铂配合物与DNA碱基对间相互作用的理论研究

用量子化学方法研究一系列Pt(II)配合物作用于嘌呤碱基N7位点后对Watson-Crick碱基对AT、GC的影响. 计算结果显示铂配体与碱基对AT、GC的作用以静电作用为主，同时极化作用也是影响GC碱基对的重要因素. 静电作用极大地增强了铂化嘌呤碱基与嘧啶碱基间的相互作用，而嘌呤碱基与嘧啶碱基间作用与未铂化碱基对作用相近. Pd(II) 和 Ni(II)的相关研究得到类似的结果. 碱基对间氢键作用“二阶微扰能”分析结果与氢键强弱变化一致.     

2-氨基嘧啶与Cu(Ⅱ)固体配合物的热化学性质

嘧啶类化合物具有抗真菌,促进植物生长调节作用,并可作为杀虫剂、除草剂、杀菌剂和医药中间体而受到人们的关注[1-3],在与金属离子形成配合物后,不仅可延长原药的活性、特效期和半衰期,还能降低对哺乳动物的毒性。本文合成了以2-氨基嘧定为配体的Cu(Ⅱ)的固体配合物,并用溶解量     

嘧啶类铜(Ⅱ)、锌(Ⅱ)配合物的合成和生物活性

嘧啶类衍生物;除草剂;嘧啶类铜(Ⅱ)、锌(Ⅱ)配合物的合成和生物活性     

杯[4]芳烃对单糖及嘧啶衍生物的分子识别和分子开关

用AM1和INDO/SCI方法对八羟基杯[4]芳烃与单糖及嘧啶衍生物形成的超分子体系进行理论研究,结果表明,主体通过CH-π相互作用对单糖类进行分子识别,尤其对赤藓糖识别效果更好;主体与嘧啶没有明显的π-π堆砌作用,但能识别含吸电子基团的嘧啶衍生物,据此可设计酸碱调控的分子开关.讨论了配合物的UV谱带与主体相比发生红移的原因.     

部分氧化碳化硅提高钯催化氧还原反应性能（英文）

燃料电池具有能量转换效率高的优点,是能量转换与储存的高效器件之一.目前,燃料电池阴极氧还原反应(ORR)动力学缓慢,并且催化ORR大量使用铂碳(Pt/C)催化剂,由于Pt储量少,价格高,载体碳材料易发生碳蚀导致催化剂稳定性降低,限制了其进一步商业化应用.钯(Pd)与Pt为同族元素,具有相似的电子结构和化学性质,其储量是Pt的50倍,同时, Pd具有良好的抗甲醇毒性和抗一氧化碳毒性,因此,被视为燃料电池中阴极Pt催化剂的潜在替代品.但商用Pd/C催化剂的ORR活性较Pt/C差,因此,大量的研究工作集中在提高Pd基ORR催化剂的活性方面:将Pd与具有3d轨道的金属形成合金或将Pd负载到不同的载体上.通过选择合适的载体影响Pd的电子结构,从而提高催化剂活性和稳定性,是一种较简单的、有利于规模化生产Pd基ORR催化剂的方法.碳化硅(SiC)具有良好的电化学稳定性、热稳定性、机械强度和较强的供电子能力,可被用作ORR的金属催化剂载体.然而,由于金属与SiC作用较弱,需要制备特殊形貌的SiC或将SiC表面改性;通常,这些SiC基载体的制备过程复杂并且成本高.而在有氧条件下制备、保存或使用SiC时,...     

新型2-芳氨基嘧啶衍生物的合成

通过间羟基苯硼酸与2,4-二氯嘧啶的Suzuki反应及其后酚羟基的烷基化得到4-芳基-2-氯嘧啶衍生物. 然后, 采用Pd(PPh3)4/dppf催化剂, 在温和的条件下实现了4-芳基-2-氯嘧啶类化合物和芳香胺的偶联. 合成了3个结构新颖的2-芳氨基嘧啶类化合物. 中间体及产物的结构均经由IR, 1H NMR, 13C NMR, MS和元素分析表征而予以证实.     

萘在贵金属Pd、Pt及Pd-Pt催化剂上的加氢活性及耐硫性能

采用等体积浸渍法制备了SiO2-Al2O3负载的Pd、Pt单金属催化剂及Pd/Pt摩尔比分别为1∶1、1∶4、4∶1的双金属催化剂(Pd1Pt1、Pd1Pt4、Pd4Pt1),对其进行X射线衍射(XRD)、透射电镜(TEM)、CO化学吸附和X射线光电子能谱(XPS)表征,并详细考察了各催化剂的萘加氢活性和耐硫性能.结果表明,在实验考察范围内,Pd4Pt1催化剂上的萘转化率最高可达98.2%,全饱和产物十氢萘选择性最高可达93.6%,十氢萘反/顺生成率之比最高可达7.8,均高于单金属Pd(97.5%,59.1%,4.3)和Pt(96.8%,39.9%,2.9)催化剂的值.萘在三种催化剂上的加氢速率顺序为vPd4Pt1vPdvPt.添加二苯并噻吩(DBT)后Pd4Pt1上的萘转化率和十氢萘选择性仍然最高,十氢萘反/顺比在Pt催化剂上不受影响,在Pd4Pt1催化剂上稍有降低,而在Pd催化剂上降低明显.在三种不同Pd/Pt摩尔比的双金属催化剂中,Pd4Pt1催化剂上的萘转化率和十氢萘选择性在添加DBT前后都是最佳的.     

4,6-二甲基嘧啶-2-硫代乙酸稀土配合物的合成、表征及抗肿瘤活性研究

报道了合成的8种4,6-二甲基嘧啶-2-硫代乙酸的稀土配合物,通过元素分析、摩尔电导、红外光谱、核磁共振氢谱和热重-差热分析,确定了配合物的组成和结构,结果表明,配合物的组成为LnL3.nH2O,其中HL=4,6-二甲基嘧啶-2-硫代乙酸,Ln=La,Ce,Pr,Nd,Sm,Eu,Gd,Tb,n=4或5。在配合物中配体羧基脱去质子后采用螯合双齿的方式与稀土离子形成配位键,同时,配合物中含有4或5个结晶水。抗肿瘤活性研究表明,部分配合物对常见的HL-60人白血病细胞、BGC-823人胃癌细胞、Bel-7402人肝癌细胞、Hela人宫颈癌细胞的抗肿瘤活性明显强于配体。     

2-巯基-4,6-二甲基嘧啶锌(Ⅱ)配合物研究

本文合成了2-巯基-4,6-二甲基嘧啶配体(HL)及其锌(Ⅱ)配合物.通过元素分析、质谱分析(ESI-MS)、红外光谱、紫外光谱和DSC热分析对配体和配合物进行了表征,推测出配体和配合物可能的组成和结构.对绿豆、小麦、玉米的培养实验表明,10-4g/g浓度的锌(Ⅱ)配合物溶液对种子的生长有一定调节作用.     

硫代二草酰二(3,5-二甲基嘧啶)锰配合物的合成及其与DNA的相互作用

以4,6-二甲基-2-巯基嘧啶和草酰氯为原料合成了硫代二草酰二(3,5-二甲基嘧啶)(L)及其锰配合物;采用红外光谱、紫外光谱、核磁共振谱对其结构进行了表征,同时研究了锰配合物与DNA的相互作用.结果表明,锰配合物的阳离子与DNA磷酸基团的氧负离子形成静电结合.     

Sc2MgGa2 and Y2MgGa2

Scandium magnesium gallide, Sc₂MgGa₂, and yttrium magnesium gallide, Y₂MgGa₂, were synthesized from the corresponding elements by heating under an argon atmosphere in an induction furnace. These intermetallic compounds crystallize in the tetragonal Mo₂FeB₂‐type structure. All three crystallographically unique atoms occupy special positions and the site symmetries of (Sc/Y, Ga) and Mg are m2m and 4/m, respectively. The coordinations around Sc/Y, Mg and Ga are pentagonal (Sc/Y), tetragonal (Mg) and triangular (Ga) prisms, with four (Mg) or three (Ga) additional capping atoms leading to the coordination numbers [10], [8+4] and [6+3], respectively. The crystal structure of Sc₂MgGa₂ was determined from single‐crystal diffraction intensities and the isostructural Y₂MgGa₂ was identified from powder diffraction data.     

Electrochemical study of (NEt4)2Cl2FeS2MoS2 and (NEt4)2Cl2FeS2MoS2FeCl2

Summary The ability of [MoS₄]^2–, anions to be used as ligands for transition metal ions has been widely demonstrated, especially with Fe²⁺. The present study has been restricted to linear complexes such as (NEt₄)₂ [Cl₂FeS₂MoS₂] and (NEt₄)₂[Cl₂FeS₂MoS₂FeCl₂]. Their electrochemical properties are described: upon electrochemical reduction, these compounds yield MoS₂, as a black precipitate, and an iron complex in solution, assumed to be [SFeCl₂]^2–. The electrochemical reduction goes through two electron transfers, coupled with the breakdown of the molecular skeleton: a DISPl and an ECE mechanism. Depending on the solvent, the following equilibrium may be observed: [Cl₄Fe₂MoS₄]^2–[Cl₂FeMoS₄]^2–+FeCl₂. The equilibrium constant, K_D, was evaluated by differential pulse polarography. K_D is tightly related to the donor number of the solvent.     

The alkali hypophosphites KH2PO2, RbH2PO2 and CsH2PO2

The structures of the hypophosphites KH₂PO₂ (potassium hypophosphite), RbH₂PO₂ (rubidium hypophosphite) and CsH₂PO₂ (caesium hypophosphite) have been determined by single‐crystal X‐ray diffraction. The structures consist of layers of alkali cations and hypophosphite anions, with the latter bridging four cations within the same layer. The Rb and Cs hypophosphites are isomorphous.     

Zur Kenntnis der Dialkalimetalldichalkogenide β-Na2S2, K2S2, α-Rb2S2, β-Rb2S2, K2Se2, Rb2Se2, α-K2Te2, β-K2Te2 und Rb2Te2

On Dialkali Metal Dichalcogenides β-Na₂S₂, K₂S₂, α-Rb₂S₂, β-Rb₂S₂, K₂Se₂, Rb₂Se₂, α-K₂Te₂, β-K₂Te₂ and Rb₂Te₂ The first presentation of pure samples of α- and β-Rb₂S₂, α- and β-K₂Te₂, and Rb₂Te₂ is described. Using single crystals of K₂S₂ and K₂Se₂, received by ammonothermal synthesis, the structure of the Na₂O₂ type and by using single crystals of β-Na₂S₂ and β-K₂Te₂ the Li₂O₂ type structure will be refined. By combined investigations with temperature-dependent Guinier-, neutron diffraction-, thermal analysis, and Raman-spectroscopy the nature of the monotropic phase transition from the Na₂O₂ type to the Li₂O₂ type will be explained by means of the examples α-/β-Na₂S₂ and α-/β-K₂Te₂. A further case of dimorphic condition as well as the monotropic phase transition of α- and β-Rb₂S₂ is presented. The existing areas of the structure fields of the dialkali metal dichalcogenides are limited by the model of the polar covalence.     

Formal [(2+2)+2] and [(2+2)+(2+2)] nonconjugated dienediyne cascade cycloadditions

[reaction: see text] Fluoranthene 2 and heptacycle 3 are easily accessible from the reaction of diyne 1 and norbornadiene (NBD) in the presence of the rhodium catalyst. The unusual [(2+2)+(2+2)] adduct 3 was confirmed by the X-ray crystal structure analysis.     

Crystal Structures of [Bu2Sn(O2PPh2)2], [Ph2Sn(O2PPh2)2], and [PhClSn(O2PPh2)OMe]2. Raman Spectra of [Ph2Sn(O2PPh2)2] and [PhClSn(O2PPh2)OMe]2

[(n‐Bu)₂Sn(O₂PPh₂)₂] ( 1 ), and [Ph₂Sn(O₂PPh₂)₂] ( 2 ) have been synthesized by the reactions of R₂SnCl₂ (R=n‐Bu, Ph) with HO₂PPh₂ in Methanol. From the reaction of Ph₂SnCl₂ with diphenylphosphinic acid a third product [PhClSn(O₂PPh₂)OMe]₂ ( 3 ) could be isolated. X‐ray diffraction studies show 1 to crystallize in the monoclinic space group P2₁/c with a = 1303.7(1) pm, b = 2286.9(2) pm, c = 1063.1(1) pm, β = 94.383(6)°, and Z = 4. 2 crystallizes triclinic in the space group , the cell parameters being a = 1293.2(2) pm, b = 1478.5(4) pm, c = 1507.2(3) pm, α = 98.86(3)°, β = 109.63(2)°, γ = 114.88(2)°, and Z = 2. Both compounds form arrays of eight‐membered rings (SnOPO)₂ linked at the tin atoms to form chains of infinite length. The dimer 3 consists of a like ring, in which the tin atoms are bridged by methoxo groups. It crystallizes triclinic in space group with a = 946.4(1) pm, b = 963.7(1) pm, c = 1174.2(1) pm, α = 82.495(6)°, β = 66.451(6)°, γ = 74.922(6)°, and Z = 1 for the dimer. The Raman spectra of 2 and 3 are given and discussed.     

Die Photoionenspektren von SCl2, S2Cl2 und S2Br2

Photoionization Mass Spectra of SCl₂, S₂Cl₂, and S₂Br₂ Photoionization mass spectra of SCl₂, S₂Cl₂, and S₂Br₂ have been measured. Heats of formation, bond energies, and ionization potentials of fragments have been calculated from appearance potentials.