Study On Synthesis Of Fluorene Derivatives And Their Optical Properties

The development of organic electroluminescent materials is one of the forefronts and active areas of the optoelectronic information materials, on account of the advantages of organic electroluminescent materials compared to inorganic counterpart. Fluorene and its derivatives which have an aromatic biphenyl structure with wide energy gap in the backbones and high luminescent efficiency have drawn much attention of materials chemists and device physicists. Fluorenone derivatives have been used as electron transporting materials in organic photo conductor(OPC) device and their electric and optical properties were studied. It is very helpful to improve the thermal and spectral stabilities by introducing the 2,7-dibromofluorenone units into the electroluminescent molecules. Aromatic Schiff base compounds are important organic synthetic intermediates, and have been used as organic non-linear optic materiaK liquid crystal materiaK optic information storage material and optic switch material et al. Substituted aromatic Schiff base compound of 2,7-dibromofluorenone have photoluminescent properties, its electron absorption spectras are discussed in relation to the molecular structure. Therefore, many chemists are devoting themselves to investigating the synthesis techniques and photophysical behaviors of new and excellent electro-luminescent materials.In the thesis , the 2,7-dibromofluorenone was synthesized fromfluorenone and bromine with water as solvent. Meanwhile, the optimum conditions of reaction solvent, catalyst, reaction time, reaction temperature and the amount of bromine were also studied in detail. The optimum reaction condition was defined.Six imino derivatives of 2,7-dibromofluorenone were synthesized from 2,7-dibromofluorenone and corresponding aromatic amine compounds with different substituents(the electron-donating group or the electron-attracting group), and the structures of the new compounds were characterized by IR> MS and 'HNMR spectra.In addition, the absorbing wavelengths^) of the seven fluorene derivatives in ethyl alcohoK tertahydrofuran^ hexamethylene were separately determined by the UV-vis spectra. The effect of the solvent and molecular structure to electron absorption spectra were studied. The results showed that the maximum absorption wavelength (Amax/nm) of its ultraviolet absorption spectra have a red shift with larging conjugate systems or electron donation group;The proton donor solvent leads to the red shift for %-^n transition and the blue shift for n-*7t transition.