Strong Cytotoxicity of Organometallic Platinum Complexes
with Alkynyl Ligands
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Abstract
The synthesis, spectroscopy, structures,
and chemical reactivity
of the organometallic complexes [(COD)Pt(CCR)<sub>2</sub>]
and [(COD)Pt(CCR)(R′)] (COD = 1,5-cyclooctadiene, R
= Ph, (Me)Ph (2Me, 3Me, or 4Me), (NO<sub>2</sub>)Ph (2NO<sub>2</sub>, 3NO<sub>2</sub>, or 4NO<sub>2</sub>), (4F)Ph, (4OMe)Ph, 2Py (2-pyridyl);
R′ = Me (methyl), Neop (neopentyl = 2,2-dimethyl-1-methyl),
NeoSi (neosilyl = trimethylsilylmethyl), Bz (benzyl)) has been explored.
The crystal structures reveal square-planar surroundings of the Pt
atoms with short Pt–C(alkynyl) bonds (<2 Å) and almost
perpendicular orientation of the CC–aryl group to the
Pt coordination plane. Nonattractive π–π stacking
and C–H···F intermolecular interactions were
observed in the crystal structures. Multinuclear (<sup>1</sup>H, <sup>13</sup>C, <sup>195</sup>Pt, and <sup>19</sup>F) NMR spectroscopy
reveals structures in solution and Pt–ligand bond strength.
The thermal stability in organic solvents, the electrochemical stability,
and the reactivity of the complexes in organic or aquatic (water-containing)
solution toward the physiologically relevant species glutathione,
chloride, and protons was tested, revealing remarkable stability or
inertness of the complexes. Cytotoxicity experiments in HT-29 colon
carcinoma and MCF-7 breast adenocarcinoma cell lines revealed highly
promising activities for selected platinum alkynyl COD complexes