Unconventional reactivity of epichlorohydrin in the presence of triphenylphosphine: isolation of ((1,4-dioxane-2,5-diyl)-bis-(methylene))-bis-(triphenylphosphonium) chloride

Research on Chemical Intermediates - The selective formation of the heterocyclic salt ((1,4-dioxane-2,5-diyl)-bis-(methylene))-bis-(triphenylphosphonium) chloride was observed when epichlorohydrin...     

Asymptotic Results for First-Passage Times of Some Exponential Processes

Methodology and Computing in Applied Probability - We consider the process {V (t) : t ≥ 0} defined by V (t) = v0eX(t) (for all t ≥ 0), where v0 > 0 and {X(t) :...     

Palladium(II)-η3-Allyl Complexes Bearing N-Trifluoromethyl N-Heterocyclic Carbenes: A New Generation of Anticancer Agents that Restrain the Growth of High-Grade Serous Ovarian Cancer Tumoroids

The first palladium organometallic compounds bearing N-trifluoromethyl N-heterocyclic carbenes have been synthesized. These η³-allyl complexes are potent antiproliferative agents against different cancer lines (for the most part, IC₅₀ values fall in the range 0.02–0.5 μm ). By choosing 1,3,5-triaza-7-phosphaadamantane (PTA) as co-ligand, we can improve the selectivity toward tumor cells, whereas the introduction of 2-methyl substituents generally reduces the antitumor activity slightly. A series of biochemical assays, aimed at defining the cellular targets of these palladium complexes, has shown that mitochondria are damaged before DNA, thus revealing a behavior substantially different from that of cisplatin and its derivatives. We assume that the specific mechanism of action of these organometallic compounds involves nucleophilic attack on the η³-allyl fragment. The effectiveness of a representative complex, 4 c , was verified on ovarian cancer tumoroids derived from patients. The results are promising: unlike carboplatin, our compound turned out to be very active and showed a low toxicity toward normal liver organoids.     

Integrated Theoretical and Empirical Studies for Probing Substrate–Framework Interactions in Hierarchical Catalysts

Soft templating with siliceous surfactant is an established protocol for the synthesis of hierarchically porous silicoaluminophosphates (HP SAPOs) with improved mass transport properties. Motivated by the enhanced performance of HP SAPOs in the Beckmann rearrangement of cyclohexanone oxime to the nylon 6 precursor ϵ-caprolactam, an integrated theoretical and empirical study was carried out to investigate the catalytic potential of the siliceous mesopore network. Inelastic neutron scattering (INS) studies, in particular, provided unique insight into the substrate-framework interactions in HP (Si)AlPOs and allowed reactive species to be studied independent of the catalyst matrix. The spectroscopic (INS, FTIR spectroscopy, MAS NMR spectroscopy) and computational analyses revealed that in the organosilane-templated SAPO, the interconnectivity of micro- and mesopores permits cooperativity between their respective silanol and Brønsted acid sites that facilitates the protonation of cyclohexanone oxime in a physical mixture at ambient temperature.     

Interface properties of ionic liquids containing metal ions: features and potentialities

Interfaces and surfaces are the regions where important events happen: catalysis, molecular recognition, charge transfer, polymerization, and many other critical processes take place at the boundary between one medium and another. In this article we discuss the interface (liquid/air) properties of ionic liquids (ILs) containing dissolved metal ions with the aim to show the possibility to use metal salts to transform ILs and their surfaces into engineered liquid supports to apply in material sciences, separation procedures or to use as optical devices.     

Polyominoes Determined by Permutations: Enumeration via Bijections

A permutominide is a set of cells in the plane satisfying special connectivity constraints and uniquely defined by a pair of permutations. It naturally generalizes the concept of permutomino, recently investigated by several authors and from different points of view [1, 2, 4, 6, 7]. In this paper, using bijective methods, we determine the enumeration of various classes of convex permutominides, including, parallelogram, directed convex, convex, and row convex permutominides. As a corollary we have a bijective proof for the number of convex permutominoes, which was still an open problem.     

Residue analysis of glucocorticoids in bovine milk by liquid chromatography–tandem mass spectrometry

A sensitive liquid chromatography–tandem mass spectrometry (LC-MS/MS) method for the simultaneous determination of 13 steroidal anti-inflammatory drugs in bovine milk is presented. Due to their weakly acid nature, analytes were separated by ion suppression reversed phase chromatography and detected in positive-ion mode by a high flow electrospray source. Dexamethasone-d4 was used as internal standard. The sample preparation was simple and reliable; it included acidic deproteinization of milk followed by sample enrichment and clean-up, utilizing a C18 solid phase extraction cartridge. Recoveries exceeded 70% with an intra-day precision not larger than 12%. The efficiency of the sample clean-up and internal standardization rendered negligible the matrix effect, estimated by comparing standard and matrix-matched calibration curves. A small-scale reconnaissance was carried out on several raw and whole fresh milk samples. A large number of analyzed samples showed a chromatographic peak, in the retention time window of cortisol, at levels included between its decision limit (CCα) and detection capability (CCβ). As a result of a heat-induced transformation, an isomeric product of triamcinolone was observed during the extract evaporation. Since this rearrangement might occur during the milk pasteurization process, LC-MS/MS and ¹H-NMR investigations were performed out to conclusively differentiate the two isomers. One- and two-dimensional proton NMR spectra were able to identify the transformation product as 9a-fluoro-11b,16a-trihydroxy-17b-hydroxymethyl-D-homoandrosta-1,4-diene-3,17a-dione.