Solution Structure and Behavior of Benzophenone-based Achiral Bisphosphine Ligands in Noyori-Type Ru（Ⅱ）-Catalysts

We herein report on solution structural studies of Ru^Ⅱ catalysts （3a, 9） composed of achiral bisphosphine ligands （4, 8） and the enantiopure 1,2-diphenylethylenediamine （DPEN）. Complete chiral induction from enantiopure （R,R）-DPEN to achiral bisphosphine ligand 3a was observed in solution, with the complex adopting a single, stable and non-fluxional （even at 70 ℃） configuration. The coordination of the C=O moiety in 4 to the cationic Run center is considered to be of key importance in providing the higher thermodynamic and kinetic rotation barrier for the flexible bisphosphine ligand in the complex. The obtained enantioselectivity （91% enantiomeric excess） and sense of chiral induction in the hydrogenation of acetophenone were found to be solely dependent on the chirality of the 1,2-diamine. Consistent with the hydrogenation product, the （R,R）-DPEN induces a M-conformation （fight-handed） chirality for flexible phosphine ligand 4 in the complex, resulting in a 2,2-configuration about the Ru^Ⅱ center.     

Effects of Self—coiling of Organic Molecules on Intramolecular Exciplex Formation and Fluoresscence Quenching in DX—H2O Solvent System

Effects of self-coiling of organic molecules on intramolecular exciplex formation of compound I,in which the carbazole chromophore and terephthalic acid methylester acceptor group are linked by one (CH2)10 chain,and the decrease of the fluorescence intensities of compounds Ⅱ，Ⅲ，and Ⅳ,in which the carbazole chromophore and 3,5-dinitrobenzoate are connected by one aliphatic chain of (CH2)10 (Ⅱ），（CH2）12（Ⅲ）,or (CH2)4(Ⅳ）,have been studied in the dioxane (DX)-H2O binary system.The results show that self-coiling of organic molecules in DX-H2O facilitates intramolecular exciplex formation of I and induces the decrease of fluorescence intensities of Ⅱ,bacause of the proximity effect brought about by selfcoiling of organic molecules under hydrophobic-lipophilic interaction(HLI) between the excited carbazole chromophore and the acceptor.Since the similar effects are observed even when the concentration of the probes are less than their CAgCs(critical aggregate concentrations )in the DX-H2O mixture with the same φ values,formation of the intermolecular exciplex has been excluded.The effects are found to be strongly depended on φ values,indication that they are mainly driven by HLI.The properties of the acceptors can also affect the intramolecular exciplex formation.With terephthalic acid methylester moiety as the acceptor,the carbazole chromophore exhibits the fluorescence spectra of the exciplex,while with 3,5-dinitrobenzoate moiety as the acceptor,only the fluorescence spectra of excited carbazolyl chromophore are observed.     

△,Λ-[Co(phen)2tpphz]^3+与B - DNA相互作用的分子 模拟

针对国际上对金属配合物同DNA间作用机量的争议,采用分子模拟手段在MM2力场下,搭建并优化了手性金属配合物△,Λ-[Co(phen)2tpphz]^3+与B-DNA[d(GTCGATCGAC)2]的模型,继而对其相互作用进行了模拟,得出的结论是：对所采用的B-DNA片断,该金属配合物有明显的立体选择性△型配合物从小沟插入占明显优势,而且,总体来看,从AT区插入更易进行。     

环多肽晶体的浮动电荷极化力场模拟

利用原子键电负性均衡结合分子力场方法(ABEEM/MM)对五种环多肽晶体进行了研究. 与传统力场相比, 该方法中的静电势包含了分子内和分子间的静电极化作用, 以及分子内电荷转移影响, 同时加入了化学键等非原子中心电荷位点, 合理地体现了分子中的电荷分布. 相对其他极化力场模型, 具有计算量较小的特点. 该模型下计算得到的环多肽分子单元相对实验测得的结构的原子位置、氢键长度和二面角的均方根偏差分别为0.009 nm、0.013 nm和5.16°, 能够很好地重复实验结果. 总体上, 其结果优于或相当于其他力场模型, 适用于对实际蛋白质体系的模拟和研究.     

盐酸拓扑替康与人血清白蛋白的相互作用及分子模拟

用荧光光谱法、分光光度法研究了盐酸拓扑替康(topotecan hydrochloride, 简记为THC)与人血清白蛋白(human serum albumins, HSA)的相互结合反应. 计算了反应的结合常数、结合位点数和热力学常数. 盐酸拓扑替康在人血清白蛋白上的结合位置与色氨酸残基间的距离为3.63 nm. 分子模型研究表明, 盐酸拓扑替康与人血清白蛋白的亚结构域IIA结合, 二者间的作用力主要为疏水作用, 此外, 蛋白质的丙氨酸(Ala-291)残基和天冬氨酸(Asp-256)残基与盐酸拓扑替康之间还存在氢键作用力.     

分子的模糊对称性

将模糊数学方法引入对分子对称点群的研究,建立描述具有不完整分子对称性的模糊点对称群(集合).建立具有模糊对称性分子轨道的模糊表示及其模糊特征标(模糊广义宇称).通过对典型的线状分子、平面分子以及非平面的立体分子等进行分析,展示了一个新的理论化学园地.初步探讨了具有模糊对称性的动态反应体系.从模糊对称性出发,探讨了分子轨道对称守恒原理的半定量特征.     

Sharpless四唑合成中捕获双四唑锌配合物

The reaction of malononitrile with ZnCl₂ and NaN₃ in the presence of 2,2′-bipyridine and water affords the first bis(tetrazole) Zn-complex intermediate, mono(2,2′-bipyridine)bis(tetrazolyl)methane aqua zinc(Ⅱ), [Zn(2,2′-bpy)(BTZ)(H₂O)]·(H₂O)₂ (1) which gives a clue for Demko-Sharpless′ tetrazole synthesis. Crystal data for 1: C₁₃H₁₈N₁₀O₄Zn, M_r=443.74, monoclinic, space group P2₁/c, a=12.5705(18), b=16.078(2), c=9.1921(13)?, β=95.010(3)°, V=1850.7(5)?³, Z=4. CCDC: 197788.     

α-单取代环十二酮构象的研究

利用分子力学计算，单晶X射线分析和~1H NMR技术研究了α-单取代环十二酮 的构象。结果表明，它们的优势构象的环骨架仍是[3333]构象，而羰基则在2-C位 置上。在晶体中，它们的优势构象为α－角顺取代[3333]-2-酮构象，而在溶液中 则取α－角顺取代和α－边外取代[3333]-2-酮两种构象，且两种构象处于动力学 平衡之中，以α－边外取代[3333]-2-酮构象占优势。     

藻胆蛋白的Langmuir-Blodgett膜——Ⅰ.R-藻红蛋白单分子膜及蛋白构象变化的研究

测定了R-藻红蛋白(R-PE)在气/液界面上的表面压-面积曲线(tt-A等温线),结果表明R-PE具有很好的成膜性能,且由n-A等温线求得的单分子占有面积与R-PE以盘状形态“平躺”于液面上时的分子占有面积相同。R-PELB膜的透射电子显微镜(TEM)图象和椭圆偏振关于R-PE单分子膜厚度的测定,说明R-PE分子在基片上的取向是其盘平面与基片表面平行。根据这些依据,提出了R-PE单分子膜的结构。将R-PE在气/液界面上形成的单分子膜在适当表面压下用LB技术转移到基片上,测得了蛋白累积单分子膜的吸收及荧光光谱,R-PE单分子膜的吸收和荧光光谱与其在水溶液中无显著差别。膜的CD光谱与R-PE水溶液的CD光谱比较说明,当R-PE成膜后其二级结构发生了变化,即蛋白的p-折叠片构象组分增加。     

偶氮苯光致异构化对紫精-曙洪络合的调控

报导了α，ω－偶氮苯，紫精双发色团化合物的合成与性质研究，结果表明偶氮苯的光致顺反异构化以可调控与之相连的紫精与曙红络合行为，其作用程度的强弱与连接两者的亚甲基链的长度有关，借助ＨＮＭＲ通过对构象进行分析解释了上述的研究结果。