Sadegh Afshari

The electronic structures and electrostatic potential of some amino derivatives of adamantane have been studied using density functional theory. The partial atomic charges and nuclear quadrupole coupling constants (NQCC) of 14N nucleus of the considered molecules have been reported. The partial atomic charges are calculated with two methods for 14N nucleus: Mulliken charges and natural bond orbital (NBO). All of the computations were carried out using the Gaussian 03 program at the B3LYP/6-311++G(d,p) level of theory. The results of both methods show reasonably good correlation with NQCC parameter, however, a much better correlation is found between NBO charges and NQCC of 14N nucleus.

Electron transport properties of pure and oxygen and/or methyl substituted pyrene between two semi-infinite aluminum atomic electrodes have been investigated by means of density functional theory plus the non-equilibrium green's function method. The electrodes were represented by a slab of Al atoms oriented along the [111] plane. The computations were carried out in the bias voltage range of 0.0 up to 2.0 V under three gate voltages including -3.0, 0.0 and +3.0 V. The results showed negative differential resistance and relatively high rectification. All of the calculations were carried out with Open source Package for Material eXplorer (OPENMX) 3.6 computer code within the generalized gradient approximation for the exchange-correlation energy and norm-conserving Kleinman-Bylander pseudo potentials. The observed rectifying and the negative differential resistance were justified using the transmission spectrum and its integration in the corresponding bias window. Also, the negative differential resistance behavior was investigated by studying the density of states of left electrode, central region and right electrode and their overlaps. © 2018 Iranian Chemical Society.

New dimer complexes of zinc(II), copper(II) and nickel(II) were synthesized using the Schiff base ligand which was formed by the condensation of 2-aminothiophenol and 2-hydroxy-5-methyl benzaldehyde. This tridentate Schiff base ligand was coordinated to the metal ions through the NSO donor atoms. In order to prevent the oxidation of the thiole group during the formation of Schiff base and its complexes, all of the reactions were carried out under an inert atmosphere of argon. The X-ray structure of the Schiff base ligand showed that in the crystalline form the SH groups were oxidized to produce a disulfide Schiff base as a new double Schiff base ligand. The molar conductivity values of the complexes in dichloromethane implied the presence of non-electrolyte species. The fluorescence properties of the Schiff base ligand and its complexes were also studied in dichloromethane. The products were characterized by FT-IR, 1H NMR, UV/Vis spectroscopies, elemental analysis, and conductometry. The crystal structure of the double Schiff base was determined by single crystal X-ray diffraction. Furthermore, the density functional theory (DFT) calculations were performed at the B3LYP/6-31G(d,p) level of theory for the determination of the optimized structures of Schiff base complexes. © 2016 Elsevier B.V. All rights reserved.

The adsorption of mercaptans on pristine, Al-doped, and mono-vacancy and Stone-Wales defected hexagonal boron nitride (h-BN) nanosheets was studied by the density functional theory method at the wB97X-D/6-311G(d) level of theory. Two types of mercaptans (i.e., methyl and ethyl mercaptan) were chosen as the adsorbates. No adsorption was observed on the pristine and defected h-BN nanosheet except for the B-vacancy defected h-BN nanosheet of which the adsorption was exothermic. In the case of the Al-doped h-BN nanosheet with substituted boron and nitrogen defect sites, not only was adsorption observed for both methyl and ethyl mercaptan but also the adsorption was exothermic. It was suggested that the Al-doped h-BN nanosheet and B-vacancy defected h-BN nanosheet could be a potential resource for adsorbing mercaptans. The electronic properties of all kinds of the studied h-BN nanosheets and the adsorption configuration of mercaptans on them were reported. © The Royal Society of Chemistry.