Solution equilibrium studies of anticancer ruthenium(II)-畏6-p-cymene complexes of pyridinecarboxylic acids
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- 作者：脡va Sija ; Christian G. Hartinger ; Bernhard K. Keppler ; Tam谩s Kiss ; 脡va A. Enyedy
- 关键词：Speciation ; Stability constants ; Antitumor agents ; Picolinic acid ; Dipicolinic acid
- 刊名：Polyhedron
- 出版年：8 January, 2014
- 年：2014
- 卷：67
- 期：Complete
- 页码：51-58
- 全文大小：1809 K
文摘
Stoichiometry and stability of antitumor ruthenium(II)-畏6-p-cymene complexes of picolinic acid and its 6-methyl and 6-carboxylic acid derivatives were determined by pH-potentiometry, 1H NMR spectroscopy and UV-Vis spectrophotometry in aqueous solution in the presence or absence of coordinating chloride ions. The picolinates form exclusively mono-ligand complexes in which they can coordinate via the bidentate (O,N) mode and a chloride or a water molecule is found at the third binding site of the ruthenium(II)-畏6-p-cymene moiety depending on the conditions. [Ru(畏6-p-cymene)(L)(H2O/Cl)] species are predominant at physiological pH in all studied cases. Hydrolysis of the aqua complex or the chlorido/hydroxido co-ligand exchange results in the formation of the mixed-hydroxido species [Ru(畏6-p-cymene)(L)(OH)] in the basic pH range. There is no indication for the decomposition of the mono-ligand complexes during 24 h in the ruthenium(II)-畏6-p-cymene-picolinic acid system between pH 3 and 11; however, a slight dissociation with a low reaction rate was found in the other two systems leading to the appearance of the dinuclear trihydroxido-bridged species [Ru2(畏6-p-cymene)2(OH)3]+ and free ligands at pH > 10. The replacement of the chlorido by an aqua ligand in [Ru(畏6-p-cymene)(L)Cl] was also monitored and equilibrium constants for the exchange process were determined.