荷叶中黄酮类化合物的缓蚀性理论研究

用DFT中的B3LYP方法,在3-21G和6-311G水平上,研究荷叶黄酮类分子的分子结构及电子结构,并用Fukui指数分析活性。综合结论：槲皮素3-O-D-吡喃木糖基（1→2）-β-D-吡喃半乳糖苷、异鼠李素、槲皮素-3-丙酯、紫云英苷、山奈酚和异鼠李素-3-O-β-D-葡萄糖苷与金属吸附作用较强。Fukui指数表明：分子的亲核进攻和亲电进攻点主要位于羰基氧原子和与独立苯环连接的羟基氧原子上。     

PDVT单体的电子结构与红外光谱

有机共轭聚合物在电致发光材料上有较大的应用前景。采用密度泛函理论B3LYP方法在6-311++G(d,p)水平上计算了PDVT的分子结构和电子结构,并对红外光谱、净电荷布局等进行了分析,结合前线轨道理论探讨了分子的稳定性和活性。计算结果表明PDVT分子中环状结构的共轭效应良好,其中C(26)的反应活性最高,最容易接受亲电试剂的进攻。前线轨道分析表明PDVT分子的内部环状结构对HOMO轨道做主要贡献,S原子对LUMO轨道做主要贡献,计算所得△Eg=0.489eV表明它更倾向于接受电子并具有适合的能带宽度。PDVT分子具有较小的空穴重组能,空穴载流子速率大,可作为良好的空穴传输材料。     

共轭亚油酸的生物合成及相关酶基因的克隆与表达

共轭亚油酸是一类在9-与11-位、10-与12-位或11-与13-位碳原子处有顺式或反式共轭双键的十八碳二烯酸.在共轭亚油酸的各种异构体中,只有c9,t11-18:2和t10,c12-18:2两种异构体具有多种生理活性,如抗癌、抗粥状动脉硬化、抗氧化、降低胆固醇、减肥等.共轭亚油酸异构酶可以专一性地催化亚油酸转化为活性共轭亚油酸异构体,因此近几年来倍受关注,利用生物合成法生产共轭亚油酸已成为该领域的发展趋势.对近年来共轭亚油酸的生物合成以及相关酶基因克隆表达方面的研究进展进行了综述.     

基于静电势电荷的抗击埃博拉病毒新药物法匹拉韦及其衍生物水溶解度logS值预测

运用分子中的原子理论(AIM),探讨了以法匹拉韦分子羰基氧原子值为目标,测试了不同基组和泛函选择的依赖性。然后用密度泛函理论(DFT B3LYP)和6-31+G(d,p)基组,优化了20种法匹拉韦及其常见衍生物的分子结构,分别得到11号羰基氧的密立根电荷(MUL-O)、自然原子轨道电荷(NBO-O)、何秀巴赫电荷(HIR-O)和静电势电荷(ESP-O)值,发现11号氧原子的ESP-O电荷值与用ACD Lab6.0预测出来的log S值相关性最好,相关系数达0.986;计算了法匹拉韦及其11种未知衍生物的ESP-O电荷值,代入相关最佳线性方程,发现所得结果与ACD Lab6.0预测结果十分接近,最大误差绝对对数值仅为0.08;分子的静电势图也显示法匹拉韦及其甲基法匹拉韦发挥其药理毒理作用可能的部位在电负性强的羰基氧原子上。     

二乙醚、二异丙醚与水分子间相互作用的理论研究

为研究聚氧乙烯醚与聚氧丙烯醚的亲水与疏水效应,本文将两者合理简化为二乙醚和二异丙醚,并在高精度的B3LYP/6-311++G**水平上,对其与水分子形成的复合物体系进行了理论研究。计算结果表明,二乙醚可与2个水分子形成氢键,作用强度为-10.40kcal·mol-1,复合物形成时电荷转移的范围较大;而二异丙醚仅可与单个水分子形成氢键,作用强度为-7.78 kcal·mol-1,复合物形成时电荷转移的范围较小。聚氧乙烯醚分子中的醚氧原子形成的两氢键体系更为稳定,亲水性更强;而聚氧烯醚分子中,由于甲基的加入对水分子的接近形成空间阻碍作用,因此醚氧原子与水分子仅能形成单氢键结构,亲水性较弱。     

甲叉膦酸型化合物阻垢机理的量子化学研究

运用密度泛函（DFT）理论，在B3LYP／6-31G水平下，系统研究了ATMP，EDTMP，HDTMP，GDMP，MADMP这5种甲叉膦酸类阻垢缓蚀剂分子结构与阻垢性能之间的构效关系。结果表明，5种膦酸分子中的氮原子及膦羧基团中的氧原子上负电荷密度较大，这使得氮原子及膦羧基易与垢晶体中的钙离子发生静电相互作用，如果氮原子与氧原子间距与方解石晶体生长面上的钙离子对间距匹配，将显著增强了阻垢剂分子与特定晶面的Coulomb吸附行为，诱导垢晶体发生畸变，有效地阻止其生长。本文还利用半经验（PM3）方法对分子势能面进行扫描，得出分子能量随二面角改变的变化率，初步探讨了分子柔性、刚性对其阻垢性能的影响。     

双亚胺共轭型聚氨酯材料的制备及其荧光和热稳定性

香草醛与邻苯二胺缩合反应生成双羟基双亚胺,再与甲苯-2,4-二异氰酸酯的加聚反应,制备了分子骨架上含有—CH=N—键节的共轭亚胺聚氨酯。热重分析分析显示出,分子骨架上引入—CH=N—键节可以提高共轭亚胺聚氨酯材料的热稳定性。而荧光分析则表明,所制备的含有亚按键节的共轭亚胺聚氨酯的N,N-二甲基甲酰胺溶液能发射紫外荧光,而且分子内或分子间相互吸引,形成D-π-A作用和氢键作用,致使分子之间聚集,从而荧光发射光谱随浓度的增大发生红移。     

示踪阻垢聚合物

示踪阻垢聚合物,合成物示踪并防止或控制垢的形成,标记单位是由式XZC-C-YY’的单体衍生出的。这里的X是氢原子或CI—C4烷基,Y是氢原子或C1-C4烷基,Y’是该分子上的—L-Arom基,这里L是含有杂原子的共价或二价有机连接基．Arom最好是至少由3个共轭芳香环组成的基,上述环是由共轭碳原子以及氮或氧原子组成,并连接到前述碳原子或取代基上。     

聚天冬氨酸阻垢缓蚀剂的量子化学研究

用量子化学计算的方法,探讨了聚天冬氨酸(PASP)的分子结构和阻垢缓蚀性能的构效关系,计算结果显示,在阻垢性能方面,聚天冬氨酸分子氮原子和羧基团中氧原子呈负电性,这使得羧基上的氧原子易与晶面上的钙离子发生静电交互作用,且PASP分子中2个氮氧离子间距与方解石有关晶面上钙离子间距匹配,因而显著加强了阻垢剂分子与特定晶面之间的吸附力,从而起到了对碳酸钙晶体的阻垢效能.在缓蚀性能方面,计算得到了PASP分子最高占据轨道能量、最低空轨道能量和最低空轨道能量与最高占据轨道能量的差.计算表明结果与机理描述相符合.     

卟吩芳香性的理论研究

使用B3LYP/6-31+G(d,p)方法对卟吩进行几何优化,表明卟吩分子是一个平面结构,吡咯环和去氢吡咯环的结构不同。使用核独立化学位移(Nucleus-Independent Chemical Shifts,NICS)和AICD(Anisotropy of the Induced Current Density)方法研究卟吩的芳香性,卟吩的芳香性是内共轭途径和外共轭途径芳香性的叠加,且外环共轭途径芳香性要更强一些。     

Density Functional Theory Study on the Re Cluster/HZSM-5 Catalysis for Direct Phenol Synthesis from Benzene and Molecular Oxygen: Active Re Structure and Reaction Mechanism

DFT calculations have been achieved to obtain a convincing model for the active structure in a Re cluster/HZSM-5 catalyst active for direct phenol synthesis from benzene and molecular oxygen. Re₁₀ clusters with interstitial N atoms composed of two Re octahedra edge-shared with each other were concluded as a stable active structure in agreement with the EXAFS analysis. The adsorption and behavior of benzene, oxygen atom and molecule and phenol on the Re cluster were examined to obtain the energy diagram for the phenol synthesis including intermediate and transition states, which explains the reaction steps for the phenol synthesis.     

CO2在La2O3(011)表面吸附和活化的DFT计算

运用广义梯度密度泛函理论方法(density functional theory,DFT),结合周期性平板模型,研究了CO2在La2O3(011)表面的吸附和活化,计算了CO2吸附的吸附能和Mulliken电荷数.结果表明,CO2在La2O3(011)表面吸附形成6种平衡构型,分别为CO2-η1、CO2-η2、CO2-...     

Molecular description of active sites in oxidation reactions: Acid-base and redox properties, and role of water

Oxidation reactions in heterogeneous catalysis usually involve a Mars and van Krevelen mechanism which includes activation of the substrate on a metallic cation, insertion of oxygen from lattice oxygen ions, a redox mechanism on the catalyst surface, and the transfer of several electrons. It follows that such a reaction necessitates both acid-base and redox properties of a catalyst the acid site being of Lewis type (cations) and the basic sites being the surface O^2- or OH^- species which could exhibit electrophilic or nucleophilic properties.

The active site should be able to fulfil the following requirements: H abstraction from the substrate, oxygen insertion, and electron transfer. It has been shown to correspond to an ensemble of atoms of limited size in an inorganic molecular complex. It could correspond to local structural defects including steps, kinks, coordinatively unsaturated cations or to clusters of atoms on the surface. Some examples are described namely:

1. (i) n-butane oxidation to maleic anhydride on (VO)₂P₂O₇ catalyst where four dimers of vanadyl cations on the (100) face were suggested to form the active site;

2. (ii) isobutyric acid oxidative dehydrogenation to methacrylic acid on iron hydroxy phosphates where trimers of iron oxide octahedra were shown to constitute the most efficient and selective catalytic site while water was observed to be absolutely necessary to facilitate the reaction which corresponds to hydroxylated surface sites ensuring the redox mechanism;

3. (iii) propane oxidative dehydrogenation to propene on VMgO samples which was shown to depend both on VO_x arrangements with respect to MgO and on the basicity of the material induced by MgO while vanadium cations induced acidic features.

     

NO2硝化正己烷及其理论计算

对NO₂硝化正己烷的反应进行了研究,分别考察了反应温度、摩尔比和反应时间的影响。结果表明：在反应温度为120℃、正己烷与NO₂摩尔比为1∶2、反应时间为4h的反应条件下,正己烷转化率可达85.9%。通过密度泛函理论（DFT）研究了NO₂硝化正己烷的反应机理,在B3LYP/6-311++G(3df,2pd)//B3LYP/6-31G*计算水平下精确计算了三个可能反应途径的活化能（E_a）。计算结果表明：该反应决速步骤为NO₂中O原子进攻正己烷中的H原子,其中2-硝基己烷和3-硝基己烷为主要产物,且计算结果与实验结果一致。分子几何结构、原子电荷和IR振动频率的数据表明C—H键的断裂和N—H键的形成是一个协同过程,参与硝化反应的原子C(5)、H(7)、O(22)、O(23)和N(21)的分子几何参数及其原子电荷有明显的变化。     

卤水净化工艺CPAM絮凝机理研究

概述了石灰-烟道气法卤水净化工艺中苛化反应和碳化反应机理。对硫酸钠型卤水净化工艺中阳离子聚丙烯酰胺（CPAM）的絮凝机理进行了探讨：CPAM分子酰胺基上的2个氢原子与碳酸钙微晶中的羰基氧原子形成一种稳定的四边形氢键结构,并且与碳酸钙微晶内部的四边形结构通过羰基双键形成一个类似哑铃的对称结构,增加了整个分子结构的稳定性,极大提高了CPAM的絮凝能力。相似地,CPAM分子酰胺基上的2个氢原子与硫酸钙微晶中硫酸根上的2个氧原子极易形成一种非常稳定的六边形氢键结构。实验表明,当CPAM加入量为2 mg/L时,可以保证硫酸钠型卤水中钙质量浓度低于10 mg/L。     

Effect of the Environment, Charge, Chemical Structure, and Size of an Azo Dye on its Energy and Optical Properties

Calculations with consideration of solvation of methylsulfonic acid showed that the hydrogen bond is weakened in substitution of a methyl group for a chromophore in an azo dye due to delocalization of excess electrons from oxygen atoms in the sulfo group and more uniform electron density distribution over the conjugation system of the dye molecule. It was shown that the PM3 method satisfactorily reproduces the energy and geometric parameters of hydrogen bond systems and in calculating the electron, UV, and optical spectra, more correct results are obtained using the geometry of supramolecular solvate systems obtained in the 3-21G nonempirical basis set.     

Identifying the Catalytic Active Sites in Heteroatom‐Doped Graphene for the Oxygen Reduction Reaction

Density functional theory (DFT) calculations can be used to help elucidate the structures of active sites on the surface of fuel cell cathode catalysts, which are exceptionally difficult to identify by experimental techniques. The cathode catalysts were modeled in nitrogen‐, boron‐, sulfur‐, and phosphorus‐doped graphene basal planes. Dually‐doped graphene structures combining nitrogen with phosphorus or sulfur are also studied. Potential energy profiles were obtained, and the energies and activation barriers of molecular oxygen binding to the doped graphene model structures were estimated in order to identify potentially active sites for the oxygen reduction reaction in fuel cells. Among the investigated doped graphene structures, the active sites for molecular oxygen chemisorption are identified in graphene doped with either two nitrogen, or two phosphorus, or one sulfur and one phosphorus atoms. Further, the analysis of atomic spin densities and charges in the model structures enables the correlation of the catalytic activity with electron density distribution.     

配合物K2[Y^Ⅲ（dtpa）（H2O）]·7H2O的合成及结构研究

介绍了稀土金属离子Y^Ⅲ与氨基多羧酸类配体二乙三胺五乙酸（dtpa）形成的配合物的分子结构。配合物K2[Y^Ⅲ（dtpa）（H2O）]·7H2O中Y^Ⅲ与来自同一个二乙三胺五乙酸的3个氮原子和5个羧基氧原子及一个水分子的氧原子配位,配位数为9,形成单帽四方反棱柱体结构。