二氢杨梅素分子结构与性质的密度泛函理论研究

Density functional theory study on molecular structure and properties of dihydromyricetin

本文基于密度泛函理论(DFT),采用B3LYP泛函结合6-31G基组上对二氢杨梅素的分子几何结构进行了优化,在此基础上以水为溶剂计算二氢杨梅素分子的活性位点以及红外光谱进行分析.静电势结果表明二氢杨梅素的亲核活性位点位于酚羟基氢原子(H23)附近;而亲电活性位点位于氧原子(O32)及其附近.前线分子轨道研究结果表明二氢杨梅素分子的最高占据轨道(HOMO)都位于酮基氧(O32)和羟基氧(O20)附近,说明这些位点易与亲电试剂反应.而最低空轨道(LUMO)位于碳原子(C12、C13、C14)区域,表明这些区域可与亲核试剂反应.简缩福井函数(f)结果证实了位于C-O-C键中的氧原子的f-值的亲电活性较其他位点氧原子大;而位于C8碳原子的f^(+)值较大,因此该位点亲核活性较强.通过理论计算所得到的二氢杨梅素的红外光谱数据与实验所得到的红外光谱数据相差不大,这就说明理论计算结果是较为可靠的.从而为实验和理论研究二氢杨梅素结构与性质的关系提供了一定的理论参考.

In this paper,the molecular geometry of dihydromyricetin was optimized based on density functional theory(DFT)using B3LYP functional combined with 6-31G group,based on which the active sites of dihydromyricetin molecules were calculated using water as solvent and the infrared spectra was analyzed.The electrostatic potential results showed that the nucleophilic active site of dihydromyricetin is located near the phenolic hydroxyl atom(H23);while the electrophilic active site is located in and near the oxygen atom(O32).The results of frontline molecular orbital studies indicate that the highest occupied orbitals(HOMO)of dihydromyricetin molecules are located near ketone oxygen(O32)and hydroxyl oxygen(O20),indicating that these sites are susceptible to reaction with electrophilic reagents.And the lowest occupied orbitals(LUMO)are located in the carbon atom(C12,C13,C14)region,indicating that these regions can react with nucleophilic reagents.The results of the simplified Fukui function(f)confirm that the electrophilic activity of the f-value of the oxygen atom reagents.The results of the simplified Fukui function(f)confirm that the electrophilic activity of the f-value of the oxygen atom located in the C-O-C bond is larger than those of the oxygen atom in other sites;while the f^(+)value of the carbon atom located in C8 is larger,so the nucleophilic activity is stronger in this site.The infrared spectral data of dihydromyricetin obtained by theoretical calculations do not differ much from those obtained experimentally,which indicates that the theoretical calculations may be reliable.Thus,it provides some theoretical reference for the experimental and theoretical studies of the relationship between the structure and properties of dihydromyricetin.