenusedinthereac tionwithfairlygoodeffect[1] ,butthereisstillabigdifferencecomparedwiththeresultsofconcentratedsulfuricacid .TheC8contentinthealkylatesobtainedwithconcentratedsulfuricacidwas 72 1% [2 ] ,butitwasonly 5 6 %withtheionicliquid .ThekeyreactioninthealkylationishydrogentransferfromC+8toC08[3] ,andthisisthemainreasonforth…     

A highly selective fluorescence switch for Cu2+ and Fe3+ based on a new diarylethene with a triazole-linked rhodamine 6G unit

A new diarylethene compound with a triazole-linked rhodamine 6G unit attached to the imino group (1O) was designed and synthesized. According to the test results, the solution color and fluorescence color of diarylethene can be modulated by lights and metal ions. The solution color could change from colorless to light purple when irradiated with UV light. When Cu²⁺ was added to the diarylethene solution, the color of diarylethene solution became blue, the fluorescence color turned from dark to bright yellow. Although the solution color did not change by adding Fe³⁺, its fluorescence color varied from dark to yellow. Moreover, it was found that the complex ratio of the diarylethene to Cu²⁺ was 1:1 and the binding stoichiometry of the diarylethene to Fe³⁺ was also 1:1 based on the data of NMR, MS, and other experiments. Based on these findings, photochromic figure of the diarylethene with UV/Vis light, Cu²⁺ and Fe³⁺ was constructed. Furthermore, the logic circuit was designed by input signals (ultraviolet stimulus, visible light stimulus, Cu²⁺ (or Fe³⁺) and EDTA) and an output signal (fluorescent intensity at 566?nm (or 575?nm)).     

A New Synthetic Route for Preparation of 2-Chloro-6-fluoro-benzonitrile and 2-Chloro-6-fluorobenzoic Acid

An effective synthetic route for preparation of 2-chloro-6-fluorobenzonitrile, 2-chloro-6-fluorobenzamide and 2-chloro-6-fluorobenzoic acid has been described. It includes diazotization,fluorination, ammoxidation and hydrolysis reactions.     

2-[2-(6-Methylbenzothiazolyl)azo]-5-Diethylaminobenzoic acid as a new analytical reagent for the spectrophotometric determination of nickel

A new thiazolylazo chromogenic reagent, 2-[2-(6-methylbenzo-thiazoly)azo]-5-diethylaminobenzoic acid (6-Me-BTAEB), has been synthesized. Its chromogenic reaction with microamounts of nickel in the presence of sodium dodecylsulfate (SDS) has been thoroughly studied. 6-Me-BTAEB reacts with nickel(II) in weak acid medium containing appropriate amounts of SDS to form a blue-violet complex with high sensitivity, good selectivity and high stability. The composition is found to be 1:2 (nickel to 6-Me-BTAEB) and its absorption maximum is at 650 nm with an apparent molar absorptivity of 1.67 × 10⁵l mole^–1 cm^–1. Beer's law is obeyed over the range 0-0.4 g of nickel per ml. The proposed method has been applied to the direct determination of nickel in aluminium alloys, pure magnesium and low alloy steels at the 0.2–0.3% (w:w) level with satisfactory results.     

Synthesis and Crystal Structures of [(Nicotinic Acid)2H]+I-, [(2-Amino-6-methylpyridine)H]+(NO3)-, and the 1:1 Complex Between 1-Isoquinoline Carboxylic Acid (Zwitter Ion) and L-Ascorbic Acid Assembled via Hydrogen Bonds

Summary. Three new complexes, namely [(nicotinic acid)₂H]⁺I^–, [(2-amino-6-methylpyridine)H]⁺ (NO₃)^–, and the 1:1 complex between 1-isoquinoline carboxylic acid (zwitter ion form) and L-ascorbic acid were synthesized. The IR spectra revealed different types of hydrogen bonds in these compounds. The X-ray structure determination has shown the first compound to consist of a packing of [(nicotinic acid)₂H]⁺ cations and I^– anions. In the dimeric cation the two nicotinic acid molecules (zwitter ions) are connected through hydrogen bonds (O–HO). Each dimer is further engaged in other hydrogen bonds with adjacent dimers giving 2D layers. The I^– ion is located at the inversion center. In the second compound the cation and anion are connected via hydrogen bonds formed between oxygen atoms of the NO₃ ^– anion and NH and NH₂ of the cation generating a layer structure. All atoms are coplanar on mirror planes. In the 1:1 complex the two molecules are connected through hydrogen bonds formed between the two oxygen atoms of the carboxylate group of 1-isoquinoline carboxylic acid (zwitter ion) and the oxygen atoms of the two adjacent hydrogen groups of the L-ascorbic acid molecule. These complex molecules are engaged in other hydrogen bonds with each other forming a 2D system normal to the long b-axis of the unit cell.