三分子体系中弱相互作用之间协同效应的理论研究

发布时间：2018-05-15 01:00

本文选题：MP2 + 非共价弱相互作用　；参考：《成都理工大学》2017年硕士论文

【摘要】：采用MP2方法,在6-311G++(d,p)基组条件下对三分子体系HX…HOCl…YH(X=F,Cl,Br,OH;Y=F,Cl,Br,OH,NH2)、OCS…NCX…NH3(X=H,Li,F,Cl,Br,SH,PH2)、C2H4…XCN…CH3Y(X=F,Cl,Br;Y=F,Cl,Br)和FH…OCO…XY(X=H,Cl,Br;Y=F,Cl,Br,CN)中两种弱相互作用之间的相互影响进行了研究。在前三个体系中,体系中间的HOCl分子、NCX分子、XCN分子既是电子供体又是电子受体,而在最后一个体系中,OCO分子只是电子受体。利用Multiwfn软件计算并比较了HOCl分子、NCX分子、XCN分子和OCO分子单独存在时与在二体复合物中时同一位置处的最大静电势值发现,前三个分子在二体复合物中时分子表面静电势明显比单独存在时要大,即和单体分子相比,二体的供电和受电能力均增大,也更容易与别的分子发生相互作用;而OCO分子在二体中时分子表明静电势比单独存在时要小,即和单体分子相比,二体的供电能力降低,更不容易与别的分子发生相互作用。通过AIM和RDG分析发现,在所有三体复合物中相邻两分子之间均具有等值面和键鞍点,表明在分子间有非共价弱相互作用形成。另外,利用软件计算了二体和三体复合物中弱相互作用的键长、振动频率、分子间相互作用能、键鞍点处的电子密度、二阶稳定化能、电荷转移量等理化参数,发现在HX…HOCl…YH、OCS…NCX…NH3和C2H4…XCN…CH3Y体系中,三体复合物中两种弱相互作用的键长与对应二体复合物相比同时缩短,振动频率、分子间相互作用能、键鞍点处的电子密度、二阶稳定化能、电荷转移量则在三体中同时增大,这些现象表明体系中两种弱相互作用之间具有相互加强的效应,即它们之间具有正协同效应;而在FH…OCO…XY体系中,三体复合物中两种弱相互作用的键长与对应二体复合物相比同时伸长,振动频率、分子间相互作用能、键鞍点处的电子密度、二阶稳定化能、电荷转移量则在三体中同时减小,这些现象表明体系中两种弱相互作用之间具有相互削弱的效应,即它们之间具有反协同效应。对比HX…HOCl…YH、OCS…NCX…NH3、C2H4…XCN…CH3Y与FH…OCO…XY体系,在前三个体系中,电子在体系中的转移方向相同,而在最后一个体系中电子的转移方向相反,因此得出结论:在电子转移方向相同的体系中存在正协同效应,在电子转移方向相反的体系中存在反协同效应。
[Abstract]:In this paper, MP2 method was used to study the effect of HX on trimolecular system under the condition of 6-311G / dapp group. HOCl. YHH X FU FU Cln BrOH OHU OHCU OHCU NH2 OCS. NCX. NH _ 3H _ 3H _ (+) H _ (+) C _ (2H _ 4) _ (C _ 2H _ 4) _ C _ 2H _ 4 _ C _ 2H _ 4 XCN. Ch _ 3Y _ (X) F _ (C _ (1) C) and F _ H _ (C _ (1) C _ (C) and F _ H. OCO. The interaction between the two weak interactions in the XYY (XYY) HGCL (BrC) is studied in this paper, and the interaction between the two weak interactions is also studied in this paper. The interaction between the two weak interactions has been studied in this paper. In the first three systems, the HOCl molecule in the middle of the system is both an electron donor and an electron receptor, while in the last system, the HOCl molecule is only an electron receptor. The maximum electrostatic potential of HOCl molecule, NCX molecule, XCN molecule and OCO molecule at the same position in the two-body complex was calculated and compared with that in the two-body complex by Multiwfn software. The surface electrostatic potential of the first three molecules in the two-body complex is obviously larger than that in the single molecule, that is, compared with the monomer molecule, the two-body has higher power supply and the ability to receive electricity, and it is also easier to interact with other molecules. However, the electrostatic potential of OCO molecule in the two-body is smaller than that in the single molecule, that is, the power supply ability of the two-body is lower than that of the monomers, and it is less easy to interact with other molecules. By AIM and RDG analysis, it is found that there are isosurface and bond saddle point between the two adjacent molecules in all trisomic complexes, which indicates that there is non-covalent weak interaction between the molecules. In addition, the bond length, vibration frequency, intermolecular interaction energy, electron density at bond saddle point, second order stabilization energy, charge transfer amount and other physical and chemical parameters of weak interaction in two-body and three-body complexes were calculated by software. HOCl. YHU OCS. NCX. NH3 and C2H4. XCN. In CH3Y system, the bond length of two weak interactions in the three-body complex is shorter than that in the corresponding two-body complex, the vibrational frequency, the intermolecular interaction energy, the electron density at the bond saddle point, and the second-order stabilization energy. These phenomena indicate that the two weak interactions in the system have mutually reinforcing effects, that is, there is a positive synergistic effect between them, while in FH, there is a positive synergistic effect between them. OCO. In XY system, the bond length of two weak interactions in the three-body complex is at the same time elongation, vibration frequency, intermolecular interaction energy, electron density at the bond saddle point, second order stabilization energy, compared with the corresponding two-body complex. The charge transfer decreases simultaneously in the three-body system. These phenomena indicate that the two weak interactions in the system have the effect of weakening each other, that is, the anti-synergistic effect between them. Contrast HX. HOCl. YHU OCS. NCX. NH _ 3H _ 2H _ 4. XCN. CH3Y and FH. OCO. In XY system, in the first three systems, the direction of electron transfer in the system is the same, but in the last system, the direction of electron transfer is opposite. Therefore, it is concluded that there is a positive synergistic effect in the system with the same direction of electron transfer. There is an anti-synergistic effect in the system with opposite electron transfer direction.
【学位授予单位】：成都理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O641.3

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