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.