The Design, Synthesis And Application Of Different Fluorescent Groups Coupling Hexaarylbiimidazole

At present, photochromic materials have wide application in smart materials field, such as optical data storage, molecular optoelectronic devices, photochemical sensing, light regulation of self-assembly nanostructures and drug release. In recent years, photoswitchable fluorophores based on the photochromic materials have made a breakthrough progress in the super resolution imaging field of biology. In this dissertation, we took photochromic material hexaarylbiimidazoles(HABI) as the research object, designed and synthesized a series of photoswitchable fluorophores. The relationship between the structure and the properties of its photochromism and the photoswitching fluorescence were discussed. Meanwhile, the block polymer self-assembly nanostructures and electrostatic spinning nanowires were studied by the super resolution imaging. This dissertation includes the following sections:In the second chapter, choosing the tetraphenylethene(TPE) as the starting point of molecular design, para-substituted p-HABI-TPE and meta-substituted m-HABI-TPE were designed and synthesized by Corey-Fuchs and Suzuki coupling reaction. The optical properties are investigated such as photochromism, photoswitching fluorescence and the fading rate. The experimental results indicated that they had different optical properties with different substituted structure completely.In the third chapter, based on the fluorescent BODIPY owning excellent fluorescence properties, photoswitchable fluorescent BODIPY-HABI was designed and synthesized with the bridge structure modification. Testing the ultraviolet absorption and fluorescence spectra,the photochromic behavior and fluorescent switch of BODIPY-HABI was studied in detail.Through the bridge structure design of molecular, the fading rate of BODIPY-HABI colored state have been significantly improved after UV irradiation(t1/2=1.2 s). In addition,BODIPY-HABI have relatively high fluorescence quantum efficiency(ΦF=15%) and fluorescence switch(Ion/off = 40). By blending this probe and block copolymer, the nanometer structure of the block copolymer self-assembly vesicles were characterized by the super resolution imaging.In the fourth chapter, with continuing the molecular design of the third chapter,introducing perylenemonoimide(PMI) as the light-emitting unit and the push-pull electronic structure, a near-infrared photoswitchable fluorescent PMI-N-HABI was designed and synthesized. Therewith, through blending the dye with the polymer and utilizing the method of electrostatic spinning, the diameter distribution of the obtained polymer nanowires was ~150 nm by SEM. In the meantime, using the switching behavior of this fluorescent probe in super resolution imaging, the diameter of the polymer nanowires is~170 nm. The results show the super resolution imaging by use of photoswitchable fluorescent probes is more convenient and faster than scanning electron microscopy.