Functionalized Tetrathienoanthracene: Enhancing π-π Interactions Through Expansion of the π-Conjugated Framework

The functionalization of tetrathienoanthracene (TTA) with bromine and 2-hexylthiophene moieties is described, and their influence at both the molecular and solid-state level has been investigated. Comparative optical and electrochemical studies indicate an increase in conjugation for the thiophene derivative compared to the parent TTA. In the solid state, these materials form slipped pi-stack structures with a number of close intermolecular contacts. Comparison of the two structures reveals a more steeply inclined slipped pi-stack for the thiophene derivative resulting in a closer interplanar separation. This, coupled with the extended molecular framework, leads to an enhanced number of pi-pi interactions within the stack. The combination of increased conjugation at the molecular level, and pi-stacked structures with strong intermolecular communication at the solid-state level, augurs well for the use of TTA materials in optoelectronic applications.