Cláudio Teodoro de Carvalho

Thermal investigation of solid 2-methoxycinnamylidenepyruvate of some bivalent transition metal ions

Solid-state M-2-MeO-CP compounds, where M represents bivalent Mn, Fe, Co, Ni, Cu, Zn and 2-MeO-CP is 2-methoxycinnamylidenepyruvate, were synthesized for the first time. Simultaneous thermogravimetry and differential thermal analysis, differential scanning calorimetry, X-ray powder diffractometry, infrared spectroscopy, TG-FTIR system, elemental analysis and complexometry have been used to characterize and to study the thermal behaviour of the compounds. The dehydration in all the compounds, except for iron occurs in a single step. The thermal decomposition of the anhydrous compounds occurs in two or three steps with the formation of the respective oxides, Mn3O4, Fe2O3, Co3O4, NiO, CuO and ZnO, as final residue. The results also provided information concerning the thermal behaviour and identification of the gaseous products evolved during the heating of these compounds.

Synthesis, characterization and thermal behaviour of heavy trivalent lanthanide malonates

Solid-state Ln-L compounds, where Ln stands for heavy trivalent lanthanides (Tb-Lu) and L is malonate, have been synthesized. Simultaneous thermogravimetry and differential thermal analysis (TG-DTA), differential scanning calorimetry (DSC), X-ray powder diffractometry, infrared spectroscopy, TG-FTIR system, elemental analysis and complexometry were used to characterize and to study the thermal behaviour of these compounds. The dehydration of the compounds begins at 303 K and the anhydrous compounds are stable up to 548 K. The results also provided information concerning the ligands denticity, thermal behaviour and identification of some gaseous products evolved during the thermal decomposition of these compounds.

Thermogravimetric and spectroscopic study (TG–DTA/FT–IR) of activated carbon from the renewable biomass source babassu

Activated carbons (ACs) with well–developed microstructure and high microporosity were obtained from biomass by potassium hydroxide activation. The preparation process consisted in producing carbon materials in the ratios of activating agent to raw material 70:30, 50:50, 30:70 and 25:75 (w/w) characterized by thermal analysis coupled to spectroscopy (TG–DTA / FT–IR), scanning electron microscopy (SEM), N2 adsorption isotherms at –196 oC and activation isotherm at 500 and 600 oC for 3.0 h. Specific surface areas (SBET) within 728 and 1712 m2 g-1 and (Smic) within 1054 and 1923 m2 g-1 were obtained, while the micropores surface area was calculated using the Dubinin-Astakhov (DA) equation and the pore size distribution calculated from density functional theory (DFT) was found to be in the range 1.09 – 1.77 nm. Adsorption isotherms were fitted using Langmuir and Freundlich non–linear models and the adsorption capacity determined for methylene blue dye was between 27.13 and 459.20 mg g-1.

Alternative binary blends and their synergistic effect on stability of soybean biodiesel

The primary antioxidant tert-butylhydroquinone (TBHQ) and an alternative additive, named 1,4-bis(ethylamino)-9,10-anthraquinone, were mixed to yield a potent blend able to be used in the field of biodiesel preservation. Physicochemical parameters such as peroxide value, total acid number, density and induction period were used to evaluate the effectiveness of the combination in stabilising soybean biodiesel during the accelerate storage period of degradation. The induction period values were also used to calculate the occurrence of synergistic effect, and it was observed a high percentage of synergism for the combined additives. The results showed that the presence of target alternative additive also enables lower the concentration of the primary antioxidant (TBHQ) in the blend. The cost-effective comparison was evaluated, and it was verified that the final cost of biodiesel can also be lowered, since the amount of additives (in the blend) required to meet the biodiesel specifications was reduced between 70 and 88%.

Copper II - polar amino acid complexes: toxicity to bacteria and larvae of Aedes aegypti

Control strategies using insecticides are sometimes ineffective due to the resistance of the insect vectors.In this scenario new products must be proposed for the control of insect vectors.The complexes L-aspartate Cu (II) and L-glutamate-Cu (II) complexes were synthesized and characterized by elemental analysis, visible ultraviolet, infrared spectroscopy and potentiometric titration. The toxicity of these complexes was analyzed in Aedes aegypti (Diptera: Culicidae) larvae and Gram-negative and Gram-positive bacteria. The interaction between the ligands and the amino acid balance and the distribution of the species as a function of pH were discussed. The lethal concentration median (LC50) for Ae. aegypti larvae were: L-glutamic acid-Cu (II) - 53.401 mg L-1 and L-aspartate-Cu (II) - 108.647 mg L-1. The minimum inhibitory concentration (MIC) required for Staphylococcus aureus and Escherichia coli was: L-glutamate-Cu (II) 500-2000 mg L-1 and L-aspartate-Cu (II) 1000-2000 mg L-1. The concentrations demonstrated toxicity that evidence the potential of the complexes as bactericide and insecticide. Metal complexes formed by amino acids and transition metals are advantageous because of low environmental toxicity, biodegradability and low production cost.

Efeito da complexação de metais aos antiinflamatórios na ação contra agentes oxidativos e radicais livres: ação do cetoprofeno

Free radicals are highly reactive species generated in living organisms for the purpose of protection. However, in some circumstances, they are responsible for the occurrence or aggravation of tissue damage. Many anti-inflammatory drugs have a direct effect on free radicals and not radical reactive species, which contributes to its actions against inflammation. Ketoprofen is a nonsteroidal anti-inflammatory agent that generates free radicals by photo irradiation and has an important hemolytic effect with that. The complexation of metals to different drugs has been used as a strategy to improve the pharmacological action of different molecules and reduce their side effects. This paper presents the results of ketoprofen and their metallic complexes action on erythrocytes and free radicals. It was observed that the cerium enhances the scavenger properties of ketoprofen on free radicals, while copper enhances its action over non-radical oxidants. Copper also reduced the hemolytic effect presented by ketoprofen meanwhile its cerium derivative maintained it.

Synthesis and Biological Activity of Fe (III) Acetate for Microbial Control at Breeding Sites of Aedes aegypti (Diptera: Culicidae)

Unconventional approaches can be used control populations of disease-carrying insect to improve health, economic, social, and environmental standards. There is a need for prolonged reduction of vector populations, using low-toxicity and low-cost products in domestic settings. Metals such copper and iron have shown to be toxic to insect larvae, with a delay in reproduction, damage to the cells of the digestive system and the production of free radicals and oxidant species, resulting in tissue damage and death. To control insect breeding, we synthesized and characterized Fe (III) acetate via carbonate. Fe (III) acetate showed no toxic effect on mosquito larvae up to 1.000 mg L -1 , but was bactericidal for Gram-positive and Gram-negative bacteria, mainly due to the action of Fe (III) acetate. DOI: http://dx.doi.org/10.17807/orbital.v10i5.1135

Synthesis and biological activity of acetates of copper (II) and iron (III) for the control of Aedes aegypti (Diptera: Culicidae)

This work aimed to the synthesis of basic acetates of Cu (II) and Fe(III) against larvae of Aedes aegypti and Gram negative and Gram positive. The transition metal ions Cu (II) and Fe (III) have bactericidal activity and are toxic to Aedes aegypti larvae in the eggs and larval stages of initial, precludes the eggs hatch and slow reproductive cycle of the insect. The theme investigates the importance of carboxyl groups in complex formation, transport and cellular internalization of the toxic ions. It is known that the bactericide or insecticide activity is due to metal ions and Cu (II)or Fe (III).