Preparation and characterization of new aliphatic-tailed five- and six-membered azomethine-diimides

Abstract New azomethine-phthalic (AzPhDIs) and azomethine-naphthalene (AzNDIs) diimides were synthesized in condensation reaction of diamines containing phthalic or naphthalene diimide core and two aldehydes: 4-(4,4,5,5,6,6,7,7,8,8,9,9,10,10,11,11,11-heptadecafluoroundecyloxy)benzaldehyde and 4-octadecyloxybenzaldehyde. The phase behavior of azomethine-diimides was examined by differential scanning calorymetry (DSC) and polarized optical microscopy (POM). AzPhDIs exhibited liquid crystalline properties in wide temperature range, whereas AzNDIs were not liquid crystalline. Thermal stability was investigated by thermogravimetric analysis (TGA). Azomethine-diimides exhibited high decomposition temperatures in the range between 360 and 401 °C. Optical properties were studied by UV–vis and photoluminescence (PL) measurements. Azomethine-diimides emitted blue light in NMP solution and blends with PMMA. The investigated compounds were electrochemically active and underwent reversible reduction and irreversible oxidation processes as evidenced by cyclic voltammetry (CV). Azomethine-diimides exhibited LUMO and HOMO levels in the range of −3.87 to −4.2 eV and −5.56 to−6.02 eV, respectively.