Synthesis And Properties Of Platinum(?)Complexes Based On 2-Phenylpyridine Derivatives

Platinum(?)complexes exhibit abundant emission spectrum properties,high luminescence quantum yields and long luminescence lifetimes.Therefore,Pt(?)complexes have shown important applications in the fields of organic light-emitting diodes(OLEDs),dye-sensitized solar cells,oxygen-sensitive probes and bio-imaging.Pt(?)complexes with square planar geometry are sensitive upon external stimuli by intra-and intermolecular Pt···Pt and/or?-?stacking interactions.This provides an idea for the construction of platinum(?)complexes with aggregation-induced emission(AIE)properties.The structures of cyclometalating ligands have important influences on the luminescence properties of cyclometalated platinum(?)complexes.The types and positions of substituents on the ligands,as well as the electron-donating or electron-withdrawing capabilities of substituents are key factors to affect luminescence properties of the corresponding complexes.Hence,the main research contents include the following three parts:1.Six neutral cyclometalated Pt(?)complexes Pt1-Pt6 with trifluoromethyl-modified2-phenylpyridine derivatives as the cyclometalating ligands and acetylacetone as auxiliary ligand were designed and synthesized.Their photophysical properties and luminescence properties in THF/H₂O were studied systematically.The results show that Pt1-Pt3 all display red-shift and have longer phosphorescence lifetimes compared with Pt(ppy)(acac).The luminescence properties show that Pt1-Pt6 all are AIE-active in a THF/H₂O system.The introduction of trifluoromethyl group at the symmetrical positions on a pyridine ring or a benzene ring of 2-phenylpyridine would lead to the similar AIE performances of the corresponding complexes.2.Three 2-phenylpyridine derivatives were synthesized by introducing a methyl group at different positions of the pyridine ring and a diphenylamino group at the 4-position of the benzene ring.Using them as the cyclometalating ligand and acetylacetone as the auxiliary ligand,three cyclometalated Pt(?)complexes Pt8-Pt10 were synthesized.Compared with Pt7without a methyl group,the luminescence properties of Pt8-Pt10 in a THF/H₂O system were studied.The results show that Pt7-Pt10 all demonstrate AIE properties in this system.Among them,Pt7 and Pt9 exhibit excellent AIE properties.3.A 2-phenylpyridine derivative with a trifluoromethyl group at the 5-position of the pyridine ring and a diphenylamino group at the 4-position of the benzene ring was prepared,which was used as the cyclometalating ligand for the synthesis of cyclometalated Pt(?)complex Pt11.Compared to Pt(ppy)(acac)and Pt3,the luminescence properties of Pt11 in THF/H₂O and CH₂Cl₂/n-Hexane systems were studied in detail,respectively.Pt11 exhibits more obvious AIE properties in both systems than the complex Pt3.The results might be caused by the much more abundant intermolecular hydrogen bonds(C-H···F)in crystal structures of Pt11 than those of Pt3.