1,721,007 research outputs found
Probing Delocalisation Across Highly Ethynylated Mono and Dinuclear Pt(II) tethers Containing Nitrogroups and Organic Models as Redox Active Probes. X-ray crystal structure of trans-[Pt(C=C-C6H4NO2)2(PPh3)2]
No full textWaiting for adoption: sterility elaboration process and its repercussions on representational world
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Stereocontrol in Alkyne Cyclocarbonylation Reactions promoted by a Bioxazoline Palladium(II) Complex
No full textInsertion of 1,2-disubstituted alkynes into [Pd(CH3)(CO)(BIOX)]+[B{3,5-(CF3)2C6H3}4]− (1), where BIOX=(4S,4′S)-(−)-4,4′,5,5′-tetrahydro-4,4′-bis(1-methylethyl)-2,2′-bioxazole, leads to the formation of five-membered palladacycles, which, by reaction with carbon monoxide, produce a mixture of two diastereomeric forms of a palladium complex containing an η3-allylic γ-lactone ligand. On leaving the mixture in solution, one isomer was converted into the other, reaching a diastereomeric excess of up to 94 %. The steric and electronic factors responsible for the epimerization process were investigated by theoretical methods. Cleavage of the η3-allyl[BOND]palladium bond by nucleophiles allowed highly substituted chiral butenolides to be synthesized in good enantiomeric excess
Insertion Reactions of 1,2-Disubstituted Olefins with an alpha-Diimine Palladium(II) Complex
No full textThe migratory insertions of cis or trans olefins CH(X)=CH(Me) (X=Ph, Br, or Et) into the metal–acyl bond of the complex [Pd(Me)(CO)( iPr2dab)] + [B{3,5-(CF3)2C6H3}4]- (1) ( iPr2dab=1,4-diisopropyl-1,4-diazabuta-1,3-diene=N,N’-(ethane-1,2-diylidene)bis[1-methylethanamine]) are described (Scheme1). The resulting five-membered palladacycles were characterized by NMR spectroscopy and X-ray analysis. Experimental data reveal some important aspects concerning the regio- and stereochemistry of the insertion process. In particular, the presence of a Ph or Br substituent at the alkene leads to the formationof highly regiospecific products. Moreover, in all cases, the geometry of the substituents in the formed palladacycle was the same as in the starting olefin, as a consequence of a cisaddition of the Pd–acyl fragment to the C=C bond. Reaction with CO and MeOH of the five-membered complex derived from trans b-methylstyrene (=[(1E)-prop-1-enyl]benzene) insertion, yielded the 2,3-substitutedg-keto ester 9 with an (2RS,3SR)-configuration (Scheme 3
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Dinuclear Gold(III) Complexes as Potential Anticancer Agents. Structure, Reactivity and Biological Profile of a Series of Gold(III) Oxo-Bridged Derivatives
No full textSix homologous gold(III) dinuclear oxo-bridged complexes, of the type [(bipynR)Au(μ-O)2Au(bipynR)][PF6]2,
bearing variously substituted 2,2’-bipyridine ligands (bipynR
= 2,2’-bipyridine, 4,4’-di-tert-butyl-, 6-methyl-, 6-neopentyl-,
6-o-xylyl- and 6,6’-dimethyl-2,2’-bipyridine), here called Auoxos, were prepared, characterised and recently tested as
potential anticancer agents. Crystal structures were obtained for five members of the series that allowed us to perform
detailed comparative analyses. Interestingly, the various Auoxos showed an acceptable stability profile in buffer solution
and turned out to manifest outstanding antitumor properties in vitro. In particular, one member of this family, Auoxo6
(bipynR = 6,6’-dimethyl-2,2’-bipyridine), produced more selective and far greater antiproliferative effects than all other
tested Auoxos, qualifying itself as the best “drug candidate”. In turn, COMPARE analysis of the cytotoxicity profiles of
five Auoxos, toward an established panel of thirty-six human tumor cell lines, revealed important mechanistic differences;
a number of likely biomolecular targets could thus be proposed such as HDAC and PKC. Biophysical studies revealed
markedly different modes of interaction with calf thymus DNA for two representative Auoxo compounds. In addition, a
peculiar reactivity with model proteins was documented on the ground of spectrophotometric and ESI MS data, most
likely as the result of redox processes. In view of the several experimental evidences gathered so far, it can be stated that
Auoxos constitute a novel family of promising cytotoxic gold compounds with an innovative mechanism of action that
merit a more extensive pharmacological evaluation
Synthesis of a Novel alpha-Diimine Palladium(II) Complex Bearing an eta3-Allyl gamma-Lactone Ligand, a Key Intermediate in Alkyne Cyclocarbonylation Processes
No full textSupramolecular interactions impacting on the water stability of tubular metal-organic frameworks
No full textTubular MOFs based on copper(II) phosphinates and bipyridine have been found to be highly stable in water. However, the possibility to form more dense and stable phases could affect their water stability, leading to slow and spontaneous transformations driven by the hydrolysis of the metal-ligands bonds. As a matter of fact, two structurally related MOFs have a very different water stability that, for one of the two MOFs, can be attributed to the existence of more stable phases that induces a slow transformation in water. For the other MOF, the non-existence of a related more stable phase, probably due to an unfavorable predicted crystal packing, yields an outstanding stability in hot water. © 2013 The Royal Society of Chemistry
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