Characterization of organic and organomineral liquid fertilizers.

The aim of this work is to study the suitability of using different charcoals in order to produce humic-like acid. Fluorescence and UV-visible spectroscopy were applied to evaluate the humidification degree by using different index: E4/E6 (2, 8), A254/A465 (8) (UVVis spectroscopic); I400/I360 (4) and I470/I360 (4) (fluorescence spectroscopy in synchronousscan mode); A440 (5) and A4/A1 (9) (fluorescence spectroscopic in emission scan)

Induction of apoptosis in leukemia cell lines by new copper(II) complexes containing naphthyl groups via interaction with death receptors

The synthesis, physico-chemical characterization and cytotoxicity of four new ligands and their respective copper(II) complexes toward two human leukemia cell lines (THP-1 and U937) are reported (i.e. [(HL1) Cu(mu-Cl)(2)Cu(HL1)]Cl-2 center dot H2O (1), [(H2L2)Cu(mu-Cl)(2)Cu(H2L2)]Cl-2 center dot 5H(2)O (2), [(HL3)Cu(mu-Cl)(2)Cu(HL3)]Cl-2 center dot 4H(2) (3), [(H2L4)Cu(mu-Cl)(2)Cu(H2L4)]Cl-2 center dot 6H(2)O (4)). Ligands HL1 and HL3 contain two pyridines, amine and alcohol moieties with a naphthyl pendant unit yielding a N3O coordination metal environment Ligands H2L2 and H2L4 have pyridine, phenol, amine and alcohol groups with a naphthyl pendant unit providing a N2O2 coordination metal environment These compounds are likely to be dinuclear in the solid state but form mononuclear species in solution. The complexes have an antiproliferative effect against both leukemia cell lines; complex (2) exhibits higher activity than cisplatin against U937 (8.20 vs 16.25 mu mol dm(-3)) and a comparable one against THP-1. These human neoplastic cells are also more susceptible than peripheral blood mononuclear cells (PBMCs) toward the tested compounds. Using C57BL/6 mice an LD50 of 55 mg kg(-1) was determined for complex (2), suggesting that this compound is almost four times less toxic than cisplatin (LD50 = 14.5 mg kg(-1)). The mechanism of cell death promoted by ligand H2L2 and by complexes (2) and (4) was investigated by a range of techniques demonstrating that the apoptosis signal triggered at least by complex (2) starts from an extrinsic pathway involving the activation of caspases 4 and 8. This signal is amplified by mitochondria with the concomitant release of cytochrome c and the activation of caspase 9. (C) 2015 Elsevier Inc. All rights reserved

A New Heterobinuclear FeIIICuII Complex with a Single Terminal FeIII–O(phenolate) Bond. Relevance to Purple Acid Phosphatases and Nucleases

A novel heterobinuclear mixed valence complex [Fe^IIICu^II(BPBPMP)(OAc)_2]ClO_4, 1, with the unsymmetrical N_5O_2 donor ligand 2-bis[{(2-pyridylmethyl)aminomethyl}-6-{(2-hydroxybenzyl)(2-pyridylmethyl)} aminomethyl]-4-methylphenol (H_2BPBPMP) has been synthesized and characterized. A combination of data from mass spectrometry, potentiometric titrations, X-ray absorption and electron paramagnetic resonance spectroscopy, as well as kinetics measurements indicates that in ethanol/water solutions an [Fe^III-(nu)OH-Cu^IIOH_2]+ species is generated which is the likely catalyst for 2,4-bis(dinitrophenyl)phosphate and DNA hydrolysis. Insofar as the data are consistent with the presence of an Fe_III-bound hydroxide acting as a nucleophile during catalysis, 1 presents a suitable mimic for the hydrolytic enzyme purple acid phosphatase. Notably, 1 is significantly more reactive than its isostructural homologues with different metal composition (Fe^IIIM^II, where M^II is Zn^II, Mn^II, Ni^II,or Fe^II). Of particular interest is the observation that cleavage of double-stranded plasmid DNA occurs even at very low concentrations of 1 (2.5 nuM), under physiological conditions (optimum pH of 7.0), with a rate enhancement of 2.7 x 10^7 over the uncatalyzed reaction. Thus, 1 is one of the most effective model complexes to date, mimicking the function of nucleases

Equilibrium studies of selenite and selenate ions with the receptor complex formed by Cu2+ and 1,4,7,13,16,19-hexaaza-10,22-dioxacyclotetracosane (OBISDIEN)

cited By 6International audienceThe complexation of selenite (SeO32-) and selenate (SeO42-) ions in the cavity of the macrocyclic ligand OBISDIEN was studied in the absence and presence of Cu2+ ions and in the presence of bromide ions. Potentiometric equilibrium determinations allowed us to determine the species formed in the absence and presence of Cu(II) ions for the systems studied in the p[H] range 2-12. In the absence of metal ions the strength of binding of SeO42- increases from the monoprotonated to hexaprotonated species of OBISDIEN. The reverse effect occurs for the HSeO3- ion, with the strength of binding decreasing from the monoprotanated to the most protonated species. In the OBISDIEN: Cu2+: Br- system, the bromide ions contribute to the stabilisation of binuclear complexes. A similar role is played by selenite anions in the OBISDIEN: Cu2+: Br-: SeO32- systems. All SeO42- ions are complexed in the OBISDIEN:Cu2+: SeO32-: Br-:1:2:1:1:6 system; in the p[H] range 2-12, selenite and bromide ions are mostly free. At p[H] 8.1 which is the p[H] of sea water, in the absence of other complexing agents, all the selenite and bromide ions are free while the selenate ions are complexed, (μ-hydroxo)(μ-selenate)dicopper(II)-OBISDIEN being the major species present. © 1995

Studies on Synthetic and Natural Melanin and Its Affinity for Fe(III) Ion

In this work, we measured the metal-binding sites of natural and synthetic dihydroxyindole (DHI) melanins and their respective interactions with Fe(III) ions. Besides the two acid groups detected for the DHI system: catechol (Cat) and quinone-imine (QI), acetate groups were detected in the natural oligomer by potentiometric titrations. At acidic pH values, Fe(III) complexation with synthetic melanin was detected in an Fe(OH)(CatH2Cat) interaction. With an increase of pH, three new interactions occurred: dihydroxide diprotonated catechol, Fe(OH)2(CatH2Cat)−, dihydroxide monoprotonated catechol, [Fe(OH)2(CatHCat)]2−, and an interaction resulting from the association of one quinone-imine and a catechol group, [Fe(OH)2(Qi−)(CatHCat)]3−. In the natural melanin system, we detected the same interactions involving catechol and quinone-imine groups but also the metal interacts with acetate group at pH values lower than 4.0. Furthermore, interactions in the synthetic system were also characterized by infrared spectroscopy by using the characteristic vibrations of catechol and quinone-imine groups. Finally, scanning electronic microscopy (SEM) and energy-dispersive X-ray (EDS) analysis were used to examine the differences in morphology of these two systems in the absence and presence of Fe(III) ions. The mole ratio of metal and donor atoms was obtained by the EDS analysis

Equilibrium studies of ternary complexes formed by bromide, sulfate, selenite and selenate ions with Zn2+, Mg2+ and 1, 4, 7, 13, 16, 19-hexaaza-10, 22- dioxacyclotetracosane (obisdien)+

cited By 1International audienceBromide, sulfate, selenite and selenate were found to form bridges in the cavity of mononuclear and binuclear Obisdien:Zn(II) and Obisdien:Mg(II) complexes in aqueous solution at 25.0°C and μ = 0.100 M (KCl). Potentiometric equilibrium measurements were used to determine the formation constants of the species formed in these systems in the p[H] range 2-12. For the Obisdien: Zn2+:anions complexes, we have established the existence of four species for bromide ion, five species for sulfate ion, six species for selenite ion and four species for selenate ion. We found that the hydroxo binuclear complexes predominate over the others species, and the binding strength decreases in the sequence: SeO42- > SeO32- > SO42- > Br-. The Obisdien:Mg(II) system presents three species in case of binding with bromide ion, four with sulfate ion, five with selenite ion and five with selenate ion. Variation of the binding strength in the Obisdien:Mg(II) complexes is the same as in the Obisdien:Zn(II) complexes: SeO42- > SeO32- > SO42- > Br-. Molecular mechanics calculations show that the dizinc(II)- and dimagnesium(II)-Obisdien complexes adopt several low energy conformations differing in their Zn to Zn and Mg to Mg separations that allow the coordination of SeO42-, SeO32-, SO42-, Br- and OH- anions

Comportamento da beta-ciclodextrina adicionada ao leite de cabra submetido ao processo de desidratação por "spray-dryer" Beta-ciclodextrin's behavior added goat's milk submitted to the "spray-dryer" dehydration process

Este trabalho avaliou o comportamento do agente encapsulante beta -ciclodextrina ( beta-CD) adicionado ao leite de cabra submetido ao processo de desidratação por "spray-dryer", através de análise termogravimétrica e de cromatografia gasosa. Após a desidratação, a amostra adicionada de beta-CD apresentou um rendimento real de 10,59% com taxa de perda de 0,04% (em relação ao valor teórico esperado 10,6% ); enquanto na amostra sem adição do agente encapsulante o rendimento real foi de 9,57%, com taxa de perda de 4,27% (valor teórico esperado 10% ). Através da análise termogravimétrica (TGA), verificou-se que são volatilizados 44% e 21% dos ácidos comerciais C8 e C10 , respectivamente. Os resultados cromatográficos mostraram uma perda de aproximadamente 30% dos ácidos C8 e 20% dos ácidos C10 , nas amostras de leite de cabra sem beta -CD em relação às amostras com beta-CD. Tais porcentagens estão de acordo com os valores estimados para os ácidos comerciais. Com base nos parâmetros estudados, podemos inferir que há menor perda dos ácidos graxos C8 e C10 na amostra de leite de cabra com beta-CD, provavelmente devido ao efeito encapsulante, aumentando a estabilidade térmica dos ácidos.<br>This work evaluated the effect of the encapsulant agent beta-cyclodextrin (beta-CD) added the goat milk submitted to the "spray-dryer" dehydration process, through thermogravimetric analysis and gas cromatography. After dehydration, the sample added of beta-CD presented a real yield of 10,59%, with a loss rate of 0,04% (in relation to the expected theoretical value 10,6%); while in the sample without addition of the encapsulant agent the real yield was 9,57%, with a loss rate of 4,27% (expected theoretical value 10% ). It was verified that the volatilization of 44% and 21% of the commercial acids C8 and C10 , respectively, through the thermogravimetric analysis (TGA). The cromatographic results showed losses of approximately 30% of the C8 acids and 20% of the C10 acids, in samples of goat milk without beta-CD, in relation to the samples with beta-CD. These percentages corroborate the values estimated for commercial acids. On the basis of these studied parameters, we can infer that there is a minor loss of the fatty acids C8 and C10 in the sample of goat milk with beta-CD, probably due to the encapsulant effect, which increase the thermal stability of the acids

Solid state and solution characterization of a new dinuclear nickel (II) complex: The search for synthetic models for urease

The X-ray molecular structure and, magnetic, and spectroscopic properties, as well as the analysis of the structural behavior in solution of a novel nickel (II) complex [Ni-2(HBPClNOL)(2)(OAc)ClO4) 1 are reported. Complex 1 was prepared by the reaction between the ligand H2BPCINOL (N-(2-hydroxybenzyl)-N-(2-pyridylmethyl)[(3-chloro)(2-hydroxy)]propylamine), [Ni(H2O)(6)](ClO4)(2) and sodium acetate. Magnetic measurements indicate the presence of a weak antiferromagnefic coupling between the Ni(II) ions in 1, resulting in J = -4.23 cm(-1). Mass spectrometric characterization of the complex 1 was also performed via ESI-MS and ESI-MS/MS experiments and reveals that there are at least three different cations in solution, one mononuclear [Ni(H2BPClNOL)(OAc)](+) and two dinuclear [Ni-2(HBPClNOL)(2)(OAc)](+) and [Ni-2(HBPClNOL)(2)(ClO4)](+) cations, as well as likely a fourth one [Ni(HBPCINOL)](+). Potentiometric titration experiments confirm that under acid conditions, the dinuclear unit is broken. However, under neutral/basic pH values the dinuclear unit is stable and shows the presence of two water molecules coordinated to the nickel ions, resulting in the cation [Ni-2(HBPClNOL)(2)(H2O)(2)](2+). This cation shows two protonation/deprotonation equilibriums with pK(a) values of 9.68 and at 10.29, which are related to the aquo/hydroxo equilibrium associated with the water molecules coordinated to the metal ions. (c) 2006 Elsevier B.V. All rights reserved.7974169915416