Topic Review
Copper(II) Complex
A dinuclear copper(II) complex of (1) (where bipy = 2,2′‑bipyridine, bzt = benzoate and ox = oxalate) was synthesised and characterised by diffractometric (powder and single-crystal XRD) and thermogravimetric (TG/DTG) analyses, spectroscopic techniques (IR, Raman, electron paramagnetic resonance spectroscopy (EPR) and electronic spectroscopy), magnetic measurements and density functional theory (DFT) calculations. The analysis of the crystal structure revealed that the oxalate ligand is in bis(bidentate) coordination mode between two copper(II) centres. The other four positions of the coordination environment of the copper(II) ion are occupied by one water molecule, a bidentate bipy and a monodentate bzt ligand. An inversion centre located on the ox ligand generates the other half of the dinuclear complex. Intermolecular hydrogen bonds and pi-pi for the organisation of the molecules in the solid state. Molar magnetic susceptibility and field dependence magnetisation studies evidenced a weak intramolecular–ferromagnetic interaction (J = +2.9 cm‑1) between the metal ions. The sign and magnitude of the calculated J value by density functional theory (DFT) are in agreement with the experimental data.
  • 1200
  • 30 Oct 2020
Topic Review
Production of Electrolytic Manganese Dioxide
The ferromanganese (FeMn) alloy is produced through the smelting-reduction of manganese ores in submerged arc furnaces. This process generates large amounts of furnace dust that is environmentally problematic for storage. Due to its fineness and high volatile content, this furnace dust cannot be recirculated through the process, either. Conventional MnO2 production requires the pre-reduction of low-grade ores at around 900 °C to convert the manganese oxides present in the ore into their respective acid-soluble forms; however, the furnace dust is a partly reduced by-product. A hydrometallurgical route is proposed to valorize the waste dust for the production of battery-grade MnO2. By using dextrin, a cheap organic reductant, the direct and complete dissolution of the manganese in the furnace dust is possible without any need for high-temperature pre-reduction. The leachate is then purified through pH adjustment followed by direct electrowinning for electrolytic manganese dioxide (EMD) production. An overall manganese recovery rate of >90% is achieved. 
  • 962
  • 08 Jul 2021
Topic Review
Water Physisorbed on Natural Clinoptilolite
Infrared spectroscopy (FT-IR) can provide very useful information on the nature of water physisorbed on zeolites. The vibrational characteristics of geomorphic clinoptilolite of natural origin and the water physically adsorbed on it have been investigated. In particular, two types of physisorbed water molecules have been identified by combining the FT-IR analysis with a mild thermal drying treatment (1h at 150°C) of the sample: the loosely-bound water and the tightly-bound water.
  • 692
  • 29 Oct 2020
Topic Review
Metal-Organic Frameworks
Metal-organic frameworks represent a porous class of materials that are build up from metal ions or oligonuclear metallic complexes and organic ligands. They can be considered as sub-class of coordination polymers and can be extended into one-dimension, two-dimensions, and three-dimensions. Depending on the size of the pores, MOFs are divided into nanoporous, mesoporous, and macroporous items. The latter two are usually amorphous. MOFs display high porosity, a large specific surface area, and high thermal stability due to the presence of coordination bonds. The pores can incorporate neutral molecules, such as solvent molecules, anions, and cations, depending on the overall charge of the MOF, gas molecules, and biomolecules. The structural diversity of the framework and the multifunctionality of the pores render this class of materials as candidates for a plethora of environmental and biomedical applications and also as catalysts, sensors, piezo/ferroelectric, thermoelectric, and magnetic materials.
  • 630
  • 13 Jan 2021
Topic Review
Ag2O–MnO2/Graphene Oxide Nanocomposite
Catalytic oxidation of alcohol to their analogous carbonyls is one of the key organic reactions in both scientific and industrial applications, with universal production of 10,000 million tons/year of carbonyls in the 20th century. Such as, aldehyde and ketone derivatives are extensively employed as precursors in insecticide, flame-retardant, cosmetic, confectionery, flavoring, pharmaceutical, and beverage industries. 
  • 577
  • 27 Oct 2020
Topic Review
Natural Clinoptilolite
Zeolites are ionic conductors and the cation electrical mobility in zeolites depends on their hydration state; consequently, the water adsorption/desorption process can be simply investigated by measuring the temporal evolution of current intensity in samples exposed to an environment with constant humidity or dry air, respectively. According to this kinetic analysis, a mechanism has been formulated for the water adsorption process able to justify the Lagergren pseudo-first-order kinetics observed for adsorption and the first-order kinetics observed for desorption. In this mechanism water molecules are first attract by the electric field of the cations and then they move at cation-framework interface to maximize the hydrogen bond interactions.
  • 477
  • 28 Oct 2020
Topic Review
ZnO and TiO2 Green Synthesis
Over the last two decades, oxide nanostructures have been continuously evaluated and used in many technological applications. The advancement of the controlled synthesis approach to design desired morphology is a fundamental key to the discipline of material science and nanotechnology. These nanostructures can be prepared via different physical and chemical methods; however, a green synthesis approach is a promising way to produce these nanostructures with desired properties with time and energy savings and/or less use of hazardous chemicals. In this regard, ZnO and TiO2 nanostructures are prominent candidates for various applications given their thermal stability, non-toxicity and cost-effective. 
  • 448
  • 06 May 2021
Topic Review
Electron Paramagnetic Resonance
Electron Paramagnetic Resonance, EPR is resonance absorption of microwave quanta by electron spins placed in a swept external magnetic field B at a definite value of magnetic field. Other used names are Electron Magnetic Resonance, EMR and Electron Spin Resonance, ESR.
  • 389
  • 24 May 2021
Topic Review
Solketal
Solketal (CAS 100–79–8) has low viscosity at room temperature (~11 cP) and freezing, boiling, and flash points of about −26 °C, 190 °C, and 80 °C, respectively. The density is 1.06 g/cm3 and the vapor pressure is 107.32 mmHg. It has low toxicity, slight odor, and it is non-irritant for humans; due to these characteristics and to the renewable origin, it is considered an environmentally friendly substance. It is completely miscible in water and in most organic compounds, which endows its solvent capacity.
  • 388
  • 07 May 2021
Topic Review
Rhenium(I) Tricarbonyl Complexes As Photosensitisers
Photodynamic therapy (PDT) is emerging as a significant complementary or alternative approach for cancer treatment. Re(I) tricarbonyl complexes is a new generation of metal-based photosensitisers for PDT that are of great interest in multidisciplinary research.
  • 378
  • 27 Oct 2020
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