Density Functional Theory Studies on Structure and Spectra of Salidroside Molecule

At present, with the continuous development of science and technology, more and more new techniques emerge in quality control quality evaluation of Traditional Chinese Medicines (TCMs). In the standardization process of TCMs, modern pharmaceutical research has made many remarkable achievements. Detection methods and technologies have made great progress from single-index detection to multi-index detection. Rhodiola Rosea is a kind of minority nationality medicine that is an indispensable part of the development of traditional Chinese medicine. Salidroside is one of the main components of Rhodiola Rosea. There are many reports on its extraction, separation and purification. However, far few reports have been reported up to now on its molecular parameters, such as bond length, bond angle, dihedral angle, frontier orbital distribution and surface electrostatic charge Distributions, which are critical factors determining its chemical properties and reaction mechanism. The parameters of bond length, bond angle and dihedral angle of salidroside were obtained by DFT / B3LYP method and 6-31 (d) basis set from Gaussian09W software. As the result of optimization, the surface electrostatic charge (ESP), the lowest occupied orbit (LUMO), the highest occupied orbit ( HOMO). Infrared (IR) and nuclear magnetic resonance (NMR) data were calculated, and their peak positions were assigned and compared with the reported data. The results reveal that there is no imaginary frequency in the infrared absorption frequency, which indicates that the optimization result is reasonable and reliable; the highest occupied orbit energy E= - 5. 82 eV, the lowest orbit energy E= - 0. 000 42 eV, and the difference is 5. 81 eV. By drawing the electron cloud distribution map of the orbit, we can see that the HOMO orbit is the pi bonding orbital of electron mainly distributing on the benzene ring with a node ; the LUMO orbit is the pi antibonding orbital of electron mainly distributing on the benzene ring with two nodes. The drawing of surface electrostatic charge can directly determine which part of the molecule is prone to nucleophilic substitution reaction and which is prone to electrophilic reaction. The electron migration direction can be obtained directly by drawing the electron difference between the first excited state and the ground state. The theoretical study of salidroside molecular calculation in this dissertation can provide important references and new ideas for further exploring the chemical reaction mechanism, structural modification and identification of active sites.