4-苯乙炔-1, 8-萘酰亚胺荧光化合物的合成及电致发光性能

采用Pd(PPh₃)₂Cl₂-CuI为催化剂,Ph₃P为配体,4-溴-1,8-萘二酸酐为原料,在乙醇溶液中高收率地合成了4-苯乙炔-1,8-萘酰亚胺和4-对甲基苯乙炔-1,8-萘酰亚胺荧光新化合物。光谱研究表明,它们的最大紫外吸收波长(λ_UV,max)分别为374,380 nm,最大荧光发射波长(λ_FL,max)分别为446,462 nm,且有较高的荧光量子效率。电致发光性能测试表明,器件的最大发光亮度达到2250 cd/m²,是一类有潜在应用价值的小分子发光材料。

The Studies of Synthesis and Electroluminescence of 4-Phenylethynyl-1,8-Naphthalimides

1,8-Naphthalimide derivatives are luminophore compounds that are widely used in various fields of science and technology and exhibit all the necessary optical characteristics for polymer materials.And they are readily available from a synthetic point of view.They have been used as fluorescent brightening agents and fluorescent dyes.Furthermore,in recent years many organic luminophores with highly p-conjugated systems on phenylacetylene-based moieties have been developed quickly.The elongated electronic pathways along p-extended conjugations in these molecules often present a bathochromic shift in the absorption and fluorescence spectra.Because of their intriguing electro-conductive,magnetic and optical properties,these compounds can be used as electrical conductors in LED displays,fluorescence sensors,lasers etc.Here,two new 4-phenylethynyl-1,8-Naphthalimide fluorescent compounds which phenylethynyl moietie is conjugated at the 4-position of the naphthalene ring are prepared through Pd(PPh₃)₂Cl₂-catalyzed Sonogashira reaction from 4-bromo-1,8-naphthalimide in ethanol with CuI as co-catalyzer and Ph₃P as ligand,and their UV/vis absorption and fluorescence emission spectral properties were studied using prepared solutions in DMF.The respective quantum yields were determined using quinine sulphate as the emission standard.Their electroluminescent characteristics were also determined as a dopped device.Reactions were carried out using 5% bis-triphenylphosphine]palladium dichloride as catalyst and 5% CuI as co-catalyst in ethanol at reflux temperature with triethylamine as base.N-alkyl-4-bromo-1,8-naphthalimides were conveniently prepared by the condensation of 4-bromo-1,8-naphthalimides and primary alkyla-mine in ethanol with good yields.Their structures are characterized using IR,NMR and EA.The absorption-emission spectra and fluorescence quantum yields are determined and the relationships between molecular structure and fluorescence properties are studied.It is shown from the absorption and fluorescent spectra that the compounds present excellent fluorescence properties.The UV/vis absorption and fluorescence spectra of target product in DMF solution are presented.For compound N-butyl-4-phenylethynyl-1,8-naphthalimide,which were unsubstituted at the p-position on the phenylacetylene,the maximum absorption(λ_max,FL) was in 374,but with a methyl at the p-position on the phenylacetylene,the λ_max,UV was shift to 380 nm,which caused an obviously hypsochromic shift.For compound N-butyl-4-phenylethynyl-1,8-naphthalimide the maximum emission(λ_max,FL) was in 446 nm,but with a methyl at the p-position on the phenylacetylene,the λ_max,FL was shift to 462 nm,presented an obviously red shift.In addition,extending the conjugated chain caused a greater bathochromic effect on the absorption and emission maximum.4-Arylalkynyl-1,8-naphthalimides showed high fluorescence quantum yields.The fluorescence quantum yield Φ_F was determined using absorption and fluorescence spectra of compounds in DMF at a concentration of 1×10^-6 mol/L.Quinine sulphate,which has a quantum yield of 0.55,was used as the standard.From the result of the test,it can be seen that these compounds have quantum yields between 0.71~0.75.The electroluminescent properties of 4-phenylethynyl-1,8-naphthalimide compounds were also measured through the doped electroluminescent devices which contains 1% 1,8-naphthali-mides and 99% CBP(4,4′-N,N′-dicarbazole-biphenyl),and their maximum brightness is 2250 cd/m² at 22.5 V and 1600 cd/m² at 25 V,respectively.From the tested electroluminescent characteristics,it can be expected that 4-arylalkynyl-1,8-naphthalimides have potential applications as electroluminescent devices.