cis‐Bis­[1,3‐bis(2‐fluoro­phenyl)­triazenido‐κ2N1,N3]­bis­(pyridine‐κN)cadmium(II)

In the title compound, [Cd(C₁₂H₈F₂N₃)₂(C₅H₅N)₂], the Cd atom lies on a crystallographic twofold axis in space group Iba2. The coordination geometry about the Cd^II ion corresponds to a rhombically distorted octahedron, with two deprotonated 1,3‐bis(2‐fluoro­phenyl)­triazenide ions, viz. FC₆H₄NNNC₆H₄F⁻, acting as bidentate ligands (four‐electron donors). Two neutral pyridine (py) mol­ecules complete the coordination sphere in positions cis with respect to one another. The triazenide ligand is not planar (r.m.s. deviation = 0.204 Å), the dihedral angle between the phenyl rings of the terminal 2‐fluoro­phenyl substituents being 24.6 (1)°. The triazenide and pyridine Cd—N distances are 2.3757 (18)/2.3800 (19) and 2.3461 (19) Å, respectively. Intermolecular C—H⋯F interactions generate sheets of mol­ecules in the (010) plane.     

Polysaccharide Structures and Their Hypocholesterolemic Potential

Several classes of polysaccharides have been described to have hypocholesterolemic potential, namely cholesterol bioaccessibility and bioavailability. This review will highlight the main mechanisms by which polysaccharides are known to affect cholesterol homeostasis at the intestine, namely the effect (i) of polysaccharide viscosity and its influence on cholesterol bioaccessibility; (ii) on bile salt sequestration and its dependence on the structural diversity of polysaccharides; (iii) of bio-transformations of polysaccharides and bile salts by the gut microbiota. Different quantitative structure–hypocholesterolemic activity relationships have been explored depending on the mechanism involved, and these were based on polysaccharide physicochemical properties, such as sugar composition and ramification degree, linkage type, size/molecular weight, and charge. The information gathered will support the rationalization of polysaccharides’ effect on cholesterol homeostasis and highlight predictive rules towards the development of customized hypocholesterolemic functional food.     

Production of Cellulolytic Enzymes by <Emphasis Type="Italic">Aspergillus phoenicis</Emphasis> in Grape Waste using Response Surface Methodology

The production of cellulolytic enzymes by the fungus Aspergillus phoenicis was investigated. Grape waste from the winemaking industry was chosen as the growth substrate among several agro-industrial byproducts. A 2 × 2 central composite design was performed, utilizing the amount of grape waste and peptone as independent variables. The fungus was cultivated in submerged fermentation at 30 °C and 120 rpm for 120 h, and the activities of total cellulases, endoglucanases, and β-glucosidases were measured. Total cellulases were positively influenced by the linear increase of peptone concentration and decrease at axial concentrations of grape waste and peptone. Maximum activity of endoglucanase was observed by a linear increase of both grape waste and peptone concentrations. Concentrations of grape waste between 5 and 15 g/L had a positive effect on the production of β-glucosidase; peptone had no significant effects. The optimum production of the three cellulolytic activities was observed at values near the central point. A. phoenicis has the potential for the production of cellulases utilizing grape waste as the growth substrate.     

Cellulosic Films Obtained from the Treatment of Sugarcane Bagasse Fibers with N-methylmorpholine-N-oxide (NMMO)

Ethanol/water organosolv pulping was used to obtain sugarcane bagasse pulp that was bleached with sodium chlorite. This bleached pulp was used to obtain cellulosic films that were further evaluated by Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), and scanning electron microscopy (SEM). A good film formation was observed when temperature of 74 °C and baths of distilled water were used, which after FTIR, TGA, and SEM analysis indicated no significant difference between the reaction times. The results showed this to be an interesting and promising process, combining the prerequisites for a more efficient utilization of agro-industrial residues.     

Increasing the antibacterial activity of gallium(III) against Pseudomonas aeruginosa upon coordination to pyridine-derived thiosemicarbazones

Reaction of N(4)-phenyl-2-formylpyridine thiosemicarbazone (H2Fo4Ph), N(4)-phenyl-2-acetylpyridine thiosemicarbazone (H2Ac4Ph) and N(4)-phenyl-2-benzoylpyridine thiosemicarbazone (H2Bz4Ph) with gallium nitrate gave [Ga(H2Fo4Ph)₂](NO₃)₃ (1), [Ga(2Ac4Ph)₂]NO₃ (2) and [Ga(2Bz4Ph)₂]NO₃ (3). In all complexes coordination of the thiosemicarbazone via the N_py–N–S chelating system occurs. In 1 the thiosemicarbazone acts as a neutral ligand while in 2 and 3 the ligand is anionic. Upon slow diffusion of 2 in DMSO [Ga(2Ac4Ph)₂]NO₃·DMSO (2a) was formed. The crystal structure of 2a was determined. Upon coordination the antibacterial activity of both gallium and thiosemicarbazones against Pseudomonas aeruginosa significantly increases.     

A study of the aerobic reaction between dopamine and Fe(III) in the presence of S<Subscript>2</Subscript>O<Subscript>3</Subscript><Superscript>2−</Superscript>

The reaction between Fe(III) and dopamine in aqueous solution in the presence of Na₂S₂O₃ was followed through UV–Vis spectroscopy, pH and oxy-reduction potential (Eh) measurements. The formation and quick disappearing of the complex [Fe(III)HL¹⁻]²⁺, HL¹⁻ = monoprotonated dopamine was observed with or without S₂O₃ ²⁻ at pH 3. An unexpected reaction occurs in presence of thiosulfate forming the stable anion complex [Fe(III)(L²⁻)₂]¹⁻, L²⁻ = dopacatecholate (λ = 580 nm) and the auto-increasing of the pH, from 3 to 7. It was proposed that H⁺ and molecular oxygen are consumed by free radical thiosulfate formed during the reaction.     

Synthesis of new aza-bicyclic 2-isoxazolines by 1,3-dipolar cycloaddition of endocyclic enecarbamates and enamides with nitrile oxides

Novel aza-bicyclic 2-isoxazolines, 4,5-dihydroisoxazole[5,4-b]pyrrolidines, and 4,5-dihydroisoxazole[5,4-b]piperidines were synthesized in a highly regioselective manner through a 1,3-dipolar cycloaddition reaction of 5- and 6-membered endocyclic enecarbamates and enamides with several nitrile oxides in good to excellent yields. Hydrogenolysis of 5- and 6-membered Cbz-cycloadducts led to secondary amines, which presented distinctive stabilities. 2-Isoxazoline bisamides were obtained in good yields through a N-benzoylation, followed by ammonolysis of the secondary amine, or directly from ammonolysis of the cycloadducts.     

Hooker’s ‘lapachol peroxide’ revisited

The structure of ‘lapachol peroxide’ was published by Hooker in 1936; however, we recently discovered a mistake in the originally proposed structure; the correct structure, according to X-ray spectroscopy, is given here.     

An expeditious synthesis of hexahydrobenzo[f]isochromenes and of hexahydrobenzo[f]isoquinoline via iodine-catalyzed Prins and aza-Prins cyclization

Homoallylic alcohols (primary, secondary, or tertiary containing an endocyclic or an exocyclic double bond) react with equimolar amounts of aldehydes (aliphatic or aromatic) and ketones (aliphatic) in the presence of 5 mol % of iodine. This Prins cyclization was used in the preparation of hexahydrobenzo[f]isochromenes and of a 4-hydroxy-tetrahydropyran, in 54-81% yield. The procedure is also efficient for an aza-Prins cyclization of a homoallylic sulfonamide and benzaldehyde, producing a hexahydrobenzo[f]isoquinoline.