Highly Soluble Aromatic Oligoazomethine Synthesized Using Maghnite-H+ for Organic Electronics

Abstract

In this study, a conjugated oligoazomethine was synthesized via polycondensation of terephthaldehyde and p-phenylenediamine, aiming to develop a thermally stable, solution-processable, and semiconductive oligomer with potential applications in optoelectronic devices. The resulting oligomer exhibited a π‑conjugated backbone with azomethine (C=N) linkages, confirmed by FTIR spectroscopy. UV–visible spectroscopy revealed a red-shift in absorption, with an optical band gap of 2.69 eV, indicating semiconductive behavior. Structural analysis using XRD showed semicrystalline characteristics, while TGA demonstrated good thermal stability with decomposition onset at 455°C. SEM images revealed a rough, globular surface morphology with porous features. Oligomer yield was optimized by varying reaction parameters, with a maximum yield of 95.1% achieved at room temperature using 5% Maghnite-H⁺ as a catalyst over 24 hours. Solubility tests confirmed good compatibility with organic solvents. Electrical conductivity measurements indicated a room temperature conductivity of 2.1 × 10⁻⁶ S/cm and an activation energy of 0.24 eV, placing oligoazomethine in the category of organic semiconductors. These properties suggest the synthesized oligo-azomethine is a promising candidate for use in optoelectronic and photovoltaic applications.