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Bipyrimidine ruthenium(II) arene complexes : structure, reactivity and cytotoxicity
The synthesis and characterization of complexes [(Ρ6-arene)Ru(N,Nâ˛)X][PF6], where arene is para-cymene (p-cym), biphenyl (bip), ethyl benzoate (etb), hexamethylbenzene (hmb), indane (ind) or 1,2,3,4-tetrahydronaphthalene (thn), N,NⲠis 2,2â˛-bipyrimidine (bpm) and X is Cl, Br or I, are reported, including the X-ray crystal structures of [(Ρ6-p-cym)Ru(bpm)I][PF6], [(Ρ6-bip)Ru(bpm)Cl][PF6], [(Ρ6-bip)Ru(bpm)I][PF6] and [(Ρ6-etb)Ru(bpm)Cl][PF6]. Complexes in which N,NⲠis 1,10-phenanthroline (phen), 1,10-phenanthroline-5,6-dione or 4,7-diphenyl-1,10-phenanthroline (bathophen) were studied for comparison. The RuII arene complexes undergo ligand-exchange reactions in aqueous solution at 310 K; their half-lives for hydrolysis range from 14 to 715 min. Density functional theory calculations on [(Ρ6-p-cym)Ru(bpm)Cl][PF6], [(Ρ6-p-cym)Ru(bpm)Br][PF6], [(Ρ6-p-cym)Ru(bpm)I][PF6], [(Ρ6-bip)Ru(bpm)Cl][PF6], [(Ρ6-bip)Ru(bpm)Br][PF6] and [(Ρ6-bip)Ru(bpm)I][PF6] suggest that aquation occurs via an associative pathway and that the reaction is thermodynamically favourable when the leaving ligand is I > Br â Cl. pK a* values for the aqua adducts of the complexes range from 6.9 to 7.32. A binding preference for 9-ethylguanine (9-EtG) compared with 9-ethyladenine (9-EtA) was observed for [(Ρ6-p-cym)Ru(bpm)Cl][PF6], [(Ρ6-hmb)Ru(bpm)Cl]+, [(Ρ6-ind)Ru(bpm)Cl]+, [(Ρ6-thn)Ru(bpm)Cl]+, [(Ρ6-p-cym)Ru(phen)Cl]+ and [(Ρ6-p-cym)Ru(bathophen)Cl]+ in aqueous solution at 310 K. The X-ray crystal structure of the guanine complex [(Ρ6-p-cym)Ru(bpm)(9-EtG-N7)][PF6]2 shows multiple hydrogen bonding. Density functional theory calculations show that the 9-EtG adducts of all complexes are thermodynamically preferred compared with those of 9-EtA. However, the bmp complexes are inactive towards A2780 human ovarian cancer cells. Calf thymus DNA interactions for [(Ρ6-p-cym)Ru(bpm)Cl][PF6] and [(Ρ6-p-cym)Ru(phen)Cl][PF6] consist of weak coordinative, intercalative and monofunctional coordination. Binding to biomolecules such as glutathione may play a role in deactivating the bpm complexes
Oxygen non-stoichiometry in Ru-1212 and Ru-1222 magnetosuperconductors
Here we report the results of thermogravimetric (TG) analysis on the oxygen
non-stoichiometry of RuSr2GdCu2O8 (Ru-1212) and
RuSr2(Gd0.75Ce0.25)2Cu2O10(Ru-1222) samples. With TG annealings carried out in
O2 and Ar atmospheres it was found that the oxygen content in Ru-1212 remains
less affected upon various annealings, while for Ru-1222 wider-range
oxygen-content tuning is possible. When heated in H2/Ar atmosphere the both
phases release oxygen upon breaking down to mixtures of metals (Ru and Cu) and
binary oxides (CeO2, Gd2O3, and SrO) in two distinct steps around 300 and 450
oC. This reductive decomposition reaction carried out in a thermobalance was
utilized in precise oxygen content determination for these phases. It was found
that the 100-atm O2-annealed Ru-1212 sample was nearly stoichiometric, while
the similarly treated Ru-1222 sample was clearly oxygen deficient. X-ray
absorption near-edge (XANES) spectroscopy was applied to estimate the valence
of Ru in the samples. In spite of the fact that the Ru-1212 phase was shown to
possess less oxygen-deficient RuO2 layer, the valence of Ru as probed with
XANES was found to be lower in Ru-1212 than that in Ru-1222.Comment: 11 pages text, 4 pages Figs. To ISS 2002 YOKOHAMA for PHYSICA
Ruthenium and osmium carbonyl clusters incorporating stannylene and stannyl ligands
The reaction of [Ruâ (CO)ââ] with PhâSnSPh in refluxing benzene furnished the bimetallic Ru-Sn compound [Ruâ(CO)â(Îź-SPh)â(Îź3-SnPhâ)(SnPhâ)â] 1 which consists of a SnPhâ stannylene bonded to three Ru atoms to give a planar tetra-metal core, with two peripheral SnPhâ ligands. The stannylene ligand forms a very short bond to one Ru atom [Sn-Ru 2.538(1) Ă
] and very long bonds to the other two [Sn-Ru 3.074(1) Ă
]. The germanium compound [Ruâ(CO)â(Îź-SPh)â(Îźâ-GePhâ)(GePhâ)â] 2 was obtained from the reaction of [Ruâ (CO)ââ] with PhâGeSPh and has a similar structure to that of 1 as evidenced by spectroscopic data. Treatment of [Osâ(CO)ââ(MeCN)â] with PhâSnSPh in refluxing benzene yielded the bimetallic Os-Sn compound [Osâ(CO)â(Îź-SPh)(Îźâ-SnPhâ)(MeCN)(Ćš-CâHâ
)] 3. Cluster 3 has a superficially similar planar metal core, but with a different bonding mode with respect to that of 1. The PhâSn group is bonded most closely to Os(2) and Os(3) [2.7862(3) and 2.7476(3) Ă
respectively] with a significantly longer bond to Os(1), 2.9981(3) Ă
indicating a weak back-donation to the Sn. The reaction of the bridging dppm compound [Ruâ(CO)ââ(Îź-dppm)] with PhâSnSPh afforded [Ruâ(CO)â(Îź-dppm)(Îźâ-S)(Îźâ-SPh)(SnPhâ)] 5. Compound 5 contains an open triangle of Ru atoms simultaneously capped by a sulfido and a PhS ligand on opposite sides of the cluster with a dppm ligand bridging one of the Ru-Ru edges and a PhâSn group occupying an axial position on the Ru atom not bridged by the dppm ligand
Formation and structural chemistry of the unusual cyanide-bridged dinuclear species [Ru-2(NN)(2)(CN)(7)](3-)(NN=2,2 '-bipyridine or 1,10-phenanthroline)
Crystallisation of simple cyanoruthenate complex anions [Ru(NN)(CN)(4)](2) (NN = 2,2'-bipyridine or 1,10-phenanthroline) in the presence of Lewis-acidic cations such as Ln(III) or guanidinium cations results, in addition to the expected [Ru(NN)(CN)(4)](2) salts, in the formation of small amounts of salts of the dinuclear species [Ru-2(NN)(2)(CN)(7)](3). These cyanide-bridged anions have arisen from the combination of two monomer units [Ru(NN)(CN)(4)](2) following the loss of one cyanide, presumably as HCN. The crystal structures of [Nd(H2O)(5.5)][Ru-2(bipy)(2)(CN)(7)] center dot 11H(2)O and [Pr(H2O)(6)][Ru-2(phen)(2)(CN)(7)] center dot 9H(2)O show that the cyanoruthenate anions form Ru-CN-Ln bridges to the Ln(III) cations, resulting in infinite coordination polymers consisting of fused Ru(2)Ln(2)(mu-CN)(4) squares and Ru(4)Ln(2)(mu-CN)(6) hexagons, which alternate to form a one-dimensional chain. In [CH6N3](3)[Ru-2(bipy)(2)(CN)(7)] center dot 2H(2)O in contrast the discrete complex anions are involved in an extensive network of hydrogen-bonding involving terminal cyanide ligands, water molecules, and guanidinium cations. In the [Ru-2(NN)(2)(CN)(7)](3) anions themselves the two NN ligands are approximately eclipsed, lying on the same side of the central Ru-CN-Ru axis, such that their peripheries are in close contact. Consequently, when NN = 4,4'-Bu-t(2)-2,2'-bipyridine the steric bulk of the t-butyl groups prevents the formation of the dinuclear anions, and the only product is the simple salt of the monomer, [CH6N3](2)[Ru((t)Bu(2)bipy)(CN)(4)] center dot 2H(2)O. We demonstrated by electrospray mass spectrometry that the dinuclear by-product [Ru-2(phen)(2)(CN)(7)](3) could be formed in significant amounts during the synthesis of monomeric [Ru(phen)(CN)(4)](2) if the reaction time was too long or the medium too acidic. In the solid state the luminescence properties of [Ru-2(bipy)(2)(CN)(7)](3) (as its guanidinium salt) are comparable to those of monomeric [Ru(bipy)(CN)(4)](2), with a (MLCT)-M-3 emission at 581 nm
Spin-memory loss at Co/Ru interfaces
We have determined the spin-memory-loss parameter, , by
measuring the transmission of spin-triplet and spin-singlet Cooper pairs across
Co/Ru interfaces in Josephson junctions and by Current-Perpendicular-to-Plane
Giant Magnetoresistance (CPP-GMR) techniques. The probability of spin-memory
loss at the Co/Ru interface is . From the CPP-MR, we
obtain that is in good agreement with
obtained from spin-triplet transmission. For
spin-singlet transmission, we have that is
different from that obtained from CPP-GMR and spin-triplet transmission. The
source of this difference is not understood.Comment: 9 pages, 9 figure
Evolution of the electronic structure across the filling-control and bandwidth-control metal-insulator transitions in pyrochlore-type Ru oxides
We have performed photoemission and soft x-ray absorption studies of
pyrochlore-type Ru oxides, namely, the filling-control system
SmCaRuO and the bandwidth-control system
SmBiRuO, which show insulator-to-metal transition with
increasing Ca and Bi concentration, respectively. Core levels and the O 2
valence band in SmCaRuO show almost the same amount of
monotonous upward energy shifts with Ca concentration, which indicates that the
chemical potential is shifted downward due to hole doping. The Ru 4 band in
SmCaRuO is also shifted toward the Fermi level () with
hole doping and the density of states (DOS) at increases. The core levels
in SmBiRuO, on the other hand, do not show clear energy
shifts except for the Ru 3 core level, whose line shape change also reflects
the increase of metallic screening with Bi concentration. We observe pronounced
spectral weight transfer from the incoherent to the coherent parts of the Ru 4d
band with Bi concentration, which is expected for a bandwidth-control
Mott-Hubbard system. The increase of the DOS at is more abrupt in the
bandwidth-control SmBiRuO than in the filling-control
SmCaRuO, in accordance with a recent theoretical
prediction. Effects of charge transfer between the Bi 6 band and the Ru
4 band are also discussed.Comment: 11 pages, 6 figure
Fluorescein Redirects a RutheniumâOctaarginine Conjugate to the Nucleus
The cellular uptake and localization of a Ruâoctaarginine conjugate with and without an appended fluorescein are compared. The inherent luminescence of the Ru(II) dipyridophenazine complex allows observation of its uptake without the addition of a fluorophore. Ruâoctaarginineâfluorescein stains the cytosol, nuclei, and nucleoli of HeLa cells under conditions where the Ruâoctaarginine conjugate without fluorescein shows only punctate cytoplasmic labeling. At higher concentrations, however, Ruâoctaarginine without the fluorescein tag does exhibit cytoplasmic, nuclear, and nucleolar staining. Attaching fluorescein to Ruâoctaarginine lowers the threshold concentration required for diffuse cytoplasmic labeling and nuclear entry. Hence, the localization of the fluorophore-bound peptide cannot serve as a proxy for that of the free peptide
Photoactivatable organometallic pyridyl ruthenium(II) arene complexes
The synthesis and characterization of a family of piano-stool RuII arene complexes of the type [(Ρ6-arene)Ru(N,Nâ˛)(L)][PF6]2, where arene is p-cymene (p-cym), hexamethylbenzene (hmb), or indane (ind), N,NⲠis 2,2â˛-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), 4,4â˛-bipyridine (4,4â˛-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 [(Ρ6-p-cym)Ru(bpm)(4-MePy)]2+ (2), [(Ρ6-p-cym)Ru(bpm)(4-BzPy)]2+ (6), [(Ρ6-p-cym)Ru(bpm)(trz)]2+ (7), [(Ρ6-p-cym)Ru(phen)(Py)]2+ (10), and [(Ρ6-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 [(Ρ6-arene)Ru(N,Nâ˛)(OH2)]2+ that otherwise would not form in the dark. The photoproducts were characterized by UVâvis 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 RuII 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 RuII arene complexes [(Ρ6-p-cym)Ru(bpm)(Py)]2+ (1), [(Ρ6-p-cym)Ru(bpm)(4-MeOPy)]2+ (3), [(Ρ6-p-cym)Ru(4,4â˛-bpy)]2+ (4), [(Ρ6-hmb)Ru(bpm)(Py)]2+ (8), [(Ρ6-ind)Ru(bpm)(Py)]2+ (9), [(Ρ6-p-cym)Ru(phen)(Py)]2+ (10), [(Ρ6-p-cym)Ru(bathophen)(Py)]2+ (12), [(Ρ6-p-cym)Ru(bpm)(NA)]2+ (15), and [(Ρ6-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 9.0â60 ÎźM)
Effect of B-site Dopants on Magnetic and Transport Properties of LaSrCoRuO
Effect of Co, Ru and Cu substitution at B and B' sites on the magnetic and
transport properties of LaSrCoRuO have been investigated. All the doped
compositions crystallize in the monoclinic structure in the space group
indicating a double perovskite structure. While the magnetization and
conductivity increase in Co and Ru doped compounds, antiferromagnetism is seen
to strengthen in the Cu doped samples. These results are explained on the basis
of a competition between linear Co-O-Ru-O-Co and perpendicular Co-O-O-Co
antiferromagnetic interactions and due to formation of Ru-O-Ru ferromagnetic
networks
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