Study On The Spectral Properties Of Several Alkaloids Of Peganum Harmala Density Functional Theory

The three alkaloid molecules of harmane,harmine and harrmaline are some of the effective biologically active ingredients extracted from plants of the Peganum harmala.Since the position of the nitrogen atom on the pyridine ring is the second position,it is assigned toβ-carboline alkaloids.Because they have good anti-inflammatory and anti-cancer effects,they have been widely developed and utilized.This dissertation contains three parts as described below:1.Infrared spectrum and optimized geometry of the harmane molecule have been calculated with density functional theory(DFT)using the Gaussian 09 package,and all the calculations were performed using M062X/6-31g(d)basis set level in this paper.The vibrational modes were assigned on the basis of potential energy distribution(PED)through the VEDA 4.The time-dependent density functional theory(TD-DFT)were used to calculate the ultraviolet absorption spectra and the excited states of the molecule under different conditions.And the results were compared with the experimental values,the feasibility of theoretical calculation method was explored,the excited states of the harmane molecule were analyzed and calculated,the frontier molecular orbital of the harmane molecule was discussed.This study provides a theoretical support for the analysis of harmane.2.Raman scattering spectrum and optimized geometries of the HRM molecule and HRM-Ag complex was calculated using density functional theory(DFT)with M062 X functional at the level of 6-31+g(d)set for C、H、N atoms and Lanl2 dz for Ag respectively in this article.The energy difference between the HOMO and LUMO orbitals of the Harmane base molecule and the Ag complex is calculated.The predicted adsorption mode of harmane on silver enhanced substrate was vertical.3.Infrared spectra and optimized geometries of the harmine and harmaline molecule were calculated using density functional theory(DFT)with M062 X functional at the level of6-31+g(d)in this article.Infrared spectra were obtained from the calculation results of the frequencies,the vibrational modes were assigned.Ultraviolet spectra and optimized geometries of the harmine and harmaline molecule were calculated using(TD-DFT),the ultraviolet spectra obtained were compared with the ultraviolet spectrum measured by experiment.