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 13C-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 Egap(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 Egap(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.
For decades, jarosites have been precipitated by controlling Fe in hydrometallurgical circuits. In addition, their synthesis, characterization, precious metals incorporation, decomposition and leaching have led to important results in this field. Nowadays, new topics related to the synthesis of these compounds have directed studies for applications such as lithium-ion batteries (as cathodes or/and anodes). Additionally, in this work, the evaluation of these kinds of compounds as biomaterials to be used in bone tissue engineering is shown, which is a novel application of these jarosite type-compounds. The method used for the synthesis of these compounds has been improved, decreasing the temperature (from 95 to 70 °C) and synthesis time (from 24 to only 3 h), which allows the doping of the potassium jarosite with calcium, strontium and magnesium (JKCa, JKCa2 and JKAll). The powders obtained this way were characterized confirming the incorporation of these elements into the structure, and the biological assays allowing the cell proliferation at 10 days conclude that these compounds are viable as a biomaterial, due to their non-toxic property. On the other hand, these jarosites show osteoinduction when added to the swine dental pulp stem cells and can be used for orthodontic purpouses.
The separation of iron from kaolin clay solutions using electro deposition was studied. Electrochemical studies of the iron electro-deposition were performed using the techniques of cyclic voltammetry, chronopotentiometry and chronoamperometry on a silver rotating disk electrode (RDE) as a working electrode. The effect of the kaolin solution pretreatment with ultrasonic method on the electrochemical reduction processes was studied. The influence of the disk speed of the electro-deposition performances was also studied. The morphology of the surface of the electro-deposit was observed by SEM. It was found that the ultrasonic pretreatment has an important effect on the reduction processes and on the morphology of the electrodeposited sample. The chemical composition of the electrode-posit was characterized by atomic absorption and ICP-ToFMS. It was shown that Fe2O3 content in the clay was 0.6% (weight). The voltammetric studies revealed that, during the electrochemical reduction processes of the kaolin solution, the iron reduction peaks were observed in the potential range from - 0.52V to -2.0V (E vs. SCE). Subsequently, the chronopotentiometry study showed that when a current of - 0.09A is applied to the electrochemical cell, the reduction of iron species occurred. It was also found that the variation of the amount of the electrodeposited iron is, of course, significantly dependent of the speed of the working electrode. For an electrode speed rate ranged from 1500 to 6500 rpm (revolutions per minute), an optimum amount of the electro deposited iron was obtained for an electrode speed of about 4000 rpm.
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