The Theoretical Research Of Excited-state Bridged And Intramolecular Proton Transfer Reaction

Excited state proton transfer （ESPT） is the most important and common reaction, exists in the physical and chemical reaction process normally. Hydrogen bond formed in most of the material in the nature and cased the quality of the material changed. Hydrogen bond is one of the first study weak interaction and some organic molecules undergoes proton transfer through hydrogen bonding interaction in the excited state. Nowadays, the research of ESPT resulting from site-specific interactions through hydrogen bond have many applications such as:the design and use of fluorescence sensors, laser dyes and LEDs, UV filters, molecular switches and so forth. Excited state proton transfer plays a very important role in the research for the new luminous materials, development of new drugs and to explore the vital signs.In the present work, all the theoretical calculations presented were accomplished using DFT and TDDFT methods based on the Gaussian 09 programs.We mainly focus on discussing the excited-state proton-transfer mechanism of 7AI-2H₂O system and the competitive excited state single or double proton transfer mechanism for bis-3, 6-（2-benzoxazolyl）-pyrocatechol in detail. Through the analysis of theoretical calculated results and the potential energy curves of 7AI-2H₂O system, we proposed the process of excited-state intermolecular proton transfer for 7AI-2H₂O system is special.The proton transfer reaction of 7AI-2H₂O system transferred along the water bridge.In addition, no specific potential energy barriers can be obtained based on the nodal plane model, so whether the conclusion is doubtful. Hence,we constructed the potential energy surfaces to investigate the excited state proton transfer of BBPC in detail and a new mechanism differs from the one proposed previously is proposed.The single proton transfer mechanism in the symmetric BBPC molecule possessing two equivalent proton transfer reactivity centers.The results of the study was not only illustrates the rationality of the quantitative calculation method with high efficiency, but also further put forward the excited state proton transfer mechanism by constructing the macromolecular potential energy surface.