Bis-dithiano perylene diimide: synthesis and characterization of a novel ring system

Abstract

We report the transformation of a 1,7-dibromo perylene diimide into a 1,6,7,12-tetrasulfur-substituted expanded ring system at room temperature in high yield. The resulting bis-dithiano perylene diimide completes the series of five sulfur-annulated perylene ring systems, the first four of which are known. We describe the synthesis and characterization of the title compound, PS₄, and other sulfur-annulated species formed under slightly different conditions. Optical and electrochemical data of both solution and solid films of this compound are reported. At slow scan rate a film of PS₄ self-organizes, rearranging its structure to accommodate its changing oxidation state. PS₄ is a lightly n-doped semiconductor in inert atmosphere (conductivity, σ = 4.6 × 10⁻⁶ S cm⁻¹) that becomes compensated in air (σ = 2.4 × 10⁻⁹ S cm⁻¹) to an unusual, almost intrinsic (undoped) state. The properties of PS₄ suggest applications in organic electronics.