质子化硼烷正离子体系电子结构的理论研究

本文用a b initio计算法和近似a b initio计算法(PRDDO)研究了质子化硼烷正离子体系的电子结构,给出了一些正离子体系的优化几何构型并讨论了它们的成键情况。计算的硼烷分子质子亲和势与实验值相当吻合。     

双(N 氧化吡啶 2-甲醛)缩1,2-丙二胺镍配合物的合成和晶体结构

合成所得双(N-氧化吡啶-2-甲醛)缩1,2-丙二胺的镍(II)配合物[Ni(piopn)(H_2O)_2](ClO_4)_2的晶体属空间群C_s~4-C_c, 晶胞参数a=0.7397(3) nm, b=1.3187(7) nm, c=2.5502(14) nm, β=102.18(4)°. 用分子轨道理论的近似方法分析了该配合物的电子结构和分子轨道, 探讨了分子的结构特征与红外光谱的关系.     

紫外吸收温差光谱法及其应用

用温差光谱法观察系列化合物的紫外吸收温差谱，发现温差谱具有很强的特征性，具有π键的富勒烯Ｃ６０的温差谱峰为负值，负峰的强度样品温差增大而负荷增大，负峰的峰位无明显移。     

含超价硫三元无机杂环化合物的理论研究(Ⅰ)

本文应用ab initio方法,研究了含超价硫化合物分子中硫原子的3d轨道的成键作用,并使用Martagh-Sargent梯度优化法,预测了该化合物的几何构型。指出硫二氮三元无机杂环中,d-pπ键在S-N间起重要作用。     

硅酸及其盐的研究 XX聚硅酸溶液中的酸强度与分子结构的关系

本文利用无机酸系列的酸强度(pKa值)与羟基上氧原子的亲电子超离域度S(E)成线性关系的规律性,找出聚硅酸系列的相应线性方程为:并由此推测低聚硅酸溶液中可能存在的硅酸结构:在三聚硅酸溶液中主要存在着六元平面环的三聚体;在四聚硅酸中则主要存在着三种环状的四聚体。     

Analysis of the Electron Localization, the Anisotropy of Electrical Conductivity, the Orbital Ordering, and Spin-Exchange Interactions in BaVS3 on the Basis of First Principles and Semi-empirical Electronic Structure Calculations

The electrical transport and magnetic properties of BaVS₃, made up of individual VS₃ octahedral chains, were examined on the basis of first principles and tight-binding electronic structure calculations. The electrical conductivity of BaVS₃ is nearly isotropic despite its one-dimensional structural feature, because of the orbital interactions associated with the short S···S contacts within each VS₃ chain and between adjacent VS₃ chains. The probable cause for the metal-insulator transition at ∼70 K was examined in terms of first principles electronic structure calculations, which indicate that the metallic and magnetic insulating states of BaVS₃ are nearly the same in energy. This is consistent with the observation that the metal-insulator transition at ∼70 K is caused by electron localization. The observed magnetic properties of BaVS₃ below ∼70 K are readily explained under the assumption that the symmetry-broken t_2g-orbitals act as the magnetic orbitals in the magnetic insulating state of BaVS₃. The probable cause for the latter was discussed.     

Structure of a de novo designed protein model of radical enzymes

The use of side chains as catalytic cofactors for protein mediated redox chemistry raises significant mechanistic issues as to how these amino acids are activated toward radical chemistry in a controlled manner. De novo protein design has been used to examine the structural basis for the creation and maintenance of a tryptophanyl radical in a three-helix bundle protein maquette. Here we report the detailed structural analysis of the protein by multidimensional NMR methods. An interesting feature of the structure is an apparent pi-cation interaction involving the sole tryptophan and a lysine side chain. Hybrid density functional calculations support the notion that this interaction raises the reduction potential of the W degrees /WH redox pair and helps explain the redox characteristics of the protein. This model protein system therefore provides a powerful model for exploring the structural basis for controlled radical chemistry in protein.     

Capillary electrophoresis of cardiolipin with on-line dye interaction and spectrophotometric detection

Cardiolipin is an important phospholipid present in the mitochondrial inner membrane. It plays a key function in mitochondrial respiration by interacting with many enzymes or cofactors related to oxidative phosphorylation complexes. We have determined the concentration of cardiolipin using on-line 10-N-nonyl acridine orange (NAO) dye interaction capillary electrophoresis (CE) and spectrophotometric detection with a sample throughput of 3 min. In addition to the presence of 0.1 mM NAO, the background electrolyte (BGE) composition has been set at 80% methanol-10% acetonitrile-10% H(2)O (all v/v) to provide both good solubility and the maximum absorbance enhancement at 497 nm for the NAO-cardiolipin complex as compared to NAO alone. Sample consumption for each injection is about 57 nL. A calibration curve is established from 0.5 microM to 0.1 mM with R (2) = 0.9912 with a detection limit of 0.05 microM for cardiolipin. In a blind study, actual mitochondrial cell membrane samples in the microL range before or after UV light exposure were analyzed using the CE method. Cardiolipin concentration decreased in the different parts of the membrane sample upon UV photolysis of the cells. Support for the theory that UV light can induce cardiolipin translocation from the inner membrane (IM) to the outer membrane (OM) was indicated by a significant percentage increase of cardiolipin (as measured by the cardiolipin in the OM as compared to the sum total in the OM and IM) from 30.7 +/- 2.4% before UV light photolysis to 38.3 +/- 2.2% after UV irradiation.     

Spontaneous reduction of metal ions on the sidewalls of carbon nanotubes

Nanotube/nanoparticle hybrid structures are prepared by forming Au and Pt nanoparticles on the sidewalls of single-walled carbon nanotubes. Reducing agent or catalyst-free electroless deposition, which purely utilizes the redox potential difference between Au3+, Pt2+, and the carbon nanotube, is the main driving force for this reaction. It is also shown that carbon nanotubes act as a template for wire-like metal structures. The successful formation of the hybrid structures is monitored by atomic force microscopy (AFM) and electrical measurements.     

高分子药物研究Ⅰ．5－氨基水杨酸与二元羧酸缩聚物的合成

通过５－氨基水杨酸与二元羧酸进行缩聚反应，合成了六种主链含有５－氨基水杨酸的高分子化合物，用红外光谱和元素分析确定了聚合物的结构。聚合物水解实验表明，它们在酸性、中性和碱性介质中均能水解，水解速率（ｒ）的大小依次为ｒｐＨ＝１３．０＞ｒｐＨ＝７．０＞ｒｐＨ＝２．０。