Journal of Physical and Theoretical Chemistry
Volume:9 Issue: 2, Summer 2012

Using a time-dependent-density functional theory (TD-DFT), Configuration Interaction Singles (CIS) and Zerner’s Intermediate Neglect of Differential Overlap (ZINDO) methods, we have investigated the UV-Visible spectra of one new intramolecular cyclization at before and after intramolecular attack. All structures were optimized at the B3LYP/6-311++G** level while UV-Visible parameters were calculated via different basis sets; 6-31++G**, 6-31+G* and 6-31G*. In the all compounds, with the presence of donors substituted λmax values are greater, when acceptors substituted are smaller, in the TD-DFT and CIS methods. In the CIS and TD-DFT methods, after the cyclization oscillator strength is low i.e. possibility of transmission and transmission intensity is low, because between two aromatic rings, carbonyl groups does not exist. The 3D-surfaces diagrams showed changes of the λmax and energy gap compared with Hammett Para-effect number in the CIS and TD-DFT methods, clearly. The calculations were performed using GAUSSIAN 09W suite of programs.

A new proton transfer compound, formulated as (Hamp-6-pic)(Hpyzd) ∙H2O (1), has been synthesized from the reaction of pyrazine-2,3-dicarboxylic acid (H2pyzd)  and 2-amino-6-methyl pyridine (amp-6-pic), in 1:1 molar ratio. Extensive O−H×××O, N−H×××N and O−H×××O hydrogen bonds involving (Hamp-6-pic)+ cation, (Hpyzd)- anion and co-crystal water molecule٫ static electronic٫ and π...π stacking interactions form a three-dimensional network.

The removal of Cd2+ and Pb2+ ions from wastewater using p-tert-butyl-calix[4] arene was investigated in terms of initial pH, initial concentration, adsorbent dosage, contact time and temperature. The maximum adsorption occurred at the pH value of 6. The adsorbent studied exhibits high efficiency for Cd (II)and Pb (II) adsorption and the equilibrium states could be achieved in 10 min. Adsorption kinetics data were modeled using the first order, the pseudo-first and pseudo-second order, Elvoich equations and intra-particle diffusion models. The results show that pseudo-second order kinetic model was found to correlate the experimental data as well.

The aim of the present study was to prepare new cluster (B6C4Si) as an antibiotic carrier. Density functional theory (DFT) method at the B3LYP level of theory in conjugate with the 6-311G** basis set was used to evaluate the interaction between B6C4Si cluster and Penicillin. Binding parameters, HOMO, LUMO and HOMO- LUMO GAP were calculated. Results show the ‍ B6C4Si HOMO–LUMO gap value of 0.13351 decreasing by attach of Penicillin. The negative values of ,  and  indicate that B6C4Si /Penicillin are thermodynamically stable. From NMR shielding calculations, it can be seen that the penicillin connects stronger to B6C4Si cluster in positive charges than negative charge. Thus by creating positive field, penicillin can be connected to the B6C4Si cluster and delivered easily by using a negative filed.

To investigate the electromagnetic interaction of molecules inside the nanotubes, first, the structure of nanotubes B16N16 was optimized with hybrid density functional theory (B3LYP) using the EPR-II basis set, then Cu, Cu+, Cu++ were located in nanotube and we studied the total energy, band gap energy, electrical potential, changes of band gap energy in terms of total energy and dipole moment in the B16N16-X(X= Cu, Cu+, Cu++) systems. Also, to investigate the electromagnetic interaction of molecules inside the nanotubes, we studied the nuclear magnetic resonance properties (NMR) and shielding parameters between nanotubes.

In this research, the removal of malachite green dye from Textile Wastewaters using polyaniline coated onto sawdust (PAni/SD) has been investigated. Ammonium peroxodisulphate was used as chemical oxidant for polymerization of polyaniline directly on the surface of sawdust. The effects of some important parameters such as pH, initial concentration, sorbent dosage, exposure time and temperature on uptake of malachite green dye were investigated.Adsorption studies have shown that pH of the malachite green solution has influence on the dye removal capacity of PAni/SD. It was found that effective dye removal is occurred under neutral or acidic conditions. The treatments of  data were carried out using both Freundlich and Langmuir adsorption isotherms.

In this study the chemical properties of B6C4Si and C16 Clusters connected vitamin C have been investigated using density functional theory (DFT). NMR parameters and HOMO- LUMO Gap energy are calculated by using density functional method (B3LYP) with 6-311G* basis set. Calculations show that HOMO- LUMO Gap energy of vitamin C decreases after connecting to B6C4Si or C16 cluster decreasing of HOMO- LUMO Gap energy, causes that vitamin C can act better as an electron donor and antioxidant. The NMR results show that vitamin C connects stronger to B6C4Si cluster in negative charges than positive charge. Thus by creating a negative field, vitamin C can be connected to the B6C4Si cluster and delivered easily by a positive filed. But for C16 cluster, the NMR results are quite different.

The B3LYP/6-31++G** density functional calculations were used to obtain minimum geometries and interaction energies between the molecular hydrogen and nanostructures of fullerenes, C20 (cage), C20 (bowl), C19Si (bowl, penta), C19Si (bowl, hexa). The H2 molecule is set as adsorbed in the distance of 3Å at vertical position from surface above the pentagonal and hexagonal sites of nanostructures. By comparing of gap energies, electronic chemical potential, hardness and results of QTAIM (Quantum  Theory of Atom in Molecules) analysis, the Si atom substitution in hexa two- fold position of C20 (bowl)may be suitable for the adsorption of hydrogen molecule.

The present study was carried out to investigate the potential of single-walled carbon nanotube (SWCNTs) and carboxylate group functionalized single-walled carbon nanotube (SWCNT-COOH) as alternative adsorbents for the removal of Basic Red 46 (BR 46) from contaminated water by using batch adsorption studies. Effects of some key operating parameters such as pH, ionic strength and contact time on the dye removal were investigated and discussed. The experimental results show that SWCNTs and SWCNT-COOH are promising adsorbents for removing BR 46. Results showed that removal of BR 46 increased with increasing contact time, pH and ionic strength. Adsorption kinetics data were modeled using the first order, the pseudo-first and pseudo-second order, Elvoich equations and intra-particle diffusion models. Results show that the pseudo-first order kinetic model was found to correlate the experimental data well.