Theoretical Study On The Reaction Mechanism Of The Thermal Cis-trans Isomerization Of Fluorine-substituted Azobenzene Derivatives

As a typical photochromic compound,azobenzene molecules have been attracting widespread attention since they were first discovered in 1834.Under certain conditions,a reversible isomerization reaction occurs between the cis and trans isomers of the azobenzene molecule.The reaction mechanism of the isomerization reaction of azobenzene molecules and how to regulate the isomerization reaction of azobenzene molecules are the topics that scientists have been working on.In this paper,we use theoretical calculations to calculate the properties of azobenzene compounds and hope to provide theoretical guidance for the practical application of azobenzene molecules.This research was based on the quantum chemical calculations of a set of valid photoswitches of azobenzene compounds,with the aim of describing their thermal isomerization.The influences of familiar fluorine substitution and additional electron-donating groups(EDGs)and electron-withdrawing groups(EWGs)on the para-position were also systematically studied.The results show that the presence of fluorine in different ortho-positions has a distinct effect on the molecular orbital distribution of the E isomer,which realizes the purpose of splitting the n??* transition between the E and Z isomers.On this basis,further para-substitution can allow tunability on the order of the energy level to the molecular orbitals through their influence on the conjugation pattern of the compound.It is the modification of the substituent on these positions that allows the photoisomerization to proceed under visible wavelength light surroundings.The thermal Z/E isomerization mechanism has also been analyzed,and a detailed comparison of these compounds has been made with respect to the thermal half-lifes 1 2?,and the rate constants kZ–E.The results reveal that isomerization is thought to be a process of globally structural change,during which the effect of the substituents is determined by the extent of their influence on the conjugated system.