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dc.contributor.advisorBrink, Alice
dc.contributor.advisorVisser, H. G.
dc.contributor.authorAlexander, Orbett Teboho
dc.date.accessioned2018-09-06T11:35:41Z
dc.date.available2018-09-06T11:35:41Z
dc.date.issued2018-02
dc.identifier.urihttp://hdl.handle.net/11660/9259
dc.description.abstractThe chemistry of lanthanides has expanded immensely across many scientific fields over the years and that was mainly due to the rare versatility exhibited by the spectroscopic and magnetic nature of these metals in the series. With the coordination nature of these lanthanoids not governed by the orbital directionality, as is the case with transition metals, the relative coordination chemistry of this series becomes of great interest and therefore is susceptible to ground breaking science across many scientific disciplines. Europium (III) metal ion in particular, has been involved in many scientific fields due to its sterling spectroscopic properties. Its ternary analogues have been extensively employed as emitting layers in the edifice of optoelectronic devises. Moreover, its applications extend as far as tailoring active luminescence bioprobes in biomedical sciences which is a vast field with a lot of other related applications in it. The main interest has always been its red narrow emission spectral profile which is susceptible to any organic matrix it is submerged in. The principle aim of this study was to gain insight into the chemistry, coordination and photoluminescence behaviour of ternary EuIII based complexes. From this idea, it was decided to synthesize a few novel ligand systems. This include (E)-1-((9-ethylcarbazol-3- ylimino)methyl)-napthanol, (E)-2-(9-ethylcarbazol-3-yliminomethyl)-6- methoxy phenol, (E)-2-methoxy-(6-(phenyliminomethyl))-phenol, (E)-1-((2-(pyridin-2-yl)hydrazono) methyl) naphthalene-2-ol, (E)-2-methoxy-6-((2-(pyridin-2-yl)hydrazono)methyl)phenol, (E)-2-(2-((2- hydroxynaphthalen-1-yl)methylene)hydrazinyl) quinolin-8-ol and (E)-2-(2-(2-hydroxy-3- methoxybenzylidene)hydrazinyl) quinolin-8-ol characterized by means of IR, UV/Vis and NMR (1H, 13C) spectroscopy. Furthermore, the solid state structural characterization was carried out using single crystal X-ray diffraction spectroscopy for compounds with suitable single crystals X-ray diffraction collection. However, the intended tailoring of ternary EuIII complexes with this novel ligand species was not successful. The ligand systems synthesized were designed with the idea to be potentially biologically active and fluorescent by itself. They were analysed for photoluminescence properties and were successfully found to be luminous and are to be sent for cell testing. A range of ternary EuIII based complexes, of the form [Eu(β-diketone)3 X] (X = 1,10-phenanthroline), were synthesized by using selected acetyl acetone derivatives (β-diketone) as parallel ligand system used in this study. The bidentate β-diketone ligands used are 1,3-Diphenyl-propanedione (DBM), 2) 4,4,4-Trifluoro-1-chlorophenyl-butanedione (TCPB), 3) 2-Bromo-1,3-diphenyl-propanedione (DBBrM), 4) 3-Chloro-2,4-pentanedione (DMC), 5) 3,3-Dimethyl-2,4-pentanedione (DMMP), and 6) Benzoic anhydride (BZAN). The EuIII based analogues with the bidentate β-diketone ligand given above were successfully synthesized and characterized by means of IR, X-ray diffraction and Elemental Analysis spectroscopy. These obtained ternary EuIII based complexes are [tris-(4,4,4-Trifluoro-1- chlorophenyl-butanedione) mono(1,10-phenanthroline) europium(III)], [tris-(2-Bromo-1,3- diphenyl-propanedione) mono(1,10-phenanthroline) europium(III)], [tris-(1,3-Diphenylpropanedione) mono (1,10-phenanthroline) europium(III)], [tris-(3-Chloro-2,4-pentanedione) mono(1,10-phenanthroline) europium(III)], [tris-(2,2,6,6-Tetremethyl-heptanedione) mono(1,10-phenanthroline) europium(III)], tris-(Benzoic Anhydride)-mono-(1,10- phenanthroline) europium(III)] and {[hexa-( Benzyl carboxylic acid) bis-(1,10- phenanthroline) di-europium(III)]-μ-[κ2-O,O’-( benzyl carboxylic acid)]2}. These above stated ternary EuIII complexes were analysed for photoluminescence and all proved to be luminous. However, there were significant differences in the spectral identity of these respective complexes and that was due to the ligand nature coordinated to the EuIII metal ion. The observed spectral identities are defined in terms of relative Stark splitting of the complexes which is induced by the symmetry imposed on the EuIII ion by the atomic orientations around the metal. The atomic orientations around the EuIII metal ion are dictated by the steric hindrance imposed by the peripheral derivatization on the acetyl acetone back bone. It was crystallographically deduced that the high quantum yield (82%) of complex [tris-(4,4,4-Trifluoro-1-chlorophenyl-butanedione) mono(1,10-phenanthroline) europium(III)] was due to strong binding of the antenna ligand to the metal ion, facilitating efficient energy transfer to give high luminous efficiency. There were successful correlations drawn between the photoluminescence and the crystallographic data obtained of the [Eu(β-diketone)3 X] (X = 1,10-phenanthroline) complexes. The respective point groups from both disciplines could be matched. However, the polyhedron constructed for atoms directly bonded to the EuIII metal ion indicates higher symmetry point groups due to observed polyhedral distortions therein. The correlation of data from these two scientific disciplines rubber stamp the proof of concept of using the method detailed in this study in analysis of the site symmetry of the EuIII metal ion in bulk organic system, UPNP or any other organic system for that matter.en_ZA
dc.language.isoenen_ZA
dc.publisherUniversity of the Free Stateen_ZA
dc.subjectLanthanidesen_ZA
dc.subjectEuropium (III) metal ionen_ZA
dc.subjectLuminescence bioprobesen_ZA
dc.subjectPhotoluminescenceen_ZA
dc.subjectChemistryen_ZA
dc.subjectThesis (Ph.D. (Chemistry))--University of the Free State, 2018en_ZA
dc.titleThe effects of structure and ligand variations on the luminescence of Europium (III) complexesen_ZA
dc.typeThesisen_ZA
dc.rights.holderUniversity of the Free Stateen_ZA


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