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Fandos R.,University of Castilla - La Mancha | Fernandez-Gallardo J.,University of Castilla - La Mancha | Otero A.,Organica y Bioquimica | Rodriguez A.,University of Castilla - La Mancha | Ruiz M.J.,University of Castilla - La Mancha
Organometallics | Year: 2010

A series of new cationic aminocarbene tantalum complexes have been synthesized and characterized. A significant contribution of the anion-cation interaction to the stability of the cationic moiety has been revealed. The complexes with a triflate or chloride counterion are very stable, even in air, while the corresponding tetraphenylborate derivatives are very unstable species. This stabilizing behavior can be explained by the establishment of hydrogen bonds between the electronegative atoms of the anion and the amine and hydroxyl protons of the cation. The presence of the hydrogen bonds has been detected by spectroscopic and structural techniques. © 2010 American Chemical Society.


Cayuela A.,University of Cordoba, Spain | Soriano M.L.,University of Cordoba, Spain | Carrion M.C.,Organica y Bioquimica | Valcarcel M.,University of Cordoba, Spain
Analytica Chimica Acta | Year: 2014

This paper reports the synthesis, passivation and functionalization of luminescent carbon dots (CDs) possessing surface thiol ending groups. A simple procedure involving amidation of passivated carbon dots (p-CDs) with cysteamine boosts their photoluminescent properties and enables their use as easily controlled fluorescent nanosensors for determining citrate-gold nanoparticles (AuNPs). The mechanism behind the quenching phenomenon was established from fluorescence measurements at high temperatures and lifetime tests, and found to involve static quenching leading to the formation of CD-AuNP nanohybrids. A method for determining AuNPs in complex matrices was developed and validated by application to spiked drinking water and mussel tissues. The limits of detection and quantitation for AuNPs thus obtained were 0.20 and 0.66nmolL-1, respectively. © 2014 Elsevier B.V.


Fandos R.,Organica y Bioquimica | Hernandez C.,Organica y Bioquimica | Otero A.,Organica y Bioquimica | Rodriguez A.,University of Castilla - La Mancha | And 4 more authors.
Inorganica Chimica Acta | Year: 2011

The reaction of [TiCp*Cl3] with [Fe(η5- C5H5)(η5-C5H4COOH)] in the presence of NEt3 yields [TiCp*{(OOC-C5H 4)FeCp}3] (1), (Cp = η5-C5H 5). The alkyl complex [TiCp*Me3] reacts with [FeCp(η5-C5H4-CH2COOH)] or anthranilic acid rendering the tris-carboxylate titanium complexes [TiCp*{(OOCCH2-C5H4)FeCp}3] (2) and [TiCp*{(OOCC6H4NH2)3] (3), respectively. Complex 3 can be protonated with triflic acid to render [TiCp*{(OOCC6H4NH2)3].HOTf (4). The reaction of [TiCp*Me3] with anthranilic acid in a 1:2 M ratio yields the alkyl carboxylate derivative [TiCp*Me{(OOCC 6H4NH2)2] (5). Complex 5 reacts with tBuNC to render the iminoacyl complex [TiCp*(η2-MeCNtBu){(OOCC6H4NH 2)2] (6). The reaction of [TiCp*Cl3] with the ferroceneacetic acid, gives [TiCp*Cl2{(OOCCH 2-C5H4)FeCp}] (7). The [TiCp*Cl] 2(μ-O)[(ΟΟC-C5H4) 2Fe] (8) can be obtained by reaction of [TiCp*Cl3] with [Fe(η5-C5H4-COOH)2] in the presence of a base. The molecular structures of 1 and 8 have been established by X-ray diffraction methods. © 2010 Elsevier B.V. All rights reserved.


Carrion M.C.,Organica y Bioquimica | Ruiz-Castaneda M.,Organica y Bioquimica | Espino G.,University of Burgos | Aliende C.,University of Burgos | And 5 more authors.
ACS Catalysis | Year: 2014

The new complex [(η6-p-cym)RuCl(κ2-N,N- dmbpy)](BF4) (p-cym = p-cymene; dmbpy = 4,4′-dimethyl-2, 2′-bipyridine) is water-soluble and active in the catalytic transfer hydrogenation (TH) of different ketones (cyclohexanone, 2-cyclohexenone, and 3-pentanone) to the corresponding alcohols using aqueous HCOONa/HCOOH as the hydrogen source at pH 4.4. A higher activity was found for the TH of the imine N-benzylideneaniline under the same conditions. Excellent results have been obtained for catalyst recycling. Aqua, formato, and hydrido species were detected by 1H NMR experiments in D2O. Importantly, when the catalytic reaction was carried out in D2O, selective deuteration at the Cα of the alcohols was observed due to a rapid Ru-H/D+ exchange, which was also deduced theoretically. This process involves a reversal of polarity of the D+ ion, which is transformed into a Ru-D function ("umpolung"). Negligible deuterium labeling was observed for the imine, possibly due to the high activity in the TH process and also to the decrease in the hydrido complex concentration due to the stability of a hydrido-imine intermediate. Both facts should ensure that the TH reaction will compete favorably with the Ru-H/D+ exchange. The basic nature of the imine hydrogenation product can also hinder the stated Ru-H/D+ exchange. On the basis of DFT calculations, all these hypotheses are discussed. In addition, calculations at this level also support the participation of the stated aqua, formato, and hydrido intermediates in the catalytic reaction and provide a detailed microscopic description of the full catalytic cycle. In the case of the imine TH process, the formation of the hydrido complex (decarboxylation step) is clearly the limiting step of the cycle. On the contrary, in the hydrogenation of cyclohexanone, both decarboxylation and reduction steps exhibit similar barriers, and due to the limitations of the solvent model employed, a definitive conclusion on the rate-determining step cannot be inferred. © 2014 American Chemical Society.


Garcia-Cano J.,University of Castilla - La Mancha | Ambroise G.,University Paris - Sud | Pascual-Serra R.,University of Castilla - La Mancha | Carrion M.C.,Organica y Bioquimica | And 10 more authors.
Oncotarget | Year: 2015

Resistance to cisplatin is a major challenge in the current cancer therapy. In order to explore new therapeutic strategies to cisplatin resistance, we evaluated, in a model of lung cancer (H1299 and H460 cell lines), the nature of the pathways leading to cell death. We observed that H1299 displayed a natural resistance to cisplatin due to an inability to trigger an apoptotic response that correlates with the induction of autophagy. However, pharmacological and genetic approaches showed how autophagy was a mechanism associated to cell death rather than to resistance. Indeed, pro-autophagic stimuli such as mTOR or Akt inhibition mediate cell death in both cell lines to a similar extent. We next evaluated the response to a novel platinum compound, monoplatin, able to promote cell death in an exclusive autophagy-dependent manner. In this case, no differences were observed between both cell lines. Furthermore, in response to monoplatin, two molecular hallmarks of cisplatin response (p53 and MAPKs) were not implicated, indicating the ability of this pro-autophagic compound to overcome cisplatin resistance. In summary, our data highlight how induction of autophagy could be used in cisplatin resistant tumours and an alternative treatment for p53 mutated patient in a synthetic lethally approach.

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