Azo-based phenylthiophene Schiff bases: Syntheses, Crystal Structures and Optical Properties

Abstract Two new organic materials based donor acceptor systems, namely N,N-dimethyl-4-((E)-(4-((E)-((5-phenylthiophen-2-yl)methylene)amino)phenyl)diazenyl)aniline A and (E)-4-((E)-(4-nitrophenyl)diazenyl)-N-((5-phenylthiophen-2-yl)methylene)aniline B were successfully synthesized. Both compounds (A and B) have been synthesized by a condensation reaction between N, N-Dimethyl-4,4’-azodianiline or 4-(4-nitrophenylazo)aniline and 5-phenylthiophene-2- carbaldehyde, with 77% and 83% yield. These two compounds were subjected to the following characterization techniques: single crystal X-ray diffraction, elemental analysis, infrared, mass, 1H NMR, 13C NMR spectroscopy and thermogravimetric analysis. The Schiff bases A and B belong to the monoclinic P21/c space group. Their crystal structures are stabilized by intra and intermolecular hydrogen bonds, as well as by weak π−π stacking. The prevalence of this interaction is illustrated by an analysis of the three dimensional Hirshfeld surface and by two-dimensional fingerprint plots. Optical properties of these compounds have been determined by UV-absorption spectroscopy, which disclosed the energy of the optical band gap.