Synthesis And Properties Analysis Of Organosilicon Functional Rhenium Complexes Luminescent Materials

The thesis mainly describes the design and synthesis of a series of novel organosilicon functional compounds,including five ligands of Bath-n(n=1- 4)and(PyPh4Si), ten complexes of Re-1- Re-10.Their photophysical,aggregation-inducedemission(AIE) and sensing properties were intensively investigated. At the same time, the theory simulation for the ground-state structures and ultraviolet-visible absorption spectra of the ligands and complexes were explored. The main results of the thesis are summarized as follows:(1)The position of the maximum emission peak of Bath-n(n=1-4) in THF solution mainly locates around 380 nm, meanwhile, the Bath-n(n=1-4) possess AIE properties. The composite materials without heavy metal elements were preparedby physical doping Bath-n(n = 1- 4)/MCM-41, which can be used as optical oxygen sensor. Among these materials, the composite material of Bath-3/MCM-41 has a high sensitivity(6.77), short quench time and reduction time(4 s/5 s), etc.(2)By adopting Bath-n(n = 1- 4) as ligands, complexes Re-1- Re-4 were synthesized. Their emission peaks in THF solutionmainly locate at 435 nm, which can be ascribed to Ï€*â†' Ï€transition and ILCT transition. But in the emission spectra of the solid powders, these emission peaks almost completely disappeared while 3MLCT emission peaks emerged at 560 nm. Accordingly, complexes Re-1- Re-4 belong to typical AIE compounds. In THF/H2 O mixed solvent, when the volume percentage of water(fH) was 60%, the maximumphosphorescence quantum efficiency(PLQY) value of complexes Re-1 and Re-3 achieved 0.36% and 0.38% respectively. When the volume percentage of water(fH) was 95%, the maximumPLQY value of complexes Re-2 and Re-4reached 0.19% and 0.48%,respectively.(3)Using 2,2-dipyridyl(bpy), 1,10-phenanthroline(phen), bathophenanthroline(bath) as azo ligands, PyPh4 Si as the second ligand, three kinds of ionic complexes Re-5-Re-7were synthesized. Their emission peaks in THF solutionmainly locate at 535 nm, the emission peaks belong to 3MLCT emission peak, and their emission peak of the solid powders locates at about 530 nm which belong to 3MLCT emission peak. In the synthetic process of complexes Re-5- Re-7, we discovered that these complexes were comparativelysensitive to the organic amines. Especially, complex Re-7 was confoundedlysensitive to diphenylamine and triphenylamine. When molar concentrations of diphenylamine and triphenylamine were 5 × 10-4 M and1 × 10-4 M in the mixed solution, the 3MLCT emission peak of complex Re-7 at 530 nm was completely quenched. For the above reasons, itis supposed that the complexes Re-5- Re-7 have potential applications in detection of organic amine. When using complex Re-7 as the dopant, polystyrene(PS) as the carrier, we prepared Re-7(0.2 –5wt%)/PS micro/nano fibers by electrospinning method. As the doping concentration of Re-7 was 0.6wt%, the fluorescence intensity of fibers was found to bethe strongest. Through analyzing the optical properties of the oxygen sensor,the fluorescenceintensityin pure oxygen is only 21.5% in pure nitrogen, and the Stern-Volmer curve was nearly linear distribution, indicating that the composite materials have practical applications in optical oxygen sensor.(4) Setting bromide three carbonyl group 2,9- two bromo-1,10- phenanthroline-rhenium(I) as index compound, we synthesized three new rhenium complexes Re-8- Re-10 with three boronic acid derivatives. The emission spectrum of complexes Re-8- Re-10 in THF solution was mainly composed of Ï€*â†'Ï€ transition(400 nm) and ILCT transition(400 nm) emission. In the emission spectrum of the solid powder, we can only observe one emission peak at 550 nm of 3MLCT emission. In the mixed solution of water and THF, the fluorescence intensity of complexes Re-8- Re-10 decreases with increasing water content, and the intensity of phosphorescence peaks gradually enhances at the same time, presenting a typical aggregation induced phosphorescence(AIPE) performance. When fHis set to be 70%, the phosphorescence quantum efficiency(PLQY) of complex Re-10 reaches up to 5.71%. All above indicated that while importing large steric groups at 2-, 9-location ofbromide three carbonyl group 2,9- two bromo-1,10- phenanthroline- rhenium(I),the luminous efficiency of rhenium complexescan be further improved, and there is also a new approach for the development of new efficient phosphorescent rhenium complexes research.(5) Ligands Bath-n(n = 1- 4) have similar frontier molecular orbital distribution, their HOMOs are mainly in Ï€ orbital of Bath and-PhSiMe3/-PhSiMe2Ph/-PhSiMePh2/-PhSiPh3, however their LOMOs are mainly in Ï€*orbital of Bath and-PhSiMe3/-PhSiMe2Ph/-PhSiMePh2/-PhSiPh3.Complexes Re-1- Re-4 and complexes Re-8-Re-10,their HOMOs are mainly composed of dÏ€(Re) orbitals of rhenium, Ï€ orbitals of CO andBr, their LUMOscomponentareÏ€*orbitals of bath/phen, and the absorption spectracomposition are mainly LLCT/MLCT transition. Furthermore, the HOMOs of complexes Re-5- Re-7 mainly consisted of dÏ€(Re) orbitals of rhenium, Ï€ orbitals of CO and Ï€ orbitals of ligand PyPh4 Si, the LUMOsconstituentof complexes Re-5- Re-7 are mainly Ï€*orbitals of bpy/phen/bath, and LLCT/MLCT transition mainly constitutestheir absorption spectra.