Ruthenium

A novel bridged binuclear Cu(II) complex with mixed ligands, di-μ-(2-aminopyridine(N,N′))-bis[(2,6-pyridinedicarboxylate)aquacopper(II)] tetrahydrate, formulated as [Cu(μ-ap)(dipic)(H2O)]2·4H2O (1) (dipic = 2,6-pyridinedicarboxylate, ap = 2-aminopyridine), has been synthesized and characterized by elemental, spectral (IR and UV–Vis.), thermal analysis, magnetic measurements and single crystal X-ray diffraction analysis. The central Cu(II) ion resides on a centre of symmetry in a distorted square-pyramid coordination environment comprising of two N atoms, one from dipic and one from the ap ring, two carboxylate O atoms from dipic, and one O atom from water. Intermolecular N–H⋯O and O–H⋯O hydrogen bonds and π–π stacking interactions seem to be effective in the stabilization of the crystal structure. The free ligands and the complex were also evaluated for their antimicrobial and radical scavenging activities (DPPH = 1,1-diphenyl-2-picrylhydrazyl hydrate) using in vitro microdilution methods. Antimicrobial screening of the free ligands and their complex showed that the free ligands and the complex possess antifungal activity against Candida sp.

We report on the synthesis of novel Ru(II) compounds (Ru-1 to Ru-8) bearing R-pdc, 4-Cl-pbinh ligands (where R=4-CF3, 4-F, 4-OH pdc=3-phenyl-5-(1H-pyrrol-2-yl)-4,5-dihydro-1H-pyrazole-1-carbothioamide, pbinh=phenoxybenzylidene isonicotinyl hydrazides) and their in vitro antitumor activity toward the cell lines murine leukemia L1210, human lymphocyte CEM, human epithelial cervical carcinoma HeLa, BEL-7402 and Molt4/C8. Some of the complexes exhibited more potent antiproliferative activity against cell lines than the standard drug cisplatin. Ruthenium complex Ru-2 displayed potent cytotoxicity with than that of cisplatin. DNA-binding, DNA cleavage and protein binding properties of ruthenium complexes with these ligands are reported. Interactions of these ruthenium complexes with DNA revealed an intercalative mode of binding between them. Synchronous fluorescence spectra proved that the interaction of ruthenium complexes with bovine serum albumin (BSA) resulted in a conformational change of the latter.

A series of mononuclear Ru(II) complexes of the type [Ru(S)(2)(K)](2+), where S = 1,10-phenanthroline/2,2'-bipyridine and K = 4-OH-btsz, 4-CH(3)-btsz, 3,4-di-OCH(3)-btsz, 4-OH-binh, 4-CH(3)-binh, 3,4-di-OCH(3)-binh, were prepared and characterized by elemental analysis, FTIR, (1)H-NMR, and mass spectroscopy. The complexes displayed metal-ligand charge transfer (MLCT) transitions in the visible region. These ligands formed bidentate octahedral ruthenium complexes. The title complexes were evaluated for their in vivo anticancer activity against a transplantable murine tumor cell line, Ehrlisch's ascites carcinoma (EAC), and in vitro cytotoxic activity against human cancer cell lines Molt 4/C(8) and CEM and murine tumor cell line L1210. The ruthenium complexes showed promising biological activity especially in decreasing tumor volume and viable ascites cell counts. Treatment with these complexes prolonged the life span of mice bearing EAC tumors by 10-52%. In vitro evaluation of these ruthenium complexes revealed cytotoxic activity from 0.21 to 24 muM against Molt 4/C(8), 0.16 to 19 microM against CEM, and 0.75 to 32 microM against L1210.

The synthesis and characterization of ruthenium compounds (Ru1-Ru12) of the type [Ru(S)(2)(K)], (where S=1,10-phenanthroline/2,2'-bipyridine and K=itsz, MeO-btsz, 4-Cl-btsz, 2-Cl-btsz, 2-F-btsz, hfc and itsz=isatin-3-thiosemicarbazone, MeO-btsz=1-(4'-methoxy-benzyl)-thiosemicarbazone, hfc=2-{[3-chloro-4-fluoro-phenylimino]methyl}phenol, 4-Cl-btsz=1-(4'-chlorobenzyl)-thiosemicarbazone, 2-Cl-btsz=1-(2'-chloro benzyl)-thiosemicarbazone, 2-F-btsz=1-(2'-fluorobenzyl)-thiosemicarbazone) are described. These ligands form bidentate octahedral ruthenium compounds. The title compounds were subjected to in vivo anticancer activity against a transplantable murine tumor cell line Ehrlich's Ascites Carcinoma (EAC) and in vitro cytotoxic activity against human cancer cell line Molt 4/C8, CEM and murine tumor cell line L1210. Ruthenium compounds (Ru1-Ru12) showed promising biological activity especially in decreasing tumor volume and viable ascites cell counts. Treatment with these compounds prolonged the life span of mice bearing EAC tumor by 10-43%. In vitro evaluation of these ruthenium compounds revealed cytotoxic activity from 0.24 to 27 microM against Molt 4/C8, 0.27 to 48 microM against CEM, and 0.94 to 248 microM against L1210. Their ligands alone failed to show cytotoxic activity at the concentrations tested (68-405 microM).

The productivity of an iron-based Fischer Tropsch (FT) process strongly depends on the synthesis gas conversion. However, iron is known to oxidize significantly at high CO conversion due to the high reactor water partial pressures. In commercial iron-based FT plant this necessitate operation at low single pass conversion, resulting in high separation and recycling cost of the tail gas and the overall economics of the process. Ruthenium has been reported to demonstrate significant stability in the presence of water, hence the employment of FT catalyst promoted with Ru is expected to permit high CO conversion. In this study the stability of an industrial Fe-based FT catalyst impregnated with ruthenium is investigated. The reactions were carried out at industrially relevant conditions in a 1 dm 3 slurry reactor at 250 C and 20 bar. It was noted that the Fe promoted with Ru was more stable at high CO conversion implying a significant resistance to deactivation in the presence of water. ...

The molecular and electronic structures, stabilities, bonding features, and spectroscopic properties of prototypical ligand stabilized [cyclo-Ru3(μ2-X)3]0,3+ (X = H, BH, CH2, NH2, OH, Cl, NH, CO, O, PH2, CF2, CCl2, CNH, N3) isocycles have been thoroughly investigated by means of electronic structure calculation methods at the DFT level of theory. All [cyclo-Ru3(μ2-X)3]0,3+ species, except [cyclo-Ru3(μ2-H)3]3+, are predicted to be aromatic molecules. In contrast, the [cyclo-Ru3(μ2-H)3]3+ species exhibits a high antiaromatic character, which would be responsible for the well-established peculiar reaction field of hydrido-bridged triruthenium core structures. The aromaticity/antiaromaticity of the model [cyclo-Ru3(μ2-X)3]0,3+ isocycles was verified by an efficient and simple criterion in probing the aromaticity/antiaromaticity of a molecule, that of the nucleus-independent chemical shift, NICS(0), NICS(1), NICS(−1), NICSzz(1), and NICSzz(−1), along with the NICS scan profiles. The versatile chemical reactivity of the antiaromatic [cyclo-Ru3(μ2-H)3]3+ molecule related to the activation of small molecules that leads to the breaking of various strong single and double bonds is thoroughly investigated by means of electronic structure computational techniques, and the mechanistic details for a representative activation process, that of the dehydrogenation of NH3, to form a triply bridging imido-group (μ3-NH) face-capping the Ru3 ring are presented. Finally, the molecular and electronic structures, stabilities, and bonding features of a series of [cyclo-Ru3(μ2-H)3(μ3-Nuc)]0,1,2+ (Nuc = BH, BCN, BOMe, C4-, CH3-, CMe3-, N3-, NH, N3-, NCO-, OCN-, NCS-, O2-, S2-, OH-, P3-, POH2-, Cl-, O22-, NCH, AlMe, GaMe, C6H6, and cyclo-C3H2Me) products formed upon reacting the archetype [cyclo-Ru3(μ2-H)3]3+ molecule with the appropriate substrates are also comprehensibly analyzed.

The new ligand 4-(isopropylbenzaldehyde)imidazo[4,5-f ][1,10]phenanthroline (ippip) and its complexes [Ru(phen)2(ippip)]2+(1),[Co(phen)2(ippip)]3+(2),[Ru(bpy)2(ippip)]2+(3),[Co(bpy)2(ippip)]3+(4)(bpy=2,2-bipyridine) and (phen=1,10-phenanthroline) were synthesized and characterized by ES+-MS, 1H and 13C NMR. The DNA binding properties of the four complexes were investigated by different spectrophotometric methods and viscosity measurements. The results suggest that complexes bind to calf thymus DNA (CT-DNA) through intercalation. When irradiated at 365 nm, the complexes promote the photocleavage of pBR322 DNA, and complex 1 cleaves DNA more effectively than 2, 3, 4 complexes under comparable experimental conditions. Furthermore, photocleavage studies reveal that singlet oxygen (1O2) plays a significant role in the photocleavage.