Design,Synthesis And Properties Of Luminescent COFs

Covalent organic frameworks(COFs)are highly crystalline and long-range ordered porous polymers with ordered π structures suitable for light-emitting materials,and have attracted much attention in the field of organic light-emitting in recent years.The polymerization mode and stacking mode of COFs have important effects on the luminescent properties of COFs,but there is still a lack of in-depth research.Based on this,in this paper,two types of luminescent two-dimensional COFs were designed and synthesized using pyrene group and benzothiadiazole group as raw materials,respectively.Stretchable light-emitting COFs were prepared by doping to facilitate the application of stretchable optoelectronic devices.The main research contents are as follows:(1)Design,synthesis and properties of pyrene-based luminescent COFs.Pyrene hydrazide COF(Py Hy-COF)was obtained by solvothermal Schiff base reaction with 1,3,6,8-tetrakis(4-carboxyphenyl)pyrene and terephthalic dihydrazide as precursor molecules.The photophysical properties and crystallinity of the material were characterized.In order to improve the dispersibility of Py Hy-COF in solution,the dispersibility of Py Hy-COF was improved by adding polyvinylpyrro-lidone to the reaction system,thereby obtaining PVP-Py Hy-COF with better dispersibility and higher fluorescence intensity.The emission spectrum peaks are all at 570 nm.COFs were doped into the flexible medium butyl acrylate by physical blending,respectively,and the stretchable photoluminescent elastomer was obtained by UV crosslinking by one-pot method.With the increase of COFs doping amount,the spectrum of the elastomer gradually shifted to red,and the emission band was located at 440-490 nm,and the maximum tensile strain of the elastomer was 7.44 times.This study can be used as a reference for the design and synthesis of luminescent COFs materials,the preparation of multidisperse luminescent COFs nanomaterials and stretchable COFs luminescent films.(2)Design,synthesis and properties of benzothiadiazole-based luminescent COFs.Using tris(4-aminophenyl)amine as the donor and 4,7-dibenzaldehyde-2,1,3-benzothiadiazole as the accep-tor,the COF(BTDA-COF),this product does not emit light.Therefore,the precursor molecules were changed to tris(4-aldehyde phenyl)amine,4,7-diphenylamino-2,1,3-benzothiadiazole,and the luminescent COF(BTNC-COF)was obtained,and the PL emission peak is 625 nm,and it is found that BTNC-COF has a cooling precipitation process.The basic test characterization of BTDA-COF and BTNC-COF was carried out respectively,and the preliminary exploration and explanation of these two phenomena belonging to the same type but with completely different luminescence properties were carried out,it provides ideas for exploring the root cause of forming such huge physical and chemical differences.