Syntheses, Structures And Properties Of Luminescent Complexes Based On Diazafluorene Ligands

Organic electroluminescent materials have made great progress in the past20years.Luminescent complexes become the focus in research, because they possess outstandingfluorescence quantum efficiency of organic matter and high stability of inorganic matter. Due tothe similar structure with phenanthroline and bipyridine, diazafluorene has excellent propertiesin electron-transporting and hole-transporting. Hence, it is a kind of good ligands for luminescentcomplexes. In this thesis, three diazafluorene ligands have been designed and synthesized，andtwo series of luminescent complexes have been designed and synthesized based on these ligands.These compounds are copper(I) halides complexes and europium(III) complexes, respectively.The structures of the new compounds have been determined and analysed by single-crystal X-raydiffraction. Other characterization methods, such as X-ray powder diffraction, elemental analysisand IR measurement, have been carried out to confirm them. In addition, their thermal stabilitiesand luminescent properties have also been investigated preliminarily. Meanwhile, therelationships between structures and properties of these compounds have been discussed. Themain contents and results are summarized as follows:1. Syntheses, structures and luminescent properties of copper(I) halides complexes based ondiazafluorene ligands. Eleven novel complexes have been obtained by the assembly of copper(I)halides with diazafluorene ligands and various phosphine ligands. The molecular formula ofthese compounds are shown as following:[CuI(DAF)(TPP)](1),{CuI(DAF)[TPP(o-CH3)]}(2、3),[CuI(DAF)(TXP-2,4)](4),{CuI(DAF)[TPP(2-OCH3)]}(5),{CuI(DAF)[TPP(P)]}(6、7),{CuI(2,7-dibr-DAF)[TPP(P)](H2O)2}(8),[CuBr(DAF)(TPP)(CHCl3)](9),{CuBr(DAF)[TPP(P)]}(10), and [CuSCN(dedaf)(TPP)](11). The structures of all complexes have beendetermined by single-crystal X-ray diffraction. The Cu atoms of these structures show twodifferent coordination modes. One is four-coordinated which exhibits distorted tetrahedralgeometry; the other is three-coordinated which exhibits nearly ideal planar geometry. Compound2,3and compound6,7are two couples of isomerides. Three-coordinated complex andfour-coordinated complex can be converted to one another under the certain conditions bystudying the transformation condition between compound6and7. The solid powders ofcompounds1-11show strong photoluminescence. The influence of the ligands to the coordination modes and emission wavelengths of copper(I) halides compounds have beenexplored preliminarily. It is indicated that these compounds trend to three-coordinated with thesteric hindrance of phosphine ligands increasing; emission wavelengths of these compounds redshift with the introduction of electron-donating groups to phosphine ligands. The red shift ismore obvious with the electron-donating ability increasing.2. Syntheses, structures and luminescent properties of europium(III) complexes based ondiazafluorene ligands. Three novel europium(III) complexes based on diazafluorene ligands,[Eu(DAF)2(NO3)3](12),{[Eu(NO3)2(H2O)5](NO3)(DAF)2·H2O}(13), and [Eu(TTA)3(DEDAF)](14), have been synthesized. The structures of these complexes have been determined bysingle-crystal X-ray diffraction. Among them, compound12and13are single-ligand complexes;compound14is dual-ligand complex. Compound12and14emit strong red luminescence, whilecompound13emits almost no fluorescence. According to the study of luminescent property,energy can be transfered from ligands to the Eu(III) ion efficiently by the “antenna effect” toshow the characteristic luminescence of the europium. It was proved that compound12couldtransform to13upon addition of a little water by X-ray powder diffraction, through which theluminescence quenching mechanism has been studied. It is exhibited that the replacement of thediazafluorene ligands by the water molecules lead to characteristic luminescence of characteristicluminescence of Eu3+quenching and the characteristic emission of the diazafluorene ligandsenhancing. Furthermore, the application of compound12and14in fluorescence determinationof trace amount of water has been explored preliminarily.