Design,synthesis And Properties Of Quinazolinone-pyridine BF₂ Complexes

Quinazolinones are widely found in natural products and drugs and have excellent pharmaceutical activity.Also some quinazolinones have performed extremely well in the arena of fluorescent dyes.However,some shortcomings limit the application of quinazolinones in fluorescent dyes.Therefore,it is particularly urgent to develop a series of fluorescent dyes based on the structure of quinazolinones.And the boron difluoride compound-based fluorescent dyes have attracted much attention as a class of fluorescent dyes with excellent performance.Therefore,in this thesis,a series of boron difluoride compounds were obtained by a simple two-step reaction using quinazolinone-2-pyridine as the parent structure,and the luminescence properties and luminescence patterns of these compounds,as well as their roles in bioimaging and other applications,were investigated.The main contents of this thesis are as follows.(1)Designed and synthesized the brominated quinazolinone-2-pyridyl boron difluoride compound,and specifically discussed the effect of introducing bromine atoms at different positions in the compound on the photophysical properties of the whole molecule,and systematically discussed the heavy atom effect of bromine atoms and the strength of the electron absorption effect at different positions and the effect on the luminescence of the whole molecule.The results show that the emission wavelength is blue-shifted when the bromine atom is located on the quinazolinone ring compared to the pyridine ring.Secondly,it can be seen that the fluorescence of the compound is stronger when the bromine atom is at positions 5 and 6 of the quinazolinone ring and at positions 4 and 5 of the pyridine ring than when the bromine atom is at positions 4 and 7 of the quinazolinone ring and at positions 3 and 6of the pyridine ring.(2)Design and synthesis of quinazolinone-pyridine-triphenylamine analogues successfully achieved the maximum absorption red-shift of the compounds to the visible region,avoiding the cellular phototoxicity caused by the excitation light being in the UV region during cell imaging.The compounds were then subjected to preliminary cellular fluorescence imaging tests,which showed that both compounds were able to enter the cell interior and display fluorescence signals,with compound5 a fluorescence imaging better than compound 5b.Thus,5a is more suitable for cellular imaging.(3)Designed and synthesized quinazolinone-pyridine-triphenylamine difluoroboron compounds with visible light excitation and red-light emission properties.In addition,the compound also has two-photon properties with two-photon excitation wavelength located near 810 nm and emission wavelength located at 675 nm,and the compound can be used as a two-photon imaging probe for in vivo imaging.Also,the compound is a good photoexcited singlet oxygen generator,capable of generating singlet oxygen under blue light irradiation at 420 nm.Finally,compound 6 can be used as an endoplasmic reticulum red light localization probe with a co-localization factor of 91%with the commercial endoplasmic reticulum fluorescent probe ER-tracker blue.Meanwhile,the compound acts as a photoexcited singly linear oxygen initiator,which can effectively induce cell death after light irradiation based on localization of the endoplasmic reticulum.