Synthesis, absorption and luminescence of a new series of soluble distyrylbenzenes featuring cyano substituents at the peripheral rings

The synthesis of a complete series of nine soluble distyrylbenzenes (DSBs) with two (2a-c) and four cyano groups (1a-f) attached to the peripheral aro matic rings is reported. They were prepared by the Wittig reaction and char acterized by H-1 and C-13 NMR, FT-IR, UV/Vis, FL, EL, mass spectra, and ele mental analysis. The optical properties have been studied in detail to moni tor structure-luminescence relationships as a function of the position of t he cyano moieties. The DSBs with cyano substituents show bathochromic shift s in their absorption spectra when compared to the parent DSB (30). The ext ent of this red-shift depends on electronic and steric factors. The bis(p-c yano)-substituted compound 2c exhibits a small Stokes shift and a remarkabl y high quantum yield of phi (F) = 0.6-0.8 in the solid state. All the new d istyrylbenzenes show electroluminescence when employed in devices with an I TO/PcCu/DSB/Al configuration and with colors ranging from red to green.