木犀草素与腺嘌呤相互作用的理论研究

本文采用密度泛函理论中的B3LYP方法,在6-31+G~*基组水平上对木犀草素—腺嘌呤复合物进行结构优化和振动频率分析,得到了16种稳定的木犀草素—腺嘌呤复合物.应用分子中的原子理论(AIM)分析、自然键轨道(NBO)理论分析得到复合物氢键性质和特征.通过基组重叠误差(BSSE)校正后的相互作用能、成键临界点电荷密度、二阶稳定化能综合分析,得出三氢键复合物C-11结构是最稳定的.综合比较DNA的四个碱基与木犀草素间的相互作用,木犀草素与胸腺嘧啶的相互作用最强,木犀草素-腺嘌呤相互作用最弱,DNA的四个碱基与木犀草素间的相互作用能均比木犀草素与水间相互作用能大,这说明木犀草素作为抗癌药物能有效的发挥作用.     

Comparison of hydrogen and halogen bonds between dimethyl sulfoxide and hypohalous acid: competition and cooperativity

A theoretical study of the complexes formed between dimethyl sulfoxide (DMSO) and hypohalous acid (HOX, X = Cl, Br, and I) has been carried out at the MP2/aug-cc-pVTZ level. For each HOX, four minima binary complexes were found, two mainly with an OH???O hydrogen bond and the other two with an OX???O halogen bond. The hydrogen-bonded complexes are more stable than the halogen-bonded analogues for HOCl and HOBr, while both types of complexes have similar stability in the iodine case. A red shift was found for the associated H–O and X–O bond stretch vibrations and a small blue shift for the distant bonds. As the oxygen of DMSO simultaneously binds with two HOCl molecules, the corresponding interactions are weakened with diminutive effect. This diminutive effect is the largest in the complexes with two OH???O hydrogen bonds but the smallest in those with two OCl???O halogen bonds.     

Lattice dynamics and phase diagrams for hydrogen bonded systems

Abstract

A variational correlated ground state wave-function theory is applied to investigate the high-pressure deformation of hydrogen-bond potential described by a double Morse potential functions. The evolution of the hydrogen bond potential with increasing pressure and the effects of deuterium isotope substitution on the quantum-fluctuation-driven phenomena are discussed. The theory was employed for predicting and interpreting the pressure dependence of the phase transition temperatue for KDP-like ferroelectrics and NQR-frequency coefficients for several deuterated and undeuterated crystals.