Synthesis and characterization of novel photoactive poly(ether-amide)s based on highly substituted phenanthrimidazole

Abstract

A new aromatic diamine monomer containing ether linkage based on the phenanthrimidazole ring, ‎1,1´-(4,4´- oxy bis(1,4-phenylene))bis(2-(4-aminophenyl)-1H-phenanthro[9,10-d]imidazole) was synthesized through four-‎components condensation of 4,4´-diamino diphenyl ether, 4-nitrobenzaldehyde, phenanthrene-9,10-dione and ammonium ‎acetate in presence of acetic acid, followed by palladium-catalyzed hydrazine monohydrate reduction. This new monomer ‎was further confirmed by FT-IR, 1H NMR, and 13C NMR spectroscopy. A series of new aromatic polyamides containing ‎phenanthrimidazole ring in the main chain was prepared by direct polycondensation of the prepared diamine with four ‎commercially available aromatic and aliphatic diacids. These polymers are essentially amorphous and were soluble in polar ‎aprotic solvents such as DMF, NMP, DMAc, and DMSO. Inherent viscosities of polyamides were in the range 0.42–0.53 ‎dL/g indicating the formation of medium molecular weight polymers. Polyamides exhibited glass-transition temperature (Tg) in ‎the range 260-280 °C. The 10% weight loss temperature in air atmosphere measured by TGA was in the range 454-526 °C ‎indicating their good thermal stabilities. The photophysical properties of diamine and polyamides were investigated by UV-Vsible and fluorescence spectroscopy.