Synthesis, Absorption and Luminescence of a New Series of Soluble Distyrylbenzenes Featuring Cyano Substituents at the Peripheral Rings

Abstract

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 aromatic rings is reported. They were prepared by the Wittig reaction and characterized by 1H and 13C NMR, FT-IR, UV/Vis, PL, EL, mass spectra, and elemental analysis. The optical properties have been studied in detail to monitor structure−luminescence relationships as a function of the position of the cyano moieties. The DSBs with cyano substituents show bathochromic shifts in their absorption spectra when compared to the parent DSB (30). The extent of this red-shift depends on electronic and steric factors. The bis(p-cyano)-substituted compound 2c exhibits a small Stokes shift and a remarkably high quantum yield of ϕF = 0.6−0.8 in the solid state. All the new distyrylbenzenes show electroluminescence when employed in devices with an ITO/PcCu/DSB/Al configuration and with colors ranging from red to green.