A Novel Oligo-Pyrazole Thin Film: Synthesis, Characterization, Optical and Morphological Properties

Abstract

Pyrazole-3,4-dicarboxylic acid 2 was synthesized via the hydrolysis of pyrazole-3-carboxylic acid 1 and subsequently heated with thionyl chloride to give the novel pyrazole-3,4-dicarbonyl dichloride 3, which was easily converted into oligo-pyrazole 4 upon its reaction with p-phenylene-diamine. These newly synthesized compounds were characterized by H-1-NMR, C-13-NMR, and FT-IR spectroscopy, and gel permission chromatography (GPC). Three novel oligo-pyrazole thin films were prepared using oligo-pyrazole 4 with these respective values of thickness: 20, 21, and 24 mu m. The optical properties of the films, including the absorbance, transmittance, and optical band gap, were determined using UV-vis spectroscopy. The E (g) values of the films were found to be 1.426, 1.537, and 1.648 eV for the 20, 21, and 24 mu m thick organic films, respectively. Atomic force microscopy (AFM) was used to examine the surface morphology and properties of the organic films. In the AFM images, a few black regions were observed and several yellow regions appeared over a large area, and the surface of the oligo-pyrazole films had an extremely low roughness value. The as-synthesized oligo-pyrazole has great potential in optoelectronic applications according to the optical properties of the as-prepared films.