Amine-Substituted Diazocine Derivatives - Synthesis, Structure, and Photophysical Properties

A series of amine-substituted diazocines were synthesized in three steps from methyl 2-aminobenzoate or methyl 3-aminonaphtholate. The saddle-shaped diazocine compounds showed similar interplane angle of 75° despite the different steric bulk of the amine substituents. In electrochemical experiments, these diazocines showed irreversible reduction most likely producing indolo[3,2-b]indoles rather than forming the 10-electron planar aromatic species. The carbazole-substituted naphthodiazocines showed the most interesting photophysical properties with evidence of transition from the saddle-shaped ground state to a planar excited state geometry.