Systematic Synthesis of Tetrathia[8]circulenes: The Influence of Peripheral Substituents on the Structures and Properties in Solution and Solid States

We developed the diversity-oriented approach for the synthesis of tetrathia[8]­circulenes with a variety of peripheral substituents. Iridium-catalyzed direct C–H borylation of tetrathienylene provided 1,4,7,10-tetraboryl­tetrathienylene as a major product. 1,4,7,10-Tetraboryl­tetra­thienylene served as an a key intermediate to achieve the selective synthesis of octasubstituted or tetrasubstituted tetrathia­[8]­circulenes via rhodium-catalyzed annulation with symmetric internal alkynes or sequential Sonogashira–Hagihara coupling and base-promoted intramolecular cyclization. A variety of substituents were installed at the peripheral positions of tetrathia[8]­circulenes systematically. The self-assembling behavior of tetrathia[8]­circulenes was investigated using ¹H NMR and AFM measurements. The number and the chain length of alkyl groups exerted a significant influence on the aggregation ability and the crystal packing structures of tetrathia[8]­circulenes in both solution and solid states. We also found that the molecular arrangement of the self-assembled tetrathia[8]­circulene molecules affected the hole mobility assessed by the FP-TRMC method.