Synthesis and Properties of Planar Liquid-Crystalline Bisphenazines

A synthetic route to fused bisphenazine compounds has been developed. Thus, 2,7-di-tert-butyl-quinoxalino[2‘,3‘,9,10]phenanthro[4,5-abc]phenazine-6,7,15,16-tetraalkoxy compounds have been synthesized in good yields. The structures of these new compounds were ascertained by nuclear magnetic resonance (NMR) and mass spectroscopy. Differential scanning calorimetry (DSC), polarized light microscopy (PLM), and wide-angle X-ray diffraction (WAXD) studies showed that some of these planar molecules display liquid crystalline phases at elevated temperatures. WAXD analysis also indicated that the molecules undergo π−π stacking in the liquid crystalline phase. Differential pulse voltammetry (DPV) showed that the compounds undergo two reduction processes. Thus, it is speculated that the materials have potential as electron transporting materials in electronic devices such as organic photovoltaic or light-emitting diodes.