Investigation on the Percutaneous Enhancing Permeation Mechanism of Azone for Ketoprofen Based on the Intermolecular Hydrogen-bonding Interaction

The permeation enhancing activity of Azone for ketoprofen through excised cavia skins was investigated using Franz diffusion cell. The possible hydrogen-bonded complexes formed between ketoprofen and the model molecule of Azone as azacyclopentane-2-one were fully optimized at the B3LYP/6-311++G** level. The intermolecular hydrogen-bonding interactions were calculated using the B3LYP/6-311++G**, B3LYP/6-311++G(2df, 2p), MP2(full)/6-311++G** and MP2(full)/6-311++G(2df, 2p) methods, respectively. The results show that the steady-state permeation rate of ketoprofen through excised cavia skins enhances over 9 times in the solvent with 2% Azone as compared with the solvent without Azone. The stable O–H···O=C and N–H···O=C hydrogen-bonded complexes could exist between azacyclopentane and ketoprofen. The hydrogen-bonding interaction energy follows the order of(a) (b) (c) (d) (g)(e) (h) (f). The formation of the complexes leads to the change of the conformation and molecular polarity of ketoprofen, and thus causes a better percutaneous permeation for the drug. The analyses of AIM(atom in molecule) and shift of electron density were used to further reveal the nature of the enhancing permeation activity of Azone for ketoprofen. The investigations of the temperature and solvent effects confirm that ketoprofen might enter into the skin by means of the Azone complex.     

Theory Studies on the Intermolecular Interactions of Urea Nitrate with RDX

Six fully optimized geometries of urea nitrate cation and RDX complexes have been obtained with DFT-B3LYP and MP2 methods at the 6-311++G** level. The intermolecular interaction energies have been calculated with basis set superposition error (BSSE) and zero point energy (ZPE) correction. The nature of intermolecular interaction has been revealed by the analysis of AIM and NBO. The results indicate that the greatest binding energy of urea nitrate with RDX is –82.47kJ/mol. The O–H…O and N–H…O hydrogen bonds are important intermolecular interactions of urea nitrate cation with RDX, and the origin of hydrogen bonds is the oxygen atom offering its lone-pair electrons to the σ(O-H)* or σ(O-H)* antibonding orbital. The intermolecular interactions strengthen the N–NO2 bond, leading to the reduced sensitivity of urea nitrate and RDX mixture explosive.     

平面型四核铜簇合物Cu4(CH2XMen)4桥键性质的密度泛函研究

采用密度泛函B3LYP方法，用LanL2DZ和6—31G^＊基组分别优化了平面型四核铜簇合物Cu4（CH2SiMe3）4和Cu4（CH2XMe2）4（X=P，As）的几何构型，并对B3LYP／LanL2DZ方法优化的结构进行了红外振动频率计算和自然键轨道分析．结果表明，簇合物均呈笼状结构，Cu—C—Cu三中心桥键之间电子的离域增强了Cu簇合物的稳定性，配位C原子的C—H平伏键与C—Cu配位键之间存在σ-超共轭效应．     

Gaussian量子化学模拟对芳烃硝化机理的探索

芳烃硝化反应是一类重要的亲电取代反应。本文综述了运用Gaussian量子化学模拟方法对芳烃硝化机理探索的进展，提倡在大学化学教学中引入Gaussian，以提高大学化学教学质量。     

电场中R-NO_2…HF(R=-CH_3、-NH_2、-OCH_3)氢键复合物结构及性能的理论研究

采用密度泛函B3LYP方法,在6-311++G(2d,p)水平上对外电场中的R-NO_2(R=-CH_3、-NH2、-OCH3)及其HF氢键体系(R-NO2…HF)进行了结构优化,然后在6-311++G(2d,p)和aug-cc-p VTZ基组水平上分别用B3LYP和MP2(full)方法进行了能量计算,并对单体R-NO_2在CCSD(T)方法下进行了更为详细的考量,最后借助分子中的原子(AIM)理论以及分子静电势揭示了结构和能量变化的本质.结果表明,在一定方向和大小的外电场作用下,单体分子的相对总能量降低,引发键键长变短,偶极矩增大,引发键离解能变大;氢键复合物比其单体引发键键长更短,引发键键能也更大.     

硝基胍H迁移异构化反应动力学的从头计算研究

采用MP2/6-31G(d,p)从头计算方法优化获得硝基胍两种异构体及过渡态的几何结构,在相同水平上计算了各驻点频率,并进行了IRC分析.利用过渡态理论,计算了在200~1773K的H迁移异构化反应的速率常数.结果表明,β型硝基胍中形成大范围的离域大∏键,存在显著的共轭效应使其比α型稳定,能量比α型低28.16kJ/mol;硝基胍由α型向β型H迁移异构化反应的活化能为132.95kJ/mol.298K时速率常数为1.99×10-11s-1,平衡常数为1.00×105;硝基胍的异构化是一个典型的同面H迁移放热反应,随温度升高,平衡常数逐渐减小,不利于α型通过H迁移向β型转化.     

硝基环丁烷炸药及其衍生物表面静电势与感度理论研究

在DFT-B3LYP/6-311++G**水平上,研究了硝基环丁烷及其衍生物和硝基环己烷C-NO_2和N-NO_2键的中点、环上方分子表面静电势及其统计量,建立了三种标题化合物实验撞击感度h50与分子表面静电势及其统计量之间的定量关系.结果表明,这些模型的相关性较差.然而,环张力贡献的引入使其相关性增强.作为一种表征分子全局性质的物理量,分子表面静电势可用于预估炸药分子的感度.随着实验数据的增多,建立撞击感度h_(50)与分子表面静电势及其静电势的统计量之间的定量关系是有必要的.     

平面型四核铜簇合物Cu_4(CH_2XMe_n)_4桥键性质的密度泛函研究

采用密度泛函B3LYP方法,用LanL2DZ和6 31G*基组分别优化了平面型四核铜簇合物Cu4(CH2SiMe3)4和Cu4(CH2XMe2)4(X=P,As)的几何构型,并对B3LYP/LanL2DZ方法优化的结构进行了红外振动频率计算和自然键轨道分析.结果表明,簇合物均呈笼状结构,Cu-C-Cu三中心桥键之间电子的离域增强了Cu簇合物的稳定性,配位C原子的C-H平伏键与C-Cu配位键之间存在σ超共轭效应.     

氮杂杯[2]-间/对-芳烃[2]三嗪与RDX氢键作用理论研究

利用MP2和mPWPW91方法,在6-311G**和6-311++G**基组水平上研究了RDX分别与硝基、氨基和迭氮基取代的氮杂杯[2]-间-芳烃[2]三嗪和氮杂杯[2]-对-芳烃[2]三嗪形成的分子间氢键相互作用,并借助自然键轨道(NBO)和分子中的原子(AIM)理论揭示了氢键的本质.结果表明,氮杂杯[2]-间-芳烃[2]三嗪复合物中氢键主要发生在RDX与三嗪环及其取代基之间;氮杂杯[2]-对-芳烃[2]三嗪复合物中氢键主要发生在RDX与杯芳烃环及其取代基之间.分子间相互作用能在-18.82~-40.62kJ/mol之间;经基组叠加误差(BSSE)校正后,相互作用能顺序为e>f≈b>a>c>d和e′>b′>f′>a′>d′>c′.两类复合物中,氨基取代的复合物分子间氢键强于硝基或叠氮基复合物分子间氢键,氨基氮杂杯[2]-对-芳烃[2]三嗪与RDX形成的氢键最强,有望作为降低火炸药感度、进行火炸药废水处理的候选物.为获得稳定性较强的RDX-氨基氮杂杯芳烃超分子炸药,应该选取介电常数较大的溶剂.     

Theoretical Studies on Intermolecular Hydrogen-bond Interactions between Hexamethylenetetramine and Nitric Acid

The structures of the complexes generated by hexamethylenetetramine and nitric acid have been fully optimized by B3LYP method at the 6-311++G** and aug-cc-pVTZ levels. The intermolecular hydrogen-bonding interactions have been calculated by the B3LYP/6-311++G**, B3LYP/aug-cc-pVTZ, MP2(full)/6-311++G** and CCSD(T)/6-311++G** methods, respectively. The NBO (nature bond orbital), AIM (atom in molecule), temperature effect and solvation effect have been analyzed to reveal the origin of the interactions. The results indicate that the stable hydrogen-bonded complexes could be generated by hexamethylenetetramine and nitric acid. The interactions follow the order of (a)>>(e)>(b)>(c)>(d)>(f)>(g). The C-N bonds which are adjacent to the methylene involving the hydrogen bonds tend to break in the chemical reaction. Due to the exothermic process, low temperature is conducive to the formation of the composition, which tallies with the experimental result.