Calix Arenas Via Aqueous Solution

The electronic structure and magnetic properties of Al2O3, GaN and Fe3O4@ Calix (8) COOH have been studied using ONIOM and DFT methods. The studies focus on how to improve the adsorption of some nano particles solution aqueous for achieving good magnetic and functionalized potential performances. The results revealed that the Fe3O4@ Calix (8) COOH and some of its derivations exhibited better thermodynamic stability. Furthermore, the particle size and magnetic property of the GaN@ Calix (8) COOH nanoparticles can be controlled by the aqueous. The electrical properties such as NMR Shielding, electron densities, energy densities, potential energy densities, ELF, LOL, ellipticity of electron density, eta index and ECP for nanoparticles@ Calix (8)COOH have been calculated. Keyword: superparamagnetic nano particle, QM/MM simulation, Calix (n).


INTRODUCTION
What makes GaN popular is not only it is more robust but it can emit in the short wavelength part of the visible spectrum.For example, there are now GaN-based high-efficiency blue and green light-emitting diodes 1 And just arenes when researchers thought things could not get better for GaN, a whole new field of research has opened up in the form of GaN nanotubes 2 .These nanotubes were synthesized by an" epitaxial casting" strategy by the research group of Peidong Yang at Lawrence Berkeley National Lab oratory.ZnO nanowires, grown on sapphire wafers, were used as templates for epitaxial overgrowth of thin GaN layers in a chemical vapor Deposition (CVD) system.The result of electron diffraction measurements showed that the nanotubes obtained in this way are single-crystal, and in this respect they are fundamentally different from theoretically simulated GaN nanotubes 3 with the conventional tubular forms of carb on atoms 4 .
On the other hand, most of the applications require magnetic particles to disperse in a nonmagnetic matrix.The matrixes play an important role in determining physical properties of the composite nanoparticle in addition to providing a means of particle dispersion 5 .Fe 3 O 4 is an electrical conductor with conductivity significantly higher than Fe 2 O 3 , and this is ascribed to electron exchange between the Fe II and Fe III centers [8][9][10][11] .
Fe 3 O 4 is ferromagnetic with a curie temperature of 858 K and The ferromagnetism of Fe 3 O 4 arises because the electron spins of the Fe II and Fe III ions in the octahedral sites are coupled and the spins of the Fe III ions in the tetrahedral sites are coupled but anti-parallel to the former [4][5][6][7] .
Nano-Magnetites have shown great potential applications in the field of in vitro and in vivo biomedicine, including cellular therapy in cell labeling, separation and purification, target-drug delivery, and hyperthermia treatment of cancers.
Magnetic nanoparticles have attracted much interest not only in the field of magnetic recording but also in the areas of medical field of magnetic sensing.Especially, nanoparticles of iron oxide are reported to be applicable as a material for use in drug delivery systems, magnetic resonance imaging, and cancer therapy [5][6][7][8] .Fe 3 O 4 is used as a catalyst in the Haber process and in the water gas shift reaction 12,13 .The latter uses an HTS (high temperature shift catalyst) of iron oxide stabilized by chromium oxide 11,12  In this work the Al 2 O 3 , GaN and Fe3O4@ Calix (8) COOH have been investigated and the catalysis's properties of these nanoparticles have been studied The data have been compared with the those nanoparticles @ CWCNNTs and BNNTs Carbon nanotube (CNT) is a representative nanomaterial.CNT is a cylindrically shaped carbon material with a nano-metric-level diameter  .Its structure, which is in the form of a hexagonal mesh, resembles a graphite sheet and it carries a carbon atom located on the vertex of each mesh. The seet has rolled and its two edges have connected seamlessly [39][40][41][42][43][44][45] .
Although it is a commonplace material using in pencil leads, its unique structure causes it to present characteristics that had not found with any other materials.CNT can be classified into single-wall CNT, double-wall CNT and multi-wall CNT according to the number of layers of the rolled graphite 46,70 .
The type attracting most attention is the single-wall CNT, which has a diameter deserving the name of "nanotube" of 0.4 to 2 nanometers.The length is usually in the order of microns, but singlewall CNT with a length in the order of centimeters has recently released.
The lids consist of hexagonal crystalline structures (six-membered ring structures) and a total of six pentagonal structures (five-membered ring structures) placed here and there in the hexagonal structure [86][87][88][89][90][91][92][93][94][95][96][97][98][99] .The first report by Iijima was on the multiwall form, coaxial carbon cylinders with a few tens of nanometers in outer diameter.Two years later single walled nanotubes were reported  . SWBNNT have considered as the leading candidate for nano-device applications because of their onedimensional electronic bond structure, molecular size, and biocompatibility, controllable property of conducting electrical current and reversible response to biological reagents hence SWBNNTs make possible bonding to polymers and biological systems such as DNA and carbohydrates  .

Table1: All Electron Densities Of Non-bonded
Interactions For Al

Computational details
Part of the systems including GaN, Al 2 O 3 and Fe 3 O 4 @ Calix (8)COOH, and @ SWBNNNTs and SWCNTs have been modeled with ONIOM method and the calculations are carried out with the Molecular Mechanics methods.In this investigation, differences in force field are illustrated by comparing the calculated energy with CHARMM, AMBER and OPLS force fields.Furthermore, a HyperChem professional release 7.01 programs is used for the additional calculations.
For non-covalent interactions between nano particles and Calix (8)COOH , the B3LYP method is unable to describe van der Waals by medium-range interactions.Therefore, the ONIOM methods including 3 levels of 1-high calculation (H), 2-medium calculation (M), and 3-low calculation (L) have been performed in our study for calculating the non-bonded interactions between nanoparticles and Calix (8)COOH.
The ab-initio and DFT methods are used for the model system of the ONIOM layers and the semi empirical methods of pm6 (including pseudo=lanl2) and Pm3MM are used for the medium and low layers, respectively.
B3LYP and the most other popular and widely used functional are insufficient to illustrate the exchange and correlation energy for distant nonbonded medium-range systems correctly.Moreover, some recent studies have shown that inaccuracy for the medium-range exchange energies leads to large systematic errors in the prediction of molecular properties.Geometry optimizations and electronic structure calculations have been carried out using the m06 (DFT) functional.This approach is based on an iterative solution of the Kohn-Sham equation of the density functional theory in a plane-wave set with the projector-augmented wave pseudo-potentials.The Perdew-Burke-Ernzerhof (PBE) exchangecorrelation (XC) functional of the generalized gradient approximation (GGA) is also used.The optimizations of the lattice constants and the atomic coordinates are made by the minimization of the total energy.
The charge transfer and electrostatic potential-derived charge were also calculated using the Merz-Kollman-Singh chelp or chelpG the charge calculation methods based on molecular electrostatic potential (MESP) fitting are not wellsuited for treating larger systems whereas some of the innermost atoms are located far away from the points at which the MESP is computed.In such a condition, variations of the innermost atomic charges will not head towards a significant change of the MESP outside of the molecule, meaning that the accurate values for the innermost atomic charges are not well-determined by MESP outside the molecule .The representative atomic charges for molecules should be computed as average values over several molecular conformations.
A detailed overview of the effects of the basis set and the Hamiltonian on the charge distribution can be found in references .The charge density proûles in this study has been extracted from ûrst-principles calculation through an averaging process as described in reference [122][123][124] .The interaction energy for capacitor was calculated in all items according to the equation as follows: Where the " ∆E S " is the stability energy.The electron density, electron spin density, electron localization function (ELF), total electrostatic potential (ESP), value of orbital wave-function, electrostatic potential from nuclear atomic charges and localized orbital locator (LOL) which has been defined by Becke and Tsirelson, as well as the exchange-correlation density, correlation hole and correlation factor, and the average local ionization energy using the Multifunctional Wavefunction analyzer have also been calculated in this study [122][123][124] .The contour line map was also drawn using the Multiwfn software 122,124 .The solid lines indicate positive regions, while the dash lines indicate negative regions.The contour line corresponding to VdW surface which is defined by R. F. W Bader is plotted in this study.This is specifically useful to analyze distribution of electrostatic potential on VdW surface.

Theoretical background Electron density
The electron density has been defined as ...(2) Where c is basis function, hi is occupation number of orbital (i), j is orbital wave function, and C is coefficient matrix.Atomic unit for electron density can be explicitly written as: ... ...( 13) where ... (14)  D 0 (r) for spin-polarized system and closeshell system are defined in the same way as in ELF 137 .

RESULT AND DISCUSSION
This study mainly focuses on the magnetic properties of nanoparticles in a non-bonded system with Calix (8) COOH and (n, n) SWCNTs core-shells.The non-bonded interaction is shown in figs1-7.As it is indicated in tables 1-7, the electrical properties can be obtained from changes in the non-bonded interactions.Electron densities, energy densities, Potential energy densities, ELF, LOL, and Ellipticity of electron density, eta index and ECP for nanoparticles @ Calix (8)COOH and nanoparticles @ SWCNTs were calculated of each simulation (Tables 1-7).
The largest electron localization is located on Al2O3 where the electron motion is more likely to be confined within that region.If electrons are completely localized in the GaN, they can be distinguished from the ones outside.As shown in tables 1-8 the large ELF is close to the Al2O3 atoms.The regions with large electron localization need to have large magnitudes of Fermi-hole integration which would lead the nanoparticles towards superparamagnetic.The fermi hole is a sixdimension function and as a result, it is difficult to be studied visually.Based on equations 12, 13 and 14, Becke and Edgecombe noted that the Fermi hole is a spherical average of the spin which is in good agreement with our results in tables and Figs.
ELF indicates that it is actually a relative localization and must be accounted within the range of [0, 1].A large ELF value corresponds to largely localized electrons which indicate that a covalent bond, a lone pair or inner shells of the atom is involved.According to equation 16, LOL can be interpreted similar to ELF in terms of kinetic energy, though; LOL can also be interpreted in terms of localized orbitals.Small (large) LOL value usually appears in boundary (inner) region of localized orbitals due to the large (small) gradient of orbital wave-function in this area.The value range of LOL is identical to ELF, namely [0, 1].
The total electrostatic potential (ESP) measures the electrostatic interaction between a unit point charges placed at r and the system of interest.A positive (negative) value implies that current position is dominated by nuclear (electronic) charges.Molecular electrostatic potential (ESP) has been widely used for prediction of nucleophilic and electrophilic sites for a long time.