Interactions of nitrogen-donor bio-molecules with dinuclear platinum(II) complexes


<div><p>Substitution reactions of the dinuclear Pt(II) complexes, [{Pt(en)Cl}<sub>2</sub>(<i>μ</i>-pz)]<sup>2+</sup> (<b>1</b>), [{Pt(dach)Cl}<sub>2</sub>(<i>μ</i>-pz)]<sup>2+</sup> (<b>2</b>) and [{Pt(dach)Cl}<sub>2</sub>(<i>μ</i>-4,4ʹ-bipy)]<sup>2+</sup> (<b>3</b>), and corresponding aqua analogs with selected biologically important ligands, viz<i>.</i> 1,2,4-triazole, L-histidine (L-His) and guanosine-5ʹ-monophosphate (5ʹ-GMP) were studied under <i>pseudo</i>-first-order conditions as a function of concentration and temperature using UV–vis spectrophotometry. The reactions of the chloride complexes were followed in aqueous 25 mmol L<sup>−1</sup> Hepes buffer in the presence of 40 mmol L<sup>−1</sup> NaCl at pH 7.2, whereas the reactions of the aqua complexes were studied at pH 2.5. Two consecutive reaction steps, which both depend on the nucleophile concentration, were observed in all cases. The second-order rate constants for both reaction steps indicate a decrease in the order <b>1</b> > <b>2</b> > <b>3</b> for all complexes. Also, the p<i>K</i><sub>a</sub> values of all three aqua complexes were determined. The order of the reactivity of the studied ligands is 1,2,4-triazole > L-His > 5ʹ-GMP. <sup>1</sup>H NMR spectroscopy and HPLC were used to follow the substitution of chloride in the dichloride <b>1</b>, <b>2</b>, and <b>3</b> complexes by guanosine-5ʹ-monophosphate (5ʹ-GMP). This study shows that the inert and bridging ligands have an important influence on the reactivity of the studied complexes.</p></div

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oaioai:figshare.com:article/1403709Last time updated on 2/12/2018

This paper was published in FigShare.

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