Ruthenium (II) polypyridine complexes in general have been extensively studied because of their unique redox and photochemical properties. A typical example of such complexes is tris(2,2’-bipyridyl) ruthenium (II). In this study, this complex was synthesized and then characterized using electronic spectroscopy and cyclic voltammetry. It was also shown that the ruthenium concentration could be accurately determined using ICP-MS. It was found that the complex is very stable in various chemical environments. It was observed from spectrophotometric investigations that persulphate and lead dioxide easily oxidize Ru(bpy)3 2+ to Ru(bpy)3 3+ in the presence of heat and H2SO4, respectively. It was also observed that the oxidation between Ru(bpy)3 2+ and cerium (IV) occurred at approximately 3:2 [Ce(IV)]/[Ru(II)] mole ratio. The resultant Ru(bpy)3 3+ solution was unstable in the presence of light and recovery of Ru(bpy)3 2+ occurred gradually. The regeneration of Ru(bpy)3 2+ from Ru(bpy)3 3+ was found to be a multistep process, which appears to involve the formation of an intermediate species. The following reaction model was found to best explain the kinetic data obtained: Ru(bpy)3 2+ + Ce(IV) → Ru(bpy)3 3+ Ru(bpy)3 3+ → Ru(bpy)3 2+ Ru(bpy)3 3+ → Ru* intermediate Ru* intermediate → Ru(bpy)3 2+ Theoretical rate constants were also calculated for the same process under the experimental conditions. The comparison between the experimental and theoretical results gave good agreement. In addition, the factors that influence the rate of the regeneration of Ru(bpy)3 2+ from Ru(bpy)3 3+ were also discussed.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:nmmu/vital:10374 |
| Date | January 2009 |
| Creators | Zheng, Sipeng |
| Publisher | Nelson Mandela Metropolitan University, Faculty of Science |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Thesis, Masters, MSc |
| Format | xiii, 99 leaves, pdf |
| Rights | Nelson Mandela Metropolitan University |
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