Synthesis and Photodynamics of Tetragermatetrathia[8]circulene.

Tetragermatetrathia[8]circulene has successfully been synthesized from tetraiodotetrathienylene through palladium-catalyzed germylation and rhodium-catalyzed intramolecular dehydrogenative cyclization. A single-crystal X-ray diffraction analysis elucidated that tetragermatetrathia[8]circulene has a highly symmetric, planar, and rigid structure. DFT calculations suggested that LUMO of tetragermatetrathia[8]circulene is stabilized due to σ*-π* interactions between σ* orbitals of the Ge-C bonds and π* orbitals of the thiophene rings. The excited dynamics of tetragermatetrathia[8]circulene have also been found to be significantly affected by the heavy-atom effect of the germanium atom.