Hanan Elhaes

Analysis of the structure and vibrational spectra of glucose and fructose

Molecular modelling using semiempirical methods AM1, PM3, PM5 and, MINDO as well as the Density Functional Theory method BLYP/DZVP respectively were used to calculate the struc- ture and vibrational spectra of d-glucose and d-fructose in their open chain, α -anomer and β-anomer monohydrate forms. The calculated data show that both molecules are not linear; ground state and the number for the point-group C is equal to 1. Generally, the results indicate that there are similarities in bond lengths and vibrational modes of both molecules. It is concluded that DFT could be used to study both the structural and vibrational spectra of glucose and fructose.

Computational spectroscopic study of copper, cadmium, lead and zinc interactions in the environment

Molecular modelling has been used to investigate the interactions of various heavy metals, in order to understand and possibly to control the nature and behaviour of metals, especially in the aquatic environment. The interactions of copper, cadmium, lead and zinc with organic acids were studied using density functional theory (DFT) calculations. Carboxylic acid was used as a model molecule. The structure of each metal carboxylate was optimized and the vibrational spectrum calculated. The results indicate that there is a shift in the calculated vS(C=O) of metal carboxylates compared with that of carboxylic acid. It was also found that hexaaqua structures of both cadmium and zinc are stable whereas those of copper and lead are not. Furthermore, dipole moment calculations indicate that cadmium carboxylate dihydrate is more representative of cadmium interactions in the aquatic environment. Moreover, hexaaquo cadmium could further interact with surrounding molecules in the aquatic environment.

A novel structure for removal of pollutants from wastewater.

Dried water hyacinth was subjected to molecular modifications using quantum mechanical calculations. The model simulates the modified plant as 3 cellulose units, one lignin and some metal oxides namely CaO; FeO and Al(OH)3 are attached through O-Linkage. The model suggests the ability to remove inorganic pollutants from wastewater according to unique hydrogen bonding and high total dipole moment. Based on this model microspheres are synthesized in the laboratory from dried water hyacinth and chitosan following self-assembly method. FTIR spectrum of microspheres exhibits only the characteristic bands for raw materials which give strong evidence that the formed material is a composite. The analysis of SEM micrographes of microspheres showed that the fibers of water hyacinth are imbedded in the crosslinked chitosan matrix. Batch adsorption kinetic models revealed that the sorption of lead ions on microsphere was very fast and the equilibrium was rapidly attained within 30 min. and properly correlated with the second-order kinetic model. Different models of isotherm sorption were used to describe the Pb (II) adsorption onto microspheres. From Langmuir isotherm, the maximum adsorption capacity (q(max)) for Pb(II) was 312.5 mg/g, which is about 3 times higher than that of the crude hyacinth. The free energy (E) was 15.798 kJ/mol which shows that the sorption process is endothermic and the mechanism of reaction is an ion-exchange. Even after four cycles of adsorption-desorption, the adsorption capacity was maintained and the decline in efficiency was less than 10%.

Spectroscopic analyses of the photocatalytic behavior of nano titanium dioxide

Nano titanium dioxide TiO2 was synthesized using hydrolysis method then subjected to several characterizations. XRD revealed that the as-prepared sample is pure anatase phase and after calcinations at 500°C for 3 h the crystallinity has increased. The crystallite size calculated by Debye-Scherrers formula is 8 nm. The HRTEM image shows an average size of about 9 nm, which is close to the XRD calculation from Scherrers formula. PM3 semiempirical quantum mechanical calculations were conducted to present the electronic as well as thermal properties for TiO2. FTIR spectra between 800 and 400 cm(-1) are the verification for the lattice vibrations of anatase TiO2. The photo catalytic degradation of methylene blue (MB) was tested by the prepared nano TiO2. Results indicate that, the maximum degradation efficiency reached 94.4% after 120 min of UV irradiation. This increase in the degradation efficiency of TiO2 could be attributed to the reduction in particle size that enhanced the crystallinity as a result of heat treatment.

Spectroscopic analysis of C80 doping with group III and group V elements using semiempirical PM3 molecular modelling technique

Semiempirical calculations at the level of PM3 of theory were carried out to study the struc- tural and electronic properties of C 80 and some of its doped derivatives with the elements of group III and V at the level of PM3 of theory. We have selected these elements to be substituted in the fullerene- C80 cage in order to show the effect of such structural change on the electronic properties of the mol- ecules studied. The theoretical IR spectra, some of physical and chemical properties of the molecules studied are obtained and discussed.

First principles study of edge carboxylated graphene quantum dots

Abstract The structure stability and electronic properties of edge carboxylated hexagonal and triangular graphene quantum dots are investigated using density functional theory. The calculated binding energies show that the hexagonal clusters with armchair edges have the highest stability among all the quantum dots. The binding energy of carboxylated graphene quantum dots increases by increasing the number of carboxyl groups. Our study shows that the total dipole moment significantly increases by adding COOH with the highest value observed in triangular clusters. The edge states in triangular graphene quantum dots with zigzag edges produce completely different energy spectrum from other dots: (a) the energy gap in triangular zigzag is very small as compared to other clusters and (b) the highest occupied molecular orbital is localized at the edges which is in contrast to other clusters where it is distributed over the cluster surface. The enhanced reactivity and the controllable energy gap by shape and edge termination make graphene quantum dots ideal for various nanodevice applications such as sensors. The infrared spectra are presented to confirm the stability of the quantum dots.

Molecular Electrostatic Potential Analysis of Nano-Scale Fullerene (C60) Crystals andSome Specific Derivatives: DFT Approach

Molecular Electrostatic Potential Analysis of Nano-Scale Fullerene (C60) Crystals and Some Specific Derivatives: DFT Approach Nano-scale fullerene (C60) crystals and its derivatives have been proven to make contributions in many types of applications. The molecular electrostatic potential of C60 doped with elements of Group III and Group V were studied by technical DFT-B3LYP /3- 21G** molecular modelling. The molecular electrostatic potential map (MEP) for substituting Fullerene by Group III and Group V, was painted on the surface using a red to blue scale. Results dedicate the substituted Fullerene to many important applications depending on the type of metal.

Studying the Polymerization of Aniline on Fullerene

Polyaniline is among a family of conductive polymers, that exhibits properties similar to some metals. Accord- ingly quantum mechanical calculations have been performed to study the possible polymerization of aniline on the surface of fullerene. Several model molecules representing the polymerization of aniline are studied; polymerization is tested with fullerene and fulleropyrrolidine surfaces. Total dipole moment, ionization potential, molecular weight, molecular dimen- sion and molecular point group for C60-aniline and C60- pyrrolidine-aniline have been computed with the semiempirical PM3 method. The molecular point group has changed into C1 point group corresponding to C60 -aniline and C60- pyr- rolidine-aniline, which reflects a change in the symmetry. Results indicate also that polarization increases the calculated total dipole moment, molecular weight and molecular dimension while ionization potential has slightly decreased. Final heat of formation increases with temperature for both C60-aniline and C60-pyrrolidine aniline. This reflects the thermal stability of the polymerized aniline on both fullerene and fulleropyrrolidine. Calculated HOMO-LUMO energy indicate that polyaniline which polymerizes on fullerene is the most probable.

Spectroscopic analyses and genotoxicity of dioxins in the aquatic environment of Alexandria

Dioxins have global concerns because of the bioaccumulation tendency and persistency in the environment. Water, seabream Pagrus auratus and seabass Dicentrarchus labrax samples were collected from Abu Qir, Alexandria to evaluate the concentration of dioxin. Fourier Transform Infrared Spectrometer (FTIR) and molecular modeling was applied for elucidating the molecular structure of fish samples. Furthermore, HPLC with UV detection was used to determine the concentration of dioxins (2,8-dichloro dibenzo-p-dioxin). RT-PCR assay was conducted to verify the expression of some immune genes in the fish species as a result of water pollution. The average detected concentrations varied from 0.2 to 1.3μg/l. Gene expression revealed that MHC class 1 and C3 were highly upregulated in liver and muscle of seabass and seabream while T2BP was highly regulated in seabass liver and seabream muscle and seabass muscle for transferrin, FTIR and molecular modeling indicate that dioxin finds its way to fish protein.

Effect of Solvents on the Electronic Properties of Fullerene Based Systems:Molecular Modelling

Numerous efforts have been formed to explain the trends in room-temperature solubility of the fullerenes [2-4]. There are many different approaches to calculate and predict C60 solubility in organic solvents. Some of them are fully mechanistic [5-9], developed from the thermodynamical point of view; others are statistically based, with good correlation coefficients, but not transparent and complicated in interpretation [10-16].