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The synthesis and characterization of complexes [(η-arene)Ru(N,N′)X][PF], where arene is para-cymene ( p-cym), biphenyl (bip), ethyl benzoate (etb), hexamethylbenzene (hmb), indane (ind) or 1,2,3,4-tetrahydronaphthalene (thn), N,N′ is 2,2′-bipyrimidine (bpm) and X is Cl, Br or I, are reported, including the X-ray crystal structures of [(η- p-cym)Ru(bpm)I][PF], [(η-bip)Ru(bpm)Cl][PF], [(η-bip)Ru(bpm)I][PF] and [(η-etb)Ru(bpm)Cl][PF]. Complexes in which N,N′ is 1,10-phenanthroline (phen), 1,10-phenanthroline-5,6-dione or 4,7-diphenyl-1,10-phenanthroline (bathophen) were studied for comparison. The Ru 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 [(η- p-cym)Ru(bpm)Cl][PF], [(η- p-cym)Ru(bpm)Br][PF], [(η- p-cym)Ru(bpm)I][PF], [(η-bip)Ru(bpm)Cl][PF], [(η-bip)Ru(bpm)Br][PF] and [(η-bip)Ru(bpm)I][PF] suggest that aquation occurs via an associative pathway and that the reaction is thermodynamically favourable when the leaving ligand is I > Br ≈ Cl. p K* 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 [(η- p-cym)Ru(bpm)Cl][PF], [(η-hmb)Ru(bpm)Cl], [(η-ind)Ru(bpm)Cl], [(η-thn)Ru(bpm)Cl], [(η- p-cym)Ru(phen)Cl] and [(η- p-cym)Ru(bathophen)Cl] in aqueous solution at 310 K. The X-ray crystal structure of the guanine complex [(η- p-cym)Ru(bpm)(9-EtG- N7)][PF] 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 [(η- p-cym)Ru(bpm)Cl][PF] and [(η- p-cym)Ru(phen)Cl][PF] consist of weak coordinative, intercalative and monofunctional coordination. Binding to biomolecules such as glutathione may play a role in deactivating the bpm complexes. [ABSTRACT FROM AUTHOR]

A series of cationic dinuclear p-cymene ruthenium trithiophenolato complexes of the type [(η- p-MeCHPr)Ru(SCH- p-X)] ( 1 X is H, 2 X is Me, 3 X is Ph, 4 X is Br, 5 X is OH, 6 X is NO, 7 X is OMe, 8 X is CF, 9 X is F, 10 X is Pr, 11 X is Bu) have been synthesized from the reaction of [(η- p-MeCHPr)RuCl] with the corresponding thiol, isolated as the chloride salts, and further studied for their electrochemical properties, cytotoxicity towards human ovarian cancer cells, and catalytic activity for glutathione (GSH) oxidation. Complex 1 was also compared with the benzene and hexamethylbenzene analogues [(η-CH)Ru(SCH)] ( 12) and [(η-CMe)Ru(SCH)] ( 13). The most active compound [ 11]Cl was structurally studied by single-crystal X-ray diffraction analysis. The concentrations corresponding to 50 % inhibition of cancer cell growth (IC values) in the A2780 and A2780cisR cell lines of these complexes except for 6 were in the submicromolar range, complex 11 showing an IC value of 0.03 µM in both cell lines. The high in vitro anticancer activity of these complexes may be at least partially due to their catalytic potential for the oxidation of GSH, although there is no clear correlation between the IC values and the turnover frequencies at about 50 % conversion. However, the cytotoxicity is tentatively correlated to the physicochemical properties of the compounds determined by the electronic influence of the substituents X (Hammett constants σ) and the lipophilicity of the thiols p-XCHSH (calculated log P parameters). [ABSTRACT FROM AUTHOR]

The structure and spectral properties of two organic ruthenium complexes used as sensitizing dyes for solar batteries (well-known N3 dye and its selenophene-conjugated analogue C105 ([Ru(bpy)(bpysef)(COOH)(NCS)] (bpy = 2,2′-bipyridine, bpysef = 4,4′-bis(5-hexylselenophene-2-yl)2,2′-bipyridine)) are comparatively studied within the density functional method. It is shown that the conjugation of the bipyridine ligand with selenophene affects the electronic structure of the C105 dye. A multilevel model for interpreting the electronic spectra of dyes is proposed based on the analysis of the shapes of molecular orbitals. The nature of the absorption bands of these ruthenium complexes in the region of 300-800 nm is explained. It is found that, in the polar acetonitrile solvent, these dyes are negatively solvatochromic, which agrees with the current classical views on the effect of the solvent on the shape of electronic absorption spectra of related compounds. [ABSTRACT FROM AUTHOR]