AbstractsBiology & Animal Science

In this thesis, the preparation of a number of new ruthenium complexes as potential redox mediators in electrochemical biosensors is reported. These complexes have been characterized by IR, ESI-MS, 1H-NMR, CHN elemental analysis and UV-Vis. Their electrochemical properties have also been investigated. A series of [RuII(Me3tacn)(acac)(L1)]PF6 complexes have been synthesized by the reaction of [RuIII(Me3tacn)(acac)(OH)]PF6 with excess L1 in the presence of Zn/Hg under inert atmosphere. (Me3tacn = 1,4,7-trimethyl-1,4,7-triazacyclononane and L1 = 1-MeIm, 4-Me2N-py, 4-MeO-py, 4-Me-py, 4-t-butyl-py, py, isoquin and 3-Cl-py). Oxidation of these Ru(II) species by (NH4)2[CeIV(NO3)6] in acetone results in the formation of their Ru(III) analogues, isolated as NO3- salts. These highly water soluble complexes display one reversible Ru(III)/Ru(II) couple in buffer solution at pH = 8. The RuIII/II redox potentials are dependent on L1, in the order of 1-MeIm < 4-Me2N-py < 4-MeO-py < 4-Me-py, 4-t-butyl-py < py < isoquin < 3-Cl-py. All complexes have also been characterized by IR, ESI-MS, 1H-NMR, CHN elemental analysis and UV-Vis. A series of [RuII(Me6tet)(L2)]PF6 complexes have been synthesized by the reaction of cis-[RuIII(Me6tet)Cl2]PF6 with various acetylacetones in the presence of CaCO3 and Zn/Hg in refluxing ethanol under inert atmosphere (L2 = acac, Meacac, tfac, bhma, bhba, phpa). Oxidation of these Ru(II) species by (NH4)2[CeIV(NO3)6] in acetone results in the formation of their Ru(III) analogues, isolated as NO3- salts; which can be converted to PF6- salts by treatment with NH4PF6 in water. The PF6- salts of these Ru(III) species can be converted to the Cl- salts by adding [nBu4N]Cl to solutions in acetone. These highly water soluble complexes display one reversible Ru(III)/Ru(II) couple in buffer solution at pH = 8. The RuIII/II redox potentials are dependent on L2, in the order of Meacac < phpa < acac < bhma < bhba < tfac. All complexes are also characterized by IR, ESI-MS, 1H-NMR, CHN elemental analysis and UV-Vis. Treatment of RuIII(acac)3 with excess py-3-COOH, py-4-COOH and TMEDA (TMEDA = tetramethylethylenediamine) in refluxing ethanol in the presence of Zn/Hg under argon affords [RuII(acac)2(py-3-COOH)2], [RuII(acac)2(py-4-COOH)2] and [RuII(acac)2(TMEDA)] respectively. Air oxidation of these Ru(II) species in aqueous solutions gives [RuIII(acac)2(py-3-COO)(py-3-COOH)], [RuIII(acac)2(py-4-COO)(py-4-COOH)] and [RuIII(acac)2(TMEDA)]+ respectively, isolated as OH- or PF6- salts. These highly water soluble complexes exhibit one reversible couple which is assigned as Ru(III)/Ru(II) couple. xix, 148 leaves : ill. 30 cm. CityU Call Number: R857.B54 K86 2008