Design,Synthesis And Structure-property Relationship Of Organic Solid-state Fluorescence Conversion Small Molecules

In recent years,organic optoelectronic functional materials have increasingly shown their unique optical characteristics and broad application prospects.Preparation of organic materials and devices with excellent photoelectric properties is one of the hotspots in the field of materials science in the 21 st century.Organic solid-state fluorescence conversion materials have a very important application prospect in information memory,security,sensing and fluorescence switch because of their less interference and higher sensitivity than the absorption spectrum.Design and synthesize new organic fluorescence conversion molecules can be used to study the fluorescence emission of luminescent materials under solid conditions more effectively.In this paper,a series of centrosymmetric compounds were synthesized by using the fluorenone molecule as the central skeleton.The compound MPF(2,7-bis(2’-methyl-[1,1’-biphenyl]-4-yl)-9H-fluoren-9-one)and MBPF(2,7-bis(2’-methoxy-[1,1’-biphenyl]-4-yl)-9H-fluoren-9-one)show very good force,heat,solvent-stimulated response fluorescence conversion propertiesof organic solid.In addition,we have designed and synthesized another series of triaryl boron organic fluorescent materials and also have obtained a number of crystalline states based on the same molecule,which exhibit different optical properties.Single crystal structure and powder diffraction(XRD)spectral tests were used to study the relationship between fluorescence and intermolecular accumulation,which provided a reliable basis for further molecular design.The details are as follows:1.Six small fluorescent molecules with fluorenone as the center skeleton were designed and synthesized,which showed strong fluorescence in solid state and had good AIE characteristics.Single crystal culture of molecular MPF obtainedtwo single crystalswith different colors and morphology,the green single crystal G-MPF and orange single crystal O-MPF.These two single crystals exhibit a reversible stimulus response to the fluorescence conversion characteristics under external stimuli(such as heating,grinding,etc.).Single crystal analysis confirmed that the fluorescence variety of the compound MPF was caused by the change of intermolecular accumulation state due to physical stimulation,which resulted in the change of the charge between the molecules and thus producing a fluorescent change.The change in this structure is also confirmed by powder diffraction(PXRD).The other molecule MBPF exhibits a solid three-color change.The amorphous form of A-MBPF emit yellow-green fluorescence,and the crystalline Y-MBPF emits yellow fluorescence and the crystalline R-MBPF emit red fluorescence.Studies have shown that the reversible conversion of these three fluorescent colors is also due to the different accumulation of molecules,the structure of the molecule itself has not changed.2.A compound based on pyridine and triaryl boron was designed and synthesized,and a number of crystal fluorescence states were obtained base on this compound.It was found that there was a space charge transfer between molecules in the state of solid state,under UV irradiation,there was no fluorescence emission due to the nonradiative transition of energy.The triaryl boron atom of this compound can be coordinated with cyanide ion,and the nitrogen atom of the pyridine amine moiety can complex with the metal ion to introduce an appropriate amount of cyanide ions and metal ions into the molecule,which can change the original accumulation state of the monomolecular crystal.So that the original intermolecular charge transfer is prohibited,under the ultraviolet radiation,the energy release by the form of radiation transition and result the fluorescence.