Modification Of Pyridimidazole Ligands And Synthesis And Optical Properties Of Copper Complexes

In rencent years,dye-sensitized solar cells(DSSCs)have attracted much attention in their application fields due to their high photoelectric conversion efficiency.The transition metal complex are mostly used in the dye photosensitizer of the photoelectric transmission layer.These metals have the disadvantages of low content,high toxicity and excessive mining.It not only increases the production cost,but also brings great damage to the environment and ecological balance.It was found that the complexes formed by monovalent copper ions have similar photophysical and photochemical properties to other noble metals.Copper is a high content,low toxicity metal and it is also friendly to the environment.We can use it replace the application of traditional noble metals in DSSCs,so that DSSCs has been further developed.In this dissertation,a series of Cu(I)complexes containing different chromophore groups,and their optical properties are studied.Firstly,A series of pyridyl imidazole nitrogen heterocyclic ligands containing 2-(1H-imidazol-2-yl)-5-(4-trifluoromethyl)with 5-bromo-2-pyridinaldehyde as raw materials-Phenyl)-pyridine(L1),2-(1H-imidazol-2-yl)-5-(4-methoxy-phenyl)-pyridine(L2),2-(1H-imidazol-2-yl)-5-p-tolylpyridine(L3),2-(1H-imidazol-2-yl)-5-phenylpyridine(L4),The ligand reacts with bis(2-diphenylphosphine)phenyl ether(POP)and copper tetraacetonitrile hexafluorophosphate([Cu(CH3CN4)(PF6)])to successfully synthesize Cu(I)complexes E1,E2,E3,E4.We found that the emission peaks of E2 and E3 with electron-donating groups are blue-shifted,while E1 with electron-withdrawing groups are red-shifted.There is no corresponding increase in quantum yield and lifetime.Then,Using 5-bromo-2-pyridinaldehyde and 9,10-phenanthrenequinone as raw materials,pyridylphenimidazole-based ligands containing different substituents 2-(5-(p-tolyl)pyridin-2-yl)-1H-phenanthro[9,10-d]imidazole(L5),2-(5-(4-(trifluoromethyl)phenyl)pyridin-2-yl)-1H-phenanthro[9,10-d]imidazole(L6),2-(5-(4-methoxyphenyl)pyridin-2-yl)-1H-phenanthrene[9,10-d]imidazole(L7),2-(5-phenylpyridine-2-yl)-1H-phenanthrene[9,10-d]imidazole(L8),Then use similar methods to synthesize the complexes E5,E6,E7,E8 and the effects of the introduction of phenanthrazole ligands on the optical properties of the complexes were tested and characterized.Compared with pyridyl imidazole complexes,the introduction of larger space ligands can significantly improve the absorbance in the ultraviolet region,the highest molar absorption number reaches more than 30000(ε?L/mol?cm),The excited state lifetime of the complex is more than 110 microseconds,and the emission wavelength is red-shifted by 50 nm.But the luminescence quantum yield decreases.Finally,Based on pyridylphenanthromidazole as a base ligand,different chromophores of naphthalene,anthracene and phenanthrene were introduced,Synthesis of Ligand2-(5-(naphthalen-1-yl)pyridin-2-yl)-1H-phenanthrene[9,10-d]imidazole(L9),2-(5-(anthracen-1-yl)pyridine-2-yl)-1H-phenanthrene[9,10-d]imidazole(L10),2-(5-(phenanthrene-9-yl)pyridin-2-yl)-1H-phenanthrene[9,10-d]imidazole(L11),Then the same method was used to synthesize complexes E9,E10,E11,and the effects of different chromophores on the optical properties of the complexes were tested and characterized.Compared with E8 complex,which does not contain a chromophore,different aromatic chromophores are introduced into the pyridyl group of the ligand,and the molar absorbance of the complex has reached more than 30000(ε?L/mol?cm),the lifespan of the complexes has improved,but the quantum efficiency of light emission has not been improved.With the help of quantum theoretical calculations,the theoretical simulation calculations were performed on the synthesized complexes using density functional theory and time-dependent density functional theory(DFT/TDDFT)methods to explain the electronic composition configuration and charge transfer type.