Synthesis, Characterization, and DNA Binding Properties of a Series of Ru, Pt Mixed-Metal Complexes

Abstract

A series of mixed-metal complexes coupling ruthenium light absorbers to platinum reactive metal sites through polyazine bridging ligands have been prepared of the form [(tpy)RuCl(BL)PtCl(2)](PF(6)) (BL = 2,3-bis(2-pyridyl)pyrazine (dpp), 2,3-bis(2-pyridyl)quinoxaline (dpq), 2,3-bis(2-pyridyl)benzoquinoxaline (dpb); tpy = 2,2':6',2' '-terpyridine). These systems possess electron-rich Ru metal centers bound to five polyazine nitrogens and one chloride ligand. This leads to complexes with low-energy Ru --> BL charge-transfer bands that are tunable with BL variation occurring at 544, 632, and 682 nm for dpp, dpq, and dpb, respectively. This tuning of the charge-transfer energy results from a stabilization of the BL(pi) orbitals in this series as evidenced by the cathodic shift in the first reduction of these complexes occurring at -0.50, -0.32, and -0.20 V vs Ag/AgCl, for dpp, dpq, and dpb, respectively. The chlorides bound to the Pt(II) center are substitutionally labile giving these complexes the ability to covalently bind to DNA. All three title bimetallics, [(tpy)RuCl(BL)PtCl(2)](PF(6)), avidly bind double-stranded DNA with t(1/2) = 1-2 min, substantially reducing the migration of DNA through an agarose gel. Details of the synthetic methods, FAB MS data, spectroscopic and electrochemical properties, and DNA binding studies are presented.

In vivo inhibition of E. coli growth by a Ru(II)/Pt(II) supramolecule [(tpy)RuCl(dpp)PtCl2](PF6)

“…Electrophoresis grade boric acid, agarose, and microbiology grade glycerol were purchased from Fischer Scientific. The complexes [Ru(tpy)Cl 3 ], [29] [PtCl 2 (DMSO) 2 ], [30] [Ru(tpy)(dpp)Cl](PF 6 ), [31] and [(tpy)RuCl(dpp)PtCl 2 ](PF 6 ) [21] were synthesized as previously reported.…”

“…The DNA binding properties of the heteronuclear bimetallic complexes, [(tpy)RuCl(BL)PtCl 2 ](PF 6 ) (BL = 2,3-bis(2-pyridyl)pyrazine (dpp) or 2,3-bis(2-pyridyl)-quinoxaline (dpq) or 2,3-bis(2-pyridyl)benzoquinoxaline (dpb), tpy = 2,2 0 :6 0 ,2 0 0 -terpyridine), have been reported recently [21]. The [(tpy)RuCl(dpp)PtCl 2 ](PF 6 ) complex shows rapid binding to plasmid DNA with significant retardation of plasmid DNA migration through the agarose gels as compared to cisplatin.…”

Photochemistry and DNA photocleavage by a new unsupported dirhodium(II,II) complex

“…The crystal structure reveals intramolecular π-stacking interactions between the two phen ligands which are offset with respect to each other, with N1-Rh1-Rh2-N3 and N2-Rh1-Rh2-N4 dihedral angles of 45 table S2), similar to the unbridged complex 2 [67]. Owing to the distortion of the phen ligands, the best least-squares planes of the two phen ligands in compound 1 are not exactly parallel to each other, and thus no unique distance between them can be defined.…”

“…These organic photosensitizers are activated with light in the 'PDT window', 600-850 nm, and systemic toxicity is avoided because the cytotoxic activity is confined to the irradiated tissues [28][29][30]. Inorganic complexes have also been investigated for the potential use as PDT agents, and various polypyridyl and porphyrin compounds that sensitize the formation of cytotoxic 1 O 2 upon excitation with visible light have been reported [31][32][33][34][35][36][37][38][39][40][41][42][43][44][45][46][47][48][49][50]. Of greater interest are photoactive transition metal complexes that operate via alternative mechanism of action and which do not require O 2 for activity; these agents have the potential to be active against cisplatin-resistant cell lines and hypoxic tumours.…”

A Structurally Diverse RuII,PtII Tetrametallic Motif for Photoinitiated Electron Collection and Photocatalytic Hydrogen Production

“…[39] The redox and photophysical properties of [ 6 ) 2 (BL = dpp or bpm) are known DNA binding agents. [41][42][43][44][45][46] A tetrametallic Ru-Pt system, [Ru{(dpq)(PtCl 2 )} 3 ](PF 6 ) 2, , in which the Ru acts as the central atom bridging three Pt centers, has been reported. [47] The tetrametallic complex [{(bpy) 2 Ru(dpp)} 2 Ru-(dpp)PtCl 2 ](PF 6 ) 6 is demonstrated to be a multifunctional DNA binding and photocleavage agent.…”