对氨基马尿酸铽二元、三元配合物的合成、表征及荧光光谱研究

在乙醇溶液中以邻菲咯啉(phen)、2,2’-联吡啶(bipy)和对氨基马尿酸(PAH,HL)为配体与铽离子(Tb(Ⅲ))合成了二元和三元稀土配合物。通过元素分析、差热-热重分析、紫外光谱、红外光谱分析,确定了配合物的组成为TbL₃(1)、TbL₃·phen·H₂O(2)和TbL₃·bipy·H₂O(3),并讨论了配合物1～3的谱学性质和荧光性能。推测出羧基中的氧原子以桥式双齿的形式与稀土离子配位。由红外光谱和热分析测试确定的配合物1及配合物2中的水分子未参与配位。研究表明,铽配合物在489,583和621 nm处出现发射峰,它们分别归属于5D₄→7F₆,5D₄→7F₅,5D₄→7F₄和5D₄→7F₃的跃迁。其中544 nm处5D₄→7F₅跃迁的强度最强,配体的共平面性和共轭性越大,配合物的荧光性能越高,三元配合物TbL₃·phen·H₂O和TbL₃·bipy·H₂O的荧光强度优于二元配合物TbL₃的荧光强度。     

色氨酸与稀土元素Eu(Ⅲ)配合物的合成及配位位置的研究

氨基酸是生命系统中蛋白质的基本结构单位.本文通过共沉淀法合成了色氨酸与稀土元素Eu(Ⅲ)的固体配合物,并对其进行了光谱及波谱研究,确定了配合物的配位机理及配位点.     

Quantitative Depth Profiling Using Online-Laser Ablation of Solid Samples in Liquid (LASIL) to Investigate the Oxidation Behavior of Transition Metal Borides

The increased demand for sustainability requires, among others, the development of new materials with enhanced corrosion resistance. Transition metal diborides are exceptional candidates, as they exhibit fascinating mechanical and thermal properties. However, at elevated temperatures and oxidizing atmospheres, their use is limited due to the fact of their inadequate oxidation resistance. Recently, it was found that chromium diboride doped with silicon can overcome this limitation. Further improvement of this protective coating requires detailed knowledge regarding the composition of the forming oxide layer and the change in the composition of the remaining thin film. In this work, an analytical method for the quantitative measurement of depth profiles without using matrix-matched reference materials was developed. Using this approach, based on the recently introduced online-LASIL technique, it was possible to achieve a depth resolution of 240 nm. A further decrease in the ablation rate is possible but demands a more sensitive detection of silicon. Two chromium diboride samples with different Si contents suffering an oxidation treatment were used to demonstrate the capabilities of this technique. The concentration profiles resembled the pathway of the formed oxidation layers as monitored with transmission electron microscopy. The stoichiometry of the oxidation layers differed strongly between the samples, suggesting different processes were taking place. The validity of the LASIL results was cross-checked with several other analytical techniques.     

类MgB2硼化物晶体电子结构比较研究

应用准确的第一原理方法，对8种类MgB₂超导体结构的二硼化物进行了电子结构 比较研究，发现其中的超导体具有特殊的能带属性.对其在高压下态密度的变化情况做了对照. 关键词： 硼化物 态密度 能带 高压     

Microwave-assisted synthesis of 4-quinolylhydrazines followed by nickel boride reduction: a convenient approach to 4-aminoquinolines and derivatives

Nickel(II) chloride/sodium borohydride combination was employed for the reduction of 4-hydrazinoquinoline derivatives to the corresponding anilines. This reductive protocol was efficiently applied for the reductive cleavage of monosubstituted hydrazines. We described herein the microwave-assisted synthesis of 4-hydrazinoquinolines, which furnished a high yielding and rapid two-step procedure for the synthesis, under mild conditions, of 4-aminoquinolines as antimalarial precursors.     

The unusual magnetotransport properties of La0.67Sr0.33MnO3 with Nb2O5 addition

Enhancements of the low-field (LFMR) and high-field magnetoresistance (HFMR) were observed in the manganite system prepared by doping Nb₂O₅ into La_0.67Sr_0.33MnO₃ powders. The maximum MR ratios at 77 K with H=1 T and 1 kOe are 30% and 20% for the 0.07 molar ratio doped sample, which are 1.7 times and 1.6 times as large as that for LSMO, respectively. An MR effect up to 6.5% was also found for the sample with x=0.03 at room temperature (RT). The spin-dependent tunneling and scattering at the interfaces of grain boundaries are responsible for the LFMR while the HFMR originates from a noncollinear spin structure in the surface layer. With increasing x, the Curie temperature (T_C) decreases monotonically from 364 to 154 K while the temperature T_P related to the peak resistivity decreases firstly to a minimum of 204 K (x=0.06) and then rises up to 240 K (x=0.1). There is a maximum resistivity ρ for the sample with x=0.06, which is higher than that for LSMO by five orders of magnitude. It is due to the enhancement of spin-dependent and independent scattering and tunneling effects on the interfaces of grain boundaries and inside the grains.     

Ligand-stabilized Nickel and Palladium Boride Colloids

A route to the first ligand stabilized nickel and palladium boride colloids with core diameters of 1.4 and 1.6 nm is described. The particles are formed by reaction of the metal complexes Cl₂M(PR₃)₂ (M = Ni, Pd, PR₃ = PPr₃, PBu₃) with B₂H₆ in toluene at room temperature with 40–70% yield. The characterization of the pyrophoric brown powders occurred by elementary analyses, resulting in smallest formula units, which then could be extended to averaged molecular formulas by mass determinations, using an analytical ultracentrifuge: [Ni₆B₁₀Cl_1.5(PPr₃)]_12.5 ( 1 ), [Ni₆B₁₀Cl_1.5(PBu₃)]_8.5 ( 2 ), [Pd₄B₆Cl(PPr₃)]_16.5 ( 3 ), and [Pd₄B₆Cl(PBu₃)]_16.5 ( 4 ). From the masses of the colloid cores and their roughly calculated densities the size of the boride particles could be estimated. The diameters of 1.6 nm for 1, 3 , and 4 are identical within the experimental error. Only 2 seems to have a slightly reduced diameter of 1.4 nm. 1–4 can be dispersed in inert organic solvents in any concentration. To confirm these relatively uncertain values high resolution transmission electron microscopy has been used. Investigations of 1 and 3 show indeed an averaged particle size of 1.6 ± 0.3 nm in agreement with the data derived from the mass determinations. Surprisingly most of the observed particles appear to have amorphous structure. This finding is supported by X-ray powder diffraction experiments, as no significant reflex data could be registered. ³¹P and ¹¹B NMR measurements have been performed too, however, do not contribute to further characterization.     

稀土元素R4OCl6四面体嵌合物的化学键研究

以SCC-DV-X,方法对Sm_4OCl_6、Eu_4OCl_6、Yb_4OCl_6和Gd_6N_2Cl_(12)等4个体系作了量化计算。结果表明,嵌入原子在四面体簇的合成中起决定性作用。体系6个骨架轨道中,3个是嵌入原子与稀土原子的成键轨道,另3个是稀土原子通过嵌入原子形成的弱键轨道。用Sm、Eu等元素能合成四面体嵌合物,与其价态较低有关,低价态使稀土元素d、f轨道收缩较少、成键能力增大。而富含f电子的Yb体系,4f为主要价轨道。     

ICP-AES法测定高纯氧化铕中稀土杂质元素

研究了锌粉还原 5709萃淋树脂分离富集 ICP AES法测定高纯氧化铕中14个稀土杂质元素的方法,用ICP AES法测定稀土元素工作曲线下限为(以氧化物计)镧为0.05mg·L-1,铈、镨、钇为0.25mg·L-1,钕、钐、铽、镝、钬为0.1mg·L-1,铒、铥、镱、镥、钇为0.05mg·L-1,回收率为90%～106%。方法简便、准确、快速,可用于99.99%氧化铕中14个稀土杂质元素的测定。     

稀土富勒烯与苯的气相加合

内嵌稀土元素的富勒烯化合物一稀土富勒烯Lit＠CZ。是一类新型的化合物．它具有独特的“超分子结构和巨大的潜在用途，将在未来的功能材料开发中起到不可估量的作用［‘］．目前关干稀土富勒烯的研究主要集中于稀土富勒烯的合成、分离、纯化、表征和理论方面．关于稀土富勒烯化