PHYSICAL CHEMISTRY RESEARCH
Year:2018 | Volume:6 | Issue:3|Papers Count:10

With the aim of exploring the electronic and optical properties of some interesting conductive copolymers in view of potential applications, a regular oligomer systems made of aniline and three reference heterocyclic compounds (pyrrole, thiophene and furan) are studied using density functional theory (DFT) and time dependent DFT (TDDFT) calculations at B3LYP/6-31+G (d, p) level. It was found that poly (aniline-co-pyrrole) has the lowest ionization potential (4.48 eV) and electro affinity (0.77 eV) while poly (aniline-co-thiophene) has the lowest band gap and longest (3.21 eV) wavelength of absorption (and therefore the highest electronic conjugation) among the studied molecules. Comparison of the theoretical data and spectroscopic results obtained by DFT calculations with those experimentally obtained show very good agreement.

A dataset of (E) -N’-benzylideneisonicotinohydrazide derivatives as the potent anti-mycobacterium tuberculosis antibodies has been investigated utilizing quantitative structure-activity relationship (QSAR) techniques. Genetic function algorithm (GFA) and multiple linear regression analysis (MLRA) were used to select the descriptors and to generate the correlation QSAR models that correlate the minimum inhibitory concentration (MIC) values against mycobacterium tuberculosis with the molecular structures of the active molecules. The models were validated, and the best model with squared correlation coefficient (R2) of 0.9202, adjusted squared correlation coefficient (Radj) of 0.91012, and leave one out (LOO) cross validation coefficient (Q2CV) value of 0.8954 was selected. R2 pred of 0.8842 was achieved for the external validation set used for confirming the predictive power of the model. Stability and robustness of the model obtained by the validation test indicate that the model can be used to design and synthesize the other (E) -N’-benzylideneisonicotinohydrazide derivatives with improved anti-mycobacterium tuberculosis activity.

In this manuscript, density functional theory was used to explore structural, vibrational and optical properties of the (Sc2O3) n (n=1-5) cluster systems using DFT/B3LYP/LanL2DZ level of computation. Different stable isomers were obtained and numerous chemical parameters such as HOMO-LUMO gap, ionization potential and electron affinity were calculated successfully. Stability of the clusters was investigated in terms of the total and binding energies. In order to determine the origin of the species, transition states or stationary points, vibrational frequencies were calculated for the most stable configurations of (Sc2O3) n (n=1-5) nanoclusters. Optical properties of scandium oxide nanoclusters were discussed using time-dependent density functional theory methods.

N-Cyclohexyl-2, 4, 4-trimethyl-2, 3, 4, 5-tetrahydro-1H-benzo [b] [1, 5] diazepine-2-carboxamide (5) was synthesized using an efficient, highly recyclable and eco-friendly catalyst heteropolyacid/triethoxysilyl) propyl] isonicotinamide (HPA/TPI-Fe3O4 nanoparticles) in onepot.The compound 5 was characterized by FT-IR, 1H NMR, 13C NMR, mass spectra and elemental analysis. The theoretical calculations on 5 were carried out at the M06-2X and B3LYP methods with a 6-311++G (2d, p) basis set. The structural parameters and the IR data of 5 were analyzed and compared with the corresponding experimental data. The results show fair correlation between the calculated13C chemical shifts with B3LYP/6-311++G (2d, p) level and experimental data. Theoretical studies on the frontier molecular orbitals, mapped molecular electrostatic potential (MEP) and corresponding graphs and charge delocalization of 5 were also carried out.

In this research, biodiesel was produced using chicken fat in the presence of calcium oxide nano-catalyst. To do so, the effect of various parameters like temperature, reaction time, catalyst amount and methanol to oil ratio was investigated on the biodiesel production. The results showed that the best conditions for biodiesel production were obtained such as the temperature of 65 °C, methanol to oil ratio of 1: 9, the catalyst amount of 1 wt.% and reaction time of 5 h which in these conditions the biodiesel efficiency was determined 94.4%. Then, for improvement of fuel properties, they were mixed with diesel in different ratios (B25, B50 and B75) and their properties such as flash point, cloud point, pour point, kinematic viscosity and density were analyzed according to international standards. The results showed that the mixture ratio of B75 and B100 had density and viscosity in the range of standard. Additionally, this fuel should not be used in cold weather since its pour point is greater than zero.

This paper reports density and speed of sound data for solutions of the ionic liquids (ILs) [C4mim] Cl and [C4mim] [CF3SO3] in aqueous solution of 0.05 w/w amino acids of alanine, serine and proline atT= (288.15, 298.15, 308.15 and 318.15) K. From the experimental data measured, the apparent molar volume (Vf), isentropic compressibility (KS), and apparent molar isentropic compression (KØ) have been calculated. TheVf values of [C4mim] Cl and [C4mim] [CF3SO3] in the investigated aqueous amino acid solutions decreased by increasing the hydrophobicity of the amino acid and follow the order: serine ˃ alanine ˃ proline. The apparent molar volume and isentropic compressibility values at infinite dilution of the investigated ILs in the aqueous amino acid solutions and their variations with temperature have been determined. The infinite dilution apparent molar volume and adiabatic compressibility for transfer of the studied ILs from water to aqueous solutions of the amino acids have been calculated and the results were discussed in terms of different interactions existing in these solutions.

In this study, a full-potential density functional theory was used to investigate the effects of Ti substitution by different cations. In both rutile and anatase, Ti atom was replaced by Ce, Au, Sn, Ag, Mo, Nb, Zr and Y. Phase stability, electronic structure and formation energy of oxygen vacancy were compared for rutile and anatase. The results indicated that substitution of Ce and Zr increases anatase stability through which photocatalytic activity is enhanced. It seems that the cationic capacity and size play a critical role in anatase to rutile phase transition, where with an equi- or higher valence than Ti, larger cations increase the stability of anatase phase. Oxygen vacancy concentration, as a second factor of photocatalytic activity, was also studied by calculating its stability due to the cationic substitution. The data revealed that Au, Ag, Y, Ce and Sn effectively reduce oxygen-vacancy formation energy. Of the studied cations, Au and Ag had maximum reduction in band gap, by creating defect states in the middle of the band gap resulting from the overlaps of d-orbitals of these elements and oxygen p-orbitals. Mo and Ce impurities did not have a significant effect on reducing gaps by creating defect states under the conduction band. Finally, Sn impurity also generated defect states in the middle of the gap merely with the lack of oxygen.

In this study, SBA-15-PAMAM mesoporous nano-adsorbent was synthesized, characterized and applied for adsorption of acid dyes (acid blue 62 (AB62) and acid red 266 (AR266)) from aqueous Media. Adsorption of AB62 and AR266 on SBA-15 ordered mesoporous silica, polyamidoamine functionalized SBA-15 (SBA-15-PAMAM), has been investigated. To evaluate the synthesized adsorbent constructional, FT-IR (Fourier transform infrared spectroscopy), TEM transmission electron microscopy images and XRD (X-ray diffraction) methods were utilized. To investigate and compare the adsorption of two acid dyes with each other, the chemical structure and molecular mass of two acid dyes on the synthesized nano-adsorbent is compared with each other. The acid blue 62 dye with the structure of Anthrachinon (MW=422.43) and the acid red 266 dye with the structure of Azo (MW=467.78) is compared with each other. To appraise the proficiency of this nano-adsorbent for adsrption of two acidic dyes from aqueous media, the efficacy of significant parameters comprising pH (2-10), adsorbent dosage (0.01-0.1 g), dye concentration (200-600 mg g-1), contact time (10-120 min) and temperature (25-45 oC) was investigated. The Langmuir, Freundlich, Tempkin and Dubin Radushkevich isotherms were perused. The empirical data were best demonstrated by the langmuir isotherm model with utmost adsorption valence of (1428.57 mg g-1) for dye AB62, and (1111.11 mg g-1) for dye AR266 at pH 2 and 25 °C, in absolute agreement with the empirical data (R2>0.9933) for dye AB62 and (R2>0.9914) for dye AR266. It was concluded that SBA-15-PAMAM adsorbent could be applied as a significant adsorbent for acidic dyes removal.

Density functional theory (DFT) and time dependent DFT (TD-DFT) calculations were carried out for the oligomers of 3, 4-Ethylenedioxythiophene-Aniline (EDOT-Ani), 3, 4-Ethylenedithiafurane- Aniline (EDTF-Ani) and Thieno [3, 4-b] benzene-Aniline (PITNAni).Structural parameters, electrical conductivity, spectral properties and electronic properties such as ionization potential (IPs), (EAs), HOMO-LUMO isosurfaces and energy gaps of EDOT-Ani, EDTF-Ani and PITN-Ani were calculated and compared using density functional theory at the B3LYP/6-31G (d) level which has been successfully used in predicting trends in conjugated systems. EDOT-Ani results showed good correlation with our previous experimental data. The vibrational frequencies with their assignments were also in close agreement with experimental frequencies. The UV-Vis spectra were simulated with TD-DFT/6-31G (d) level of theory and the maximum wavelength (lmax), optical band gap (Eg opt) and oscillator straight (f) of three oligomers were compared with each other and with experimental values. Among the studied copolymers, PITN-Ani showed the narrowest band gap which could be attributed to its higher donor acceptor property compared to two other polymers.

In this article the behavior of tetrahydrofuran (THF) +2-alkanol namely 2-propanol, 2-butanol, 2-pentanol, 2-hexanol and 2-heptanol binary mixtures through the density and viscosity measurements has been studied as a function of composition and within the temperature range of 293.15-313.15 K. The excess molar volume, isobaric thermal expansivity, partial molar volumes, and viscosity deviations have been calculated. For all binary mixtures, values of excess molar volume are positive and viscosity deviations are negative while increasing with the alkyl chain of the alcohol. The results provide information on the interactions among the molecules in the pure state as well as the binary liquid mixtures. The measured densities and viscosities have been applied to test the applicability of the PC-SAFT model and friction theory coupled with the Peng-Robinson-Stryjek-Vera equation of state.