Journal of Physical and Theoretical Chemistry
Volume:13 Issue: 3, Winter 2017

In this study an appropriate computational approach was presented for estimating the boiling temperatures of 41 different types of olefins and their derivatives. Based on the guidelines of this approach, several structural indices related to the organic components were applied using graph theory. Meanwhile, in addition to evaluating the relation between the boiling temperatures of olefins with the structural indices, the property estimation was done with the help of multiple non-linear regression model and other suitable coefficients. For specifying the best structural descriptors out of seven descriptors for determining the considered boiling temperatures, the most appropriate one was specified with the help of multiple non-linear regression model. It was determined that a combined model of Harary and Randic indices is appropriate for determining the boiling temperatures of olefins. The best model to predict Tboil of olefins was obtained as follows: Tboil/K= 0.112 H**2 + 2.148 exp (χ) + 290.606

Abstract. Topological indices are the numerical value associated with chemical constitution purporting for correlation of chemical structure with various physical properties, chemical reactivity or biological activity. Graph theory is a delightful playground for the exploration of proof techniques in Discrete Mathematics and its results have applications in many areas of sciences. A graph is a topological concept rather than a geometrical concept of fixed geometry, and hence Euclidean metric lengths, angles and three-dimensional spatial configurations have no meaning. One of the useful indices for examination of structure- property relationship is Randic' index. In this study, the relationship between the Randic'(1X), Balaban (J) and Szeged (Sz) indices and Harary numbers (H) to the thermal energy (Eth), heat capacity (Cv) and entropy(S) of monocarboxylic acids (C2- C20) are established. The thermodynamic properties are taken from HF level using the ab initio 6-31 G basis sets from the program package Gussian 98. Then, some useful topological indices for examination of the structure- property relationship are presented.

Pollution of water resources by various pollutants is nowadays a global environmental issue. Among the different type of water pollutants, dye represents a major polluting group. In this study, Azolla filiculides roots have been used for adsorption of Malachite Green (MG), a cationic dyed from aqueous solution. In this study, effects of operating parameters such as initial concentration of dye (5-30 mg/L), contact time (5-120 min), adsorbent dosage (0.05- 0.5) and pH (6-11) in the batch system investigated. The adsorption process data successfully were described by Langmuir, Freundlich, Temkin and BET isotherms. The kinetics of the adsorption data were analyzed using 3 kinetic models such as pseudo second- order, Intra-particle diffusion and Elovich to understand the adsorption behavior of Malachite Green onto Azolla filiculoides roots. The result showed the removal of MG was increased by increasing contact time and adsorbent dose, and pH. According to the analysis of the different kinetic models for adsorption of MG on Azolla filiculoides roots follows of Pseudo second – order kinetic. The Temkin model described the adsorption result very well. This study indicated can be used as an effective and inexpensive adsorbent to removal of Malachite Green from aqueous solution. The positive value of change in enthalpy shows that the adsorption MG dye onto Azolla filiculoides roots is endothermic. Furthermore, the negative value of indicated that the adsorption MG dye was thermodynamically spontaneous.

Abstractl Density functional theory (DFT) was used to investigate the effects of intra-moecular interactions and implicit water molecules on the relative stability and the NMR shielding tensors of hallucinogenic harmine in the monomeric and dimeric states. Results represented that the relative stability and the NMR shielding tensors are dependent on the resonance interactions and chemical environment However, their values are obviously different in the considered states and the media. The energetic data demonstrated that dimeric and monomeric states of harmine in water medium are more stable than they are in the gaseous form. Based on NBO interpretation and NMR calculations it can also be concluded that by increasing lone pair electrons contribution of nitrogen atoms in resonance interactions and aromaticity development in the monomeric – dimeric states, the values of NMR chemical shielding around them increase. Keywords: Harmine, NMR chemical shielding, NBO interpretation, monomer, dimer β-Carboline derivatives (H-pyrido [3, 4-b] indol derivatives) (BC) make up a group of drug-binding alkaloids, widely distributed in nature. Harmine [C13H12N2O] (MeO-1-1Me-9H-7pyrido [3,4-b]-indole ) is a well known member of the β-caroline alkaloid family

In the present study we focused on the electronic and structural properties of Na and Mg adsorption on the surface of the (6, 6) armchair SiCNTs. The adsorption energy (Eads), band gap energy (Eg), partial density of state (PDOS), chemical potential (μ), global hardness (η), electrophilicity index (ω), global softness (S), work function values (φ) and work function change (Δφ) are calculated by using DFT methods and B3LYP/6-311++G (d, p) level of theory. Adsorption of Na and Mg atoms on the surface of SiCNTs reduce the gap energy (Eg) of nanotube and so the conductivity and chemical reactivity of nanotube/Na or Mg increase significantly from pristine model. The order of decreasing of the Eg values for the studied systems is: SiCNTs > C-SiC/Mg > Si-SiC/Mg > C-SiC/Na > Si-SiC/Na. On the other hand the work function of the SiCNTs/Na or Mg complex alters significantly from pristine model and consequently the field emission current densities of system enhance. The predicted adsorption energies (Eads) follow the order: Si-SiC/Mg> Si-SiC/Na> C-SiC/Mg> C-SiC/Na.

Using Gaussian 03, software the thermodynamic functions such as Gibbs free energy, G, Enthalpy, H, and Entropy, S, of Alanine and Valine amino acids were theoretically studied at different solvents. First, the Density Functional Theory (B3LYP) level with 3-21G, 6-31G and 6-31+G basis sets were employed to optimization of isolated Alanine and Valine amino acids in the gas phase. Moreover, Vibrational frequencies were calculated in gas phase on the optimized geometries at the same level of theory to obtain the thermodynamic functions such as Gibbs free energy, G, Enthalpy, H, and Entropy, S,. Then, the calculation about the solvent effects on the thermodynamic functions of Alanine and Valine amino acids were performed for the various solvents (Water, Methanol and Ethanol) by using self consistent Reaction-Field (SCRF=PCM) model at B3LYP/6-31+G. Thermodynamically analysis shows the relative Gibbs free energy changes, G, Enthalpy changes, H, are negative values but the Entropy changes, S, are positive values for Alanine and Valine amino acids. Also, the results shows, with increasing of dielectric constant of solvents the stability of considered amino acids increases.

In the present work, the quantum theoretical calculations of the molecular structure of the 1-(1, 3-Benzothiazol-2-yl)-3-(thiophene-5-carbonyl) thiourea has been predicted and are evaluated using Density Functional Theory (DFT) in gas phase. The geometry of the title compound was optimized by B3LYP/6-311+G and B3LYP/6-311+G* methods and the experimental geometrical parameters of the title compound such as bond lengths (Å), bond angles (°) and torsion angels (°) were compared with calculated results. The theoretical 1H and 13C NMR chemical shift (GIAO method) values of the title compound are calculated and compared with the experimental results. The computed data are in good agreement with the experimental data. Frontier molecular orbitals (FMOs) such as HOMO orbital, LUMO orbital and HOMO-LUMO energy gap, molecular electrostatic potential (MEP), electronic properties such as ionization potential, electron affinity, global hardness, electronegativity, electronic chemical potential, electrophilicity, chemical softness and NBO analysis of the title compound were investigated and discussed by theoretical calculations.

ABSTRACTIn this work, the micro powder was the product of cedar leaf (MPCL) is used as a low-cost adsorbent for the removal of Pb2+ ions from aqueous solutions. Bath experiments were used to determine the best adsorption conditions The adsorption percentage of Pb2+ ions MPCL samples at different initial pH, contact time (tc), adsorbent dosage and temperature (T) were investigated. Effective removal of metal ions was demonstrated at pH values of 5. Metal adsorption onto MPCL was evaluated by Langmuir and Freundlich isotherms. Results indicate that the Langmuir isotherm model is the most suitable one for the adsorption process using MPCL (R2=0.9987), thus indicating the applicability of monolayer coverage of Pb(II) ion on MPCL surface. The relationship between thermodynamic parameters was used to predict the absorption process. According to Thermodynamic analysis, the process exothermic and natural (ΔHo= -21.65 kJmol-1 and ΔSo = - 56.4 kJmol-1 K-1).Keywords: Pb2+; adsorption; micro powder; cedar leaf; Thermodynamic; MPCL

6-Amino-1,2,4-triazolo[4,3-b][1,2,4,5]tetrazine (ATTz)is an explosive material, that has been synthesized from the reaction of 3,6-diaminotetrazine , with nitrous acid and then sodium azide. In the simplest terms, an explosive is defined as a substance, which on initiation by friction, impact, shock, spark, flame, heating, or any simple application of an energy pulse, undergoes a rapid chemical reaction evolving a large amount of heat and so exerting a high pressure on its surroundings. The vast majority of explosives release gaseous products on explosion. In this study the reaction of 6-Amino-1,2,4-triazolo[4,3-b][1,2,4,5]tetrazine (ATTz) with boron nitride Nano- cages in different conditions of temperature, by density functional theory methods was investigated. For this purpose, the material on both sides of reaction was geometrically optimized, and then the calculation of the thermodynamic parameters was performed on all of them. The values of ΔH, ΔG, ΔS for this reaction at different temperatures were obtained, and finally, the best temperature for the synthesis of explosives nano derivatives, according to the results of thermodynamic parameters were evaluated.