Synthesis and reactivity of (C6F5)3B-N-heterocycle complexes. 1. Generation of highly acidic sp3 carbons in pyrroles and indoles

The reaction of pyrroles and indoles with B(C(6)F(5))(3) and BCl(3) produces 1:1 B-N complexes containing highly acidic sp(3) carbons, for example, N-[tris(pentafluorophenyl)borane]-5H-pyrrole (1) and N-[tris(pentafluorophenyl)borane]-3H-indole (2), that are formed by a new formal N-to-C hydrogen shift, the mechanism of which is discussed. With some derivatives, restricted rotation around the B-N bond and/or the B-C bonds was observed by NMR techniques, and some rotational barriers were calculated from experimental data. The acidity of the sp(3) carbons in these complexes is shown by their ability to protonate NEt(3), with formation of pyrrolyl- and indolyl-borate ammonium salts. The driving force for this reaction is given by the restoration of the aromaticity of the heterocycle.     

Multilinear regression and comparative molecular field analysis (CoMFA) of azo dye-fiber affinities. 2. Inclusion of solution-phase molecular orbital descriptors

For a data set with 30 direct azo dyes taken from literature, quantitative structure-activity relationship (QSAR) analyses have been performed to model the affinity of the dye molecules for the cellulose fiber. The electronic structure of the compounds was characterized using quantum chemical gas-phase (AM1) and continuum-solvation molecular orbital parameters. As regards the solution phase, COSMO appears to be better suited than SM2 in quantifying relative trends of the aqueous solvation energy. For the dye-fiber affinity, the leave-one-out prediction capability of multilinear regression equations is superior to CoMFA, with predictive squared correlation coefficients ranging from 0.63 (pure CoMFA) to 0.89. At the same time, solution-phase CoMFA is superior to previously derived AM1-based CoMFA models. As a general trend, the dye-fiber affinity increases with increasing electron donor capacity that corresponds to an increasing hydrogen bond acceptor strength of the azo dyes. The discussion includes the consideration of structural features that are likely to be involved in dye-fiber and dye-dye hydrogen bonding interactions, and possible links between CoMFA electrostatic results and the atomic charge distribution of the compounds.     

Efficiency of the dry–wet method for the MALDI‐MSI analysis of latent fingermarks

Matrix‐assisted laser desorption/ionisation mass spectrometry imaging (MALDI‐MSI) has proven to be a powerful analytical tool to investigate problems in several fields of life science. A novel application is in the field of forensics, particularly in the analysis of latent fingermarks. This technology enables images of the fingermark ridge detail and additional intelligence to be simultaneously obtained. Although several methods are available to deposit the MALDI matrix, to make the technology forensically operational, another deposition approach was devised and reported, namely the ‘dry–wet’ method. In the present study, the efficiency of the dry–wet method was evaluated and compared with the conventional spray coat methodology. Results indicate that the dry–wet method is superior for all the donors' typologies in terms of ion signal intensity and clarity of the ridge details. To underpin the reasons of this efficiency, scanning electron microscopy analyses were carried out in parallel to MALDI‐MSI experiments using matrices of different particle size. Results have confirmed that the particle size plays an important role in the efficiency of the method as higher quality images and higher intensity spectra are produced as the matrix particle size decreases. Copyright © 2013 John Wiley & Sons, Ltd.     

Health benefits of pistachios consumption

The health benefits of nuts, mainly in relation to the improvement of dysmetabolic conditions such as obesity, type 2 diabetes mellitus and the related cardiovascular diseases, have been widely demonstrated. Compared to other nuts, pistachios have a lower fat and caloric content, and contain the highest levels of unsaturated fatty acids, potassium, γ-tocopherol, phytosterols and xanthophyll carotenoids, all substances that are well known for their antioxidant and anti-inflammatory actions. This variety of nutrients contributes to the growing body of evidence that the consumption of pistachios improves health, leading to a greater potential of healthy antioxidant and anti-inflammatory activity, glycemic control, and endothelial function. The present review examines the nutrients and phytochemicals present in pistachios as well as the potential health benefits of including pistachios in a diet.     

Ultrafast heme dynamics in ferrous versus ferric cytochrome c studied by time-resolved resonance Raman and transient absorption spectroscopy

Cytochrome c (Cyt c) is a heme protein involved in electron transfer and also in apoptosis. Its heme iron is bisaxially ligated to histidine and methionine side chains and both ferric and ferrous redox states are physiologically relevant, as well as a ligand exchange between internal residue and external diatomic molecule. The photodissociation of internal axial ligand was observed for several ferrous heme proteins including Cyt c, but no time-resolved studies have been reported on ferric Cyt c. To investigate how the oxidation state of the heme influences the primary photoprocesses, we performed a comprehensive comparative study on horse heart Cyt c by subpicosecond time-resolved resonance Raman and femtosecond transient absorption spectroscopy. We found that in ferric Cyt c, in contrast to ferrous Cyt c, the photodissociation of an internal ligand does not take place, and relaxation dynamics is dominated by vibrational cooling in the ground electronic state of the heme. The intermolecular vibrational energy transfer was found to proceed in a single phase with a temperature decay of approximately 7 ps in both ferric and ferrous Cyt c. For ferrous Cyt c, the instantaneous photodissociation of the methionine side chain from the heme iron is the dominant event, and its rebinding proceeds in two phases, with time constants of approximately 5 and approximately 16 ps. A mechanism of this process is discussed, and the difference in photoinduced coordination behavior between ferric and ferrous Cyt c is explained by an involvement of the excited electronic state coupled with conformational relaxation of the heme.     

Out‐of‐Water Constitutional Self‐Organization of Chitosan–Cinnamaldehyde Dynagels

An investigation of the constitutional adaptive gelation process of chitosan/cinnamaldehyde ( C / Cy ) dynagels is reported. These gels generate timely variant macroscopic organization across extended scales. In the first stage, imine‐bond formation takes place “in‐water” and generates low‐ordered hydrogels. The progressive formation of imine bonds further induces “ out‐of‐water” increased reactivity within interdigitated hydrophobic self‐assembled layers of Cy , with a protecting environmental effect against hydrolysis and that leads to the stabilization of the imine bonds. The hydrophobic swelling due to Cy layers at the interfaces reaches a critical step when lamellar self‐organized hybrids are generated (24 hours). This induces an important restructuration of the hydrogels on the micrometric scale, thus resulting in the formation of highly ordered microporous xerogel morphologies of high potential interest for chemical separations, drug delivery, and sensors.     

A new sustainable protocol for the synthesis of nitroaldol derivatives via Henry reaction under solvent-free conditions

A new protocol for the Henry addition of nitroalkanes to aryl- and alkyl-aldehydes promoted by PS-BEMP under solvent-free conditions (SolFC) is presented. The corresponding nitroaldol products were obtained in good yields and short times; furthermore minimization of the reaction waste was achieved by reducing the use of organic solvents. Extension of the protocol was obtained by setting up the tandem Michael-Henry reaction of α,β-unsaturated aldehydes and nitroalkane to yield the corresponding dinitro derivatives.     

Synthesis and reactivity of N-heterocycle-B(C6F5)3 complexes. 4. Competition between pyridine- and pyrrole-type substrates toward B(C6F5)3: structure and dynamics of 7-B(C6F5)3-7-azaindole and [7-Azaindolium]+[HOB(C6F5)3]-

Reaction between 7-azaindole and B(C6F5)3 quantitatively yields 7-(C6F5)3B-7-azaindole (4), in which B(C6F5)3 coordinates to the pyridine nitrogen of 7-azaindole, leaving the pyrrole ring unreacted even in the presence of a second equivalent of B(C6F5)3. Reaction of 7-azaindole with H2O-B(C6F5)3 initially produces [7-azaindolium]+[HOB(C6F5)3]- (5) which slowly converts to 4 releasing a H2O molecule. Pyridine removes the borane from the known complexes (C6F5)3B-pyrrole (1) and (C6F5)3B-indole (2), with formation of free pyrrole or indole, giving the more stable adduct (C6F5)3B-pyridine (3). The competition between pyridine and 7-azaindole for the coordination with B(C6F5)3 again yields 3. The molecular structures of compounds 4 and 5 have been determined both in the solid state and in solution and compared to the structures of other (C6F5)3B-N-heterocycle complexes. Two dynamic processes have been found in compound 4. Their activation parameters (DeltaH = 66 (3) kJ/mol, DeltaS = -18 (10) J/mol K and DeltaH = 76 (5) kJ/mol, DeltaS = -5 (18) J/mol K) are comparable with those of other (C6F5)3B-based adducts. The nature of the intramolecular interactions that result in such energetic barriers is discussed.     

Copper(II) complexes with ligands derived from 4-amino-2,3-dimethyl-1-phenyl-3-pyrazolin-5-one: synthesis and biological activity

The synthesis of Cu(II) complexes derived from Schiff base ligands obtained by the condensation of 2-hydroxybenzaldehyde or terephtalic aldehyde with 4-amino-antipyrine (4-amino-2,3-dimethyl-1-phenyl-3-pyrazolin-5-one) is presented. The newly prepared compounds were characterized by( 1)H-NMR, UV-VIS, IR and ESR spectroscopy. The determination of the antimicrobial activity of the ligands and of the complexes was carried out on samples of Escherichia coli, Klebsiella pneumoniae, Acinetobacter boumanii, Pseudomonas aeruginosa, Staphylococcus aureus and Candida sp. The qualitative and quantitative antimicrobial activity test results proved that all the prepared complexes are very active, especially against samples of Ps. aeruginosa, A. Boumanii, E. coli and S. aureus.