Type of Document	Dissertation
Author	Northrop, Aaron R.
URN	etd-08192004-104617
Title	Synthesis and Characterization of Redoxactive Ruthenium Complexes with Pendant Alkyl-Thiol Ligands Designed to Form Self Assembled Monolayers on Gold
Degree	Doctor of Philosophy
Department	Chemistry and Biochemistry, Department of
Advisory Committee	Advisor Name Title Kenneth A. Goldsby Committee Chair Albert E. Stiegman Committee Member Fred L. Petrovich Committee Member Nancy L. Greenbaum Committee Member
Keywords	Ruthenium Gold
Date of Defense	2003-12-01
Availability	unrestricted
Abstract The synthesis and characterization of two types of ruthenium(II) complexes designed to give redox-active self-assembled monolayers (SAMs) via the thiol-on-gold route are presented here. The first of these complexes is based on the synthetically versatile [Ru(Me4bpp)(R2mal)(L)]+ complex, where Me4bpp is 2,6-bis(3,5-dimethyl-Npyrazolyl) pyridine, R2mal is a â-diketonate, and in this study, L is a long-chain nitrilethiol ligand. This work represents the first reported use nitriles as ligands to form metal complexes appropriate for SAMs. A hybrid synthetic approach, which proceeded by synthesis of the free ligand to a precursor nitrile-thioacetate followed by coordination to the metal center and conversion to the desired thiol, minimized the occurrence of undesired oxidation of the terminal thiol to the disulfide and eliminated the existence of a persistent impurity created during ligand synthesis. 1H- and 13C-NMR techniques, less commonly used for studies of metal complexes of this type, proved essential to following ligand transformations remote from the metal center after coordination and were especially helpful in identifying the presence or lack of the undesired disulfide. A second approach to redox-active complexes based on bis(bipyridine) ruthenium(II) complexes utilized â-ketonato ligands substituted with long alkyl chains containing terminal functional groups. The synthesis of these complexes required modification of the hybrid synthesis utilized for the nitrile-thiol complexes resulting in coordination of a diketonate containing a terminal bromide rather than the terminal thioacetate utilized for the nitriles. A synthetic scheme was devised and implemented to achieve conversion of the terminal bromide of these ligands to the thioacetate. A short chain model of these complexes based upon 3-ethyl-2,4-pentanedionate displayed interesting NMR characteristics attributed to the chiral Ru(bpy)2 center. The ability to coordinate the alkyl substituted â-diketonato ligands to ruthenium(II) centers containing the tridentate Me4bpp ligand was also explored. While coordination of the diketonates proved successful, the products contained impurities resulting from changes in the inner-coordination sphere of the metal complex, as deduced from the high redox potentials observed by solution cyclic voltammetry. NMR confirmed successful synthesis of complexes of this type with acetonitrile and pyridine substituted at the sixth coordination site; however, the low yields of these complexes hampered full characterization and suggest that this might not be an ideal route to metal complexes for the formation of SAMs.
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