Study On The Fluorescence Properties Of The Ground State And Excited State Of 4THBO/DPP Molecules Based On Density Functional

With the deepening of human physics and chemistry research,laser technology came into being,and people opened the microscopic molecular and atomic world.The fluorescent properties of molecules can be applied to optoelectronic devices such as fluorescent probes,fluorescence imaging,proton transfer lasers,Organic light emitting diodes(OLEDs),etc.More experiments are studying the molecular fluorescence properties and excited proton transfer processes.In this paper,the timedependent density functional theory method(TDDFT)combined with the IEFPCM is used to study the molecular ground state and excited state fluorescence properties.Compared with the high requirements of the experiment on the equipment,theoretically analyzing the ultrafast proton transfer process of the excited state of matter is of great significance.This paper explores heteroatom substitution and position for 2-[4 '-(N-4,6-dichloro-1,3,5-triazin-2-yl)hydroxyphenyl] benzoxazole(4THBO)The effects of molecular fluorescence mechanism and the effects of aprotic and protic solvents on the molecular fluorescence mechanism of 4-(Nsubstituted-amino)-1H-pyrrolo [2,3-b] pyridine(DPP)were explored.The main contents are divided into the following two aspects:(1)By using density functional theory and time-dependent density functional theory(TDDFT),the influence of heteroatom substitution and position effect on the fluorescence properties of the excited state proton transfer of 4thbo molecule is calculated.The results show that the effect of heteroatom substitution is due to the reduction of the electronegativity of heteroatom,which promotes the process of excited state proton transfer of 4thbo molecule,so the emission fluorescence changes from the violet region to the visible region,The fluorescence peak shifts red.For the position effect of substituents,there are different conjugation effects due to the change of para and inter substituents,which makes the fluorescence peak of 4thbo change from violet to visible.(2)Using DFT and TDDFT theoretical methods,the effects of protic and aprotic solvents on the excited proton transfer fluorescence mechanism of DPP molecules were calculated.The above results indicate the double fluorescence phenomenon and fluorescence quenching of DPP molecules in aprotic solvents,and clarify the two different proton transfer fluorescence mechanisms of DPP molecules in protic solvents and aprotic solvents.Because DPP molecules are DNA derivatives,they help to study the biological activity of DNA derivatives in solvents.The computational simulation in this paper can make up for the lack of experimental molecular mechanism of excited proton transfer fluorescence molecules that cannot be observed experimentally.We hope that from the perspective of the fluorescence mechanism,it will help the development of the photoelectric properties of such molecules and also the design of biological fluorescent probes.