Synthesis and optoelectronic properties of a series of novel spirobifluorene derivatives starting from the readily available reagent 4,4′-bisalkylated biphenyl

Five novel spirobifluorene derivatives, SPF-DM, SPF-MB, SPF-BB, BSPF-NA1 and BSPF-NA2 were synthesized starting from the readily available reagent 4,4′-bisalkylated biphenyl. Their linear absorption, fluorescence and thermal properties were examined and their redox potential levels were estimated by cyclic voltammetry. These compounds possess high thermal stability. SPF-MB and SPF-BB possess excellent spectral sensitivities to pH changes and can be used as optical pH sensors of a wide pH range. The recognition behavior of SPF-BB toward various metal ions has been evaluated in a acetonitrile/water (15:1, v/v) solvent system. SPF-BB is highly selective in recognizing Ag+. The electroluminescent properties of SPF-DM, SPF-MB, BSPF-NA1 and BSPF-NA2 are demonstrated with a device configuration of ITO/MoO3 (6 nm)/NPB (80 nm)/EML (30 nm)/TPBI (40 nm)/LiF (1 nm)/Al (100 nm). The devices of BSPF-NA1 and BSPF-NA2 display a yellow emission in the EL spectra and their maximum brightness reached 380 and 311 cd m−2, respectively. At low turn-on voltage (7.9 V) a light blue emission was observed in the device of SPF-DM and its maximum brightness reached 391 cd m−2. Notably, the device of SPF-MB has a white emission with CIE coordinates (0.293, 0.307).

Figure optionsDownload as PowerPoint slideHighlights
► Novel spirobifluorene derivatives were synthesized starting from the readily available reagent 4,4′-bisalkylated biphenyl.
► These compounds possess high thermal stability.
► SPF-MB and SPF-BB can be used as optical pH sensors of a wide pH range.
► SPF-BB is highly selective in recognizing Ag+.
► Organic light emitting diodes were fabricated by using these compounds as the emitting layer.