DSpace Collection: Thesis - Chemistry

Computational Study on Hydrogen Bonded Complexes formed by Anthyridone and 2,6-diaminopyridine-3,5-dialdehyde and their Derivatives

Tue, 18 Dec 2012 05:58:51 GMT

Title: Computational Study on Hydrogen Bonded Complexes formed by Anthyridone and 2,6-diaminopyridine-3,5-dialdehyde and their Derivatives

Authors: Teshome, Assefa

Abstract: Computational study was performed on a hydrogen bonded complex formed by antyridone and 2,6-diaminopyridine-3,5-dialdehyde. Six other complexes were designed based on the structure of the complex by changing the R- group of monomer A in to C6H5, p-toluene, p-phenol, OH and OCH3, the X group of monomer B in to chlorine. The binding energies of the complexes were calculated based on their optimized geometry using DFT/B3LYP at 6-31 G level. The electronic spectra for the complexes were calculated with ZINDO and IR spectra of the monomers and complex 1 were computed using DFT/B3LYP at 6-31 G level. It was indicated that all complexes could be formed, via hydrogen bonds. Complexes 2 - 4 were hindered due to steric effect. Electron donating nature was the stability factor. The first absorptions in the electronic spectra of the complexes were red shifted compared with those of the monomers. The stretching vibrations of the N – H bonds were increased with the formation of the hydrogen bond.

Description: A Thesis Submitted to the School of Graduate Studies of Addis Ababa University in Partial Fulfillment of the Degree of Masters of Science in Chemistry

Determination of Selected Trace Metals and Physicochemical Parameters of Commercially available Honey in Ethiopia

Thu, 13 Dec 2012 08:40:23 GMT

Title: Determination of Selected Trace Metals and Physicochemical Parameters of Commercially available Honey in Ethiopia

Authors: Weldegebriel, Yohannes

Abstract: Trace mineral content and some quality parameters (physicochemical properties) such as pH, electrical conductivity and ash content of honey were determined using FAAS, pH- meter, conductivity meter and furnace, respectively. Fe was found in highest amount with mean concentration ranging from 5.37 to 12.43 μg/g followed by Ni with mean concentration range of 0.8 to 4.46 μg/g, Cr (1.20-4.33 μg/g), Zn (1.92-4.22 μg/g), Co (0.60-1.17 μg/g), Cd (ND-0.69 μg/g), Mn (0.16-0.885 μg/g) and Cu (0.09-0.4676 μg/g). The non-essential metal Pb was not detected. Similarly, the ranges of physicochemical properties analyzed could be summarized as: pH 4.11-4.33, ash content 0.17-0.46 % and electrical conductivity of 0.10-0.29. The metals content and the physicochemical properties investigated in honey samples were found within the ranges established by national and international standards. The quality of some samples of honey was evaluated from the point of view of physicochemical properties and content of trace metals. The optimized wet digestion method for honey analysis was found efficient for the metals analyzed and it was validated through the recovery experiment and a good percentage recovery was obtained (93-104%).

Description: A Thesis submitted In Partial fulfillment of requirements for the Degree of Master of Science in Chemistry

Phytochemical Investigation On The Root of Rumex Abyssinicus (Makmako)

Thu, 13 Dec 2012 08:15:43 GMT

Title: Phytochemical Investigation On The Root of Rumex Abyssinicus (Makmako)

Authors: Bizuayehu, Zinaye

Abstract: The n-hexane: ethylacetate (7:3) extract of Rumex abyssinicus afforded two known anthraquinone, chrysophanol and Emodin. The root of rumex abyssinicus is traditionally used for the treatment of sexually transmitted disease such as gonorrhea, Lung-TB and leporsy. Structural determination was accomplished by means of IR, UV, 1D and 2D NMR.

Description: A Thesis submitted In Partial Fulfillment of the Requirements for Master of Science Degree in Chemistry

Voltammetric Determination of Stability Constants of Lead Complexes with Vitamin C

Thu, 13 Dec 2012 08:11:58 GMT

Title: Voltammetric Determination of Stability Constants of Lead Complexes with Vitamin C

Authors: Tibeb, Melesse

Abstract: The electrochemical behaviour of the complex between L-ascorbic acid (AA) and Pb (II) was studied by using Square-wave voltammetry (SWV) and Cyclic voltammetry (CV). L-ascorbic acid forms a 1:1 complex with Pb (II) in 0.1 M sodium perchlorate at pH 5.0. It was found that the reduction processes of Pb (II)-ascorbic acid complex was irreversible. The stability constant of the Pb (II) - ascorbate complexes were evaluated with the De Ford-Hume procedure at different ligand concentrations using square wave voltammetry (SWV). The logarithm values of stability constant of 1:1 Pb (II)-ascorbic acid complex was found to be 0.908.

Description: A Thesis Submitted to In Partial Fulfillment of the Requirements for Master of Science Degree in Chemistry