Luminescent properties of dipropargylfluorene derivatives

Dipropargylfluorene (DPF)––2-substituted, X=Br, Ac, NO2––were synthesized via the reaction of fluorene derivatives and propargyl bromide in the presence of aqueous NaOH solution and triethylbenzylammonium chloride in high yields. The thermal properties of DPF and its homologues were studied by differential scanning calorimeter and thermogravimeter. 2-Substituted DPFs were found to be more thermally stable than that of DPF itself. In general, these compounds had the wide processing window. DPF–NO2 exhibited to melt and react at 140 and 222 °C, respectively. DPF–NO2 showed characteristic UV–visible absorption band at 363 nm and blue photoluminescence (PL) spectrum at 445 nm corresponding to the photon energy of 2.79 eV under the excitation wavelength of 363 nm. The bandgap energy of this material was estimated to be 2.9 eV from the analysis of the absorption edge. It was found that the PL intensity of DPF–NO2 was greater than those of other two homologues (DPF–Br, DPF–Ac).