Synthesis And Property Of Alkyl Fuluorene

Polyfluorene is an important class of blue light-emitting polymer material, which is widely used in flat panel displays(PLEDs), solar cells, biological and chemical sensors. As mass effect or formation of chains oligomer among the polyfluorene molecules, there is a tailing phenomena in light spectrum, meaning poor color purity and poor stability. Thus, people had done a lot of work to focus on the modification of polyfluorene, and synthesized a number of light-emitting polyfluorene derivative. Polyalkylfluorine is considered as a promising polymer due to its better solubility and processability with alkyl side chain connected to the bridge carbon.A series of poly alkyl fluorene monomers with different alkyl chain(-C4H9,-C8H17,-C14H29) are synthesized by using of fluorene as raw material, according to different synthetic routes, choosing different solvents and catalysts in this paper. R=-C4H9,-C8H17,-C14H29 Synthetic route 1 of A:First 2,7-dibromo fluorine is synthesized, and second it is alkylated. Alkyl bromide fluorene is prepared under different reaction conditions by using TEBA, tetrabutylammonium bromide as phase transfer catalyst, toluene, DMSO and THF as solvent, 50% NaOH and potassium tert-butoxide as activator respectively.Synthetic route 2 of A:First fluorene is alkylated, and second it is bromide by number 2 and 7. Alkyl fluorene is prepared under different reaction conditions by using butyl lithium and sodium tert-butoxide as activator respectively.Desired product B is prepared with the methods of Grignard reaction and butyl lithium as activator respectively.The structure was characterized by 1HNR and IR. The luminescence was detected by UV and fluorescence. Conclusions were as follows:1. The shorter the alkyl chain connected to fluorine is, the UV maximum absorption wavelength is greater. As the alkyl chain weaken fluorene conjugation, leading to a blue shift of maximum absorption. The longer the chain is, the greater the degree of blue shift is.2. The length of alkyl chain connected to fluorene had little effect on increasing the maximum absorption wavelength. Absorption wavelength was all around 310nm. However, with the chain length increaseing, the fluorescence intensity gradually increased. May be the increasing chain length hindered fluorescence quenching.3. The effect of choice of synthetic route on the reaction conditions and yield showed that, good yield could be got by bromide first and alkylation second, at the same time, the reaction conditions were simple. The highest yield of the product was got by using THF as solvent, potassium tert-butoxide as activator at room temperature.4. Synthetic steps of carboxylic-alkyl-fluorene with Grignard reagent were trouble, but conditions were simple with high yield.