Synthesis and Luminescence Properties of U-Shaped Polycyclic Molecules Containing Syn-Facial Functionalized Quinoxaline Rings

Rigid U-shaped molecules containing syn-facially situated quinoxaline rings have been synthesized in three steps, by a combination of the Diels−Alder reaction, the ruthenium-catalyzed oxidation, and the Zn(OAc)₂-catalyzed condensation of the resulting bis-α-diketones with benzene-1,2-diamines. The unsymmetric bis-quinoxalines, with electronically different substituents, and the quinoxaline ring-attached α-diketones were also prepared. Their luminescence properties were examined and described.