The effect of anti-hydrogen bond on Fermi resonance: A Raman spectroscopic study of the Fermi doublet ν1—ν12 of liquid pyridine

The effects of anti-hydrogen bond on the ν₁—ν₁₂ Fermi resonance (FR) of pyridine are experimentally investigated by using Raman scattering spectroscopy. Three systems, pyridine/water, pyridine/formamide, pyridine/carbon tetrachloride, provide varying degrees of strength for the diluent-pyridine anti-hydrogen bond complex. Water forms a stronger anti-hydrogen bond with pyridine than with formamide, and in the case of adding non-polar solvent carbon tetrachloride, which is neither a hydrogen bond donor nor an acceptor and incapable of forming hydrogen bond with pyridine, the intermolecular distance of pyridine will increase and the interaction of pyridine molecules will reduce. The dilution studies are performed on the three systems. Comparing with the values of Fermi coupling coefficient W of the ring breathing mode ν ₁ and triangle mode ν ₁₂ of pyridine at different volume concentrations, which are calculated according to the Bertran equations, in three systems, we find that the solution with the strongest anti-hydrogen bond, water, shows the fastest change in the ν₁—ν₁₂ Fermi coupling coefficient W with the volume concentration varying, followed by the formamide and carbon tetrachloride solutions. These results suggest that the stronger anti-hydrogen bond-forming effect will cause a greater reduction in the strength of the ν₁—ν₁₂ FR of pyridine. According to the mechanism of the formation of anti-hydrogen bond in the complexes and the FR theory, a qualitative explanation for the anti-hydrogen bond effect in reducing the strength of the ν₁—ν₁₂ FR of pyridine is given.     

全原子分子动力学模拟结合核磁共振波谱研究N-甘氨酰甘氨酸水溶液的结构和弱相互作用

采用分子动力学模拟方法结合核磁共振化学位移系统研究了甘氨酰甘氨酸水溶液体系饱和溶解度范围的弱相互作用. 径向分布函数表明体系中不同类型的原子显示出形成氢键的不同能力. 氢键网络分析发现了不同氢键所能形成的分子簇结构. 随温度变化核磁共振化学位移值用于研究形成氢键的变化情况,并和模拟得到的结果进行比较,模拟和实验结果得到了较好的吻合.     

铜催化的乙酰苯胺间位碳氢芳基化反应机理的理论研究

通过系统的理论计算研究了Gaunt报道的一个新颖的间位选择性C-H键芳基化反应的机理. Oxycupration机理含有一个关键的Cu(III)基团和酰胺氧原子对苯环C2=C3键的反式加成步. 但是计算结果表明这个反应路径的活化能太高(>175.56 kJ/mol),所以是动力学禁阻的. 提出了一个含有关键的酰胺导向的Cu(III)-Aryl对底物C2=C3键的顺式加成步的机理,这一步是反应的决速步,也是决定产物区域选择性的一步. 这个机理的活化能与实验条件是符合的,而且这个机理预测的产物区域选择性与实验     

三种二元水溶液体系中氢键对拉曼线宽的影响

采用显微共聚焦拉曼光谱对三种二元水溶液(乙腈/水、二甲基亚砜(DMSO)/水和丙酮/水)进行测量,得到含有氢键作用的水溶液体系拉曼频移和线宽随浓度的变化规律。应用混合模型和相互作用体系的线宽经验公式对实验结果进行了分析。结果表明,含有氢键作用的水溶液体系中,氢键作用越强线宽越大,并且线宽随单位浓度变化率大;同种氢键体系中,线宽不仅受浓度浮动的影响,氢键作用也是一个重要的影响因素,定量分析证明线宽与浓度、氢键作用关系很好地符合Ojha等提出的线宽公式。     

4－羧基杂氮硅三环中羧基红外光谱的研究

１－甲基及１－乙烯基－４－羧基杂氮硅三环在１６４５～１６３５ｃｍ－１均有与４－羧基相联系的弱吸收。对１－氯烷基取代物在上述范围的红外光谱研究表明，此吸收应归属于氢键存在下羧基上Ｃ＝０的伸缩振动，这种氢键形成于４－羧基与另一杂氮硅三环的桥氧之间，给杂氮硅三环化合物的质子化机理提供了直接证据。     

Theoretical study on non-sequential double ionization of carbon disulfide with different bond lengths in linearly polarizedlaser fields

By using a two-dimensional Monte-Carlo classical ensemble method, we investigate the double ionization(DI) process of the CS_2 molecule with different bond lengths in an 800-nm intense laser field. The double ionization probability presents a "knee" structure with equilibrium internuclear distance R = 2.9245 a.u.(a.u. is short for atomic unit). As the bond length of CS increases, the DI probability is enhanced and the "knee" structure becomes less obvious. In addition,the momentum distribution of double ionized electrons is also investigated, which shows the momentum mostly distributed in the first and third quadrants with equilibrium internuclear distance R = 2.9245 a.u. As the bond length of CS increases,the electron momentum becomes evenly distributed in the four quadrants. Furthermore, the energy distributions and the corresponding trajectories of the double-ionized electrons versus time are also demonstrated, which show that the bond length of CS in the CS_2 molecule plays a key role in the DI process.     

弯曲型Lamb波传播特性与固井质量相关性研究

轻质水泥在油田固井中的广泛应用使得传统测井方式无法有效的对固井水泥胶结质量做出评价。为了研究新的可行的评价方法,本文采用传递矩阵方法对套管中传播的弯曲型Lamb波进行建模,并通过对所建模型进行数值计算研究了套管外水泥等介质的声学参数变化对弯曲型Lamb波衰减率的影响。数值计算的结果表明,弯曲型Lamb波的衰减率与水泥的声学参数以及水泥与套管的胶结状况有较强相关性,据此可对水泥与套管胶结状况进行评价。本文的计算结果与分析对弯曲型Lamb波在水泥胶结评价中的应用具有一定的参考意义。     

H++CO2散射在30电子伏能量下电荷转移和非电荷转移的非绝热分子动力学模拟

在大气化学、天体物理学和癌症质子疗法中都涉及到高能H⁺+CO₂散射反应.本文在最简电子-核动力学（SLEND）基础上系统研究在30 eV下的H⁺+CO₂散射.SLEND用经典力学描述核,用单行列式Thouless波函数描述电子.本文模拟了CO₂在42个取向共3402条轨线,为理解H⁺+CO₂散射中的各个反应过程和机制提供了系统描述：非电荷转移散射（NCTS）,电荷转移散射（CTS）和C=O双键的断裂,这些关于反应的有用信息不能完全从实验中获取.本文提供了散射的详尽细节,包括随CO₂取向不同主彩虹角和次彩虹角的出现和合并.SLEND NCTS和CTS的微分散射截面通过高等半经典方法计算,显示NCTS散射截面对所有散射角都同实验符合得很好,而CTS散射截面只大散射角时同实验结果符合得很好而在小角散射时稍差.无论是CTS还是NCTS SLEND都预言了主彩虹角的特征,这同实验完全一致.     

The triel bond: a potential force for tuning anion–π interactions

Using ab-initio calculations, the mutual influence between anion–π and B···N or B···C triel bond interactions is investigated in some model complexes. The properties of these complexes are studied by molecular electrostatic potential, noncovalent interaction index, quantum theory of atoms in molecules (QTAIM) and natural bond orbital (NBO) analyses. According to the results, the formation of B···N or B···C triel bond interactions in the multi-component systems makes a significant shortening of anion–π distance. Such remarkable variation in the anion–π distances has not been reported previously. The strengthening of the anion–π bonding in the multi-component systems depend significantly on the nature of the anion, and it becomes larger in the order Br^? > Cl^? > F^?. The parameters derived from the QTAIM and NBO methodologies are used to study the mechanism of the cooperativity between the anion–π and triel bond interactions in the multi-component complexes.     

Influence of ligand-bridged substitution on the exchange coupling constant of chromium-wheels host complexes: a density functional theory study

Designing and introducing novel wheel-shaped supramolecular as host complexes with new magnetic properties is the theme of the day. So in this study, new eight binuclear chromium (III) complexes, as models of real chromium-wheel host complexes, were designed based on changing of bridged-ligands and exchange coupling constants (J) of them were calculated using the broken symmetry density functional theory approach. Substitution of fluorine ligand in fluoro-bridged model [Cr₂F(tBuCO₂)₂(H₂O)₂(OH)₄]^?1 by halogen anions (Cl^?, Br^? and I^? ) decreased the antiferromagnetic exchange coupling between Cr(III) centres such that by going from F^? to I^? the J values became more positive. In the case of hydroxo-bridged model [Cr₂OH(tBuCO₂)₂(H₂O)₂(OH)₄]^?1, replacement of hydroxyl by methoxy anion (OMe^?) strengthened the antiferromagnetic property of the complex but substitution by sulfanide (SH^?) and amide (NH₂^?) anions weakened it and changed the nature of complexes to ferromagnetic. Because of their different magnetic properties, these new investigated complexes can be suggested as interesting synthetic targets. Also, the J value changes due to ligand substitution were evaluated and it was found that the Cr–X bond strength and partial charges of involved atoms were the most effective factors on it.