白藜芦醇顺反异构体及第一三重激发态结构的理论研究  

A theoretical study on the structures of cis / trans-resveratrol and the first triplet state

作　　者：何云清[1,2] 胡启山[1,2] 胡文[1] 刘柳斜[3] 

机构地区：[1]四川文理学院化学化工学院,达州635000 [2]特色植物开发研究四川省高校重点实验室,达州635000 [3]四川师范大学化学与材料科学学院,成都610066

出　　处：《原子与分子物理学报》2015年第4期572-578,共7页Journal of Atomic and Molecular Physics

基　　金：特色植物开发研究四川省高校重点实验室开放课题重点项目(sctz201302);四川省大学生创新创业训练项目(201310644016);四川文理学院化学化工学院大学生应用创新能力训练计划项目(hg2014xly03)

摘　　要：在B3LYP/6-311++G(d,p)水平对白藜芦醇顺反异构体及第一三重激发态进行了结构优化、频率计算和自然键轨道(Natural Bond Orbital,NBO)分析.在MP2/6-311++G(d,p)//B3LYP/6-311++G(d,p)水平比较了白藜芦醇顺反异构体的能量.反式白藜芦醇整个分子呈平面结构,顺式白藜芦醇两苯环之间存在约30o扭角.第一三重激发态中两苯环几乎处于互相垂直的关系,C7-H5与C8-H6键也是几乎互相垂直的关系.顺式和反式白藜芦醇C7-C8的σ键成键情况分别为sp1.53-sp1.53和sp1.59-sp1.60,C7与C8各自提供p轨道形成π键,即形成C7=C8双键.三重态中,C7-C8的成键情况为sp1.92-sp1.89,没有p-pπ键,C7、C8均还有一个2p轨道未参与杂化,NBO分析证实C7、C8的各自剩下的2p轨道均几乎独立形成了高能量的反键轨道,分别垂直于单羟基和双羟基苯环,C7-C8键长明显长于白藜芦醇顺反异构体.顺式白藜芦醇比反式白藜芦醇的自由能高约1.3-2.5 kcal/mol,反式构型是热力学稳定构型.含时密度泛函方法(Time-Dependent Density Functional Theory,TD-DFT)方法,B3LYP/6-311++G(d,p)水平计算得反式和顺式白藜芦醇最强紫外吸收峰分别在330 nm和319 nm.The geometry optimizations, vibration frequencies, and natural bond orbital （NBO） analysis of cis/ trans -resveratrol and the first triplet state were performed at B3LYP/6 -3 11 ＋ ＋ G（ d, p） level, free energies of two isomers were obtained at B3 LYP/6 - 3 11 ＋ ＋ G （ d, p ）//B3 LYP/6 - 3 1 1 ＋ ＋ G （ d, p ） level. Trans - resveratrol is a planar structure, a torsional angle of benzene rings of cis - resveratrol is about 30°. One benzene ring of the first triplet state is perpendicular to the other, and C7 - H5 bond is perpendicular to C8 - H6. C7 - C8 σ bonds in cis/trans -resveratrol are sp^1.53 -sp^1.53 and sp^1.59 -sp^1.60, respectively, and a w bond is formed using p orbital from C7 and C8. C7 - C8 in the triplet state is sp^1.92 - sp^1.89 σ bond, 2p orbital of C7 or C8 forms one high energy antibonding orbital independently, and similar to C8, and is perpendicular to the benzene ring with one hydroxy and two hydroxies, respectively, with its C7 - C8 bond length longer than that in cis/trans - resveratrol. Trans -resveratrol is the thermodynamic stable structure because its free energy is lower than that of cis - resveratrol 1.3 - 2. 5 kcal/mol. The strongest ultraviolet absorption peaks of trans - and cis - resveratrol are at 330 nm and 319 nm, respectively, achieved at B3LYP/6 -311 ＋ ＋ G（d,p） level using TD -DFT method.

关 键 词：白藜芦醇 异构体 三重态 自然键轨道 前线轨道 UV 

分 类 号：O561.1[理学—原子与分子物理]