Synthesis And Application Of Cationic AIE Molecules Based On Geminal Cross-couplings

The development of functional aggregation-induced emission（AIE）new materials and new applications of AIE materials has been a hot research topic in the AIE field.Based on good water solubility and biocompatibility,ionic AIE materials have unique advantages in biochemical detection and biomedical imaging.The commonly used AIE material synthesis methods have significant limitations in the development of AIE materials.The method of synthesizing AIE materials by geminal cross couplings（GCC）developed successfully promoted the derivation and application of tetraarylethene AIE materials,and has unique advantages in the preparation of ionic AIE materials.in this thesis,Neutral conjugated tetraarylethenes OFn（n=1-3）and the corresponding cationic conjugated oligoelectrolytes OFn+（n=1-3）with aggregation-induced emission activity have been designed and synthesized using geminal cross couplings（GCC）.The ion-induced emission effect of the cationic molecule OFn+（n=1-3）and its application in cell imaging and super-resolution imaging were studied.The specific content of the thesis is summarized as follows:（1）A series of neutral conjugated fluorescent molecules OFn（n=1-3）and corresponding cationic conjugated oligomeric electrolyte OFn+（n=1-3）were obtained by geminal cross couplings（GCC）.We then have studied the fluorescence spectral properties of OFn（n=1-3）and OFn+（n=1-3）.We found that the introduction of AIE active groups reverses the ACQ properties of oligomeric fluorene molecules.The synthesized novel OFn（n=1-3）and OFn+（n=1-3）both have significant AIE properties.At the same time,OFn+（n=1-3）has an ion-induced emission property in aqueous solution.（2）The OFn+（n=1-3）was used as a bio-probe for co-localization fluorescence imaging of cell lysosomes.The OFn+（n=1-3）probe perform targeted localization imaging of lysosomes in cells,and the OFn+（n=1-3）probe has the advantages of being directly used for imaging without washing and good photobleaching resistance compared to the lysosomal commercial probe.The time and space distribution of lysosomes after chloroquine stimulation was studied by selecting OF₁+as imaging probe.The imaging results show that the OF₁+probe has good biocompatibility and fatigue resistance,which enables it to be used for long-term localization of lysosomes in cells.（3）A universal method for super-resolution imaging of nanostructures based on AIE mechanism is proposed.In this method single molecule localization imaging of nanostructures is achieved by using OF₁+probe which AIE behavior is driven by the electrostatic interaction between anions and cations to obtain a random switch of fluorescence.Based on this method,super-resolution imaging was carried out with inorganic silver nanowires,natural polymer bacterial cellulose and synthetic high molecular polystyrene-b-polyacrylic acid block copolymer（PSt-b-PAA）micelles as representative nanomaterials.The fine nanostructure of the above materials was directly observed under a super-resolution fluorescence microscope with an optical resolution of20-30 nm.