Synthesis and Characterization of Water Stable η3-Allyl Dicarbonyl Complexes of Molybdenum(II)

Trabalho apresentado nas VIII Jornadas CICECO, 18-19 de março 2011, Aveiro, PortugalN/

Arsenite oxidase in complex with antimonite and arsenite oxyanions - insights into the catalytic mechanism

Arsenic contamination of groundwater is among one of the biggest health threats affecting millions of people in the world. There is an urgent need for efficient arsenic biosensors where the use of arsenic metabolizing enzymes can be explored. In this work we have solved the crystal structures of four complexes of arsenite oxidase (Aio) obtained in complex with arsenic and antimony oxyanions and the structures determined correspond to intermediate states of the enzymatic mechanism. These structural data were complemented with DFT calculations providing a unique view of the molybdenum active site at different time points that, together with mutagenesis data, enabled to clarify the enzymatic mechanism and the molecular determinants for the oxidation of As(III) to the less toxic As(V) species

Gauge and Yukawa Unification with Broken R-Parity

We study gauge and Yukawa coupling unification in the simplest extension of the Minimal Supersymmetric Standard Model (MSSM) which incorporates R-Parity violation through a bilinear superpotential term. Contrary to what happens in the MSSM, we show that bottom-tau unification at the scale M_GUT where the gauge couplings unify can be achieved for any value of tan(beta) by choosing appropriately the sneutrino vacuum expectation value. In addition, we show that bottom-tau-top unification occurs in a slightly wider tan(beta) range than in the MSSM.Comment: 9 pages, including one figure. Late

Synthesis, Characterization and Catalytic application of Water Stable η3-Allyl Dicarbonyl Complexes of Molybdenum(II)

Trabalho apresentado em EuropaCat X – Catalysis across disciplines, 28 Aug - 02 Sep 2011, Glasgow, ScotlandN/

Efficient isomerization of α-pinene oxide to campholenic aldehyde promoted by a mixed-ring analogue of molybdenocene

The MoIV complex [(eta5-indenyl)(eta5-cyclopentadienyl)Mo(MeCN)2](BF4)2 (1) has been used to promote two acid-catalyzed epoxide ring-opening reactions under ambient conditions. The alcoholysis of styrene oxide in neat ethanol gave 2-ethoxy-2-phenylethanol in quantitative yield within 10 min. The use of an ionic liquid (IL) as cosolvent benefitted catalyst solubility and recycling while not impairing catalytic performance. Complex 1 in 1,2-dichloroethane was effective for the isomerization of alpha-pinene oxide to campholenic aldehyde (CPA), leading to 87% yield at 1 h reaction. The same yield could be achieved within 1 min by using the IL [Choline][NTf2] as solvent. CPA yields at 1 min reached near-quantitative values (98%) upon recycling of the catalyst/IL mixture, demonstrating an unparalleled combination of activity, selectivity and recyclability for this commercially important reaction. Considering the catalytic features of the 1/IL system, a CPA process flow diagram is proposed and compared to patented technology.publishe

Carbon Monoxide Abrogates Ischemic Insult to Neuronal Cells via the Soluble Guanylate Cyclase-cGMP Pathway

Purpose Carbon monoxide (CO) is an accepted cytoprotective molecule. The extent and mechanisms of protection in neuronal systems have not been well studied. We hypothesized that delivery of CO via a novel releasing molecule (CORM) would impart neuroprotection in vivo against ischemia-reperfusion injury (IRI)-induced apoptosis of retinal ganglion cells (RGC) and in vitro of neuronal SH-SY5Y-cells via activation of soluble guanylate-cyclase (sGC). Methods: To mimic ischemic respiratory arrest, SH-SY5Y-cells were incubated with rotenone (100 nmol/L, 4 h) ± CORM ALF186 (10–100 µmol/L) or inactivated ALF186 lacking the potential of releasing CO. Apoptosis and reactive oxygen species (ROS) production were analyzed using flow-cytometry (Annexin V, mitochondrial membrane potential, CM-H2DCFDA) and Western blot (Caspase-3). The impact of ALF186± respiratory arrest on cell signaling was assessed by measuring expression of nitric oxide synthase (NOS) and soluble guanylate-cyclase (sGC) and by analyzing cellular cGMP levels. The effect of ALF186 (10 mg/kg iv) on retinal IRI in Sprague-Dawley rats was assessed by measuring densities of fluorogold-labeled RGC after IRI and by analysis of apoptosis-related genes in retinal tissue. Results: ALF186 but not inactivated ALF186 inhibited rotenone-induced apoptosis (Annexin V positive cells: 25±2% rotenone vs. 14±1% ALF186+rotenone, p<0.001; relative mitochondrial membrane potential: 17±4% rotenone vs. 55±3% ALF186+rotenone, p<0.05). ALF186 increased cellular cGMP levels (33±5 nmol/L vs. 23±3 nmol/L; p<0.05) and sGC expression. sGC-inhibition attenuated ALF186-mediated protection (relative mitochondrial membrane potential: 55±3% ALF186+rotenone vs. 20±1% ODQ+ALF186+rotenone, p<0.05). ALF186 protected RGC in vivo (IRI 1255±327 RGC/mm2 vs. ALF186+IRI 2036±83; p<0.05) while sGC inhibition abolished the protective effects of ALF186 (ALF186+IRI 2036±83 RGC/mm2 vs. NS-2028+ALF186+IRI 1263±170, p<0.05). Conclusions: The CORM ALF186 inhibits IRI-induced neuronal cell death via activation of sGC and may be a useful treatment option for acute ischemic insults to the retina and the brain

Molybdenum(II) Diiodo-Tricarbonyl Complexes Containing Nitrogen Donor Ligands as Catalyst Precursors for the Epoxidation of Methyl Oleate

Resumo alargado de "Molybdenum(II) Diiodo-Tricarbonyl Complexes Containing Nitrogen Donor Ligands as Catalyst Precursors for the Epoxidation of Methyl Oleate"Com o apoio RAADRI

Intercalation of a molybdenum η3-allyl dicarbonyl complex in a layered double hydroxide and catalytic performance in olefin epoxidation

Com o apoio RAADRI

Spontaneous CO release from Ru(II)(CO)2-protein complexes in aqueous solution, cells, and mice.

We demonstrate that Ru(II)(CO)2-protein complexes, formed by the reaction of the hydrolytic decomposition products of [fac-RuCl(κ(2)-H2NCH2CO2)(CO)3] (CORM-3) with histidine residues exposed on the surface of proteins, spontaneously release CO in aqueous solution, cells, and mice. CO release was detected by mass spectrometry (MS) and confocal microscopy using a CO-responsive turn-on fluorescent probe. These findings support our hypothesis that plasma proteins act as CO carriers after in vivo administration of CORM-3. CO released from a synthetic bovine serum albumin (BSA)-Ru(II)(CO)2 complex leads to downregulation of the cytokines interleukin (IL)-6, IL-10, and tumor necrosis factor (TNF)-α in cancer cells. Finally, administration of BSA-Ru(II)(CO)2 in mice bearing a colon carcinoma tumor results in enhanced CO accumulation at the tumor. Our data suggest the use of Ru(II)(CO)2-protein complexes as viable alternatives for the safe and spatially controlled delivery of therapeutic CO in vivo.We thank the FCT, the EU, and the EPSRC for funding. G.J.L.B. is a Royal Society University Research Fellow.This is the final published version. It first appeared at http://onlinelibrary.wiley.com/doi/10.1002/anie.201409344/abstract