New pi-conjugated system with a rigid framework of 1,8-anthrylene-ethynylene cyclic dimer and its monoanthraquinone analogue.

Two types of pi-conjugated compounds were synthesized by Sonogashira coupling, and their structures and properties were investigated by X-ray analysis and spectroscopic measurements. The monoanthraquinone compound features an out-of-plane deformation of the inner carbonyl moiety and dimer formation in crystals and solution.