Facile And Reversible Co Insertion Into The Ir-ch3 Bond Of [ir4(ch3)(co)8(μ4- η3-ph2pccph)(μ-pph2)]

Reaction of [Ir4H(CO)10 (μ-PPh2)] with BuLi, Ph2PC≡CPh and then Mel gives [Ir4 (CH 3)(CO)8 (μ4-η3-Ph 2PCCPh)(μ-PPh2)], which undergoes a reversible two-step CO insertion under extremely mild conditions to yield Ir4{(CH 3C(O)}(CO)8-(μ4:η3-Ph 2PCCPh)(μ-PPh2)] as the final product; the structures of both species have been established by X-ray diffraction studies.121008101

Synthesis And Structural Characterisation Of [ir4(co)8(ch3)(μ4-η 3-ph2pccph)(μ-pph2)] And Of The Carbonylation Product [ir4(co)8{c(o)ch3}(μ4-η 3-ph2pccph)(μ-pph2)]

Deprotonation of [(μ-H)Ir4(CO)10(μ-PPh2)], 1, gives [Ir4(CO)10(μ-PPh2)]- that reacts with Ph2PCCPh and CH3I to afford [Ir4(CO)8(CH3)(μ4-η 3-Ph2PCCPh)(μ-PPh2)], 2 (34%), besides [Ir4(CO)9(μ3-η3-Ph 2PC(H)CPh)(μ-PPh2)] and [(μ-H)Ir4(CO)9(Ph2PC≡CPh)(μ-PPh2)]. Compound 2 was characterised by a single crystal X-ray diffraction analysis and exhibits a flat butterfly of metal atoms, with the Ph2PCCPh ligand interacting with all four Ir atoms and the methyl group bonded terminally to a wingtip Ir atom. Carbonylation of 2 yields initially (25°C, 20 min) a CO addition product that, according to VT 31P{1H} and 13C{1H} studies, exists in solution in the form of two isomers 4A and 4B (8:1), and then (40°C, 7 h), the CO insertion product [Ir4(CO)8{C(O)CH3}-(μ4-η 3-Ph2PCCPh)(μ-PPh2)], 5. The molecular structure of 5, established by an X-ray analysis, is similar to that of 2, except for the acyl group that remains bound to the same Ir atom. The process is reversible at both stages. Treatment of 2 with PPh3 and P(OMe)3 affords the CO substitution products [Ir4(CO)7L(CH3)(μ4-η 3-Ph2PCCPh)(μ-PPh2)] (L = PPh3, 6 and P(OMe)3, 7), instead of the expected CO inserted products. According to the 1H and 31P{1H} NMR studies, the PPh3 derivative 6 exists in the form of two isomers (1:1) that differ with respect to the position of this ligand.1013545Hoffmann, R., (1982) Angew. Chem. Int. Ed. Engl., 21, p. 711Bau, R., Chiang, M.Y., Wei, C.-Y., Garlaschelli, L., Martinengo, S., Koestzle, T.F., (1984) Inorg. Chem., 23, p. 4758Ragaini, F., Porta, F., Demartin, F., (1991) Organometallics, 10, p. 185Albano, V.G., Canziani, F., Ciani, G., Chini, P., Martinengo, S., Manassero, M., Giordano, G., (1978) J. Organomet. Chem., 150, pp. C17Chinara, T., Aoki, K., Yamazaki, H., (1990) J. Organomet. Chem., 353, p. 367Chinara, T., Aoki, K., Yamazaki, H., (1994) J. Organomet. Chem., 473, p. 273González-Moraga, (1993) Cluster Chemistry, , Chapter 3, Springer-Verlag, BerlinBenvenutti, M.H.A., Vargas, M.D., Braga, D., Grepioni, F., Parisini, E., Mann, B.E., (1993) Organometallics, 12, p. 2955Benvenutti, M.H.A., Vargas, M.D., Braga, D., Grepioni, F., Mann, B.E., Naylor, S., (1993) Organometallics, 12, p. 2947Yamamoto, A., (1986) Organotransition Metal Chemistry, , WileyMorison, E.D., Bassner, L.S.L., Geoffroy, G.L., (1986) Organometallics, 5, p. 408Pereira, R.M.S., Fujiwara, F.Y., Vargas, M.D., Braga, D., Grepioni, F., (1997) Organometallics, 16, p. 4833Delgado, E., Chi, Y., Wang, W., Horgath, G., Low, P.J., Enright, G.D., Peng, S.-M., Carty, A.J., (1998) Organometallics, 17, p. 2936Vargas, M.D., Pereira, R.M.S., Braga, D., Grepioni, F., (1993) J. Chem. Soc. Chem. Commun., p. 1008Hengefelt, A., Nast, R., (1983) Chem. Ber., 116, p. 2025Livotto, F.S., Raithby, P.R., Vargas, M.D., (1993) J. Chem. Soc. Dalton Trans., p. 1797Brauer, G., (1965) Handboock of Preparative Inorganic Chemistry, 1, p. 645Sheldrick, G.M., (1990) Acta Crystallogr., A46, p. 467Sheldrick, G.M., (1976) SHELX76, Program for Crystal Structure Determination, , University of Cambridge, Cambridge, EnglandWalker, N., Stuart, D., (1983) Acta Crystallogr., Sect. B, 39, p. 158Keller, E., (1992) SHAKAL92, Graphical Representation of Molecular Models, , University of Freiburg, FRGKubota, M., McClesky, T.M., Hayashi, R.K., Carl, G., (1987) J. Am. Chem. Soc., 109, p. 7569Wade, K., (1976) Adv. Inorg. Chem. Radiochem., 18, p. 1Benvenutti, M.H.A., Vargas, M.D., Hitchcock, P.B., Nixon, J.F., (1995) J. Chem. Soc. Chem. Commun., p. 866Carty, A.J., Mac Laughlin, S.A., Nucciaroni, D., (1987) Phosphorus 31-NMR Spectroscopy in Steereochemical Analysis of Organic Compounds and Metal Complexes, , Chapter 16Verkade, J. G.Quin, L. D. EdsVCHKeister, J.B., (1980) J. Organomet. Chem., 190, pp. C36Aime, S., Dastrù, W., Gobetto, R., Viale, A., (1998) Organometallics, 17, p. 3182Johnson, B.F.G., Lewis, J., Orpen, A.G., Raithby, P.R., Süss, G., (1979) J. Organomet. Chem., 173, p. 187Araujo, M.H., Vargas, M.D., unpublished resultsMonti, D., Frachey, G., Bassetti, M., Haynes, A., Sunley, G.J., Maitlis, P.M., Cantoni, A., Bocelli, G., (1995) Inorg. Chim. Acta, 240, p. 485Garcia Alonso, J., Llamazares, A., Riera, V., Diaz, M.R., García Grande, S., (1991) J. Chem. Soc. Chem. Commun., p. 1058Cotton, J.D., Crisp, G.T., Daly, V.A., (1981) Inorg. Chim. Acta, 47, p. 165Bondietti, G., Laurenczy, G., Ross, R., Roulet, R., (1994) Helv. Chim. Acta, 77, p. 1869Laurenczy, G., Bondietti, G., Merbach, A.E., Moulet, B., Roulet, R., (1994) Helv. Chim. Acta, 77, p. 547Braga, D., Grepioni, F., Vargas, M.D., Ziglio, C.M., manuscript in preparatio

Safflower oil: an integrated assessment of phytochemistry, antiulcerogenic activity, and rodent and environmental toxicity

Gastric ulcers are a significant medical problem and the development of complications lead to significant mortality rates worldwide. In Brazil, Carthamus tinctorius L., Asteraceae, seeds essential oil, the safflower oil, is currently used as a thermogenic compound and as treatment for problems related to the cardiovascular system. In this study, by Raman spectroscopy, it was shown that oleic and linoleic acids are the compounds present in higher concentrations in the safflower oil. We demonstrated that safflower oil (750 mg/kg, p.o.) decrease the ulcerogenic lesions in mice after the administration of hydrochloric acid-ethanol. The gastric ulcers induced by non-steroidal anti-inflammatory drug (NSAID) in mice treated with cholinomimetics were treated with four different doses of safflower oil, of which, the dose of 187.5 mg/kg (p.o.) showed significant antiulcerogenic properties (**p < 0.01). Moreover, the safflower oil at doses of 187.5 mg/kg (i.d.) increased the pH levels, gastric volume (**p < 0.01) and gastric mucus production (***p < 0.001), and decreased the total gastric acid secretion (***p < 0.001). The acute toxicity tests showed that safflower oil (5.000 mg/kg, p.o.) had no effect on mortality or any other physiological parameter. Ecotoxicological tests performed using Daphnia similis showed an EC50 at 223.17 mg/l, and therefore safflower oil can be considered “non-toxic” based on the directive 93/67/EEC on risk assessment for new notified substances by European legislation. These results indicate that the antiulcer activity of Safflower oil may be due to cytoprotective effects, which serve as support for new scientific studies related to this pathology.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Universidade Santa Cecília Programa de Pós-graduação em Sustentabilidade de Ecossistemas Costeiros e Marinhos Laboratório de Pesquisa em Produtos NaturaisUniversidade Estadual de Campinas Departamento de Fisiologia e Biofísica Laboratório de Produtos NaturaisUniversidade Santa Cecília Laboratório de EcotoxicologiaUniversidade Federal de São Paulo (UNIFESP) Instituto do MarUniversidade Camilo Castelo Branco Instituto de Engenharia BiomédicaUNIFESP, Instituto do MarFAPESP: 2009/01788-5SciEL

All-sky search for long-duration gravitational wave transients with initial LIGO

We present the results of a search for long-duration gravitational wave transients in two sets of data collected by the LIGO Hanford and LIGO Livingston detectors between November 5, 2005 and September 30, 2007, and July 7, 2009 and October 20, 2010, with a total observational time of 283.0 days and 132.9 days, respectively. The search targets gravitational wave transients of duration 10-500 s in a frequency band of 40-1000 Hz, with minimal assumptions about the signal waveform, polarization, source direction, or time of occurrence. All candidate triggers were consistent with the expected background; as a result we set 90% confidence upper limits on the rate of long-duration gravitational wave transients for different types of gravitational wave signals. For signals from black hole accretion disk instabilities, we set upper limits on the source rate density between 3.4×10-5 and 9.4×10-4 Mpc-3 yr-1 at 90% confidence. These are the first results from an all-sky search for unmodeled long-duration transient gravitational waves. © 2016 American Physical Society

All-sky search for long-duration gravitational wave transients with initial LIGO

We present the results of a search for long-duration gravitational wave transients in two sets of data collected by the LIGO Hanford and LIGO Livingston detectors between November 5, 2005 and September 30, 2007, and July 7, 2009 and October 20, 2010, with a total observational time of 283.0 days and 132.9 days, respectively. The search targets gravitational wave transients of duration 10-500 s in a frequency band of 40-1000 Hz, with minimal assumptions about the signal waveform, polarization, source direction, or time of occurrence. All candidate triggers were consistent with the expected background; as a result we set 90% confidence upper limits on the rate of long-duration gravitational wave transients for different types of gravitational wave signals. For signals from black hole accretion disk instabilities, we set upper limits on the source rate density between 3.4×10-5 and 9.4×10-4 Mpc-3 yr-1 at 90% confidence. These are the first results from an all-sky search for unmodeled long-duration transient gravitational waves. © 2016 American Physical Society

Search for Gravitational Waves Associated with Gamma-Ray Bursts Detected by Fermi and Swift during the LIGO-Virgo Run O3b

We search for gravitational-wave signals associated with gamma-ray bursts (GRBs) detected by the Fermi and Swift satellites during the second half of the third observing run of Advanced LIGO and Advanced Virgo (2019 November 1 15:00 UTC-2020 March 27 17:00 UTC). We conduct two independent searches: A generic gravitational-wave transients search to analyze 86 GRBs and an analysis to target binary mergers with at least one neutron star as short GRB progenitors for 17 events. We find no significant evidence for gravitational-wave signals associated with any of these GRBs. A weighted binomial test of the combined results finds no evidence for subthreshold gravitational-wave signals associated with this GRB ensemble either. We use several source types and signal morphologies during the searches, resulting in lower bounds on the estimated distance to each GRB. Finally, we constrain the population of low-luminosity short GRBs using results from the first to the third observing runs of Advanced LIGO and Advanced Virgo. The resulting population is in accordance with the local binary neutron star merger rate. © 2022. The Author(s). Published by the American Astronomical Society

Narrowband Searches for Continuous and Long-duration Transient Gravitational Waves from Known Pulsars in the LIGO-Virgo Third Observing Run

Isolated neutron stars that are asymmetric with respect to their spin axis are possible sources of detectable continuous gravitational waves. This paper presents a fully coherent search for such signals from eighteen pulsars in data from LIGO and Virgo's third observing run (O3). For known pulsars, efficient and sensitive matched-filter searches can be carried out if one assumes the gravitational radiation is phase-locked to the electromagnetic emission. In the search presented here, we relax this assumption and allow both the frequency and the time derivative of the frequency of the gravitational waves to vary in a small range around those inferred from electromagnetic observations. We find no evidence for continuous gravitational waves, and set upper limits on the strain amplitude for each target. These limits are more constraining for seven of the targets than the spin-down limit defined by ascribing all rotational energy loss to gravitational radiation. In an additional search, we look in O3 data for long-duration (hours-months) transient gravitational waves in the aftermath of pulsar glitches for six targets with a total of nine glitches. We report two marginal outliers from this search, but find no clear evidence for such emission either. The resulting duration-dependent strain upper limits do not surpass indirect energy constraints for any of these targets. © 2022. The Author(s). Published by the American Astronomical Society