Synthesis and characterisation of lanthanide complexes for application as responsive probes

A range of new lanthanide complexes have been synthesised. The ligands and ligand precursors were characterised by NMR (1H, 13C), electrospray mass spectrometry, UV-Vis and IR spectroscopy. Several ligands or ligand precursors have been crystallised and analysed by X-ray crystal diffraction. The complexes were characterised by electrospray mass spectrometry, UV-Vis, IR spectroscopy and luminescence spectroscopy. In Chapter 2 a quinoxaline chromophore was incorporated in a macrocyclic ligand and it was shown that quinoxaline was capable of sensitising Ln(III) luminescence in the visible and NIR region. The Eu(uT) emission intensity and lifetime were shown to be responsive to pH. In Chapter 3 two N-(2-nitrophenyl)acetamide-derived chromophores were incorporated into macrocyclic ligands and shown to be capable of sensitising Ln(III) emission. A combined structural, spectroscopy and computation study was undertaken to investigate the spectral differences between the ligands. In Chapter 4 a synthetic strategy towards the synthesis of metal-ion responsive lanthanide complexes is detailed. The Eu(III) complexes were titrated against various metals and it was shown that the metal-based luminescence was sensitive to the concentration of Hg(II) and Cu(II). Hydroxyquinoline, aminoanthracene, amidopyrene, amidoquinoline and amidoanthraquinone chromophores were incorporated into macrocyclic ligands in Chapter 5 in order investigate the feasibility of adapting the synthetic strategy presented in Chapter 4 to synthesise responsive probes containing long-wavelength absorbing chromophores. Binding studies demonstrated the potential for these complexes to respond to the presence of Group 12 metals with changes in the overall emission intensity, relative intensity of hyperfine transitions and luminescence lifetimes. In Chapter 6 the synthetic strategy presented Chapter 4 was utilised to synthesis a ligand capable of forming bimetallic complexes with Ln(III) ions. Combined luminescence and relaxivity studies indicated that the binding of Hg(II) resulted in a change in Ln(III) coordination environment, whereas the binding of Cu(II) caused quenching of emission without increasing q