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- Microwave-assisted peroxidative oxidation of toluene and 1-phenylethanol with monomeric keto and polymeric enol aroylhydrazone Cu(II) complexesPublication . Sutradhar, Manas; Alegria, Elisabete; Roy Barman, Tannistha; Scorcelletti, Francesco; Guedes Da Silva, M. Fátima C.; Fatima, C.; Pombeiro, ArmandoCu(II) complexes in two different tautomeric forms (keto and enol) derived from the aroylhydrazone Schiff base 2-hydroxy(2-hydroxybenzylidene)benzohydrazide (H2L) have been synthesized and characterized by elemental analysis, IR spectroscopy, ESI-MS and single crystal X-ray crystallography. While the compound with the enol form of the ligand exists as the 1D polymer [Cu(kappa KNOO',2 kappa O',3 kappa O"-L)](n) (1), that with the keto form of the ligand occurs as the monomer [Cu(KNOO'-HL)CI(CH3OH)] (2). Both complexes act as good catalysts for the microwave-assisted peroxidative oxidation of toluene and 1-phenylethanol with tert-butyl hydroperoxide. Complex 2 exhibits the highest activity in both reactions, leading selectively to,a maximum product yield of 39 and 92%, respectively.
- Catalytic oxidation of a model volatile organic compound (toluene) with tetranuclear Cu(II) complexesPublication . Sutradhar, Manas; Alegria, Elisabete; Roy Barman, Tannistha; Lapa, Hugo; Guedes Da Silva, M. Fátima C.; Pombeiro, ArmandoA tetranuclear Cu(II) cubane [Cu-2(mu-1 kappa ONO':2 kappa OO':3 kappa O-HL)(mu-1 kappa ONO':2 kappa OO'-HL)](2).4dmf (1) derived form (2,3-dihydroxybenzylidene)-2-hydroxybenzohydrazide (H3L) was synthesized at room temperature and characterized by elemental analysis, IR spectroscopy, ESI-MS and single crystal X-ray diffraction. The known tetranuclear Cu(II) open-cubane [Cu(HL)](4).4EtOH (2) was synthesized from the same pro-ligand following a similar method or the reported one. The different tautomeric forms (keto and enol) of the organic ligands in 1 and 2 explain their different structural features. Both complexes were screened as catalysts for the peroxidative oxidation of toluene with tert-butyl hydroperoxide, achieving benzaldehyde and o-cresol as the main products. Complex 1 exhibits the highest activity (maximum product yield of 11%).
- Oxidovanadium complexes with tridentate aroylhydrazone as catalyst precursors for solvent-free microwave-assisted oxidation of alcoholsPublication . Sutradhar, Manas; Martins, Luisa; Silva, Maria de Fátima C. Guedes da; Pombeiro, ArmandoAroylhydrazone oxidovanadium compounds, viz, the oxidoethoxidovanadium(V) [VO(OEt)L1] (1) (H2L =salicylaldehyde-2-hydroxybenzoylhydrazone), the salt like dioxidovanadium(V) (NH3CH2CH2OH)(+) [VO2L](-) (2), the mixed-ligand oxidovanadium(V) [VO(hq)L](Hhq = 8-hydroxyquinoline) (3) and the vanadium(IV) [VO(phen)L] (phen=1,10-phenanthroline) (4) complexes (3 and 4 obtained by the first time), have been tested as catalysts for solvent-free microwave-assisted oxidation of aromatic and alicyclic secondary alcohols with tert-butylhydroperoxide. A facile, efficient and selective solvent-free synthesis of ketones was achieved with yields up to 99% (TON= 497, TOF= 993 h(-1) for 3) and 58% (TON =291, TOF= 581 h(-1) for 2) for acetophenone and cyclohexanone, respectively, after 30 min under low power (25W) microwave irradiation. (C) 2015 Elsevier B.V. All rights reserved.
- Antiproliferative activity of heterometallic sodium and potassium-dioxidovanadium(V) polymersPublication . Sutradhar, Manas; Alegria, Elisabete; Ferretti, Francesco; Raposo, Luís R; Guedes Da Silva, M. Fátima C.; Baptista, Pedro; Fernandes, Alexandra; Pombeiro, ArmandoThe syntheses of the heterometallic sodium and potassium-dioxidovanadium 2D polymers, [NaVO2(1 kappa NOO';2 kappa O ''-L)(H2O)](n), (1) and [KVO2(1 kappa NOO';2 kappa O';3 kappa O ''-L)(EtOH)](n) (2) (where the kappa notation indicates the coordinating atoms of the polydentate ligand L) derived from (3,5-di-tert-butyl-2-hydroxybenzylidene)-2-hydroxybenzohydrazide (H2L) are reported. The polymers were characterized by IR, NMR, elemental analysis and single crystal X-ray diffraction analysis. The antiproliferative potential of 1 and 2 was examined towards four human cancer cell lines (ovarian carcinoma, A2780, colorectal carcinoma, HCT116, prostate carcinoma, PC3 and breast adenocarcinoma, MCF-7cell lines) and normal human fibroblasts. Complex 1 and 2 showed the highest cytotoxic activity against A2780 cell line (IC50 8.2 and 11.3 mu M, respectively) with 1 > 2 and an IC50 in the same range as cisplatin (IC50 3.4 mu M; obtained in the same experimental conditions) but, interestingly, with no cytotoxicity to healthy human fibroblasts for concentrations up to 75 mu M. This high cytotoxicity of 1 in ovarian cancer cells and its low cytotoxicity in healthy cells demonstrates its potential for further biological studies. Our results suggest that both complexes induce ovarian carcinoma cell death via apoptosis and autophagy, but autophagy is the main biological cause of the reduction of viability observed and that ROS (reactive oxygen species) may play an important role in triggering cell death.