Ruthenium(II) complexes with 2-(diphenylphosphinomethyl)aniline

2-(Diphenylphosphinomethyl)aniline. H2L1, reacts with [RuCl2(PPh3)(3)] to yield the monomeric complexes [RuCl2(H2L1)(PPh3)(CH3CN)], [RuCl2(H2L1)(2)]and the chloro-bridged dimer [(H2L1)(PPh3)Ru(mu-Cl)(2)Ru(PPh3) (H2L1)] depending on the conditions applied. Exclusively the monochelate [RuCl2 (H2L1)(dmso)(2)] is formed during reactions of H2L1 with [RuCl2(dmso)(4)]. H2L1 acts as a neutral, bidentate ligand in all complexes. The products are studied spectroscopically and by X-ray diffraction. (C) 2012 Elsevier Ltd. All rights reserved.

Aminoacylase 1-catalysed deacetylation of bioactives epoxides mycotoxin-derived mercapturates; 3,4-epoxyprecocenes as models of cytotoxic epoxides

The mycotoxin aflatoxin B1 (AFB1) is a carcinogenic food contaminant which is metabolically activated by epoxydation. The metabolism of mycotoxins via the mercapturate metabolic pathway was shown, in general, to lead to their detoxication. Mercapturic acids thus formed (S-substitued-N-acetyl-L-cysteines) may be accumulated in the kidney and either excreted in the urine or desacetylated by Acylase 1 (ACY1) to yield cysteine S-conjugates. To be toxic, the N-acetyl-L-cysteine-S-conjugates first have to undergo deacetylation by ACY 1. The specificity and rate of mercapturic acid deacetylation may determine the toxicity, however the exact deacetylation processes involved are not well known. The aim of this study was to investigate the role of ACY1 in the toxicity of some bioactive epoxides from Aflatoxin B1. We characterized the kinetic parameters of porcine kidney and human recombinant aminoacylase-1 towards some aromatic and aliphatic-derived mercapturates analogue of mycotoxin mercapturic acids and 3,4-epoxyprecocene, a bioactive epoxide derivated from aflatoxin. The deacetylation of mercapturated substrates was followed both by reverse phase HPLC and by TNBS method. Catalytic activity was discussed in a structure function relationship. Ours results indicate for the first time that aminoacylase-1 could play an important role in deacetylating mercapturate metabolites of aflatoxin analogues and this process may be in relation with their cyto- and nephrotoxicity in human. (C) 2012 Published by Elsevier Masson SAS.

Exploring the intrinsic polar [4?+?2+] cycloaddition reactivity of gaseous carbosulfonium and carboxonium ions

Gas-phase reactions of model carbosulfonium ions (CH3-S+?=?CH2; CH3CH2-S+?=?CH2 and Ph-S+?=?CH2) and an O-analogue carboxonium ion (CH3-O+?=?CH2) with acyclic (isoprene, 1,3-butadiene, methyl vinyl ketone) and cyclic (1,3-cyclohexadiene, thiophene, furan) conjugated dienes were systematically investigated by pentaquadrupole mass spectrometry. As corroborated by B3LYP/6-311?G(d,p) calculations, the carbosulfonium ions first react at large extents with the dienes forming adducts via simple addition. The nascent adducts, depending on their stability and internal energy, react further via two competitive channels: (1) in reactions with acyclic dienes via cyclization that yields formally [4?+?2+] cycloadducts, or (2) in reactions with the cyclic dienes via dissociation by HSR loss that yields methylenation (net CH+ transfer) products. In great contrast to its S-analogues, CH3-O+?=?CH2 (as well as C2H5-O+?=?CH2 and Ph-O+?=?CH2 in reactions with isoprene) forms little or no adduct and proton transfer is the dominant reaction channel. Isomerization to more acidic protonated aldehydes in the course of reaction seems to be the most plausible cause of the contrasting reactivity of carboxonium ions. The CH2?=?CH-O+?=?CH2 ion forms an abundant [4?+?2+] cycloadduct with isoprene, but similar to the behavior of such alpha,beta-unsaturated carboxonium ions in solution, seems to occur across the C?=?C bond. Copyright (c) 2012 John Wiley & Sons, Ltd.

New Improved Version of J 1 ...J 4 Interferometry Method and its Application to Nanometric Vibration Measurements

Piezoelectric ceramics, such as PZT, can generate subnanometric displacements, bu t in order to generate multi- micrometric displacements, they should be either driven by high electric voltages (hundreds of volts ), or operate at a mechanical resonant frequency (in narrow band), or have large dimensions (tens of centimeters). A piezoelectric flextensional actuator (PFA) is a device with small dimensions that can be driven by reduced voltages and can operate in the nano- and micro scales. Interferometric techniques are very adequate for the characterization of these devices, because there is no mechanical contact in the measurement process, and it has high sensitivity, bandwidth and dynamic range. A low cost open-loop homodyne Michelson interferometer is utilized in this work to experimentally detect the nanovi brations of PFAs, based on the spectral analysis of the interfero metric signal. By employing the well known J 1 ...J 4 phase demodulation method, a new and improved version is proposed, which presents the following characteristics: is direct, self-consistent, is immune to fading, and does not present phase ambiguity problems. The proposed method has resolution that is similar to the modified J 1 ...J 4 method (0.18 rad); however, differently from the former, its dynamic range is 20% larger, does not demand Bessel functions algebraic sign correction algorithms and there are no singularities when the static phase shift between the interferometer arms is equal to an integer multiple of  /2 rad. Electronic noise and random phase drifts due to ambient perturbations are taken into account in the analysis of the method. The PFA nanopositioner characterization was based on the analysis of linearity betw een the applied voltage and the resulting displacement, on the displacement frequency response and determination of main resonance frequencies.