3,6-二羟基哒嗪质子转移过程的理论研究

为了探索3,6-二羟基哒嗪分子醇式和酮式结构互变异构化的反应机理,本研究组采用DFT B3LYP/6-311+G(d)方法对标题化合物异构化反应的势能面进行了研究,在探讨各种可能的反应途径中,发现至少有34种异构体和43种过渡态.结果表明,6-羟基-3(2H)-哒嗪酮不论是单体,与水形成配合物,还是二聚体,比其相对应的异构体能量低,表明在通常情况下是以6-羟基-3(2H)-哒嗪酮形式稳定存在的,这与前人通过实验数据对互变异构体的比率进行预测的结果是一致的;在考察的可能反应途径中,直接进行的分子内质子转移过程需要的活化能为142.2 kJ·mol^-1,水助催化时,反应活化能为41.3 kJ·mol^-1,考虑溶剂效应后,其活化能为59.2 kJ·mol^-1,二聚体双质子转移的活化能为16.8 kJ·mol^-1,二聚体双质子转移所需活化能最低,在室温下就可以进行.由此可见氢键在降低反应活化能方面起着重要的作用.     

非层状二维CdSe的制备及厚度对带隙的影响

二维半导体材料的天然带隙有望弥补石墨烯的零带隙缺陷,打破后者在场效应晶体管、开关器件、逻辑电路等领域的应用瓶颈.相较于层状半导体材料,非层状半导体材料多以较强的离子键/共价键结合,且各向同性,因此要获取其二维结构存在一定挑战.本论文通过化学气相沉积法实现了非层状Cd Se在云母衬底上的二维各向异性生长.详细表征了二维Cd Se的微观形貌、晶体结构和光学特性等.结果表明,样品具有显著的光致发光(PL)效应,说明厚度减薄至纳米级时不会破坏Cd Se的直接带隙属性.此外,随着厚度减小,样品的PL峰逐渐蓝移.为了进一步解释该现象,采用基于密度泛函理论的第一性原理计算方法,研究了不同厚度的Cd Se的能带结构,结果显示均为直接带隙,且随厚度减小,带隙值增大,与实验现象吻合.由此可知,通过生长参数调控二维Cd Se的厚度,即可实现对其带隙的有效调控,这对相关光电器件的性能提升具有指导意义.     

水杨醛缩L-异亮氨基酸Schiff碱过渡金属Cu(Ⅱ),Zn(Ⅱ),Ni(Ⅱ)配合物的电化学合成及表征

采用Cu, Zn, Ni为“牺牲”阳极, 在无隔膜电解槽和含配体水杨醛缩L-异亮氨基酸Schiff碱的乙腈溶液中电解合成了Cu(Ⅱ), Zn(Ⅱ)和Ni(Ⅱ)配合物. 利用元素分析、红外光谱、紫外光谱、热分析等手段对配合物的结构进行了表征, 测定了Cu(Ⅱ)配合物的电化学性质. 结果表明, 配合物的化学组成为ML·nH2O(L=C13H15NO3, M=Cu(Ⅱ), Zn(Ⅱ), Ni(Ⅱ), n=1, 1, 2), 配合物具有相似的空间结构, 配体均以三齿进行配位; 电合成配合物的电化学效率Ef 接近0.5 mol/F[Zn(Ⅱ), Ni(Ⅱ)]和1.0 mol/F[Cu(Ⅱ)], Cu(Ⅱ)配合物中Cu(Ⅱ)L/Cu(Ⅰ)L电对的可逆半波电位Er1/2为-0.79 V.     

Hydrothermal Synthesis, Crystal Structure and Magnetic Properties of a Novel Zero-dimensional Manganese（Ⅱ） Complex with 2,2′-Diphenic Acid and 1,10-Phenanthroline Ligands

A novel metal-organic coordination polymer [Mn3(2,2′-dipha)3(phen)6]n·3nH2O (2,2′-dipha = 2,2′-diphenic acid, phen = 1,10-phenanthroline) 1 has been hydrothermally synthe- sized and structurally characterized by single-crystal X-ray diffraction, elemental analyses, IR spectroscopy, and magnetic susceptibility measurements. The crystal crystallizes in triclinic, space group P1 with a = 16.921(5), b = 18.307(5), c = 18.450(5) , α = 113.369(5), β = 108.529(5), γ = 102.984(5)o, V = 4553(2) 3, C114H72Mn3N12O14.25, Mr = 2002.66, Dc = 1.461 g/cm3, μ(MoKα) = 0.488 mm1, the final F(000) = 2058, Z = 2, R = 0.0491 and wR = 0.0980 for 9087 observed reflections (I > 2σ(I)). In the crystal structure, the manganese atom is six-coordinated with two carboxylate oxygen atoms from different carboxylate groups of the same dipha and four nitrogen atoms from two different phen ligands, showing a slightly distorted octahedral geometry. Fur- thermore, it exhibits a zero-dimensional structure with dipha-Mn-phen- as building units. Variable- temperature magnetic measure shows an overall anti-ferromagnetic behavior for compound 1.     

UO22+·nH2O和PuO22+·nH2O(n=2,4,5,6)密度泛函理论研究

首先用密度泛函理论(DFT)方法研究了铀酰和钚酰离子的几何与电子结构,计算结果与实验基本符合,表明DFT方法也能用于含铀和钚重原子的化合物计算.然后对铀酰和钚酰水合离子的几何构型、Mulliken集居数分布以及铀酰(钚酰)与配体水分子的结合能进行计算,计算结果表明UO22+·5H2O和PuO22+·5H2O分别为铀酰和钚酰系列水合离子中最稳定的配合物.     

Au改性纳米TiO2材料对NPE-10光催化降解的活性

以钛酸四丁酯和氯金酸为原料，通过溶胶凝胶法制备了Au掺杂的纳米TiO2光催化剂粉体，并用 XRD， BET，XPS和固体紫外可见吸收光谱等技术对其晶相结构，比表面积，表面组成及紫外可见光响应范围进行了表征，对其光催化降解非离子表面活性剂壬基酚聚氧乙烯醚（NPE-10）的活性进行了考察. 结果表明，掺杂的Au在纳米TiO2粉体材料中可能以两种形态存在，即以Au3+离子形式替代Ti4+进入TiO2晶格和以Au原子态形式暴露于粉体表面.前者使TiO2在480～650 nm出现了更强的光吸收，并大大地增强了粉体表面对氧物种的吸附；后者中处于表面原子态的Au又会成为光生电子的受体，有效地避免了光生电子空穴对的复合. 通过对掺杂量及处理温度的优化，在nAu3+/nTi4+=0.005， 500 ℃煅烧的条件下可以制得具有较高的光催化活性的Au/TiO2粉体. 对NPE-10的光催化氧化试验显示，日光照射4小时后降解效率可以达到91.8%；而用未改性的纳米TiO2，在同样条件下，NPE-10的光催化降解效率仅能达到50.2%，商品Degussa P-25也只能达到66%.     

Density Functional Study on the Mechanism of Collision Reaction among Protons, N2 and Water Vapor

The mechanism of collision reaction among protons, N2 and water vapor was theoretically studied using Density Functional Theory. The geometries of reactants, transition states, intermediates and products were optimized at the B3LYP/6-311 G^** level by the BERNY gradient analysis method. Transition states and intermediates have been identified by vibrational frequency analysis. The relationship among reactants, intermediates, transition states and products was affirmed by IRC calculation. The variations of energy and geometry along the IRC-determined reaction paths were described. The possible reaction pathways were represented and the optimal one was decided from the viewpoint of energy.     

1H and 13C NMR assignments for four triterpenoid saponins from Albizziae cortex

Four triterpenoid saponins were isolated from Albizziae cortex, and a complete assignment of their (1)H and (13)C NMR spectra was carried out using 1D and 2D NMR ((1)H-(1)H COSY, HSQC, HMBC, and HSQC-TOCSY) methods. Their (1)H NMR assignments were reported for the first time and some of their (13)C NMR spectral data reported in literature were corrected.     

二芳醚基哌嗪类衍生物的合成及细胞毒活性研究

根据拼合原理, 设计并合成了21个未见报道的新的二芳醚基哌嗪类衍生物, 其结构用1H NMR, ESI-MS, HRMS进行了确证, 初步生物活性测定实验证明部分目标化合物具有良好的细胞毒活性. 化合物4i分别对人食管癌(Eca109)细胞株和人鼻咽癌(CNE)细胞株的IC50为7.13和4.54 μmol•L－1, 与对照品顺铂(DDP)相近. 化合物5d对人鼻咽癌细胞株也表现较好的活性, 其IC50为8.49 μmol•L－1.