The Investigation Of Photo-physical And Photo-chemical Properties Of Two Kinds Of Chinese Medicine Monomer

Traditional Chinese medicine monomer generally refers to the Chinese herbal medicine which extracted from single effective active ingredient purity. Studying the structure of Chinese medicine monomer and the changes of conformation as well as the dynamic properties when they interact with other molecules have an important meaning for further research on the mechanism and drug toxicology and pharmacokinetic of medicine. Raman spectrum analysis is used to analysis scattering light which frequency is different from incident light to get the molecular information of vibration and rotation and it can be used to study molecular structure. It can provide the changes of structure and composition of the material at the molecular level. In addition, studying the characteristics of Raman spectrum of traditional Chinese medicine monomer can provide an analysis and appraisal method for complicated components. Excited state intramolecular proton transfer (ESIPT) is a kind of proton transfer, and it is one of the basic process of nature. It is of great significance for photo-physical and photo-chemical properties research and also one of the hot topics in the study of theory and experiment. At the same time, the investigation of photo-physical and photo-chemical properties of medicines can also provide a promising pathway to design new drugs based on this, and possibly other traditional Chinese medicine monomers.In this work, we used experiment and quantum chemistry calculations to research the Raman spectrum of paeonol and ESIPT coupled charge transfer of paeonol and baicalein. We measured the Raman spectrum of paeonol by Raman spectrometer and the assignment of the Raman vibrational bands of paeonol was accomplished according to the DFT calculations. The combination of experiment and calculations indicated that the intermolecular hydrogen bonding is formed in ethanol solution and it has a large influence on the Raman spectrum of paeonol. The analysis of charge transfer demonstrated that the paeonol-Ag complex is a strong chemisorbed system. We confirmed the adsorption geometry of paeonol-Ag complex according to the SERS spectra. The ESIPT reaction of paeonol was predicted on the basis of the large Stokes shift which is observed in steady-state absorption and fluorescence spectra in ethanol solution. It was later confirmed by subsequent theoretical calculations. The potential energy profiles of paeonol along with the bond O21-H22indicated that ESIPT was a barrier-less process. The frontier molecular orbitals of paeonol showed that the S1state was a localized excited state with ICT characteristics. Finally, the excited state intramolecular proton transfer (ESIPT) coupled charge transfer of baicalein had also been investigated. The Steady-state spectroscopic experiment and quantum chemistry calculations both indicated that the intramolecular proton transfer of baicalein taken place in the excited state. The Steady-state spectrum also indicated that S1is a dark state. The frontier molecular orbits and the charge difference densities (CDDs) of baicalein showed clearly that the Si state is a charge-transfer state whereas the S2state is a locally excited state. The potential energy profiles of baicalein also illustrated that the ESIPT is a process of barrier-less.