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The objective of this thesis is to examine the photophysical and structural properties of Ru(II)/Re(I) based bimetallic complexes based on p-[N-2-(2’-pyridyl)benzimidazolyl]-[N-2-(2’-pyridyl)indolyl]-benzene (L1) ligand, as well as the photophysical and photochemical properties of N^C-chelate 4-coordinate organoboron compounds that contain a metal acetylide group. Ligand L1 was synthesized and fully characterized. Due to the incorporation of two distinct chelating sites, an N^N-chelate site and an N^C-chelate site, L1 has been found to be very effective in selective binding to two different metal ions. Two new heterobimetallic complexes Ru(II)-Pt(II) and Ru(II)-Pd(II) using L1 as the bridging ligand were prepared and fully characterized. All Ru(II)-containing complexes have been found to be luminescent. The Pt(II) unit appears to enhance phosphorescent efficiency of the Ru(II) unit while the Pd(II) unit has little influence. Using L1 as the bridging unit, two new Re(I) based heterobimetallic complexes Re(I)-Pt(II) and Re(I)-Pd(II) were also successfully synthesized. Results indicate that there is communication between the two different metal centers. The preliminary results indicated that the mononuclear Re(I) complex based on L1 is a promising candidate for the electrocatalytic CO2 reduction. Pd(II) and Pt(II) complexes were synthesized with an atropisomeric bis-pyridyl chelate ligand bis{3,3’-[N-Ph-2-(2’-py) indolyl]} (L4). To examine the potential use of the trans-chelate L4 ligand in oxidative coupling reactions catalyzed by Pd(II) compounds, acetoxylation of arenes by PhI(OAc)2 using PhI(OAc)2/L4 (2:1) as the catalyst was examined and found to accelerate the reaction, but lower the overall yield. Finally, to examine the impact of metal ions on photochromic properties of N^C-chelate organoboron compounds, three metal acetylide compounds that contain a photo-active N^C-chelate BMes2 unit (B(ppy)Mes2) were prepared and fully characterized. The studies indicated that by taking advantage of different heavy metals the photoisomerization quantum efficiency of the boron chromophores can be readily tuned through the adjustment of 3LC state localized on the chelate backbone or the involvement of MLCT state in the lowest energy electronic transition. / Thesis (Ph.D, Chemistry) -- Queen's University, 2013-01-07 15:20:45.675

The objective of my MSc thesis is to study the self-assembly process of macrocyclic complexes, as well as the properties that affect the obtained supramolecular architectures. The possibility of substrate recognition within the cavity of these complexes is also of interest. Preparation of three new ligands based on the triazole-pyridine chelating units connected through variable spacer groups, as well as the complexes formed with octahedral metal ions, are described herein. The first ligand contained a naphthalene spacer region, which was longer than the previously examined xylene spacer. This extension increases the distance between metal ions in the complex, as well as the size of the cavity. More work is required to obtain the unsaturated double-stranded complex, which could potentially bind substrate molecules within its cavity. The triple-stranded saturated complexes with [Fe(H2O)6](BF4)2 and [Ni(H2O)6](BF4)2 both gave insight into the process of self-assembly. The next two ligands were designed to probe the effect that increasing the length of an aliphatic spacer had on complex self-assembly. Both ethyl and propyl spacer units had been previously studied, so butyl and pentyl spacer groups were the natural next step to analyze. The length of the alkyl spacer was found to be very important in the nature of the obtained complex. As the length of the alkyl chain, and the corresponding flexibility increased, so too did the complexity of the resulting supramolecular architectures. / Thesis (Master, Chemistry) -- Queen's University, 2013-09-03 12:21:39.581

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The contamination of groundwater by arsenic is currently a major concern in Bangladesh. Arsenic in groundwater was first detected in 1993 following reports of many people suffering from arsenical diseases. Further investigations showed the extent of the problem with large areas of the country's water supply being affected and millions of people at serious risk of arsenic poisoning. Technology for arsenic removal from water already exists. However, the socioeconomic conditions which prevail in Bangladesh, do not permit implementation of this type of technology on grounds of cost. The main objective of this study was to develop a low cost technique for the removal of arsenic from contaminated groundwater using the naturally occurring iron, which is another water quality constraint in Bangladesh. The approach was to form arsenic-iron complexes by coprecipitation and adsorption of arsenic on iron. It has been demonstrated that provided the iron levels are sufficiently high (say >_ 1.2 mg/1), simple shaking of a container and allowing the arsenic-iron complex to settle out for 3 days could reduce the concentration of arsenic from 0.10 mg/l to Bangladesh standard (0.05 mg/1). In experimental program, As(III) form of arsenic was used as this form is more likely to be present in groundwater. From laboratory studies, it was shown that the removal rate was largely controlled by the Fe/As ratio, pH and the As concentration. Arsenic removal increases with increasing Fe/As ratio and is favoured by increasing pH in the range of 5 to 8. Separation of the precipitates was achieved by settlement. Following prolonged settlement, it was found that arsenic removal could exceed the removal achieved by filtration through a 0.45 μm filter paper. The experiments demonstrated that about 77% arsenic removal could be achieved from water containing 0.2 mg/l As(III), 4.0 mg/1 Fe at pH 7.5 by manual flocculation (1 min manual mixing) and 3 days settlement. The use of ordinary charcoal, which is cheap and easily available, was investigated for removal of arsenic and was found to be ineffective. From maps of the known distributions of As, Fe and pH, it was evident that 63% of the area in Bangladesh complied with the Bangladesh standard for arsenic. By interpreting the maps and applying the potential removal by coprecipitation-adsorption and settlement technique, it was estimated that a further 8% of area would comply with the Bangladesh standard freeing an additional 7 million people from arsenic contamination.

M.Sc. (Chemistry) / Please refer to full text to view abstract