Sustainable and rapid preparation of nanosized Fe/Ni-pentlandite particles by mechanochemistry

In recent years, metal-rich sulfides of the pentlandite type (M₉S₈) have attracted considerable attention for energy storage applications. However, common synthetic routes towards pentlandites either involve energy intensive high temperature procedures or solvothermal methods with specialized precursors and non-sustainable organic solvents. Herein, we demonstrate that ball milling is a simple and efficient method to synthesize nanosized bimetallic pentlandite particles (Fe_4.5Ni_4.5S₈, Pn) with an average size of ca. 250 nm in a single synthetic step from elemental- or sulfidic mixtures. We herein highlight the effects of the milling ball quantity, precursor types and milling time on the product quality. Along this line, Raman spectroscopy as well as temperature/pressure monitoring during the milling processes provide valuable insights into mechanistic differences between the mechanochemical Pn-formation. By employing the obtained Pn-nanosized particles as cathodic electrocatalysts for water splitting in a zero-gap PEM electrolyzer we provide a comprehensive path for a potential sustainable future process involving non-noble metal catalysts.

A sustainable and rapid mechanochemical method for the preparation of bimetallic nanosized pentlandite particles as cathode material is developed and tested within zero-gap PEM cells.     

Copper(II) complexes containing pyridine-based and phenolate-based systems: Synthesis,characterization, DFT study,biomimetic catalytic activity of catechol oxidase and phenoxazinone synthase

A template Schiff condensation of 2,6-pyridine dicarbaldehyde or 2,6-diformyl-4- bromophenol and 1,3–diamino-2-hydroxy propane or 3,4-diaminotoluene in the presence of copper(II) salts (CuX₂) (X = Cl, Br, CH₃COO, or ClO₄) affords different types of copper(II) complexes. Depending on the employed molar ratio of the dicarbonyl compounds and diamines, different types of copper(II) complexes formed during the template condensation reaction. Structural formulation of the complexes was confirmed by elemental analysis (C, H, N, and M), physical measurements such as thermal analysis (TAG & DTG), molar conductivity, and magnetic moments in addition to spectral studies (UV–Vis, IR, and ESR). Homobinuclear in a four-coordinate square planar and five-coordinate square pyramidal and trigonal bipyramidal in monomeric structures are proposed. A mononuclear hexa-coordinate in an octahedral geometry is suggested as well. Oxidase biomimetic catalytic activity of these newly synthesized copper(II) complexes was examined toward the aerobic oxidation of 4-tert-butylcatechol (4-TBCH₂) and o-aminophenol under catalytic conditions. Both catalytic and kinetic investigations demonstrate promising oxidase catalytic activity and based on the kinetic results, probable mechanistic catalytic implications are discussed. Geometrical structures of representative copper(II) complexes were determined by optimizing their bond lengths, bond angles, dihedral angles, and the structural index (τ).     

Effect of the storage tank thermal insulation on the thermal performance of an integrated collector storage solar water heater (ICSSWH)

The thermal behavior of an integrated collector storage solar water heater (ICSSWH) is numerically studied using CFD simulations. Based on the good agreement between the numerical results and the experimental data from literature, we propose a geometrical change allowing limiting the main disadvantage of this solar system which is its high night losses due to the non-insulated storage tank surface. A second 3D CFD model of an ICSSWH in which the storage tank is partially insulated is developed and three values of this tank thermal insulated fraction are studied. Numerical results show that the partially insulated tank based ICSSWH presents lower thermal losses during the night and this night thermal losses coefficient is reduced from 14.6 to 11.64 W K^?1 for the tank thermal insulation fraction τ = 1/4. Similarly, the modified system presents the advantage of its lower thermal losses even during the day. Regarding the thermal production, it is seen that the modified system presents higher water temperature at night and that for all the tank thermal insulation fractions. Concerning the operation of this modified system during the day, the water temperature is lower during the day and that up to 16 h but the water temperature which achieves 324 K for the storage tank thermal insulation fraction τ = 1/8 still sufficiently high to satisfy a family hot water needs.     

Lacitemzine, a novel sesquiterpene acid from the Tunisian plant Pulicaria laciniata (Coss. et Kral.) Thell.

The flowers of Pulicaria laciniata (Coss. et Kral.) Thell. (Asteraceae) afforded a new sesquiterpene acid 1, named lacitemzine together with the three known compounds, 4-hydroxy-3-methoxypyridine 2, β-sitosterol-3-O-β-d-glucoside 3 and 1,3,5-trimethoxybenzene 4. The structure of compound 1, 2-(2,6-dimethyl-3,4,5,6,7,8,9,10-octahydro-5,8-oxaazulen-9-yl)acrylic acid, contains a guaiane skeleton and was elucidated by spectroscopic procedures including 2D-NMR and X-ray diffraction.     

Hydrogen bonding and π–π interactions in 1‐benzofuran‐2,3‐dicarboxylic acid and its 1:1 cocrystals with pyridine,phenazine and 1,4‐phenylenediamine

The structure of 1‐benzofuran‐2,3‐dicarboxylic acid (BFDC), C₁₀H₆O₅, (I), exhibits an intramolecular hydrogen bond between one –COOH group and the other, while the second carboxyl function is involved in intermolecular hydrogen bonding to neighbouring species. The latter results in the formation of flat one‐dimensional hydrogen‐bonded chains in the crystal structure, which are π–π stacked along the normal to the plane of the molecular framework, forming a layered structure. 1:1 Cocrystallization of BFDC with pyridine, phenazine and 1,4‐phenylenediamine is associated with H‐atom transfer from BFDC to the base and charge‐assisted hydrogen bonding between the BFDC⁻ monoanion and the corresponding ammonium species, while preserving, in all cases, the intramolecular hydrogen bond between the carboxyl and carboxylate functions. The pyridinium 2‐carboxylato‐1‐benzofuran‐3‐carboxylic acid, C₅H₆N⁺·C₁₀H₅O₅⁻, (II), and phenazinium 3‐carboxylato‐1‐benzofuran‐2‐carboxylic acid, C₁₂H₉N₂⁺·C₁₀H₅O₅⁻, (III), adducts form discrete hydrogen‐bonded ion‐pair entities. In the corresponding crystal structures, the two components are arranged in either segregated or mixed π–π stacks, respectively. On the other hand, the structure of 4‐aminoanilinium 2‐carboxylato‐1‐benzofuran‐3‐carboxylic acid, C₆H₉N₂⁺·C₁₀H₅O₅⁻, (IV), exhibits an intermolecular hydrogen‐bonding network with three‐dimensional connectivity. Moreover, this fourth structure exhibits induction of supramolecular chirality by the extended hydrogen bonding, leading to a helical arrangement of the interacting moieties around 2₁ screw axes. The significance of this study is that it presents the first crystallographic characterization of pure BFDC, and manifestation of its cocrystallization with a variety of weakly basic amine molecules. It confirms the tendency of BFDC to preserve its intramolecular hydrogen bond and to prefer a monoanionic form in supramolecular association with other components. The aromaticity of the flat benzofuran residue plays an important role in directing either homo‐ or heteromolecular π–π stacking in the first three structures, while the occurrence of a chiral architecture directed by multiple hydrogen bonding is the dominant feature in the fourth.     

Microwave-assisted one-step synthesis of fenamic acid hydrazides from the corresponding acids

A facile and efficient method for synthesis of fenamic acid hydrazides from their acids in one-step reaction under microwave irradiation and solvent-free conditions was developed. Compared with the two-step conventional heating method, the process was simple, the reaction time was very short and the yields were almost quantitative.     

New bioactive labdane diterpenoids from Marrubium aschersonii

A phytochemical investigation of the ethanol extract of Marrubium aschersonii Magnus (Lamiaceae) collected from Tunisia led to the isolation and identification of two new labdane diterpenoids, marrubaschs A (1) and B (2), along with two known compounds (3 and 4). Their structures were elucidated by spectroscopic methods including HRESIMS and NMR techniques. All compounds were evaluated for their inhibitory effects on the nitric oxide (NO) production induced by lipopolysaccharide in RAW 264.7 macrophage cells. Compound 2 exhibited weak inhibition of NO production with an IC₅₀ value of 35 ± 1.0 μM.     

Diamondoid framework solid with Sn(OCH3)2–tetrapyridylporphyrin linkers,CuI nodes and [CuICl2]− counter‐ions

We report on the synthesis of a new metal–organic framework (MOF) composed of Sn(OCH₃)₂–tetrakis(pyridin‐4‐yl)porphyrin linkers, Cu⁺ connecting nodes and [CuCl₂]⁻ counter‐ions, namely poly[[bis(methanolato‐κO)[μ₅‐5,10,15,20‐tetrakis(pyridin‐4‐yl)porphyrin‐κ⁸1κN⁵:1′κN¹⁰:1′′κN¹⁵:1′′′κN²⁰:2κ⁴N²¹,N²²,N²³,N²⁴]copper(I)tin(II)] dichloridocuprate(I)], [CuSn(C₄₀H₂₄N₈)(CH₃O)₂][CuCl₂]. Its crystal structure consists of a single‐framework coordination polymer of the organic ligand and the Cu^I ions. The latter are characterized by a tetrahedral coordination geometry [with CN (coordination number) = 4], linking to the pyridyl N‐atom sites of four different ligands and imparting to the positively charged polymeric assembly a diamondoid PtS‐type topology. Correspondingly, every porphyrin unit is coordinated to four different Cu^I connectors. The [CuCl₂]⁻ anions occupy the intra‐lattice voids, along with disordered molecules of the water crystallization solvent. The asymmetric unit of this structure consists of two halves of the porphyrin scaffold, located on centres of crystallographic inversion, and the Cu⁺ and [CuCl₂]⁻ ions. This report provides unique structural evidence for the formation of tetrapyridylporphyrin‐based three‐dimensional MOFs with a diamondoid architecture that have been observed earlier only on rare occasions.     

Schiff bases of indoline-2,3-dione (isatin) with potential antiproliferative activity

ABSTRACT: BACKGROUND: Cancer is one of the most dreaded diseases and it is a leading cause of mankind death worldwide. Recent reports documented a remarkable antiproliferative activity of isatin nucleus against various cancer cell lines. The current work describes the antiproliferative activity of Schiff bases of combinatorial mixtures of the isatin derivatives M1-M22 as well as the individual compounds 1-11(A-K) of these combinatorial mixtures. RESULTS: The designed combinatorial library composed from eleven hydrazides A-K and eleven isatin derivatives 1-11 has been synthesized to formally generate 22 mixtures, M1-M22 of 121 Schiff bases, and their antiproliferative activity against K562 chronic myelogenous leukemia cells was evaluated. The indexed method of analysis of the prepared library was applied to elucidate the active components in the tested mixtures M1-M22. The predictions from the crossing procedure was validated through evaluation of the antiproliferative activity of individual compounds 1-11(A-K) of the library. Individual compounds 1-11(A-K) were also evaluated against the non-tumorigenic MCF-12A cell line to investigate their selectivity. A pharmacophore model was developed to further optimize the antiproliferative activity among this series of compounds. CONCLUSIONS: Variable antiproliferative activity was revealed with the investigated mixtures M1-M22 and the individual compounds 1-11(A-K). Most of the tested mixtures and several individual Schiff bases displayed high potency with IC50 values in the low micromolar range. A considerable selectivity of some individual compounds to the tumorigenic K562 cell line compared with the non-tumorigenic MCF-12A cell line was observed as indicated by their selectivity index (SI).     

Synthesis of biocompatible and thermally sensitive poly(N‐vinylcaprolactam) nanogels via inverse miniemulsion polymerization: Effect of the surfactant concentration

The goal of this study was to develop a new route to prepare thermally responsive polymer nanogels. Poly(N‐vinylcaprolactam) nanogels were prepared via inverse miniemulsion polymerization (W/O) at 70 °C using n‐hexadecane as a nonpolar continuous phase, potassium persulfate as an initiator, and N,N′‐methylenebisacrylamide as a crosslinker. Sorbitan monooleate (Span 80) was used as surfactant and its influence on the polymerization kinetics and on the colloidal characteristics of the nanogels were principally investigated. It was observed that the addition of a strong “lipophobe” is required to stabilize the resulting miniemulsion. The nanogels were characterized in terms of morphology, size, zeta potential, and thermoproperties using transmission electron microscopy and dynamic light scattering. It was observed that all the nanogels obtained collapsed when the lower critical solution temperature (LCST) was raised. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3932–3941, 2010