The fomazan compounds 3-(p-isopropylphenyl)-5-(o,m,p-nitrophenyl)-5-phenylformazans (1-3) have been synthesized and characterized by FTIR, UV Vis and H-1 NMR spectroscopic techniques and elemental analysis. Quantum chemical calculations of the molecular structures, vibrational frequencies, gauge including atomic orbital H-1 chemical shift values were carried out using the density functional B3LYP method with the 6-311 + G(d,p) basis set. The TD-DFT calculations were carried out using the B3LYP, CAM-B3LYP and PBE1PBE functionals with the 6-311 + G(d,p) basis set to determine the maximum absorbtion wavelength of the UV Vis spectra for (1-3). The non-linear optical properties are addressed theoretically. Besides, OFT calculations of the molecular electrostatic potential, the natural bond orbital and thermodynamic properties of (1-3) were carried out at the B3LYP/6-311 + G(d,p) level of theory. (C) 2014 Elsevier Ltd. All rights reserved.