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- η6-(2-phenoxyethanol) ruthenium(II)-complexes of 2,2′-bipyridine and its derivatives: Solution speciation and kinetic behaviourPublication . Nogueira, Guilherme; Domotor, Orsolya; Pilon, Adhan; Robalo, Maria Paula; Avecilla, Fernando; Garcia, M. Helena; Enyedy, Eva Anna; Valente, AndreiaA novel family of Ru-II-arene compounds with the general formula of [Ru-II(eta(6)-(2-phenoxyethanol))(L) Cl](+) (L: 2,2'-bipyridine (bpy) (3), 4,4'-dimethyl-2,2'-bipyridine (4) and 4,4'-diyldimethanol-2,2'-bipyridine (5)) was synthesized and characterized by standard spectroscopic and analytical methods. Complex 3 was further studied by single-crystal X-ray diffraction analysis, showing a pseudo octahedral geometry and strong pi-pi lateral stacking interactions in the crystal packing. Effect of the substituents on the electrochemical properties and on the aqueous solution stability was monitored by cyclic voltammetry, UV-Vis and H-1 NMR spectroscopy. Complexes 3-5 presented multiple irreversible redox processes according to their cyclic voltammograms recorded in acetonitrile, and their Ru-II/Ru-III oxidation peaks were found at ca. +1.6 V. Hydrolysis of the binuclear [Ru-II(eta(6)-(2-phenoxyethanol))(mu(2)-Cl)Cl](2) precursor (1) resulted in binuclear hydroxido bridged species [(Ru-II(eta(6)-(2-phenoxyethanol)))(2)(mu-OH)(3)](+) and [(Ru-II(eta(6)-(2-phenoxyethanol)))(2)(mu-OH)(2)Z(2)] (Z = H2O/Cl-) in the presence of chloride ions in water. The hydrolytic behaviour of this Ru-II precursor is similar to that of the analogous species [Ru-II(eta(6)-p-cymene)(mu(2)-Cl)Cl](2) regarding the hydrolysis products and their stability constants. Formation of complexes 3 -5 by reaction of the Ru-II precursor with the (N, N) bidentate ligands was found to be relatively slow in aqueous solution. The complexation is complete already at pH 1 due to the formation of [Ru-II(eta(6)-(2-phenoxyethanol))(L)Z] complexes of significantly high stability in all cases, which are predominant species up to pH 6. However, besides the formation of the mixed hydroxido species [Ru-II(eta(6)-(2-phenoxyethanol))(L)(OH)] + at neutral and basic pH values, the slow oxidation of the RuII centre takes place as well leading to the partial loss of the arene moiety. The rate of these processes depends on the pH and its maximum was found at pH 8-9. Additionally the chlorido/aqua co-ligand exchange processes of the [Ru-II(eta(6)-(2-phenoxyethanol))(L)Cl](+) species were also monitored and only similar to 5% of the chlorido ligand was found to be replaced by water in 0.1 M chloride ion containing aqueous solutions at pH 5.
- Methyl-cyclopentadienyl ruthenium compounds with 2,2 '-bipyridine derivatives display strong anticancer activity and multidrug resistance potentialPublication . Côrte-Real, Leonor; Gonçalves Teixeira, Ricardo; Girio, Patrícia; Comsa, Elisabeta; MORENO, Alexis; Nasr, Rachad; Baubichon-Cortay, Helene; Avecilla, Fernando; Marques, Fernanda; Robalo, Maria Paula; Mendes, Paulo; Prates Ramalho, João P.; Garcia; Falson, Pierre; Valente, AndreiaNew ruthenium methyl-cyclopentadienyl compounds bearing bipyridine derivatives with the general formula [Ru(eta(5)-MeCp)(PPh3)(4,4'-R-2,2'-bpy)](+) (Ru1, R = H; Ru2, R = CH3; and Ru3, R = CH2OH) have been synthesized and characterized by spectroscopic and analytical techniques. Ru1 crystallized in the monoclinic P2(1)/c, Ru2 in the triclinic P (1) over bar, and Ru3 in the monoclinic P2(1)/n space group. In all molecular structures, the ruthenium center adopts a "piano stool" distribution. Density functional theory calculations were performed for all complexes, and the results support spectroscopic data. Ru1 and Ru3 were poor substrates of the main multidrug resistance human pumps, ABCB1, ABCG2, ABCC1, and ABCC2, while Ru2 displayed inhibitory properties of ABCC1 and ABCC2 pumps. Importantly, all compounds displayed a very high cytotoxic profile for ovarian cancer cells (sensitive and resistant) that was much more pronounced than that observed with cisplatin, making them very promising anticancer agents.
- Novel ruthenium methylcyclopentadienyl complex bearing a bipyridine perfluorinated ligand shows strong activity towards colorectal cancer cellsPublication . Gonçalves Teixeira, Ricardo; Brás, Ana Rita; Côrte-Real, Leonor; Tatikonda, Rajendhraprasad; Sanches, Anabela; Robalo, Maria Paula; Avecilla, Fernando; Moreira, Tiago; Garcia, M. Helena; Haukka, Matti; Preto, Ana; Valente, AndreiaThree new compounds have been synthesized and completely characterized by analytical and spectroscopic techniques. The new bipyridine-perfluorinated ligand L1 and the new organometallic complex [Ru(η5-MeCp)(PPh3)2Cl] (Ru1) crystalize in the centrosymmetric triclinic space group P
1¯. Analysis of the phenotypic effects induced by both organometallic complexes Ru1 and [Ru(η5-MeCp)(PPh3)(L1)][CF3SO3] (Ru2), on human colorectal cancer cells (SW480 and RKO) survival, showed that Ru2 has a potent anti-proliferative activity, 4–6 times higher than cisplatin, and induce apoptosis in these cells. Data obtained in a noncancerous cell line derived from normal colon epithelial cells (NCM460) revealed an intrinsic selectivity of Ru2 for malignant cells at low concentrations, showing the high potential of this compound as a selective anticancer agent. - New iron(II) cyclopentadienyl derivative complexes: synthesis and antitumor activity against human leucemia cancer cellsPublication . Valente, Andreia; Santos, Ana Margarida; Côrte-Real, Leonor; Robalo, Maria Paula; Moreno, Virtudes; Font-Bardia, Merce; Calvet, Teresa; Lorenzo, Julia; Garcia, M. HelenaA new family of "Fe-II(eta(5)-C5H5)" half sandwich compounds bearing a N-heteroaromatic ligand coordinated to the iron center by a nitrile functional group has been synthesized and fully characterized by NMR and UV-Vis spectroscopy. X-ray analysis of single crystal was achieved for complexes 1 and 3, which crystallized in the monoclinic P2(1)/c and monoclinic P2(1)/n space groups, respectively. Studies of interaction of these five new complexes with plasmid pBR322 DNA by atomic force microscopy showed very strong and different types of interaction. Antiproliferative tests were examined on human leukemia cancer cells (HL-60) using the MTT assay, and the IC50 values revealed excellent antiproliferative activity compared to cisplatin. (C) 2014 Elsevier B.V. All rights reserved.
- Ruthenium carboranyl complexes with 2,2 '-bipyridine derivatives for potential bimodal therapy applicationPublication . Gonçalves Teixeira, Ricardo; Marques, Fernanda; Robalo, M. Paula; Fontrodona, Xavier; Garcia, M. Helena; Geninatti Crich, Simonetta; Vinas, Clara; Valente, AndreiaRuthenium complexes of carboranyl ligands offer the possibility of dual action (chemo + radiotherapy) that might result in significant clinical benefits. In that frame, we describe herein the development of ruthenium-carboranyl complexes bearing bipyridyl derivatives with the general formula [3-CO-3,3-{kappa(2)-4,4 '-R-2-2,2 '-bipy}-closo-3,1,2-RuC2B9H11] (R = CH3,RuCB1or R = CH2OH,RuCB2). Both compounds crystallized in the monoclinic system, showing the expected three-legged piano stool structure. The ruthenacarboranes are stable in cell culture media and were tested against two cell lines that have shown favorable clinical responses with BNCT, namely melanoma (A375) and glioblastoma (U87).RuCB1shows no cytotoxic activity up to 100 mu M whileRuCB2showed moderate activity for both cell lines. Cell distribution assays showed thatRuCB2presents high boron internalization that is proportional to the concentration used indicating thatRuCB2presents features to be further studied as a potential anticancer bimodal agent (chemo + radiotherapy).