锚联膦,胺配体对胶体钯的配位俘获及其负载催化剂的催化性能

本文继采用含硫配体(-SH,-SR)对高分子保护金属胶体的配位俘获之后,采用锚联在SiO_2表面的较含硫配体配位能力弱的P,N配体分别与聚乙烯吡咯烷酮(PVP)保护的胶体钯在室温下反应,在P/Pd大于3.5,N/Pd大于7时,可以实施对保护金属胶体的配位俘获,证实了配位俘获法是一种具有普遍意义的方法,经原子吸收光谱分析,溶液中残留的金属钯的量小于0.36 ppm(P/Pd=3.5)。经电子能谱证实,锚联膦胺配体与金属钯之间存在配位作用,这是实施保护胶体负载化的关键。透射电镜分析表明,在整个配位俘获的过程中,无论是在载体上或是在溶液中,胶体钯的颗粒大小与分布均保持不变。因此,配位俘获法是一种能控制多相催化剂中金属颗粒大小与分布的有效方法。由此合成的钯催化剂具有很高的催化活性,良好的选择性和稳定性,在对Cis,Cis-1,3-环辛二烯的选择性加氢中,其活性仅比均相的PVP-Pd胶体催化剂稍低,选择性达100％。在周转数达12,000次/个钯原子后,其催化活性仍保持不变,随着P/Pd比的增大,催化活性迅速下降。     

Synthesis of a novel rigid molecule family for the investigation of electron and energy transfer

Three new rigid bridging ligands for metal complexation (7=bmb, 8=bqb and 11=btb) were prepared from a rigid triptycene spacer connected to two bipyridine ligands using a Horner–Emmons type reaction. The triptycene spacer is substituted by methoxy groups in the case of bmb and in the case of bqb by a benzoquinone substituent. The corresponding metal complexes (ruthenium and/or osmium) were synthesised and the different luminescence behaviour was tested. They show great potential for the investigation of intramolecular electron and energy transfer reactions. The dinuclear metal complex Ru---bqb---Os is an interesting system in which the bridging ligand bqb acts as a redox switch, able to tune the conductivity for energy or electrons across the bridge.     

Polarography in solution of some problems in organic chemistry: recent applications

Applications of chromatographic and atomic absorption methods are compared with those of electroanalytical techniques. The limitations of electroanalytical procedures and their advantages, such as speed, sensitivity and speciation are discussed. Among applications of polarography and voltammetry to a solution of basic problems, attention has been paid to the possibility to distinguish the degree of conjugation (e.g. of compounds containing the grouping CNNC), to a contribution to understanding of solution chemistry of mitomycin C and to processes involved in the reduction of cephalosporins. Among practical applications, the possibility to analyze suspensions, which can be carried out without separation offers advantages. Examples are interactions in suspensions of bile salts in the presence of metal (II) ions, adsorptions of various pesticides and other toxic materials on lignin and the possibility to follow alkaline cleavage of lignin in buffers pH 8-12 at 25 °C. Most of these studies would not be possible to carry out using other techniques.     

Control of optical properties of gel-derived oxide coating films containing fine metal particles

Control of the optical properties of gel-derived oxide films containing fine metal particles is described. The duration of the aging of Si(OC₂H₅)₄-derived sols and the amount of water for hydrolyzing Si(OC₂H₅)₄ were found to greatly affect the size and the shape of Au particles formed in the silica matrix, and accordingly the optical absorption of the Au/SiO₂ composite films. Employing dielectric media with high refractive indices like TiO₂ was shown to shift the absorption peak of Au particles to longer wavelengths. Pd/TiO₂ and Pt/TiO₂ composite films showed absorption in the visible region.     

Synthesis of naphthyridines and phenanthrolines using catalysts based on transition and rare-earth metals

Liquid-phase condensation of 3-, 4-, and 8-aminoquinolines with aliphatic and aromatic aldehydes catalyzed by transition and rare-earth metal complexes is an efficient method for synthesis of substituted 1,7- and 1,6-naphthyridines and 1,10-phenanthrolines.Institute of Organic Chemistry, Ural Branch, Russian Academy of Sciences, 450054 Ufa; Eastern Scientific-Research Institute of Coal Chemistry, 620219 Sverdlovsk. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 5, pp. 1139–1148, May, 1992.     

若干3d过渡金属的硫代脯氨酸配合物

合成了七个新的过渡金属的硫代脯氨酸(tcH)配合物,它们分别是:[M(tc)_2](M=Mn(Ⅱ),Co((Ⅱ))和Ni(Ⅱ)),[Ni(tc)(Ac)(H_2O)],[Ni(tc)(tcH)(H_2O)]NO_3·H_2O,[Ni(tc)(Py)_2(H_2O)NO_3和[Fe(tc)_2(Cl)(H_2O)]。上述配合物的磁化率,摩尔电导,热量分析,红外及电子光谱数据表明,它们都具有八面体构型,tcH主要通过亚氨氮和羧基氧原子与金属键合。文章对这些配合物的可能结构作了初步的讨论。     

一种低磁矩、大功率复合稀土石榴石铁氧体的工艺和性能研究

为满足低场区几百兆赫的超大功率器件的性能要求,以钇铁石榴石铁氧体为基础,制备了一种低磁矩复合稀土石榴石铁氧体YGd CaVInIG,研究了少量Mn3+替代Fe3+和预烧温度、烧结温度对铁氧体性能和结构的影响。实验表明,以少量Mn3+替代Fe3+可以提高铁氧体电阻率,降低磁损耗和介电损耗。Mn3+掺入量以x为0.04～0.06比较合适,铁氧体最佳予烧温度为1050℃,最佳烧结温度1350～1380℃,保温5h,氧气中烧结,其性能为:4πMs=500±10%kA·m-1,ΔH=5.25～5.55kA·m-1,TC>180℃,tgδe≤0.5×10-5,这种材料适合微波低频段器件性能要求。X射线衍射分析指出,掺Mn3+的YGdCaVInIG铁氧体相变完全,呈单相复合石榴石铁氧体,空间群为I230,点阵常数1.25057～1.25101nm,单胞分子数n为7.75～7.80。     

GRAFT COPOLYMERIZATION OF VINYL MONOMERS ONTO STARCH INITIATED BY TRANSITION METAL-THIOUREA REDOX SYSTEMS

In this paper, the capabilities of grafting acrylonitrile (AN) onto starch initiatedby Fe(III)-TU, V(V)-TU, Cr(VI)-TU, Mn(VII)-TU redox systems were compared in thepresence of sulfuric acid of different concentrations. It was shown that the grafting capabili-ty of Mn(VII)-TU is the highest in these initiating systems. Using Mn (VII-TU as initia-tor, the effects of various acids (HClO_4, H_2SO_4, HNO_3, HCl) on the graft copolymerizationof acrylonitrile onto starch were discussed, and the capabilities of graft copolymerizationof methyl methacrylate (MMA), acrylamide (AM), acrylic acid (AA) onto starch wereinvestigated. The experimental results show that the order of the influences of differentacids is HClO_4>H_2SO_4>HNO_3>HCl, and the order of grafting capabilities of differentmonomers grafted onto starch is MMA>AN>AM>AA. The structure and morphology ofgraft copolymers were studied with infrared spectroscopy and scanning electron microscopy.The size, shape and roughness of surface of the grafted starch granules are changed aftergrafting.     

顺磁性聚酯金属配合物的合成及其驰豫性能的研究

本文通过二乙三胺五乙酸（ＤＴＰＡ）或乙二胺四乙酸（ＥＤＴＡ）的双酸酐与二元醇或二元酚进行聚合反应，制备了两个系列共１５种新的聚酯型大分子配体及其顺磁性金属配合物，用核磁、红外光谱以及元素分析表征了配体和配合物的结构。初步试验结果表明，与相应的小分子金属配合物相比，聚酯金属配合物具有较高的弛豫性能。     

氮杂冠醚研究Ⅶ、双仲胺型氮杂冠醚对过渡金属离子的选择性萃取作用

合成了五种新型双仲胺型氦杂冠醚，研究了它们对过渡金属离子进行液—液萃取，并用原子吸收法测定其浓度。实验结果表明：这类冠醚对Ａｇ￣＋、Ｐｄ￣（２＋）、和Ｐｔ￣（４＋）等贵金属离子有较强的选择配位性能，对选择性分离这些金属离子有重要的意义。