Synthesis, Solid State Structures, and Properties of Linear and Tripodal Flexible Molecules with Pyrazinopyrazine Moieties

Pyrazino[2,3-b]pyrazine (PP), which is a naphthalene analogue with iminium nitrogen atoms at 1,4,5,8-positions instead of sp2-carbon atoms, is attractive as a building block for nitrogen-highly-contained π-conjugated systems. In this study, we synthesized PP-based linear and tripodal molecules, in which PP moieties are bonded with the central benzene ring at 1,4-positions and 1,3,5-positions, respectively, giving conformationally flexible and moderately π-conjugated molecules. It is noteworthy that the tripodal one forms unique interdigitated dimer with a small cavity in a crystalline state because of flexible tripodal molecular shape.