Synthesis And Property Analysis Of Rhenium Complexes Based On 2,2’-Bipyridine Derivatives As Ligands

In this paper,four derivatives of 2,2’-bipyridinewere designed and synthesized,and L-1 L-4 were used to prepare fourrheniumcomplexes of Re-1 Re-4.Finally,the photophysical properties ofL-1 L-4andRe-1 Re-4 were systematically studied.The main contents of this thesis are as follows:1.L-1 L-4 were synthesized by carrying out the reactions of Claisen-Schmidt condensation reaction,Kr?hnke ring-closure reaction and Suzuki coupling reaction.Structures and properties L-1 L-4were characterized by 1HNMR,UV-Vis absorption spectra,fluorescence spectra and electrochemistry etc.The fluorescence spectra of the ligands in THF solution and solid state show that the emission peaks of the ligands are in the range of 358 430 nm,which belongs to blue-violet light region.Electrochemical studies present that the incorporation of the aldehyde groups in the ligand L-3 increased the EHOMO energy level by 0.2 eV compared to others,while the carbazole group introduced in L-4 reduced the ELUMO energy level by 0.62 0.69 eV.2.Re-1 Re-4 were synthesized withL-1 L-4as ligands,respectively.The emission peaks of the four Re（I）complexes in THF solution are all located at 350 nm,which are the π → π* transition emission of the ligand.The normal and the low temperature emission peak are around 580 nm,which are the metal-to-ligand（3MLCT）transition emission.These spectra indicate that Re-1 Re-4are belonged to aggregation-induced phosphorescent complexes.The emission spectra of Re-1 Re-4 in THF solution and powder state show that thesecomplexes belong to AIPE compounds,and the values of the photolumencent quantum yieldsshould be 1.16%(f_H2O=80 %)for Re-1,1.32%(f_H2O=96 %)for Re-2,0.33%(f_H2O=80 %)for Re-3 and 6.57%(f_H2O=80 %)for Re-4,respectively,in the THF/H2 O mixed solvent.3.Finally,the ground-state geometries and the UV-Vis absorption spectra of Re-1 Re-4 were theoretically studied at b3lyp（lanl2dz + 6-31g）level by the DFT and TDDFT method,respectively.It is found that the frontier molecular orbital distributions of complexes Re-1 Re-3are similar to each other.The LUMOs of Re-1 Re-4are mainly composed of π* orbitals of dpy.As far as the HOMOs of Re-1 Re-3 are concerned,they aremainly composedof the d（Re）orbitals of rhenium,π orbitals of CO and Br,but that ofRe-4 is mainly composedof π orbit of carbazole group.This difference of the distribution of HOMO of Re-4 to Re-1 Re-3 is mainly assigned to the strong electron-donating ability of carbazole group.