Photoactivatable Organometallic Pyridyl Ruthenium(II) Arene Complexes

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• 作者：Soledad Betanzos-Lara ; Luca Salassa ; Abraha Habtemariam ; Olga Novakova ; Ana M. Pizarro ; Guy J. Clarkson ; Barbora Liskova ; Viktor Brabec ; Peter J. Sadler
• 刊名：Organometallics
• 出版年：2012
• 出版时间：May 14, 2012
• 年：2012
• 卷：31
• 期：9
• 页码：3466-3479
• 全文大小：736K
• 年卷期：v.31,no.9(May 14, 2012)
• ISSN：1520-6041

文摘

The synthesis and characterization of a family of piano-stool Ru^II arene complexes of the type [(畏⁶-arene)Ru(N,N鈥?(L)][PF₆]₂, where arene is p-cymene (p-cym), hexamethylbenzene (hmb), or indane (ind), N,N鈥?is 2,2鈥?bipyrimidine (bpm), 1,10-phenanthroline (phen), 1,10-phenanthroline-5,6-dione (phendio), or 4,7-diphenyl-1,10-phenanthroline (bathophen), and L is pyridine (Py), 4-methylpyridine (4-MePy), 4-methoxypyridine (4-MeOPy), 4,4鈥?bipyridine (4,4鈥?bpy), 4-phenylpyridine (4-PhPy), 4-benzylpyridine (4-BzPy), 1,2,4-triazole (trz), 3-acetylpyridine (3-AcPy), nicotinamide (NA), or methyl nicotinate (MN), are reported, including the X-ray crystal structures of [(畏⁶-p-cym)Ru(bpm)(4-MePy)]²⁺ (2), [(畏⁶-p-cym)Ru(bpm)(4-BzPy)]²⁺ (6), [(畏⁶-p-cym)Ru(bpm)(trz)]²⁺ (7), [(畏⁶-p-cym)Ru(phen)(Py)]²⁺ (10), and [(畏⁶-ind)Ru(bpy)(Py)]²⁺ (13). These complexes can selectively photodissociate the monodentate ligand (L) when excited with UVA or white light, allowing strict control of the formation of the reactive aqua species [(畏⁶-arene)Ru(N,N鈥?(OH₂)]²⁺ that otherwise would not form in the dark. The photoproducts were characterized by UV鈥搗is absorption and ¹H NMR spectroscopy. DFT and TD-DFT calculations were employed to characterize the excited states and to obtain information on the photochemistry of the complexes. All the Ru^II pyridine complexes follow a relatively similar photochemical L-ligand dissociation mechanism, likely to occur from a series of ³MC triplet states with dissociative character. The photochemical process proved to be much more efficient when UVA-range irradiation was used. More strikingly, light activation was used to phototrigger binding of these potential anticancer agents with discriminating preference toward 9-ethylguanine (9-EtG) over 9-ethyladenine (9-EtA). Calf thymus (CT)-DNA binding studies showed that the irradiated complexes bind to CT-DNA, whereas the nonirradiated forms bind negligibly. Studies of CT-DNA interactions in cell-free media suggest combined weak monofunctional coordinative and intercalative binding modes. The Ru^II arene complexes [(畏⁶-p-cym)Ru(bpm)(Py)]²⁺ (1), [(畏⁶-p-cym)Ru(bpm)(4-MeOPy)]²⁺ (3), [(畏⁶-p-cym)Ru(4,4鈥?bpy)]²⁺ (4), [(畏⁶-hmb)Ru(bpm)(Py)]²⁺ (8), [(畏⁶-ind)Ru(bpm)(Py)]²⁺ (9), [(畏⁶-p-cym)Ru(phen)(Py)]²⁺ (10), [(畏⁶-p-cym)Ru(bathophen)(Py)]²⁺ (12), [(畏⁶-p-cym)Ru(bpm)(NA)]²⁺ (15), and [(畏⁶-p-cym)Ru(bpm)(MN)]²⁺ (16) were cytotoxic toward A2780 human ovarian cancer cell line in the absence of photoirradiation (IC₅₀ values in the range of 9.0鈥?0 渭M).