Preparation,Structure And Properties Of Tetraphenyl Ethylene Derivatives Based On Ionic Self-Assembly

Conventional organic luminescent materials have good luminescence properties in solution,while the fluorescence intensity decreases or does not emit light in aggregated or solid film states.Aggregation-induced emission material is a kind of material that produces a strong fluorescence emission in the aggregation state or solid film state,but weakly or even non-luminous in the dilute solution state.Such materials can fundamentally solve the problem of aggregation leading to quenching.Among them,Tetraphenyl Ethylene(TPE)has the advantages of simple synthesis,excellent luminescent performance and easy functionalization,and is one of the typical AIE materials.Ionic Self-Assembly(ISA)is a kind of supramolecular chemical method which is coupled with molecules with opposite charge by electrostatic attraction.It has the advantages of simple operation,no by-product,high reaction efficiency and high yield.Therefore,the preparation of tetraphenyl ethylene liquid crystal material by ISA method has important scientific significance and application value.In this dissertation,the tetraphenyl ethylene derivatives with ether bond and biphenyl structure were synthesized by the reaction of McMurry and Suzuki coupling,and then the carboxylate salt of tetraphenyl ethylene was reacted with dimethyldistearylammonium bromide(DOAB)and dihexadecyldimethylammonium bromide(DHAB)to prepare novel tetraphenylethylene liquid crystal material with helium supramolecular structure and aggregation-induced luminescence properties.In this dissertation,the aggregation-induced emission properties of complex products were studied by UV-Vis absorption spectroscopy and fluorescence emission spectroscopy.The polarized light microscopy,differential scanning calorimetry,one-dimensional/two-dimensional X-ray diffraction were used to investigate the phase behavior and aggregation structure of the preparated ionic complex.The experimental results show that the above-mentioned ionic complexes are typical aggregation-induced emission liquid crystal materials with solid fluorescence quantum yield of 46%-66%.Meanwhile,the complexes have the complex hierarchical supramolecular structure: at room temperature,the complex molecules arranged in a loose helical columnar supramolecular liquid crystalline structure;upon heating,the molecules arranged in long-range ordered liquid crystalline structure.Therefore,thiskind of tetraphenyl ethylene ion complexes have the special supramolecular liquid crystalline structures and excellent aggregation-induced emission properties,which have potential application value in the field of light-emitting devices and other fields.