Journal of Physical and Theoretical Chemistry
Volume:13 Issue: 1, Spring 2016

In this paper the photocatalytic degradation of the anionic surfactant, linear alkylbenzene sulfonicacid (LABSA) was investigated using UV radiation in the presence of TiO2. Our findingsdemonstrate that various parameters exert their individual influence on the photocatalytic degradationof surfactant in wastewaters. The mentioned parameters have been categorized as follow: the initialpH of the solution to be degraded, the impacts of oxidizing agents on photocatalytic degradation,amount of TiO2, initial concentration of pollutant and irradiation time. The optimal degradationconditions of LABSA are: 200 mg/L TiO2, pH 6.0, 1mM K2S2O8 and concentration of LABSA 20mg/L. Finally, about 96.14% of LABSA was removed by irradiation in 150 min.

We have investigated structure and electronic properties of Au and Si liner chains using the firstprinciplesplane wave pseudopotential method. The transport properties and conductance of these twoliner chains are studied using Landauer approaches based on density functional theory (DFT). Weobtain density of states and band gap using Kohn-Sham and Wannier functions as well as quantumconductivity and current for Au and Si liner chains. We study the effect of Hubbard U on quantumconductivity and current for Au liner chain within DFT+U for strongly correlated systems. Wecompare the source of the states around Fermi level of these systems that have important role inconductivity. We present I-V characteristics of the Si and Au liner chain. Results show Ohmicbehavior of current flow in the liner chains in terms of applied bias voltage. We show that Hubbard Ucorrection removes the unphysical contribution of d electrons to the conductance of Au liner chain,resulting in a single transmission channel and a more realistic conductance of 1G0 that is in goodagreement with experimental results. Our calculations reveal that monatomic chains of Si and Au aremetallic therefore they can be used as connectors between nanoelectronic devices.

The use of appropriate level of theories for studying weak interactions such as 8-8 stackinginteractions of aromatic molecules has been an important aspect, since the high level methods havelimitations for application to large molecules. The differences in the stacking energies of variousaromatic molecular structures are found significant. It is also very important for identifying the mostfavored stacked models of aniline and hydrated aniline molecules. The effect of basis set in thestacking energies of MP2 calculations is small. The values for HF and MP2 level of theories calculateless electron correlation energy whereas CCSD (T) methods may be used for the calculation of betterelectron correlation energy. The moderately accurate calculations, MP2 level of theories were foundfeasible for most of the simple aromatic systems such as benzene, pyridine, aniline etc. In our studies,it has been investigated to study the different 8-8 stacking interaction energies and the effect ofchange in conformations for aniline and hydrated aniline systems.

The spectroscopic properties of the 2,2,6,6-tetramethyl-piperidine-1-oxyl (TEMPO) radicalderivatives of the fullerene (C60) were theoretically investigated. The ground state optimizedstructures of the radical adducts of the fullerene were calculated by using DFT (B3LYP) with 6-31G(d) level. It was concluded that a 6-6 ring junction of C60 moiety generally covalently links to thepiperidine ring of the TEMPO derivatives, directly. The optimization characteristics of all thefullerene radical derivatives indicate generally a annulene structure while C60+TEMPO indicate acyclopropane structure which is formed by the link of the carbon of the piperidine ring doubly to a 6-6 ring junction of C60. The calculated isotropic hyperfine coupling constants, vibrational frequenciesand UV- Vis transition energies of all the radical adducts were seen to be in good agreement with thecorresponding experimental data. The UV-Vis transitions and their energies were determined withcorresponding to the experimental values. In the IR analysis the shifts of vibrational frequencies havebeen commented by comparison with those belonged to the pure C60. Also the some selectedgeometrical parameters with together the cage width and the cage length for the ground stateoptimized structures of all the radical adducts were listed, and the binding energies of the radicalswere obtained.

Tetrahedrane is most strained and the smallest cage compound. It attracts organic chemists because ofits unusual bonding nature and highly symmetrical structure. However, many efforts to isolate theparent tetrahedrane have been unsuccessful because of the high reactivity and very short lifetimecaused by the strain in this molecule. Modeling of molecules for determination of structuralproperties of them prior to synthesizing molecule in the laboratory is an important method. Thecomputational chemistry is more completely in understanding a problem. In present study, the densityfunctional theory (DFT-B3LYP) method with 6-31G (d) basis set was used for optimizing andstudying the electronic structural and detonation properties of tetrahedrane derivatives at 298.15 Ktemperature and 1 atmosphere pressure. The results show the tetrahedrane system with more electronwithdrawing groups will be deviated from standard and stable state. And also, the –NHNH2, -NHNO2, -NO2 and -ONO2 groups give the detonation property to the tetrahedrane system.

In this work we use density functional theory based on the ultra-soft pseudo-potential to calculate thestructural, mechanical and thermal properties of narrow single walled BN, AlN and GaN nanotubes.The electron-electron interactions were expressed within the local density approximation (LDA). Wehave also obtained the Phonon dispersion and elastic constants of these nanotubes using the densityfunctional perturbation theory. Furthermore the values of Young's modulus, radial breathing modefrequencies and phononic band gaps for BN, AlN and GaN nanotubes (4,0) are reported. Finally it isdemonstrated that the behavior of heat capacity of these nanotubes strongly depends on the mass ofcations.

Enaminones are those structures made up three various functional groups including carbonyl, alkeneand amine groups which arelocated along with each other in a conjugate fashion. These compoundsare of much attention due to special characteristics and numerous applications. In the paper, sixvarious enaminone structures were theoretically optimized and after concluding, were compared withequivalent experimental results. These enaminone structures have been studied for substituent effecton hydrogen bond, method and basic set effects on the geometrical parameters, vibrationalfrequencies, stability, complex forming, NBO computation and etc. Drawing molecular structures andcomputer calculations were performed with Gauss view (5.0) and Gaussian (09) softwarerespectively. The utilized methods in the paper were the HF and DFT and of DFT methods of basicfunctions BLYP, B3LYP, B3P86, B3PW91, SVWN, BVWN and BPV86. Also Basis sets of 6-311G,6-311G*, 6-311G**, 6-311+G*, 6-311+G**, 6-311++G* 6-311++G**, LANL2DZ and SDD havebeen utilized which have been applied as proportional to molecular structure and desirable purpose.Generally the results of computer calculations and comparing them with experimental equivalentsindicate that theoretical procedures could well be helpful and effective in enaminone studies and offerreasonable and well results.

The synthesis and characterization a new derivatives of 2'-iodo-meta terphenyl from the reaction ofexcess aryl-Grignard and 2, 6- dichloroiodobenzene with quenching of m-terphenyl-2'-magnesiumbromide by iodine is reported. Via the reactions three carbon-carbon bonds are constructed and mterphenylsare obtained in good yields.

The understanding of the intermolecular pair potential is important for determining the physical andchemical properties of the matter. The new data for noble gasses was calculated with Soft-CoreDouble Yukawa Potential (SCDY). We studied the effect of the Soft- Core potential on the phasebehavior with Hartree-Fock-Dispersion (HFD) Potential. This model had a steep repulsionexponential term and double Yukawa potential which represents correctly the radial dependence ofrepulsive and long range energy respectively. The method was analyzed using sigma plot (SP-13)software. In order to find a correlation between variables Spearman correlation coefficient was used.Results showed that high content values for Ne-Ne, Ar-Ar, Kr-Kr, Xe-Xe of the pair potential whichwere fitted with HFD-B Potential. This work was used the Yukawa potential and evaluation of it’sthe parameters to present potential. The results were accurate and in according to previous studies. Inconclusion, was summarized that potential was adjusted in two forms of (HFD and SCDY) potentials.