The influence of Ni2+ lons on the distribution of Mg2+ and Cu2+ lons in spinel ferrites

Cation distribution in quenched and furnace-cooled samples of composition Ni_xM_1?xFe₂O₄ (where M is either Mg²⁺ or Cu²⁺) has been studied through magnetization measurements. It has been found that cation distribution in these mixed ferrites cannot be predicted by site preference energies. In magnesium-nickel ferrites, cation distribution is controlled by heat treatment up to x = 0.5, beyond which the effect of heat treatment diminishes. Addition of Ni²⁺ ions in copper ferrite reduces the diffusibility of Cu²⁺ ions and the distribution tends toward inverse spinel in the high-nickel region.     

以[M(DETA)2)]n+(M=Cu2+, Ni2+, Co3+)为客体的MnPS3夹层化合物的合成、结构表征与磁性研究

将过渡金属配合物阳离子([M(DETA)₂]ⁿ⁺(M=Cu²⁺,Ni²⁺,Co³⁺;DETA=Diethylenetriamine,二乙烯三胺)作为客体插入层状MnPS₃层间得到了相应的3个夹层化合物。通过X-射线粉末衍射、元素分析和红外光谱对夹层化合物的结构进行了表征。结果表明,与主体MnPS₃ 0.65 nm的层间距相比较,夹层化合物(Mn_0.88PS₃[Cu(DETA)₂]_0.12)的层间距扩大了0.32 nm,由此推测客体[Cu(DETA)₂]²⁺在层间以平面四方的配位形式存在,而另2个夹层化合物(Mn_0.79PS₃[Ni(DETA)₂]_0.21和Mn_0.74PS₃[Co(DETA)₂]_0.17)的层间距扩大了0.48 nm,说明客体[(M(DETA)₂]ⁿ⁺,M=Co³⁺,Ni²⁺) 在主体层间以八面体配位形式存在。磁性测试结果表明过渡金属离子[(M(DETA)₂]ⁿ⁺(M=Cu²⁺,Co³⁺)的插入能引起主体MnPS₃的磁性在35~40 K发生由顺磁向亚铁磁性的转变并表现自发磁化,而客体[Ni(DETA)₂]²⁺却使夹层化合物的反铁磁相互作用增强,抑制了自发磁化的发生。     

Investigation of the Mn2+-F− distance for Mn2+ in fluoride lattices with hexahedral coordination

The Mn²⁺-F^? distance for Mn²⁺-doped CaF₂, CdF₂, SrF₂ and BaF₂ is derived from the experimental isotropic superhyperfine constant A_s. The results obtained indicate the existence of inwards relaxation processes in all these cases, as well as values of the Mn²⁺-F^? distance which are ≈0.1 A larger than those found for systems with [MnF₆]^4? units. This allows one to explain the low 10D_q values recently found by Alonso an Alcalá in CdF₂: Mn²⁺.     

铜转运蛋白C端金属结合域与Ag+及Hg2+的相互作用

铜转运蛋白(CTR1)不仅参与铜的细胞摄取,而且在其它重金属离子的摄取过程中也发挥重要作用. 本文采用紫外-可见(UV-Vis)光谱,核磁共振(NMR)和质谱(MS)的方法,研究了人源CTR1 (hCTR1)的C端金属结合域(C8)与Ag⁺和Hg²⁺的相互作用. 研究表明,Ag⁺和Hg²⁺都能与C8结合,但二者与C8的结合机制明显不同. 每个C8分子可以结合两个Ag⁺离子,但一个Hg²⁺却可以与两个C8形成桥联. 此外,Ag⁺离子与C8的配位是一个中等速度的交换过程,而Hg²⁺离子则为快速交换过程. C8的半胱氨酸残基是两种离子的重要结合位点,同时组氨酸残基也参与两种金属离子的配位,其中Ag⁺优先结合组氨酸,而Hg²⁺则对半胱氨酸的结合具有显著的优势. 虽然HCH基序对C8 与金属配位至关重要,一些远端的其它氨基酸也可以参与C8 与银离子的配位,这可能与CTR1 在摄取Ag⁺过程中的金属转移机制相关. 这些结果为理解hCTR1 蛋白摄取重金属离子的作用机制提供了必要的信息.     

ESR spectra and magnetic constants of α-Al2O3:Co2+,H+ and α-Al2O3 :Co2+,X+

New anisotropic ESR spectra of Co²⁺ doped sapphire, different from hitherto known, are reported. The new spectra which are observed, beside the well-known spectra of α-Al₂O₃:Co²⁺, are shown to form two sets, each one consisting of six spectra (1–6) and (7–12). The spectra of both sets are proven to be interrelated by B_3a symmetry. g and A tensors for each set will be given. Evidence is given that the two sets are to be assigned to the defects α-Al₂O₃:Co²⁺,H⁺ and α-Al₂O₃:Co²⁺,X⁺. The former is concluded to consists of a Co²⁺ ion at the substitutional site (c) and a proton located in a potential minimum along a straight line between O^2- ions situated in O²⁺ triangles above and below the CO²⁺ ion. The potential function for the proton has been calculated by quantum-chemical calculations to clucidate the geometrical structure of the paramagnetic center. The α-Al₂O₃:Co²⁺,X⁺ could not be fully analyzed but some evidence is presented, that X⁺ might be alkali ions.     

The system ZrO2CaO studied by the electron spin resonance of Mn2+ ions

We have used the electron spin resonance of Mn²⁺ ions to study the zirconia-calcia system from 9 to 60 mole% CaO. With the exception of single crystals of calcia-stabilized zirconia (CSZ) with 15 and 20 mole% CaO, the experiments were carried out on polycrystalline samples. From the different values measured for the hyperfine coupling constant A with increasing amount of calcia, we have deduced that Mn²⁺ substitutes for Ca²⁺ in the three following host lattices: cubic CSZ, CaZrO₃, and CaO.     

Electrochemical production of NH2• radicals by the system Cu2+/VO2+/NH2OH and their reactions with benzene and toluene

Electroinitiated production of NH₂^. radicals was demonstrated to occur in aqueous acid solution when in the system Cu²⁺/VO²⁺/NH₂OH Cu²⁺ is reduced to metallic copper on a mercury cathode. The first stage of this process involves the reduction of vanadyl to V³⁺ by metallic copper. The electrochemical system Cu²⁺/VO²⁺ was demonstrated to follow a depolarization scheme of the type of the catalyzed electrode process.For the reaction Cu+2 VO²⁺k₁→Cu²⁺+2 V³⁺ a k₁ value of 32 M^?1 s^?1 at 50°C was calculated.The second stage of the process is the reduction of NH₂OH by V³⁺ to give aminyl radicals. In presence of benzene and toluene these radicals add to the aromatic ring to give new radicals which are oxidized by Cu²⁺ to the corresponding amines.The cuzrent yield of this process attains values as high as 70%. The yield dependence on H₂SO₄ concentration, electrolytic current and dioxane concentration is discussed.     

Interfering influence of silver on the voltammetric behaviour of Cd2+ and Zn2+ ions on hmde in supporting electrolytes containing nitrates

A new kind of secondarily formed peaks was found in cyclic and stripping voltammetry in neutral sulphate, perchlorate and nitrate supporting electrolytes containing some divalent cations and a substance (for example O₂), the reduction of which gives as a by-product OH^? ions. The hydroxides deposited in the vicinity of the mercury electrode, in the course of a cathodic scan, react during the anodic scan according to the reaction Hg+Me(OH)₂=Hg(OH)₂+Me²⁺+2e forming a new, separate anodic peak.It was found that silver exerts a catalytic effect on the reduction of NO₃^? ions on the mercury electrode. In neutral nitrate supporting electrolyte containing Ag⁺ ions the hydroxides of some cations (Cd²⁺, Zn²⁺, Mn²⁺, Co²⁺ and Ni²⁺) were deposited during the cathodic scan or during the preelectrolysis. Afterwards, in the course of the anodic scan, a new peak, of the kind described above, was observed. The same effect was formerly interpreted, for Zn²⁺ and Cd²⁺, as evidence for the formation of intermetallic compounds, AgZn and AgCd.     

Circular dichroism of Mn2+ ions in α-Zn(H2O)6SeO4 crystal

The circular dichroism (CD) of Mn²⁺ ions in α-Zn(H₂O)₆SeO₄. crystal has been measured at 77–300°K. CD lines associated with the spin forbidden transition ⁶A₁ → ⁴A₁,⁴_aE are observed, and compared with uniaxial rotational strengths calculated on the basis of ligand field theory. The CD bands of Mn²⁺ and Ni²⁺ simultaneously doped into a Zn(H₂O)₆SeO₄ crystal have the same sign, which accords with a theoretical prediction.     

Multiple scattering method applied to the electronic structure and spectra of the impurity ions Cu2+, Ni2+, Co2+, Fe2+ and their tetrahedral environments in ZnO,ZnS and CdS

The multiple scattering method with local exchange and muffin-tin potentials is applied to tetrahedral clusters with Cu²⁺, Ni²⁺, Co²⁺ and Fe²⁺ as central ions and oxygen and sulphur as ligands. The calculated orbital energy differences ?(t₂^*) - ?(e^*) are compared to Δ_t values deduced from optical spectra. The agreement is fairly good.     

EPR of Mn2+ in single crystals of calcium hexachlorostannate hexahydrate

An EPR study has been carried out on Mn²⁺-doped single crystals of calcium hexachlorostannate hexahydrate [Ca(H₂O)6] SnCl₆ in the temperature range 77–378 K at X-band frequencies (9.3 GHz). Mn²⁺ ions substituting the divalent metal exhibit a unique magnetic complex with the z-axis directed along the c-axis of the crystal. The temperature dependence of the zero-field splitting parameter is discussed.     

Optical transitions of Mn2+ in fluoride glasses

The optical properties of Mn²⁺ ions have been extensively investigated in numerous host materials. The 3d⁵ electrons associated with the manganese ion are sensitive to crystal field and the optical transitions yield valuable information on the local environment. Thus, the Mn²⁺ ion optical spectra in fluorozirconate and fluorohafnate glasses suggest that these ions are in positions of low crystal field. Most likely Mn²⁺ substitutes for Ba²⁺ ions in these glasses. As the glass undergoes devitrification the Mn²⁺ ion spectrum changes suggesting that optical methods can be used for studying the temperature dependence of glass transitions.     

Les antimonites antiferromagnetiques MnSb2O4 et NiSb2O4

Neutron diffraction has been used to study the variation of antiferromagnetic order in the antimony isomorphous MnSb₂O₄ (T_N ～ 60 K) and NiSb₂O₄ (T_N ～ 46 K). The magnetic moments have been related to the Mn²⁺ and Ni²⁺ spins and magnetostrictive effects have been interpreted. The influence of the method of synthesis is mentioned: polycrystalline MnSb₂O₄ has been obtained from hydrothermal synthesis. Orthorhombic distortions are not connected with magnetic interactions but with structural defects.     

Effet Jahn-Teller cooperatif et affinite tétraedrique des ions Mn2+ et Zn2+ dans le système Mn3O4Zn2SnO4

Comparison between synthesis in air and in vacuum of the solid solution tMn₃O₄ + (1 ? t)Zn₂SnO₄, and cristallographic study of the nonoxidized compounds allowed us to establish the distribution and the electronic configuration of cations in tetrahedral (A) and octahedral (B) sites. The competitive aspect of Zn²⁺ and Mn²⁺ ions to occupy tetrahedral site is discussed. In air, the non-oxidizable character of Mn²⁺ on an A-site is clearly borne out, whereas the B-site displaced manganese oxidizes to Mn³⁺. In vacuum, the critical concentration of Mn³⁺ ion at the octahedral site, involving a cooperative Jahn-Teller effect, is about 50%.An important fact has also been put forward: the microscopic distortion of the oxygen octahedra, which the ratio of long and short anion-cation distances expresses, is equal to the unit-cell macroscopic deformation that the ratio $\text{c}\text{a}\text{√2}$ represents.     

Mn2+对聚N-异丙基丙烯酰胺的性能影响

合成了聚N-异丙基丙烯酰胺(PNIPAM)与Mn²⁺的配合物，并用荧光光谱、UV-Vis、FTIR、XPS进行了初步表征。说明Mn²⁺与PNIPAM侧链羰基氧或亚氨基氮原子发生了配位作用。由于Mn²⁺的发射光谱与PNIPAM激发光谱部分重叠以及Mn²⁺位于561 nm的发射峰在Mn²⁺-PNIPAM体系发射光谱中消失，说明发生了较好的F?rster能量传递。因此，在307 nm紫外区荧光强度比PNIPAM增强了314%，使该配合物表现出较好的抑菌效果，而此时少量Mn²⁺对其低临界溶解温度(LCST)影响不大。     

Synthesis of a new pyrene-devived fluorescent probe for the detection of Zn2+

A novel pyrene-based receptor bearing benzothiazole was synthesized as a good turn-on fluorescent sensor for the recognition of Zn²⁺. The probe showed an excellent selectivity for Zn²⁺over most other competing ions (eg, Cr³⁺, Li⁺, Cd²⁺, Al³⁺, Pb²⁺, Li⁺, Mg²⁺, Ag⁺, Ca²⁺, Ni²⁺, Mn²⁺, Fe³⁺, Hg²⁺, Ba²⁺, K⁺, Na⁺, Cu²⁺, Fe²⁺) in EtOH-HEPES (65:35, v/v, pH?=?7.20), which might be attributed to the photoinduced electron transfer (PET) mechanism. The formation of 1:1 stoichiometric PBZ-Zn²⁺ complex was determined based on the Job's plot, ¹H NMR titration and ESI-MS. The binding constant of the complex was 4.04?×?10⁴?M^?1 with a detection limit of 2.58?×?10^?7?M. The potential application of the PBZ in real water samples for recognizing Zn²⁺ was investigated. Bio-imaging study also revealed that PBZ could be applied to detecting Zn²⁺ in live cells. These results indicated that PBZ could be a favorable probe for Zn²⁺.     

[M(phen)3][Ni(mnt)2](M2+=Ni2+，Fe2+；phen=1，10-菲咯啉，mnt2-=马来二腈二硫烯)离子对配合物的合成、晶体结构、电子光谱和磁性质

本文制备了2种新的离子对配合物[M(phen)3][Ni(mnt)2](phen=1,10-菲咯啉,mnt2-=马来二腈二硫烯;M2+=Ni2+,1;Fe2+,2),并进行了结构表征。2种离子对配合物晶体的空间群都为P21/n,具有类似的晶胞参数和堆积结构。紫外可见-近红外光谱显示在近红外区域没有出现明显的吸收峰。在2到400 K的温度范围内,化合物1表现居里-外斯型的顺磁性行为,并在磁性[Ni(phen)3]2+离子之间存在弱的反铁磁作用,而且在八面体配位环境下Ni2+离子自旋基态S=1。化合物2在40 K向上显示抗磁性,意味[Fe(phen)3]2+离子处于低自旋态。低于40 K时,弱居里尾巴可能是由于小部分顺磁性[Ni(mnt)2]-杂质导致的。     

Theoretical study of the 2Σu+ and 2Σg+ states of Li2− and Na2−

Ab initio calculations are performed to obtain potential energy curves for the X¹Σ_g⁺ state of Li₂ and Na₂ and the X²Σ_g⁺ and A²Σ_g⁺ states of their anions. The A²Σ_g⁺ M₂^? curves are found to intersect the X¹Σ_g⁺M₂ curves at low energies and are expected to play a major role in the e^? + M₂ → M^? + M process.