2019 International Conference on Applied Mathematics, Statistics, Modeling, Simulation (AMSMS 2019) ISBN: 978-1-60595-648-0 Theoretical Investigation the Compounds of Lanthanum Coordinated with Dihydromyricetin Wen-bo LAN1, Chang-ming NIE2, Xiao-feng WANG1, Li-ping HE1, 1 3,* Yu LIU and Yan-bin MENG 1College of Public Health, Xiangnan University, Chenzhou 423043, China 2School of Chemistry and Chemical Engineering, University of South China, Hengyang, 421001 China 3Medical Department, Xiangnan University, Chenzhou 423043, China *Corresponding author Keywords: Dihydromyricetin, Lanthanum, Density functional theory, Binding energy. Abstract. In order to study in depth the complexes formed by dihydromyricetin and lanthanum which may have a good medical effect. Theoretical study of the molecular structure of dihydromyricetin (DMY) compound containing lanthanum were carried out by using density functional theory (DFT) under the B3LYP/6-311G (d, p) level. All the results shown that the coordination compounds of lanthanum with dihydromyricetin (DMY) could form some different molecular modeling, for example, in this article it involved two complexes, one with a ratio of 1:3 (1La:3DMY), the other with a ratio of 1:4 (1La:4DMY). The main parameters of infrared frontier, atomic charge distribution, binding energy, and molecular orbital and energy from the theoretical simulation for La-3DMY and La-4DMY compounds were analyzed and compared with each other. What’s more, this work was expected to provide significant information for understanding the characteristics of La-DMY compounds at the molecular level and offer valuable comprehensive guides for future experiments. Introduction Dihydromyricetin (DHM, Fig. 1), often called ampelopsin, as a major bioactive constituent of rattan tea, belongs to the flavonoid [1-3]. Furthermore, DHM has a significant hypoglycemic, hypolipidemic effect, and element of lanthanum has been shown a wide range of applications in the field of clinical physiotherapy. Lanthanum chloride, a non-radioactive light Rare earth compound, has specific selectivity and high affinity to tumor cells and tumor tissues that can induce apoptosis [4-6]. Therefore, we hypothesized that compound formed by DHM with lanthanum will have a better medical effect. What’s more, before researching, there are medical properties that we can calculate them at the molecular level and make some important predictions. With the rapid development of computational chemistry, the calculation accuracy at the B3LYP level by density functional theory has been demonstrated to reach the level of high-precision [7-11]. Meanwhile, computational chemistry calculations have been introduced into the molecular structure of compound and complication [12-18]. The theoretical study is low cost, green and high-efficiency, which turned out to be very satisfying. It could provide some important theoretical basis and reasonable guidance for the theoretical plan and synthesis experiment on the effective compounds. What’s more, until current study, there is no report on combining the compounds of DHM with lanthanum. In this article, we chose the appropriate oxygen atoms as the coordination atoms and carry out a theoretical study on La-3DMY and La-4DMY by using computational chemical software in DFT (density functional theory) calculations with the B3LYP/6-311G** basis set level. Some meaningful structural information and important properties of La-3DMYand La-4DMY were obtained, for example, the molecular configuration parameters, the IR spectral properties, the mulliken atomic charge, the molecular orbital and the binding energy. 23 Computational Software and Methods By using the Gaussian 09 software package, all the information for the compounds La-3DMY and La-4DMY have been obtained under the density functional theory (DFT)/B3LYP calculations level [19-22]. And the scalar relativistic effects were taken into account through using the Lanl2DZ basis sets on the lanthanum atom. While the other atoms for C, H, O et al. were adopted the 6-311G (d,p) basis set [23-24]. For the La-3DMY and La-4DMY, the main parameters of infrared and characterization are compared and analyzed with each other. All the information, including the geometric structures, infrared spectroscopy, frontier molecular orbital, and binding energy obtained under the optimized structure were calculated and analyzed. Figure 1. Molecular structure of dihydromyricetin. Rescults and Discussion TheLa-3DMY and the La-4DMY Structures Figure 2. Optimized structures of La-3DMY and La-4DMY. Firstly, we chose the coordination atoms by calculating the DMY. And by analyzing the atomic coordination bond angle, we found that the lanthanum atoms more likely formed coordination bond with two adjacent atoms of oxygen. And through theoretical calculation, the result was shown (in figure 1) that the oxygen (Oa) and (Ob) have more natural negative charges than any other two adjacent oxygen atoms, which means the oxygen might have better coordination ability for lanthanum. In addition, where were Oa and Ob have the smallest space location and we have tried other O atoms to coordinate with lanthanum and found that the compound formed with other O atoms have large higher energy than the corresponding compound which lanthanum coordinated with O a and O b atoms. The theoretical calculation of the molecules was performed by using the DFT calculation in the level of B3LYP/6-311G** for the La-3DMYand La-4DMY. Their optimized configurations were shown in Fig. 2, (a) and (b) represent La-3DMY and La-4DMY, respectively. From the optimized structure, it could be seen that the lanthanum occupies the central position of the compounds molecular structure. The main structural parameters from the molecular simulation were listed in Table 1 and Table 2. As shown in Table 1, the average bond length of La-O in La-3DMY is 2.550Å, and the average bond length of La-O in La-4DMY is 2.561Å. The bond lengths of La-O in La-3DMY are slightly shorter than those of the La-4DMY. It means that the bond energy of La-O in La-3DMY is 24 stronger than that of La-4DMY. The O-La-O bond angles of the La-3DMY and the La-4DMY were listed in Table 2. These results could offer valuable structural parameter guides for future experiments. Table 1. The comparison of bond length (Å) of the La-3DMY and the La-4DMY value of quantum chemistry. Bonds La-3DMY La-4DMY La-O1 2.539 2.582 La-O2 2.552 2.536 La-O3 2.548 2.571 La-O4 2.514 2.554 La-O5 2.513 2.577 La-O6 2.632 2.555 La-O7 \ 2.582 La-O8 \ 2.528 Table 2. The comparison of bond angles (°) of the La-3DMY and La-4DMY value of quantum chemistry. Bonds La-3DM La-4DM Bonds La-3DMY La-4DMY O1-La-O2 65.19 62.67 O3-La-O5 146.98 90.29 O1-La-O3 111.84Y 70.31Y O3-La-O6 97.84 144.68 O1-La-O4 91.88 106.68 O3-La-O7 \ 86.68 O1-La-O5 93.26 82.05 O3-La-O8 \ 137.65 O1-La-O6 148.31 82.40 O4-La-O5 94.59 144.84 O1-La-O7 \ 162.64 O4-La-O6 111.36 150.17 O1-La-O8 \ 150.36 O4-La-O7 \ 86.75 O2-La-O3 99.77 96.45 O4-La-O8 \ 85.65 O2-La-O4 146.22 90.41 O5-La-O6 64.66 63.38 O2-La-O5 110.41 138.89 O5-La-O7 \ 68.65 O2-La-O6 99.99 90.20 O5-La-O8 \ 103.53 O2-La-O7 \ 151.98 O6-La-O7 \ 103.28 O2-La-O8 \ 98.38 O6-La-O8 \ 74.70 O3-La-O4 64.65 62.62 O7-La-O8 \ 62.84 Infrared Spectroscopy The La-3DMY and the La-4DMY’s infrared spectra obtained by molecular simulations under the same B3LYP level were shown in Fig. 3. There was no imaginary frequency in the calculated infrared vibrations for the two complexes structures. It means that these two structures are at a stable level. The result showed that the C=O stretching vibration absorption peak of the La-3DMY appeared at 1646 cm-1, the C-O stretching vibration absorption peak from the coordination atoms appeared at 1514cm-1, and the stretching vibration absorption peak from the O-H almost appeared at 3661cm-1 and 3691cm-1. While, in the La-4DMY, the C=O stretching vibration absorption peak of the La-4DMY appeared at 1644 cm-1 and 1604cm-1, where were in 1604cm-1 may be caused by the O of the C=O (O-10) formed a hydrogen bond [25-26]. The numbers of O atoms were shown in Fig. 2 b. The coordination atoms of C-O stretching vibration absorption peak appeared at 1514cm-1, the O-H stretching vibration absorption peak almost appeared at 3661cm-1 and 3691cm-1, only the O-H (O-9) stretching vibration absorption peak appeared at 3290cm-1, which may be caused by the hydrogen bond from the O (O9). Atomic Charge Distribution Under the computational simulation, we obtained the La-3DMY and the La-4DMY’s atomic charges, and the atomic charges for the La-3DMYand the La-4DMY were listed in Table 3. The numbers for the part atoms were shown in Fig. 2. The net charges of the coordination atoms of O1, O2, O3, O4, O5 and O6 in La-3DMY were −0.470, −0.504, −0.419, −0.511, −0.418 and −0.511, respectively. While 25 the charges of the coordination atoms of O1, O2, O3, O4, O5 O6, O7 and O8 were -0.602, -0.603, -0.603, -0.602, -0.538, -0.532, -0.537 and -0.532, respectively. The positive electric charge values of La in the La-3DMY and the La-4DMY were +1.562 and +2.426, respectively.