Kifah S. M. Salih

Dry reforming of methane (DRM) using a heterogeneous catalyst presents one of the CO₂ mitigation pathways to address global warming and climate change challenges. Such a suitable DRM catalyst with optimum activity and stability is still under intense research. We herein present a facile, slightly modified version of the conventional wet impregnation method to synthesize a NiO-faujasite nanocatalyst for DRM with the help of aniline, judiciously chosen based on the hard-soft acid-base (HSAB) principle. The resulting catalyst was characterized by the N₂ adsorption isotherm, PXRD, SEM/TEM, XPS, ²⁹Si solid-state NMR, H₂-TPR, NH₃-TPD, and DRM reaction, and its results were compared with those without aniline assistance. A smaller NiO nanoparticle with better dispersion was observed for our aniline-assisted sample resulting in a significant increase in activity (peaking at 86% CH₄ conversion with a H₂/CO ratio of 0.93) and stability for a 12 h time on stream. We hope that this work would pave the way to utilize the HSAB principle to synthesize more nanocatalysts with optimum overall performance.

The use of transition metals in cross‐coupling reactions has been verified as a powerful tool in synthetic organic chemistry to access valuable pharmaceutical intermediates and functional organic molecules. Copper compounds were described for building a variety of Carbon‐Carbon and Carbon‐Heteroatom bonds more than a century ago. Whereas nickel‐catalyzed cross‐coupling was emerged in the 1972. The general reactivity of the reaction conversion was enhanced during the last two decades, particularly under microwave irradiation conditions. The focus of this review article accentuates the recent development and sustainable achievement of copper‐ and nickel‐catalyzed cross‐coupling of different electrophiles and nucleophiles or two sort of nucleophiles under microwave irradiation conditions. The published cross‐coupling protocols during the last ten years were critically reviewed, this includes the type and amount of metal catalyst used, solventless and ligandless conditions and the application in the synthesis of complex heterocycles. Furthermore, various proposed reaction mechanisms covering radical path or through the involvement of metal complexes in different oxidation states were highlighted and discussed.

A new series of azomethine‐functionalized compounds was synthesized from the condensation of 2‐hydroxy‐1,3‐propanediamine and 2‐thienylcarboxaldehydes in the presence of a drying agent. The derivatives were spectroscopically characterized by NMR, LC‐MS, UV/Vis, IR and elemental analysis. Variable temperature ¹H‐NMR (−60 to +60 °C) was performed to investigate the effect of solvent polarity; the capability of solvent to form H‐bond was found to dramatically influencing the tautomerization process of the desired structures. The calculated thermochemical parameters (ΔH₂₉₈, ΔG₂₉₈ and ΔS₂₉₈) at DFT and MP2 levels of theory explained that 3 b exists in equilibrium with two tautomers. The basis of the electronic absorptions was pursued through Time‐Dependent Density‐Functional Theory (TD‐DFT). Analysis of the structural surfaces was inspected and the molecular electrostatic potential (MEP) demonstrated that the three functionalized compounds were relatively analogous in the electronic distributions. Furthermore, the electrophilic and nucleophilic centers lying on the molecular surfaces were probably playing a key‐role in stabilizing the compounds through the nonclassical C−H⋅⋅⋅π interactions and hydrogen bonding. The impact of solvent polarity on absorption spectra were investigated via solvatochromic shifts. For instance, compound 3 c displayed a gradual shift of the maximum absorption to the red area when the solvent polarity was increased, recording a 21 nm of bathochromic shift. In contrast, no significant solvent‐effect on 3 a and 3 b was observed. The solvation relation was pursued between Gutmann's donicity numbers the experimental λ_max; exhibited almost positive linear performance with a minor oscillation, that ascribe to the possible weak interface between the molecules of solute and designated solvents. The bandgap energy of all products were assessed experimentally using optical absorption spectra following Tauc approach, giving −4.050 (3 a), −3.900 (3 b) and −3.210 (3 c) eV. However, the ΔE were computationally figured out from TD‐DFT simulation to be −4.258 (3 a), −4.022 (3 b) and −3.390 (3 c) eV.

A new tetradentate Schiff base (SB), (E)-4-fluoro-2-(1-((2-(piperazin-1-yl)ethyl)imino)ethyl)phenol, was synthesized from condensation of 2-(1-piperazinyl)ethylamine and 5-fluoro-2-hydroxyacetophenone. This ligand was coordinated with three copper(II) salts (CuCl₂, CuBr₂ and Cu(NO₃)₂⸱3H₂O) separately, giving rise to new neutral water-soluble Cu(II)/ƞ⁴-NNNO complexes (1–3). The new materials were fully characterized by standard spectroscopic, elemental, thermal, electronic, absorption, and fluorescence analyses. The chromotropism investigation of the aqueous solutions of the complexes revealed notable outcomes. A turn off-on halochromism effect was observed, both in the acidic and basic mediums. The green-colored solution was changed to colorless (off) upon the addition of HCl, while the initial green color was reversibly restored (on) after the addition of NaOH. On the other hand, bathochromic solvatochromism shifts were noticed in various solvents. Interestingly, complex 2 displayed a remarkable blue fluorescence shift (Δλ = 90 nm) when compared to its SB ligand. The oxidation capability of the three complexes was successfully demonstrated for the conversion of o-catechol to o-benzoquinone in aqueous solutions and in the presence of H₂O₂, an environmentally friendly oxidant, under mild reaction conditions.

Natural products with novel chemistry are urgently needed to battle the continued increase in microbial drug resistance. Mushroom-forming fungi are underutilized as a source of novel antibiotics in the literature due to their challenging culture preparation and genetic intractability. However, modern fungal molecular and synthetic biology tools have renewed interest in exploring mushroom fungi for novel therapeutic agents. The aims of this study were to investigate the secondary metabolites of nine basidiomycetes, screen their biological and chemical properties, and then investigate the genetic pathways associated with their production. Of the nine fungi selected, Hypholoma fasciculare was revealed to be a highly active antagonistic species, with antimicrobial activity against three different microorganisms: Bacillus subtilis, Escherichia coli, and Saccharomyces cerevisiae. Genomic comparisons and chromatographic studies were employed to characterize more than 15 biosynthetic gene clusters and resulted in the identification of 3,5-dichloromethoxy benzoic acid as a potential antibacterial compound. The biosynthetic gene cluster for this product is also predicted. This study reinforces the potential of mushroom-forming fungi as an underexplored reservoir of bioactive natural products. Access to genomic data, and chemical-based frameworks, will assist the development and application of novel molecules with applications in both the pharmaceutical and agrochemical industries.