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Ruthenium polypyridyl compounds as luminescent probes for biological materials

Ryan, Eleanor M. (1991) Ruthenium polypyridyl compounds as luminescent probes for biological materials. PhD thesis, Dublin City University.

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Abstract

The synthesis and characterisation of ruthenium (II) bis-(1 ,10-phenanthroline) and bis-(2 ,2 1-bipyridyl) complexes containing amino and isothiocyanate phenanthroline and pyridine ligands are described. These complexes were characterised using HPLC, UV/vis spectroscopy, electrochemistry, NMR, IR, and emission spectroscopy. HPLC was used to determine the purity of the various complexes. Electronic spectra and electrochemical measurements indicate that most likely, the 2 ,2 '-bipyridyl and 1 ,10-phenanthroline ligands are the emitting ligands and the amino and isothiocyanate phenanthroline and pyridine ligands act as the spectator ligands. These complexes were subsequently conjugated to biological materials, including albumins, immunoglobulins and poly-L-lysine. The complexes were bound at different sites on the biomolecules, via the lysine residues, the carbohydrate moieties and via the tyrosine residues. The effect of conjugation on the spectroscopic properties of the complexes was examined. The absorption spectra were found to exhibit changes in the MLCT band with the absorption wavelength maximum experiencing slight red shifts together with general band broadening effects. The emission decay behaviour was also investigated. The unbound complexes were found to exhibit single exponential decay behaviour and the bound complexes exhibited essentially double exponential behaviour. From the double exponential decay fits, the first short-lived species was suggested to be a quenched bound species whilst the second species probably arises from a bound species which is considerably protected from the effects of quenching molecules. The synthesis and characterisation of a number of bis-(1 ,10-phenanthroline) (phen), and bis-(4,4'-dimethyl- 2, 2'-bipyridyl) (dmbpy), ruthenium (II) complexes containing a series of pyridyltriazole ligands are described. The ruthenium ion may bind via the Nl'/ N 2 ' or n4' of the triazole ring. The most favourable coordination mode being dependent on the position of a substituent on the triazole ring. Coordination isomers were obtained and separated by semi-preparative HPLC methods. The electrochemical results suggest that the phen and dmbpy ligands are the emitting ligands and that the pyridyltriazole ligands are the spectator ligands. The acid-base chemistry of those pyridyltriazole complexes which can undergo protonation / deprotonation reactions was investigated and the results substantiated the coordination modes proposed using NMR data for the complexes. The ground state pKa values show that there is a strong a-donating effect from the triazole ring to the ruthenium ion. Also, the excited state pKa* values are lower than the ground state pKa values which indicates that the pyridyltriazole ligands do not participate in the emission process. This study completes investigations which were initially conducted on the 2 ,2 '-bipyridyl analogues.

Item Type:Thesis (PhD)
Date of Award:1991
Refereed:No
Supervisor(s):Vos, Johannes G. and O'Kennedy, Richard
Uncontrolled Keywords:Ruthenium (II) complexes; Biomolecules
Subjects:Biological Sciences > Biochemistry
Physical Sciences > Chemistry
DCU Faculties and Centres:DCU Faculties and Schools > Faculty of Science and Health > School of Chemical Sciences
Use License:This item is licensed under a Creative Commons Attribution-NonCommercial-No Derivative Works 3.0 License. View License
ID Code:19329
Deposited On:23 Sep 2013 14:25 by Celine Campbell. Last Modified 24 Oct 2016 12:49

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