The development of inorganic dyes for the application of photocatalytic CO2 reduction
The work presented in this thesis focuses on the synthesis and characterisation of inorganic dyes which may be used as potential catalysts for CO2 reduction. Chapter 1 is an introductory chapter concerned with introducing the area of CO2 reduction and the complexes developed to date. It begins with a brief overview of the area of CO2 reduction before introducing the significant photocatalysts developed to date for this purpose. The chapter concludes with an introduction to the photocatalysts developed within this research. Chapters 3 and 4 of this thesis describe the synthesis and characterisation of mononuclear and dinuclear ruthenium (II) and rhenium (I) complexes using various synthetic routes and ligands. The experimental methodology (i.e. the materials, methods and instrumentation) used while conducting this research, is described in Chapter 2. The investigation into the preparation of photocatalysts begins in chapter 3 with the development of homonuclear and heteronuclear supramolecular complexes containing ruthenium and rhenium metal centers using the “complexes as metals / complexes as ligands” approach. A range of ‘azole’ type bridging ligands 3,5-bis(pyridin-2-yl)-1,2,4-triazole (Hbpt), 3,5-bis(pyridin-2-yl)-1,2,4-triazole (Hbpzt), 2,5-Bis(2-pyridyl)-1,3,4-thiadiazole (dptd) were prepared to connect these two centres with an aim to study the effect of bridging ligands on catalytic activity. Characterisation was carried out by 1 HNMR, and CHN with a discussion of their electronic properities included. Chapter 4 continues with a description of a synthetic study to prepare [Ru(bpy)2(tpphz)Re(CO)3Cl](PF6)2. Synthesis of the bridging ligand, tetrapyrido[3,2-a:2’,3’:3’’,2’’-h:2’’’,3’’’-j]phenazine (tpphz) is described with subsequent novel synthetic routes leading to the development of ruthenium and rhenium precursor complexes. Further investigation in the preparation of [Ru(bpy)2(tpphz)Re(CO)3Cl](PF6)2 is detailed and characterisation is carried out by 1 HNMR and IR. Chapter 5 details the analysis of [Ru(bpy)2(bpt)Re(CO)3Cl]PF6 conducted by ion chromatography using a Dionex ICS-1500 system for oxalate and formate. System installation, calibration and validation are described with respect to the detection of oxalate and formate. Irradiation studies of the heteronuclear complex using blue light over a twenty four hour period are described. Chapter 6 concludes this thesis with a summary of the work completed during this research. Possible future work is also described before concluding remarks.
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