Studies On Design, Synthesis And Characterization Of Novel Organic Fluorescent Molecules Based On 2,4-Dicyano-3-amino-fluorene

Compared to inorganic electroluminescent materials,organic electroluminescent materials have attracted much attention in the research of optoelectronic information materials for their various advantages such as easy of controlling in design,synthesis; much wider selectivity of raw materials;realization of full color display;more simply fabrication process and etc.In this dissertation,a series of multi-functional groups substituted fluorene based organic light-emitting materials were designed and synthesized.Then their optoelectronic properties,thermal stabilities,electrochemical properties and quantum computation were investigated.The dissertation was divided into the following partsFirstly,six novel 1-aryl-2,4-dicyano-3-dialkylamino-9,9-dialkylfluorene molecules were designed and synthesized through the construction of fluorene skeleton.It is expected that the charges transport properties could be enhanced in these typical D-Ï€-A molecules by incorporating several electron donating and accepting groups The chemical structures for these compounds were characterized by ¹H NMR,¹³C NMR,HRMS and elemental analysis.All the compounds were examined by UV-Vis absorption and fluorescence emission spectrum.The main absorption bands in UV-Vis spectrum for these compounds are located around 240, 300 and 380 nm.The emission spectrum expressed that all of these compounds are blue light-emitting in hexane dilute solution with a maximal emissive wavelength ranging from 423-427 nm.High glass transition temperatures are obtained for compounds mfm3 and mfm4 by DSC analysis.The HOMO energy level are located at the scope from 5.29 to 5.35 eV calculated by the cyclic voltammetry data,which indicated that these compounds are potentially characterized by excellent hole transport abilities.Quantum chemical calculations for molecules mfm1 and mfm2 are performed on a Gaussian 98 soft package in the level of B3LYP/6-31G^*.Calculated hole transport reorganization energy for molecule mfm2 is very low,which indicated the good hole transport abilities for these compounds.All the data and calculations indicated that these compounds have the potential applications to organic blue electroluminescent materials.Secondly,we synthesized and characterized two new star-shaped molecules ss1 and ss2 containing a triphenylamine/benzene moiety as the central core and three 2,4-dicyano-3-diethylamino-9,9-diethylfluorene moieties as the peripheral functional groups.UV-Vis absorption spectrum and fluorescence emission spectrum are investigated for two compounds.Two strong absorption bands were found at 300 and 390 nm in UV absorption spectrum.Compound ss1 presented dual fluorescence in high polar solvents but did not for compound ss2.Fluorescent lifetime analysis assisted the occurrence of TICT excited state and emission in the dual fluorescence. Both compounds exhibited moderate fluorescence and high thermal stabilities, indicating their potential application to blue light emitting materials.The elementary quantum calculations indicated the HOMO for molecule ss1 is much delocalized than that for molecule ss2.HOMO and LUMO are separated in both molecules.Finally,we developed a general method for the synthesis of highly substituted 2-cyanoanilines under mild reaction conditions.Raw materials are commercial supplied but the yields are moderate in this reaction.All the products are high blue fluorescent.All the compounds synthesized by the reaction were examined by UV-Vis absorption and fluorescence emission spectrum.