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Title: Coordination chemistry of functionalised triarylimidazole-based ligands with Re(I) and U(VI)
Author: Bonello, Rhodri Owen
ISNI:       0000 0004 5351 1525
Awarding Body: Cardiff University
Current Institution: Cardiff University
Date of Award: 2014
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Reported in this thesis is the investigation of the luminescent and photophysical behaviour of triarylimidazole ligands, also known as “lophine” ligands. A series of Re(I) and U(VI) complexes have been isolated and characterised incorporating these ligands. Triaryl imidazole ligands were isolated as substituted imidazole [4,5-f]-1,10-phenanthroline derivatives. Alterations to the substituents on this motif provided the ability to “tune” the solubility and optical properties of the ligand. Among the substituents incorporated onto the ligand system were extended chromophores, sterically bulky substituents, alkyl groups and substituents containing potential additional coordination sites. All isolated ligands and complexes were fully characterised through numerous spectroscopic techniques, including 1H NMR, 13C NMR, IR and electronic absorption spectroscopies, and further confirmation was obtained through high-resolution mass spectrometry. Crystal structures were obtained for a selection of the rhenium-coordinated imidazole [4,5-f]-1,10-phenanthroline derivatives, confirming the molecular structure in each case. The photophysical behaviour of the rhenium-imidazole [4,5-f]-1,10-phenanthroline derivative complexes were investigated, often displaying extended lifetimes of emission as a result of phosphorescence emission from an excited triplet to a ground singlet state. The complexes displayed a significant bathochromic shift in comparison to their respective free ligands, which was attributed to lower energy emission as a result of a metal-to-ligand charge transfer. Coordination of imidazole [4,5-f]-1,10-phenanthroline derivatives to U(VI) resulted in the formation of luminescent complexes. The luminescent properties of these complexes were investigated and owing to their short emission lifetimes were attributed to ligand-centred fluorescence. A significant bathochromic shift was observed for each of the complexes compared to their respective free ligands, which was attributed to the electron withdrawing effect of the uranyl centre. Small angle neutron scattering (SANS) experiments were also performed on a selection of U(VI) complexes in order to determine the partitioning of uranyl complexes in a microemulsion as a potential method for uranyl detection.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: QD Chemistry