Functionalized anthrathienothiophenes: synthesis, properties, and integration into OFETs

For more than two decades, the silylethyne functionalization scheme has been used to induce strong π-stacking interactions in linear acenes and heteroacenes. As part of our efforts to better understand the crystal engineering aspects of silylethyne functionalization, along with an interest in studying the impact of ring topology on the electronic and optical properties of heteroacenes, we describe here the integration of thieno[3,2-b]thiophene (a non-linear isomer of the well-known anthradithiophene) into our well established crystal engineering scheme. By utilizing the thienothiophene moiety coupled with an asymmetric solubilizing group (isopropenyldiisopropylsilylethyne), we were able to achieve charge carrier mobilities (μ) upwards of 0.22 cm² V⁻¹ s⁻¹. Based on their increased stability and promising initial mobilities, the use of this thienothiophene moiety may offer a new approach to the formation of larger heteroacene analogues with more than 5 aromatic rings.