Heterodinuclear ruthenium(ii)–cobalt(iii) complexes as models for a new approach to selective cancer treatment

Abstract

Heterodinuclear ruthenium(II)-cobalt(III) complexes have been prepared as part of investigations into a new approach to selective cancer treatment. A cobalt(III) centre bearing amine ligands, which serve as models for cytotoxic nitrogen mustard ligands, is connected by a bridging ligand to a ruthenium(II)-polypyridyl moiety. Upon excitation of the ruthenium centre by visible light, electron transfer to the cobalt(III) centre results in reduction to cobalt(II) and consequent release of its ligands. We have synthesised several such structures and demonstrated their ability to release ligands upon excitation of the ruthenium centre by visible light.

Palladium(II) Complexes of Ambidentate and Potentially Cyclometalating 5‐Aryl‐3‐(2′‐pyridyl)‐1,2,4‐triazine Ligands

“…The 5‐aryl‐3‐(2′‐pyridyl)‐1,2,4‐triazine moieties themselves have been used for decades as versatile ligands for transition‐metal complexes with some medical or technical applications. The most important application is probably that of 3‐(2‐pyridyl)‐5,6‐diphenyl‐1,2,4‐triazine‐ p , p′ ‐disulfonic acid [PyTZ(HO 2 SOPh) 2 ], following the nomenclature in Scheme , also called FerroZine™, for the colorimetric detection of Fe II in biological or other systems .…”

“…Antiviral and cytotoxic (or antiproliferative) properties have been reported for complexes of other transition metals with 3‐(2′‐pyridyl)‐1,2,4‐triazine ligands , . Amongst them are Ni II complexes, such as [(PyTZPh 2 ) 2 NiCl 2 ] .…”

Theoretical insight into photo-induced intramolecular electron transfer in heterodinuclear Ru(II)–Co(III) complexes

“…The molecular structures of the reference complex [(bpy) 2 -Ru(pytp)Co(tren)] 5þ ([RueCo] 5þ for short) [13] and the newly designed heterodinuclear complexes 1 À 3 are illustrated in Fig. 1.…”

“…The Ru(II) center was supposed to donate electron to Co(III) center and reduced it to Co(II) by virtue of the photo-induced IET process [7]. In experiments, the release of the cytotoxic nitrogen mustard ligands from the heterodinuclear Ru(II)eCo(III) complexes was confirmed by the external visible light [13]. However, the intrinsic mechanisms of the photo-induced IET of heterodinuclear Ru(II)eCo(III) systems, including the spectral response range, absorption intensity, electronic excitation pathway, IET rate, etc., are still vacant.…”

“…The cytotoxic nitrogen mustard ligand would become easy to be released after a photo-induced conversion from an inert Co(III) complex to a labile Co(II) complex under the visible light [8,12]. Hartshorn and co-workers have reported the synthesis and NMR spectroscopic analysis on a diversity of heterodinuclear Ru(II)eCo(III) complexes containing such a hypoxiaselective cytotoxic nitrogen mustard ligand [13]. In these heterodinuclear systems, Ru(II) served as electron donors and Co(III) as acceptors, which were linked by a bridge ligand.…”