Theoretical studies and spectroscopic characterization of novel 4- methyl-5-((5-phenyl-1,3,4-oxadiazol-2-yl)thio)benzene-1,2-diol Somayeh Soleimani Amiri a, * , Somayeh Makarem a , Hamid Ahmar b , Samaneh Ashenagar c a Department of Chemistry, Karaj Branch, Islamic Azad University, Karaj, Iran b Department of Chemistry, Faculty of Science, University of Zabol, Zabol, Iran c Young Researchers and Elite Club, Karaj Branch, Islamic Azad University, Karaj, Iran article info Article history: Received 27 January 2016 Received in revised form 16 April 2016 Accepted 18 April 2016 Available online 20 April 2016 Keywords: 4-Methyl-5-((5-phenyl-1,3,4-oxadiazol-2- yl)thio)benzene-1,2-diol Theoretical study Electronic properties IR NMR abstract The structural, electronic, and spectroscopic properties of 4-methyl-5-((5-phenyl-1,3,4 oxadiazol-2-yl) thio)benzene-1,2-diol (MPOTB) have been carried out at ab initio and DFT levels. A detailed study of geometrical parameters, Infrared spectrum, chemical shifts ( 13 C NMR, 1 H NMR), and electronic properties of the title compound is presented. The correlation between the theoretical and the experimental 13 C, and 1 H chemical shifts of MPOTB were about 1.02e1.03 and 0.98e1.00, respectively. The electronic properties, such as molecular electrostatic potential, NBO atomic charges, HOMO and LUMO energies were performed at above levels. Rather high hardness of MPOTB introduces it as a stable molecule. As a result, the calculated findings were compared with the observed values and generally found to be in good agreement. © 2016 Elsevier B.V. All rights reserved. 1. Introduction 1,3,4-Oxadiazole derivatives are important heterocyclic com- pounds with a broad range of biological, medicinal, and pharma- cological properties [1e3]. Some of them have antibacterial, antifungal, anti-inflammatory, and hypoglycemic activity. These also lie in the field of photosensitizer, liquid crystals, and electron- conducting and hole-blocking materials in organic light-emitting diodes [1,2]. In view of these useful properties, a number of pre- parative methods have been reported for the synthesis of these molecules [1,4e8]. Recently, highly improved computers have a good ability to correctly describe the physicochemical properties of small mole- cules with nearly chemical accuracy. So, regarding the importance of 1,3,4-oxadiazole derivatives, computational chemistry could be valuable to discover physicochemical properties of relatively small molecules [9]. Ab initio and density functional theory (DFT) calcu- lations could provide excellent vibrational frequencies, NMR data, and single-crystal X-ray analyses of the organic compounds. The geometric parameters and single-crystal X-ray structure of the molecule determine both experimentally and theoretically via X- ray crystallography and the computational methods in the ground state, respectively [10]. Hence, it can play an important role in the modern drug discovery. The computational prediction of molecular properties for the selected medium-sized organic is more essential than modeling interactions with macromolecules in the drug development. Conformational modeling and simulation of the spectroscopic parameters can help in the interpretation of the NMR data from pharmaceuticals, synthetic intermediates, metabolites, degradation products and undesired impurities. In this work, 4-methyl-5-((5-phenyl-1,3,4-oxadiazol-2-yl)thio) benzene-1,2-diol molecule (MPOTB) optimized at the HF/6-31G(d), B3LYP/6-31G(d), and M063X/6-311þþG(d,p) levels of theory, while other calculation were performed at two first levels [11e14]. The calculated IR and NMR spectra were compared with the experi- mental data. The optimized geometrical parameters and the X-ray crystallography data were exposed parallel results. 2. Computational methods The theoretical computations were performed at Hartree Fock, B3LYP and M062X levels using the Gaussian 09W program package * Corresponding author. E-mail addresses: s.soleimani@kiau.ac.ir, solesomy@yahoo.com (S. Soleimani Amiri). Contents lists available at ScienceDirect Journal of Molecular Structure journal homepage: http://www.elsevier.com/locate/molstruc http://dx.doi.org/10.1016/j.molstruc.2016.04.053 0022-2860/© 2016 Elsevier B.V. All rights reserved. Journal of Molecular Structure 1119 (2016) 18e24