Fe-MOF Catalytic Nanoarchitectonic toward Electrochemical Ammonia Production.

Electrochemical reduction of nitrate into ammonia has lately been identified as one among the promising solutions to address the challenges triggered by the growing global energy demand. Exploring newer electrocatalyst materials is vital to make this process effective and feasible. Recently, metal-organic framework (MOF)-based catalysts are being well investigated for electrocatalytic ammonia synthesis, accounting for their enhanced structural and compositional integrity during catalytic reduction reactions. In this study, we investigate the ability of the PCN-250-Fe3 MOF toward ammonia production in its pristine and activated forms. The activated MOF catalyst delivered a faradaic efficiency of about 90% at -1 V vs RHE and a yield rate of 2.5 × 10-4 mol cm-2 h-1, while the pristine catalyst delivered a 60% faradaic efficiency at the same potential. Theoretical studies further provide insights into the nitrate reduction reaction mechanism catalyzed by the PCN-250-Fe3 MOF catalyst. In short, simpler and cost-effective strategies such as pretreatment of electrocatalysts have an upper hand in aggravating the intrinsic material properties, for catalytic applications, when compared to conventional material modification approaches.

Anticorrosion, Thermal Degradation, and Hydrophobic Performances of Graphene/TiO2 Nanocomposite Coatings.

Globally, researchers have devoted consistent efforts to producing excellent coating properties since coating plays an essential role in enhancing electrochemical performance and surface quality. In this study, TiO2 nanoparticles in varying concentrations of 0.5, 1, 2, and 3 wt.% were added into the acrylic-epoxy polymeric matrix with 90:10 wt.% (90A:10E) ratio incorporated with 1 wt.% graphene, to fabricate graphene/TiO2 -based nanocomposite coating systems. Furthermore, the properties of the graphene/TiO2 composites were investigated by Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), ultraviolet-visible (UV-Vis) spectroscopy, water contact angle (WCA) measurements, and cross-hatch test (CHT), respectively. Moreover, the field emission scanning electron microscope (FESEM) and the electrochemical impedance spectroscopy (EIS) tests were conducted to investigate the dispersibility and anticorrosion mechanism of the coatings. The EIS was observed by determining the breakpoint frequencies over a period of 90 days. The results revealed that the TiO2 nanoparticles were successfully decorated on the graphene surface by chemical bonds, which resulted in the graphene/TiO2 nanocomposite coatings exhibiting better dispersibility within the polymeric matrix. The WCA of the graphene/TiO2 coating increased along with the ratio of TiO2 to graphene, achieving the highest CA of 120.85° for 3 wt.% of TiO2. Excellent dispersion and uniform distribution of the TiO2 nanoparticles within the polymer matrix were shown up to 2 wt.% of TiO2 inclusion. Among the coating systems, throughout the immersion time, the graphene/TiO2 (1:1) coating system exhibited the best dispersibility and high impedance modulus values (Z0.01 Hz), exceeding 1010 Ω cm2.

ZnCl2 catalyzed new coumarinyl-chalcones as cytotoxic agents.

A new series of coumarin-yl-chalcone derivatives (3a-m) had been designed and synthesized through different reactions such as aromatic addition, cyclization and Claisen-Schmidt reactions in good yields (54-78%). 5-acetyl-4-(2-hydroxyphenyl) -6-methyl-3, 4-dihydropyrimidin-2(1H) -one (1) has been synthesized by multi-component one pot reaction of salicylaldehyde, methyl acetoacetate and urea, which was further reacted with malonic acid employing ZnCl2 catalyst to yield 5-acetyl-4-(4-hydroxy-2-oxo-2H-chromen-8-yl) -6-methyl-3, 4-dihydropyrimidin-2(1H) -one (2). The title compounds (3a-m) were synthesised by reacting 5-acetyl-4-(4-hydroxy-2-oxo-2H-chromen-8-yl) -6-methyl-3, 4-dihydropyrimidin-2(1H)-one (2) with different aromatic aldehydes in the presence of potassium hydroxide. In silico studies, a preliminary screening method for predicting the anti-cancer activity was performed for the synthesized compounds (3a-m) against Src, Alb tyrosine kinase and homology model protein (PDB ID: 4csv). The derivatives 3h and 3m showed moderate binding energies. The in vitro cytotoxic activity was evaluated for the compounds 3h and 3m by using human cancer cell-line morphology and MTT assay against three human cell-lines A549 (Lung), Jurkat (Leukemia) and MCF-7 (Breast). The results indicate that the derivatives 3h and 3m display significant anti-cancer activity, however it was found to be less cytotoxic when compared to the standard used i.e. Imatinib.

Isoreticular Microporous Metal-Organic Frameworks for Carbon Dioxide Capture.

The isoreticular principle has been applied to construct two copper metal-organic framework (MOF) analogues with different porosities for the adsorptive capture of CO2 from N2 and CH4 at 1 atm and 298 K. By using a 4-substituted isophthalate linker with a bulky nitro group, the microporous MOF [Cu(BDC-NO2)(DMF)] (UTSA-93 or CuBDC-NO2; H2BDC-NO2 = 4-nitroisophthalic acid and DMF = N,N'-dimethylformamide) has been synthesized with mot topology, showing a compact pore structure with a size of 6.0 × 7.0 Å2 in contrast to that of 6.9 × 8.5 Å2 in the prototypical MOF with a bromo group. The optimized pore structure allows the nitro-functionalized MOF to capture CO2 with a higher capacity of about 2.40 mmol g-1 under ambient conditions, in contrast to 1.08 mmol g-1 in the bromo-functionalized analogue. The adsorption selectivity of CuBDC-NO2-a for a CO2/N2 (15:85) mixture (28) under ambient conditions is also higher than that of the bromo-substituted prototype (25) and comparable with those of several MOF materials. Moreover, dynamic breakthrough experiments of the nitro-functionalized MOF have been performed to illustrate its separation potential toward a CO2/N2 mixture.

Copper-Promoted One-Pot Approach: Synthesis of Benzimidazoles.

A facile, one-pot, and proficient method was developed for the production of various 2-arylaminobenzimidazoles. This methodology is based for the first time on a copper catalyst promoted domino C-N cross-coupling reaction for the generation of 2-arylaminobenzimidazoles. Mechanistic investigations revealed that the synthetic pathway involves a copper-based desulphurization/nucleophilic substitution and a subsequent domino intra and intermolecular C-N cross-coupling reactions. Some of the issues typically encountered during the synthesis of 2-arylaminobezimidazoles, including the use of expensive catalytic systems and the low reactivity of bromo precursors, were addressed using this newly developed copper-catalyzed method. The reaction procedure is simple, generally with excellent substrate tolerance, and provides good to high yields of the desired products.

Facile Synthesis of Mesoporous α-Fe2O3@g-C3N4-NCs for Efficient Bifunctional Electro-catalytic Activity (OER/ORR).

Mesoporous α-iron oxide@graphitized-carbon nitride nanocomposites (α-Fe2O3@g-C3N4-NCs) were synthesized using urea-formaldehyde (UF) resins at 400 °C/2 h. The mesoporous nature of the prepared nanocomposites was observed from electron microscopy and surface area measurements. The electrochemical measurements show the bifunctional nature of mesoporous α-Fe2O3@g-C3N4-NCs in electrolysis of water for oxygen evolution and oxygen reduction reactions (OER/ORR) using 0.5 M KOH. Higher current density of mesoporous α-Fe2O3@g-C3N4-NCs reveals the enhanced electrochemical performance compared to pure Fe2O3 nanoparticles (NPs). The onset potential, over-potential and Tafel slopes of mesoporous α-Fe2O3@g-C3N4-NCs were found lower than that of pure α-Fe2O3-NPs. Rotating disc electrode experiments followed by the K-L equation were used to investigate 4e- redox system. Therefore, the mesoporous α-Fe2O3@g-C3N4-NCs bifunctional electro-catalysts can be considered as potential future low-cost alternatives for Pt/C catalysts, which are currently used in fuel cells.

A Twofold Interpenetrated Metal-Organic Framework with High Performance in Selective Separation of C2 H2 /CH4.

A twofold interpenetrated metal-organic framework, PMOF-3, composed of four kinds of polyhedra exhibits the highest selectivity of 157 for C2 H2 /CH4 separation at 296 K and 1 atm owing to the synergistic effect of the open metal sites, C≡C triple bonds, and microporous structure.

A Threefold Interpenetrated Pillared-Layer Metal-Organic Framework for Selective Separation of C2 H2 /CH4 and CO2 /CH4.

A new threefold interpenetrated pillared-layer microporous metal-organic framework, [Zn2 (cca)2 (4-bpdb)]n ⋅(DMF)2n (UTSA-85) (H2 cca=4-carboxycinnamic acid, 4-bpdb=1,4-bis(4-pyridyl)-2,3-diaza-1,3-butadiene, and DMF=N,N-dimethylformamide), has been designed and generated by the solvothermal reaction of mixed ligands (H2 cca and 4-bpdb) and Zn(NO3 )2 ⋅6 H2 O. Single-crystal XRD analysis disclosed that discrete paddle-wheel Zn2 (COO)4 clusters as secondary building units linked the cca ligands to give two-dimensional layers, which were further pillared by 4-bpdb ligands to form a threefold interpenetrated pillared-layer structure. The desolvated framework, UTSA-85 a, was revealed to exhibit permanent porosity with a BET surface area of 558 m2 g-1 and a high selectivity of 64 for C2 H2 /CH4 separation at 296 K owing to the microporous (≈5.0 Å) structure and functional azine groups that decorated the pore channels.