Doctor of Philosophy (Ph.D.) Theses and Dissertations
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- ItemOpen AccessSynthesis, characterisation and antimicrobial activity of mental (11) complexes of (E)-N'-(4-phenylbutan 2-ylidene) isonicotinohydrazones and their mixed ligand complexes.(Department of Chemistry, Faculty of Science. Obafemi Awolowo University., 2022) OGUNSAKIN, Olanike Esther.This study synthesised hydrazide-hydrazone metal(II) complexes, its derivatives, along with the mixed ligand complexes with N,N’-chelating ligands, characterised the synthesised compounds and their metal complexes, carried out an in silico studies of the ligands and their metal complexes and also determined the antimicrobial activity the synthesised compounds and their metal complexes. These were with a view to establishing the geometry and antimicrobial activity compounds against some selected strains of microorganisms. The ligands (E)-N´-(4-Phenylbutan-2-ylidene) isonicotinohydrazone(L1) and (Z)-3-hydroxy-N´-(4-phenylbutan-2-ylidene)-2-naphthohydrazone(L2) were synthesized by adding ethanolic solution of isonicotinic acid hydrazide and 3,2-napthoic hydrazide on ethanolic solution of 4-phenyl-butan-2-one in the ratio of 1:1 and then refluxed at 80 oC for 6 hours. Metal complexes of the ligands were synthesized by reacting ethanolic solution of the chloride salts of the metal with ethanoic solution of the ligands in the ratio 1:2 and the mixture stirred for one hour, precipitates formed were washed with ethanol and dried over calcium chloride in a desiccator. The mixed ligand complexes of these ligands were carried out by reacting ethanoic solution of metal chloride salts to a stirring ethanolic solution of the hydrazide-hydrazone as the primary ligand and then adding ethanolic solution of N,N'-chelating ligand as the secondary ligand in 1:1 molar ratio. These compounds were characterised using physicochemical parameters, infra-red and uv-visible spectroscopy, elemental analysis, conductivity and magnetic susceptibility measurements. Antimicrobial screening of the compounds was investigated against two Gram-positive bacteria and two Gram-negative bacteria using the cup-plate agar diffusion and the microbroth dilution techniques to determine the minimum inhibitory concentration and minimum bactericidal concentration. The molecular docking studies were carried out using the Molegro Virtual Docker to predict the most probable kind of interactions, binding affinity and ligand orientation of these compounds at the active site of the selected proteins. The complexes displayed varying colours ranging from green to yellow with high melting points. The infra-red spectra of the ligands displayed medium bands in the range of 1588-1599 cm-1 C=N for the synthesised hydrazones and 3188,3286 cm-1 for the NH2 of the hydrazide, which shifted to a higher or lower frequency on chelation. The appearance of new weak bands at 543-659 cm-1 and 418-545 cm-1 assignable to M-O and M-N bonds indicated coordination of the ligands to metal ions. The electronic spectra of the complexes revealed intraligand transitions from π-π* and n-π*. There were d-d transitions in the visible region of the spectra, proving a strong interaction between the ligands and its complexes. The observed molar conductivities were within the range 169.21 - 172.00 Ω-1cm2mol-1 and 84.21 - 99.17 Ω-1cm2mol-1 suggesting 1:2 and 1:1 electrolytic ratio of the complexes except for [Fe(ISH)2(H2O)2]Cl3 with conductivity value of 314.19 Ω-1cm2mol-1 suggesting a 1:3. Magnetic moments studies indicated an octahedral geometry for these complexes. That is, the synthesised metal complexes displayed six coordinate geometries, while the in silico studies also revealed that these compounds exhibited a good interaction with the target proteins. The study concluded that the novel (E)-N´-(4-Phenylbutan-2-ylidene) isonicotinohydrazones, its derivatives and their mixed ligand complexes synthesised interacted in silico with target proteins and had antimicrobial activity comparable with streptomycin, hence, they could serve as precursor for drug synthesis.
- ItemOpen AccessAssessment of vehicular emission contributions to ambient air quality along high and low density traffic routes in Lagos and Ile-Ife, southwestern Nigeria.(Department of Chemistry, Faculty of Science. Obafemi Awolowo University., 2021) JOSHUA, Oluwasesan HezekiahThe study characterized air emissions from vehicles in Lagos and Ile-Ife, determined theground-level concentrations of associated pollutants along with the ambient air quality levels of selected air pollutants and evaluated the vehicular emissions using the results obtained above. These were with a view to assessing the vehicular emission contributions to ambient air quality along low- and high-density routes in Ile-Ife and Lagos. Four sampling points were established during dry and wet season periods over an averaging period of 24-hour, while traffic count, meteorology, and ambient measurements were carried out simultaneously at each of the sampling points. The vehicle emission measurement which is one of the inputs for predicting ground level concentrations using the BREEZE ROAD Model was carried out using Infra-Red gas analysers for CO, NO2, and SO2 concentrations and handheld aerosol real-time particulate matter (PM2.5) sampler for PM2.5 concentration. Ambient PM2.5 concentrations were measured using Air metric particulate matter sampler, while ambient gaseous concentrations of CO, NO2, SO2, O3, and volatile organic compounds (VOC) were measured using CO data logger, Ogawa sampler, and 3 M air monitor badge. The samples collected using the Ogawa sampler and 3 M air monitor badge were analysed using Gas Chromatography Flame Ionization Detector. The measured ambient mean PM2.5 concentration in Lagos was 152.58± 61.65 µg/m3 while that of Ile-Ife was 93.13±2.24 µg/m3. The measured concentrations of NO2 in Lagos ranged from 21.98 to 64.95 µg/m3and that for Ile-Ife ranged from 10.00 to 55.04 µg/m3. Sulphur dioxide concentration ranged from 20.56 to 58.09 µg/m3 in Lagos and 16.35 to 60.69 µg/m3 in Ile Ife. Carbon monoxide concentrations in Ile-Ife sampling points ranged from 1,030.68 to 3,000.42 µg/m3 while that of Lagos sampling points ranged from 1,030.68 to 3,664.64 µg/m3.Comparative high average level (40.02± 8.5 µg/m3) of VOC was recorded in Lagos than Ile-Ife with an average value of 17.33± 5.46 µg/m3. However, all ambient pollutant values were below Federal Ministry of Environment (FMEnv) and World Health Organization (WHO) limits except PM2.5 and SO2. The predicted mean ground level vehicular concentrations of PM2.5, NO2, SO2, and CO for Lagos were 117.00 ± 25.46, 33.87 ± 5.32, 16.78 ± 13 and 1885.7 ± 565.69 µg/m3respectively while that of Ile-Ife were 86.50 ± 3.54, 13.17 ± 7.98, 15.61 ± 10.97 and 1028.60 ± 969.73 µg/m3respectively. Generally, the average percentile contribution of major vehicle criteria pollutants on the airshed along low and high-density traffic routes were 31 and 42% respectively. The study concluded that the pollutant concentration values obtained, apart from those of PM2.5 and SO2 which were below FMEnv and WHO limits, could cause adverse health by those having regular impacts of the parameters investigated.
- ItemOpen AccessA mathematical model for explosions with chain branching and chain breaking kinetics(Department of Mathematical Obafemi Awolowo University, 1989) Samuel Segun OKOYAA mathematical model for explosions with chain branching and chain breaking kinetics is presented in this thesis to give further insight into the theory of combustion reactions under physically reasonable assumptions.
- ItemOpen AccessEffects of asunle dumpsite, Obafemi Awolowo University, Ile-Ife on the spatio-temporal variations in water quality and ambient polycyclic aromatic hydrocarbon (PAH) levels.(Institute of Ecology and Environmental studies, Faculty of Science, Obafemi Awolowo University., 2022) Adebayo, Abdulquddus AdelayoThis study characterised the solid waste of Asunle Dumpsite, Obafemi Awolowo University, Ile-Ife and the polycyclic Aromatic Hydrocarbon (PAH) congeners of ambient air within three kilometers radius of the dumpsite. It determined the physico-chemical characteristics and plankton composition of water within 500m radius of the dumpsite . It also assessed of the efficacy of institutional, financial and legal frameworks established for the management of the dumpsite. These were with the view to determine the effects of Asunle dumpsite on the spatio-temporal variations in water quality and ambient PAH levels
- ItemOpen AccessThe effect of vegetation physiognomy on sediment yield in Ile- Ife area of southwestern Nigeria(Department of Botany, Obafemi Awolowo University., 1999) Samson Olajide OKEA study was carried out to discern the magnitude of runoff and sediment yield under various vegetation physiognomy with a view to establishing the relationship between runoff /sediment yield and various vegetation parameters in Ile- Ife area of Southwestern Nigeria .