Journal of Physical and Theoretical Chemistry
Volume:14 Issue: 1, Autumn 2017

The study examined corrosion inhibition of corrosion inhibition of 5-methyl-2H-imidazol-4-carboxaldehyde and 1H-Indole-3-carboxaldehyde on mild steel in acidic medium using weight loss and Density Functional Theory (DFT) methods. DFT calculations were carried out at B3LYP/6-31+G** level of theory in aqueous medium on the molecular structures to describe electronic parameters. The values of thermodynamic parameters such as free energy of adsorption (ΔGºads), adsorption equilibrium constant (Kads), adsorption entropy (ΔSºads), adsorption enthalpy (ΔHºads) and activation energy (Ea) were calculated, analyzed and discussed. The adsorption process on mild steel surface showed that 4-methylimidazol-5-carboxaldehyde and Indole-3-carboxaldehyde obeyed Freundlich and Temkin adsorption isotherms respectively. Also, the molecular parameters associated with inhibition efficiency such as EHOMO, ELUMO, band gap energy (ELUMO- EHOMO), softness (S), electron affinity (EA) and number of electrons transfer were calculated. The higher inhibitory property of 5-methyl-2H-imidazol-4-carboxaldehyde was attributed to the presence of higher number of protonation sites as a result of higher number of nitrogen atoms, increase in number of plane protonated species and higher net charges on the ring atoms.

There are only a handful reports about the sensor systems having the ability of detecting the existence of the noble gases. Chemical reluctance of these gaseous species causes them to have no chemical interactions like hydrogen bonding with the chemically designed nano-sized sensors. Noble gasses usually have no atomic charges nor do change the total polarity of the molecular sensor systems. These conditions might be more strongly observed for the cases of the lighter noble gases like helium. These properties impede designing molecular sensors for detecting the existence of the noble gasses. Due to these, in this project, we have tried to examine the ability of N4B4 cluster, C20 fullerene, and the graphene segment as especial nano-sized systems in adsorbing and detecting the existence of some noble gasses, by changing their electrical conductivity. The results showed that the N4B4 cluster could sense the existence of the noble gases, better and more selective than the C20 fullerene, or the graphene segment.

In this manuscript a simple, rapid, and sensitive electrochemical method for the direct determination of thioridazine (TR) was developed. The electrochemical behavior of TR was studied at carbon ionic liquid electrode (CILE). The cyclic voltammetric results showed that CILE remarkably improved electrocatalytic activity towards the oxidation of TR in slightly acidic solutions. It led to a significant enhancement of the anodic peak current for TR with three anodic peaks at 0.59V, 0.78V and 0.93V, respectively and could effectively accumulate the drug at the electrode surface. The electrocatalytic performance was further exploited as a sensitive detection scheme for the determination of TR by differential-pulse voltammetry (DPV). Under optimized conditions, the calibration linear range and detection limit were 0.25 to 100 𝜇M and 50 nM, respectively. The proposed method was successfully used to quantification of TR in pharmaceutical samples. Also the analytical performance of this sensor has been evaluated for detection of TR in human serum samples.

In the present work, the quantum theoretical calculations of the molecular structure of the (N-(2-benzoylphenyl) oxalamate has been investigated and are evaluated using Density Functional Theory (DFT). The geometry of the title compound was optimized by B3LYP method with 6-311+G(d) basis set. 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 of the chemical shift are in good agreement with the experimental data. Frontier molecular orbitals (FMOs) such as HOMO orbital, LUMO orbital and energy gap between HOMO and LUMO, molecular electrostatic potential (MEP), electronic properties such as ionization potential (I), electron affinity (A), global hardness, global hardness (η), electronegativity (χ), electronic chemical potential (μ), electrophilicity (ω) and chemical softness (S) of the title compounds were investigated discussed by theoretical calculations. The FMO analysis suggests that charge transfer is taking place within the molecule. Also the electronic structure of the title compound was studied by using Natural Bond Orbital (NBO) analysis in order to understand hyper conjugative interactions and charge delocalization.

The technetium-99m complex of the L,L-ethylenedicysteine diethylester (EC), of the brain imaging agent, was reported as a good choice for replacement of the renal nuclear medicines like OIH radiopharmaceutical. This present research work studies the structural, electronic and spectral properties of the EC compound and its complex with technetium-99m radionuclide from theoretical insight. All computations were done by Gaussian 03 package at B3LYP/6-31+G(d,p) level of theory. The frontier molecular orbital (FMO) computations show the stability of 99mTc-EC structure is lower than the EC molecule. In contrast, the highest reactivity is related to the 99mTc-EC complex. From the nuclear magnetic resonance (NMR) calculations, the comparison between chemical shifts of carbon atoms of 99mTc-EC to EC molecule shows the carbon atoms of technetium-99m-EC complex are more shielded. Also, the natural bond orbital (NBO) analysis shows more d orbitals of technetium atom and more p orbitals of sulfur, nitrogen and oxygen atoms are used for Tc-S, Tc-N and Tc-O molecular orbital hybrids.

In this research, the effects of B, O and B&O−doped on the SO2 gas adsorption on the surface of the (4, 4) armchair AlNNTs are investigated by using DFT method. From optimized structures the geometrical and electrical properties, adsorption energy, gap energy, global hardness, electrical potential, HOMO−LUMO orbitals, density of states (DOS) plots, electrostatic potential (ESP) plots and NMR parameters are calculated and are analyzed. The adsorption energy of the all adsorption models is negative and exothermic in thermodynamic view of point. Doping of B atom increases the adsorption energy of nanotube/SO2 complex, whereas doping O atom decreases the adsorption energy of system. The positive values of ∆N of nanotube/SO2 complex indicate that the charge transfer occur toward to the SO2 gas, which suggests that their electronic properties of system could be notably changed upon chemisorption’s of SO2. The NMR results reveal that the isotropy the electrostatic properties of nuclei are mainly dependent on electronic density at their sites, therefore because of the SO2 gas adsorption, the electronic densities of nuclei and the CS tensors undergo changes.

Dye contamination in water is a serious environmental problem around the world. Erythrosine is a water-soluble xanthenes class of dye that widely used as colorant in many industries. Used cigarette filter ash loaded with Al/ Fe oxides was synthesized by a low-cost, simple, and environmentally benign procedure. The adsorbent was characterized by several methods including energy dispersive X-ray spectroscopy (EDX), scanning electron microscopy (SEM) and Brunauer Emmet and Teller (BET) analysis. Then, the potential of used cigarette filter ash loaded with Al/ Fe oxides was investigated for adsorption of erythrosine. The effect of different parameters including contact time, pH, adsorbent dosage and initial dye concentration on the removal yield was studied. The experimental data were fitted well with the Langmuir isotherm model. Maximum monolayer adsorption capacity based on Langmuir isotherm is 32.68 mg g-1. The process for purifying water treatment presented here is clean and safe. Therefore, this adsorbent was considered to be applicable for managing water pollution caused by erythrosine.

The binding energy and geometrical structure of all the possible dimeric systems of isothiocyanic acid (HNCS) with ozone have been investigated in the gas phase, theoretically. Six minima located on the singlet potential energy surface of the HNCS–ozone system at the MP2 level with binding energies (corrected with ZPE and BSSE) in the range 492.29–531.40 kcal/mol. All intermolecular interactions in the HNCS–ozone system are significant interactions with remarkable EI values. In this study, the interaction of ozone molecule toward HNCS molecule was studied by using MP2 calculations at the cc-pVDZ level of theory. It was found that the HNCS-ozone dimer system show considerable changes after interatomic interactions with EI= -531.40 kcal/mol after BSSE and ZPE corrections. Therefore, it is obvious that the dimer systems in this study are so much stable than that of Vessally’s investigation for HNCS-SSO dimeric system or Wierzejewska and Wieczorek investigation for HNCS–Xe and HNCS–N2 system.