Search

The effect of two different anionic membranes on manganese deposition was studied in a two-compartment electrochemical reactor with a titanium cathode and a dimensionally stable RuO 2 |Ti anode. Chronopotentiometry, ICP-OES, SEM, XRD and elemental mapping were used to understand the changes in concentration and characteristics of the metallic deposition at different current densities with the anionic membranes AMI 7001s and Neosepta AMX. The results demonstrate that AMI reduces more manganese than AMX below -100 A m -2 , generating more metallic deposition but also more low-solubility manganous by-products, whereas both membranes exhibited similar behaviours above -100 A m -2 reaching the maximum current efficiency (63%) at -200 A m -2 . It was also observed that the membranes have a significant effect on sulphate consumption since they are anions., Competing Interests: The authors declare no conflict of interest., (This journal is © The Royal Society of Chemistry.)

Electrochemical reduction of ionic species during manganese deposition from sulphated aqueous solutions has been studied in an electrochemical reactor with two anionic exchange membranes. Thermodynamic analysis, voltammetries, and chronopotentiometries were used to determine the reaction mechanism of the reductions developed, with the results demonstrating that the effect of the elemental selenium on the hydrogen evolution leads to the formation of elemental sulphur by reducing the sulphate ions with both membranes. It was also evident that in the range of -25 to -50 A m -2 the electrodeposition of metallic manganese begins, with minimal interference from parasitic reactions., Competing Interests: The authors declare no conflict of interest., (This journal is © The Royal Society of Chemistry.)

In this work a Metal-Organic Framework (MOF) was prepared using a solvothermal method, taking as precursors 1. 2-di-(4-pyridyl)-ethylene, 1.2.4.5-benzenetetracarboxylic acid and Co(No 3 ) 2 -6H 2 O. This MOF was called UV-11 and was evaluated using microscopic, spectroscopic and electrochemical techniques. According to the obtained results, the melting point of the compound is located in a higher interval than its precursors. Stereoscopic microscopy analysis shows the presence of pink crystals in the form of needles. MEB technique displays a laminar morphology as well as crystals with approximate sizes (36 mm wide and 150 mm long). EDS analysis corroborated the presence of precursor elements such as cobalt, carbon and oxygen. Furthermore, the XRD technique shows the cobalt-related phases in the sample, which is cobalt bis (pyridine-6-carboxylic-2-carboxylate). A modified carbon paste electrode was prepared using MOF UV-11 and by cyclic voltammetry electrochemical technique, semi-reversible redox processes are identified, as well as thermodynamic and kinetic parameters were obtained with the Laviron equation, and electrochemical performance properties from the cyclic voltammetry experimental data., (Copyright © 2020 Meza-Pardo, Morales-Tapia, Veloz Rodríguez, Reyes-Cruz, Perez-Labra, Urbano-Reyes, Rivera-Villanueva and Cobos-Murcia.)

Objective: Malaria parasites invade, grow and multiply inside erythrocytes and obtain nourishment from haemoglobin. Then, the released haem group is oxidized to haematin and inert dimeric haemozoin bio-crystals form, which provides the parasite a unique way to avoid the toxicity associated with the haem group. Therefore, antimalarial drugs are designed to inhibit dimer formation; however, recent electrochemical studies indicate that an inert dimer also promotes a toxic oxidizing environment. Therefore, this work explores drug reactivity in the presence of monomers and dimers to evaluate their contribution to redox activity., Materials and Methods: Three medicines mixed with haemozoin or β-haemozoin in carbon paste electrodes were tested using cyclic voltammetry., Results: The data indicated again that the substances modify the natural redox state of haemozoin and β-haemozoin. This effect could be attributed to the natural oxidation potential of the drugs. In addition, it was found that the oxidation potential decreased through quinine, lumefantrine and artemether with the same tendency in the presence of haemozoin but with less current density. Additionally, it was observed that the oxidation response between the monomer haemozoin and antimalarial drugs is carried out at more negative potentials., Conclusions: Together, the total results indicate that antimalarials per se can contribute to oxidation processes and that in combination with monomeric or dimeric haemozoin can increase or decrease the oxidizing power of the haemozoin forms. The various oxidizing environments suggest that the cell membranes can also be damaged by the unique presence of the antimalarial.

In this work, two oligophenyleneimines type pentamers with terminal aldehydes, designated as DAFCHO (4,4'-((((((2,5-bis(octyloxy)-1,4-phenylene)bis(methanylylidene))bis(azanyl ylidene))bis(9H-fluorene-7,2-diyl))bis(azanylylidene))bis(methanylylidene))bis(2,5-bis(octyloxy) benzaldehyde)) and FDACHO (4,4'-((((((2,5-bis(octyloxy)-1,4-phenylene)bis(methanylylidene))bis (azanylylidene))bis(4,1-phenylene))bis(azanylylidene))bis(methanylylidene))bis(2,5-bis(octyloxy) benzaldehyde)) were synthesized by mechanochemistry method using 2,5-bis(octyloxy) terephtal aldehyde and 2,7-diaminofluorene or 1,4-phenylenediamine. All compounds were spectroscopically characterized using ¹H and 13 C-NMR, FT-IR and mass spectrometry MALDITOF. The optical properties of the compounds were analyzed by UV-vis spectroscopy using different solvents. We observed that DAFCHO and FDACHO exhibit interesting photochromic properties when they are dissolved in chloroform and exposed to sunlight for 3, 5 and 10 min. The value of the energy band gap was calculated from the absorption spectra without irradiation E gap(optical) . It was 2.50 eV for DAFCHO in chloroform solution, and it decreased to 2.34 eV when it is in films. For FDACHO, it was 2.41 eV in solution and 2.27 eV in film. HOMO (Highest Occupied Molecular Orbital), LUMO (Lowest Unoccupied Molecular Orbital) and E gap(electrochemical) values were obtained by electrochemical studies. The results indicate that the compounds can be considered as organic semiconductors since their values are 2.35 eV for DAFCHO and 2.06 eV for FDACHO. The structural and electronic properties of the compounds were corroborated with a DFT (Density Functional Theory) study.

Background: Understanding the significance of hemozoin (Hz) in the process through which Plasmodium is released from the heme group in the food vacuole during hemoglobin degradation, will allow the development of more effective drugs against malaria. Therefore, the development of methodologies to obtain Hz synthetically will facilitate an in vitro evaluation of new anti-malarial drugs., Methods: We present a methodology with good results to obtain Hz from fecal material of blood-sucking insects Meccus longipennis . The preparation of biological cultures of the parasite ( Plasmodium ) transmitter of the disease is not necessary., Results: The hemozoin molecule and its dimer were obtained using the method described and it was possible to validate a comparison with the positive and negative controls using different analytical techniques., Conclusion: The proposed method allows obtaining hemozoin and its dimer demonstrating equivalence with positive controls that demonstrate that the present procedure may be an alternative for the evaluation of antimalarial drugs., Competing Interests: Conflict of interests The authors declare that there is no conflict of interests.