Study On The Effects Of Different Substituent On The Excited State Proton Transfer

Under the action of visible light,physical or chemical changes have occurred within the material,these changes we called as the "photophysical and photochemical reaction".Nowadays technology is highly developed,photophysical and photochemical reactions have penetrated into many scientific research directions,for example: energy,materials,physics,chemistry,biology and some other aspects of social life.The reaction mechanism of photophysical and photochemical reaction process should are investigated in detail,in order to further promote the progress of technology and facilitate the people's lives.According to the time sequence of reaction,the photophysical and photochemical reaction is divided into the primary and secondary reaction process.The primary reaction process absorbs energy,which leads to the changes of the electronic structure and energy state of the molecule.The secondary reaction occurs in the high energy state of molecules,and the excited state in the high energy level could produce some physical or chemical reactions which were very fast and difficult occurred in the ground state.The hydrogen bonding interaction is an important bridge in photophysical and photochemical reaction process,as a kind of weak interaction with special statues,attract attentions from experimental and theoretical scientists,and has produced a new research field of excited state hydrogen bonding dynamics.The excited state hydrogen bonding dynamics analyzes the influence of intramolecular and intermolecular hydrogen bonding for the spatial structure of the molecule,steady state spectral properties and excited state inactivation process and so on,and further explain the excited state intramolecular proton transfer and photoinduced charge transfer and so on.In this paper,the effects of different polar solvents and substituents on the excited state proton transfer and charge transfer are discussed.We focus on the molecular structure,steady spectra properties and excited state deactivation process.It includes the changes of excited state bond length and angle in the space structure,the relationship between steady state spectral shift(sizeand direction)and intramolecular or intermolecular hydrogen bond strength change,the changes of excited state potential energy along the main bond lengths in excited state potential energy curve.This paper is divided into three parts: the first part briefly introduces the difference between the photophysical and photochemical reactions and the thermochemical reaction,the electronic structure of molecules and their changes before and after photoexcitation,and the energy dissipation form of the molecule in the excited state,illustrated in the first chapter.The second part is the theoretical basis and research methods.Simply introduced the modern quantum chemistry,it's basic theory is quantum mechanics and calculation methods were the density functional theory and time-dependent density functional theory,which detailed listed in the second chapter.The third part include chapter 3-5,presented the effects of different substituents on the hydrogen bonding of excited states are introduced in detail.The third chapter study the excited interamolecular proton transfer of6-amino-2(-2'-hydroxy phenyl)benzoxazole(6A-HBO)in the heptane,dichloromethane,methanl and acetonitrile solvents.The fourth chapter explored the excited charge transfer and proton transfer of 6-amino-2-(2'-methoxy phenyl)benzoxazole(6A-MBO)in the heptane and dichloromethane solvents.Through the analysis of excited state molecules structure,the frontier molecular orbital,steady state electronic spectra and potential energy curves,etc,for judge which happen in the excited state.Chapter 5 summarized and prospected briefly.In a word,the basic theory and calculation methods of photophysical and photochemical reactions are briefly described.Through changed the substituent group of fluorescent molecules in different polar solvents,analysis of the corresponding excited molecule space structure,steady state spectra and energy curves,and explored the effect of substituents on the excited state intramolecular electron and proton transfer.