Preparation And Properties Of Phthalazine-based AIEgens

With the rapid development of science and technology in recent years,organic fluorescent materials have become indispensable in various fields.However,one of the main problems associated with the large?-conjugated planar structure of many fluorescent molecules developed in the past is the aggregation-induced burst(ACQ)phenomenon when the molecule is in the aggregated state or solid state,which leads to fluorescence burst.However,fluorescent molecules with AIE effect can effectively solve this problem,which is important for the development of high-performance fluorescent materials and has been widely used in the fields of electroluminescence,fluorescent probes,bioimaging,and photostimulation-responsive materials.Based on the special luminescent properties of AIE molecules,six AIE fluorescent molecules were designed and successfully synthesized in this thesis,and their potential applications in electroluminescence,bioimaging,fluorescent probe detection and other fields were investigated.1.Organic fluorescent materials have great potential for the construction of organic light emitting diodes(OLEDs),and so far more and more functional materials with AIE effects have been developed and utilised.Therefore,in this paper,we designed and synthesised a series of fluorescent molecules with a hole-dominant triphenylamine(TPA)molecule as the electron donor and a phthalazine molecule as the electron acceptor,and connected with different push-pull electron-capable groups,and confirmed their structures by a series of characterisation means,and then tested their optical properties by UV-Vis absorption spectroscopy and fluorescence emission spectroscopy,and determined that all these partial compounds exhibited The absolute fluorescence quantum yields in the solid state were determined using integrating spheres up to 43%,and finally their properties were further investigated by electrochemical and thermal stability tests.2.Cysteine(Cys)is essential for the development and maintenance of many physiological processes in eukaryotic cells and therefore it is extremely important to detect Cys in cells.To this end,a turn-on AIE fluorescent probe with an aldehyde group as the reactive group was designed and synthesised.The fluorescence spectroscopy titration experiments have determined that the probe has good selectivity and anti-interference properties for Cys,and that the fluorescence intensity is enhanced 25-fold when 100?M of Cys is added to the probe(10?M)body.Based on the curves fitted to the fluorescence titration experiments,a minimum detection limit of 1.5?M was calculated,which is lower than the Cys concentration in cells,offering the possibility of quantitative detection of intracellular Cys by the probe molecule and for biological cell imaging.3.Mercury,a globally widespread polluting heavy metal,is also very toxic to humans at very low concentrations of Hg^2+.In this paper,a burst fluorescent probe with AIE properties was designed and synthesized around the visual detection of Hg²⁺.Through fluorescence spectroscopy titration experiments found that with the increase of Hg²⁺concentration in the solution,the fluorescence intensity of the probe molecule gradually decreased,showing a good linear relationship,and the LOD was 2.97×10^-8mol/L,which was lower than the allowable concentration of Hg²⁺in the domestic drinking water standard.And the fluorescent probe molecule has the advantages of good selectivity,high sensitivity,low detection limit and fast response speed.