Half-Sandwich Ruthenium and Osmium Complexes with Hydrazinocurcuminoid-like Ligands

Ruthenium and osmium half-sandwich complexes with hydrazinocurcuminoid
ligands, 4,4′-((1E,1′E)-(1-(pyridin-2-yl)-1H-pyrazole-3,5-diyl)bis(ethene-2,1-diyl))bis(2-methoxyphenol)
(HZPcurc) and 4,4′-((1E,1′E)-(1-(pyridin-2-yl)-1H-pyrazole-3,5-diyl)bis(ethene-2,1-diyl))diphenol
(HZPbdcurc), have been synthesized and characterized using NMR spectroscopy
and mass spectrometry. Two of the complexes were also characterized
in the solid state using X-ray diffraction analysis, confirming the
pseudo-octahedral “three-legged piano-stool” geometry.
Density functional theory (DFT) studies are performed on the ligands
to evaluate their coordinating capabilities and on the resulting ruthenium
and osmium complexes. The complexes are highly soluble in water and
stable under physiological conditions. Their cytotoxicity against
MCF-7 human breast adenocarcinoma and A2780 human ovarian carcinoma
cells, both normal and cisplatin-resistant, was investigated, and
good activity and selectivity with respect to nontumorigenic cells
(HEK293T) were observed.