A fluorene derivative having two diarylethene units at the 9,9'-positions was synthesized, and the photochromic behavior was examined in solution. Upon irradiation with UV (240nm), the solution of the diarylethene dimer turned yellow. It can returned to ring-open form upon irradiation with visible light (405nm). Two diarylethene chromophores are connected to the fluorene without π-conjugation between them in the dimer. Its synthesis can be performed on a large scale from cheap commercial products and no expensive drugs were concerned in the synthetic route.
Two bisindolylmaleimide derivatives were prepared in good yields, characterized and successfully employed in the fabrication of organic light-emitting-diodes (OLEDs). The absorption spectra and photoluminescence spectra of the compounds in solution and in thin film were also measured and they show larger Stokes shifts (>100nm). With the electroluminescence devices configured as ITO/NPB/dopant:Alq3 /Alq3/LiF/Al, they exhibit yellow (A) and orange (B) color. In particularly, the two devices can be turned on at 5.2 V (device A) and 5.9V (device B), and reached the maximum brightness of 15066 and 8593cd/m2 at 21V, respectively. From the cyclic voltammetry and the onset absorption, the highest occupied molecule orbital (HOMO) and the lowest unoccupied molecule orbital (LUMO) energy levels can be estimated as A (5.3, 2.9eV) and B (5.4, 3.1eV).