Synthesis,NMR,and spectroscopic properties of a novel fluorene-based derivative with D-π-A structure

A new type of fluorene derivative,2-(2,4-difluorophenyl)-7-(4-methoxyphenyl)-9,9-dioctylfluorene(compound 1)was synthesized and characterized by elemental analysis,IR spectra and NMR Spectroscopy.Its optoelectric properties were measured by UV-Vis absorption spectra and fluorescence spectra.The results show that compound 1has low-energy absorption bands ranging from 350 nm to 400 nm in dichloromethane solution,which can be assigned to theπ-π* charge transfer transitions.The optical band gap(Eg)of compound 1was estimated to be 3.39 eV.The title compound exhibits strong blue photoluminescence under 310 nm excitation at room temperature.The fluorescence quantum yields of compound 1in CH2Cl2 was up to 0.70.In addition,the wavelength of the absorption and emission spectra of compound 1depend on the polarities of the solvents.