Ruthenium(II)–arene complexes with functionalized pyridines: Synthesis, characterization and cytotoxic activity

Abstract

Ruthenium(II)–arene complexes of general formulae [(η 6- p-cymene)Ru(L 1–3)Cl 2], where L 1–3 is 3-acetylpyridine ( 1), 4-acetylpyridine ( 2) and 2-amino-5-chloropyridine ( 3), correspondingly, [(η 6- p-cymene)Ru(HL 4,5)Cl 2], where HL 4 and HL 5 are respectively isonicotinic acid ( 4) and nicotinic acid ( 5) and [(η 6- p-cymene)Ru(HL 6–9)Cl], where H 2L 6–9 represent 2,3-pyridinedicarboxylic acid ( 6), 2,4-pyridinedicarboxylic acid ( 7), 2,5-pyridinedicarboxylic acid ( 8) and 2,6-pyridinedicarboxylic acid ( 9), were prepared by the reaction of [(η 6- p-cymene) 2RuCl 2] 2 ( 10) with the corresponding ligand in 1:2 molar ratio in isopropanol. The complexes were characterized by elemental analysis, mass spectrometry, IR and NMR spectroscopies. According to these data the molecules adopt the usual “three-leg piano-stool” geometry which is common for this type of complexes. The structures of 1 and 7 were determined by X-ray crystallography. The complexes revealed low antiproliferative activity in six investigated tumor cell lines (HeLa, B16, FemX, MDA-MB-361, MDA-MB-453 and LS-174). The reaction of 6 with 9-methyladenine was studied by 1H NMR, 1H, 1H COSY and 1H, 1H NOESY spectroscopy.