Theoretical Study Of Excited State Proton Transfer Mechanism For Biology Molecular

Hydrogen bond is omnipresent in nature,and human life cycles are maintained with hydrogen bonds.It has gained widespread concern because of its significance in physical reactions,chemistry reactions,especially in the process of biological macromolecules.Hydrogen bond is the direct carriers of solute interactions with solvents.In the complex life system,it has significant impact on structure and function of many biological macromolecules.Proton transfer reaction is one of the important reactions in the biological field,such as acid-base neutralization reaction,which is based on the hydrogen bond.Particularly,excited state proton transfer have many applications such as:the treatment of cancer,AIDS and other special drug researches,the design and use of fluorescence sensors,molecular design of drugs and molecular switches.The excited state proton transfer refers to the isomerization of the proton that on the proton donor transfer to the adjacent proton acceptor along the molecular hydrogen bond.However,what role does the hydrogen bond play in the excited state proton transfer,and how does it affects the structures and functions of the biology macromolecules?It is the concern of this research.In the present work,all the theoretical calculations presented were accomplished based on density functional theory and time dependent density functional theory methods.We mainly focus on discussing three aspect in detail.The effects of the number of solvent molecules on proton transfer reaction,the influence of solvent polarity on proton transfer reaction,and the proton transfer mechanism of natural product molecules.We found that the hydrogen bond strengthened in the excited state by the analysis of the molecular structure and the infrared vibration spectrum of the molecular system in the ground state and the excited state.The hydrogen bond strengthening will promote the proton transfer reaction.The calculated absorption spectra and fluorescence spectra are in good agreement with the experimental values,which proves the rationality of the method we chose.Finally,the mechanism of proton transfer is proposed by using the method of constructing the ground state and excited potential energy curve.In conclusion,our investigations not only testify the rationality and efficiency of the calculated method we applied,but also explain the excited state proton transfer mechanism based on constructed potential energy curves.