Synthesis Of Aggregation-Inducing Emission Compounds And Research On Its Performance

Since the discovery of Aggregation Induced Emission(AIE)by the group of Tang in 2001,due to its potential applications in the fields of chemistry,biosensing,bioimaging,thermal/pressure sensitive,and electroluminescent devices,many researchers have become increasingly interested in the development and use of AIE active materials.Up to now,many AIE-active molecules have been developed for cell imaging,with emission wavelengths ranging from blue to red,covering the entire visible light range.In order to avoid autofluorescence from biological samples and reduce photocytotoxicity,it is desirable to develop AIE luminophores with red or near-infrared emission.In this dissertation,the optical properties and cell imaging applications of AIE active derivative based on barbituric acid were investigated.The electron-donating(D)and electron-accepting(A)groups in the conjugated molecules resulted in narrow bandgap and red emission AIE compounds.Based on this idea,four D-?-A AIE compounds CSB-1,MSB-2,PSB-1 and PSB-2 were designed and synthesized.The successful synthesis of the compounds was characterized by nuclear magnetic resonance(NMR),infrared spectroscopy(IR)and mass spectrometry(MS).The optical properties of the series of compounds under different conditions were systematically investigated,and the mechanism of enhanced fluorescence emission of the AIE-active compounds was explored.By analyzing the SXRD results,the fluorescence enhancement mechanism was restricted by intramolecular motion.(RIM),and due to unique herringbone deposition method of PSB-2,the fluorescence enhancement mechanism is a synergistic effect of RIM and herringbone stacking.In the practical application of the compound,the emission wavelength of the nanoparticles based on the compound PSB-2is located in the red light region,which can effectively avoid the influence of the cell's autofluorescence and reduce the photocytotoxicity.We incubated PSB-2 with Drosophila S2 cells.After incubation,Drosophila S2 cells were successfully stained.Co-localization of PSB-2 and Lysotracker Blue demonstrated that the stained organelles were lysosomes.And a strong intracellular red fluorescence signal was detected with minimal background noise.To further compare the effects of different substituents on the optical properties of barbituric acid derivatives,four new D-?-A barbituric acid derivatives FOB-1,FTB-1,BFTB-2 and TFTB-4 were successfully synthesized.These compounds exhibited typical intramolecular charge transfer(ICT),AIE activity and solvatochromic effects.The thiophene-based barbituric acid derivatives FTB-1,BFTB-2,and TFTB-4 have significant mechanofluorochromic(MFC)activity,corresponding to MFC values of 15,28,and 12 nm,respectively.Among them,the change in the emission color of the compound BFTB-2 can be observed with the naked eye.The MFC behavior of the compounds was reversible when treated by grinding and methylene chloride fuming.We explored the mechanism of fluorescence enhancement of compounds,the mechanism of solvochromism and the mechanism of MFC.XRD studies of the powders showed that the mechanism of the MFC of FTB-1 and BFTB-2 is explained by the transformation of the crystalline phase and amorphous phase of the compound under the stimulation of external forces.The red shift of TFTB-4 was attributed to the planarization of the molecular conformation caused by grinding.In conclusion,the optical properties of different series of AIE active compounds designed and synthesized were compared in this study,and the mechanism of fluorescence enhancement was systematically explored and explained.It is of great practical significance to design and synthesize new high-efficiency AIE active materials.