2,7-Disubstituted 1,3,6,8-tetraazabenzopyrenes: Synthesis, characterization, optical and electrochemical properties

The syntheses of 2,7-diamino-1,3,6,8-tetraazabenzopyrene framework was achieved through CuI-catalyzed double annulation of 1,4-diiodoanthraquinone with guanidine. In addition, the preparation of series of 2,7-disubstituted 1,3,6,8-tetraazabenzopyrenes functionalized by NR2, CO, Cl, alkoxy and phenoxy groups with good yields was achieved through the simple transformations such as diazotization, alkylation and nucleophilic aromatic substitution. The properties of 1,3,6,8-tetraazabenzopyrenes synthesized were studied by DFT-calculations, optical and photoluminescence spectroscopy, cyclic voltammetry and light-induced EPR spectroscopy. The luminescence of amino derivatives is quenched in acidic solutions depending on the degree of protonation.