In this study, the novel low band gap and thermally stable poly(azomethine-urethane)s (PAMUs) were synthesized to investigate aliphatic and aromatic group effects on some physical properties such as thermal stability, optical and electrochemical properties. For this reason, we firstly synthesized the new Schiff bases via condensation reaction of 5-nitrovanilin with aromatic and aliphatic diamines. Then, these monomers were converted to PAMUs derivatives by the step-polymerization reaction with aromatic and aliphatic diisocyanates. The structures of the compounds were confirmed by FT-IR. UV-vis, H-1 NMR, and C-13 NMR techniques. The molecular weight distribution parameters of the compounds were determined by the size exclusion chromatography (SEC). The compounds were also characterized by solubility tests. TG-DTA, and DSC techniques. Cyclic voltammetry (CV) measurements were carried out and HOMO-LUMO energy levels and electrochemical band gaps (E'(g)) were calculated from their absorption edges. Additionally, optical band gaps (E-g) were determined by using UV-vis spectra of the materials. Fluorescence measurements were carried out in THF, DMF, and DMSO solutions to determine the optimum concentrations and the maximal emission and excitation intensities. (C) 2011 Elsevier B.V. All rights reserved.