RESUMO
A five-step approach, starting from simple 1,5-disubstituted indoles, has been implemented for the synthesis of diversely substituted indole-pyrido-indene pentacyclic compounds up to 54 % yield via domino radical-mediated processes in the presence of the radical reagents DLP/TTMSS and AIBN/TTMSS. Reactions proceeded with diverse key starting radical cyano-precursors strategically synthesized which were subsequently transformed into the target pentacyclic compounds through an aryl/iminyl radical-mediated domino reactions sequence. In addition to the routine spectroscopic techniques, the structure of radical precursors, as well as, the target pentacyclic products were unequivocally established by single crystal X-ray diffraction, confirming the effectiveness of the proposed synthetic sequence.
RESUMO
The impact of pig slurry (PS) application on the structural dynamics of humic substances (HS) and on the mobility of Cu, Zn, Ni, and Pb in a dystrophic Red Nitosol planted with winter forage grasses was evaluated. After four PS applications, the humic acids (HA) and fulvic acids (FA) were characterized by spectroscopy techniques allied to chemometrics methods. The metals contents in soil, in HS and in the tissues of plant were quantified. PS application increases the total organic carbon, especially the nonhumic carbon, which contribute to increase FA content. The carbon in FA and HA increases with the highest PS dose applied, especially aliphatic structures in FA and aromatic structures in HA. The amount of Pb and Cu in FA and HA increases respectively, as well as Cu, Zn, Ni, and Pb bioavailable. PS applications increase the biomass production in grasses and the metals content accumulated in the tissues. Our study shows that the PS application modifies the structure of SOM, incorporating fragments, and modifying its dynamics, which regulates the dynamics and the accumulation of metals in soils and plants. The association of metals with soluble structures seems to inactivate their toxicity and does not affect plant growth.
Assuntos
Metais Pesados , Poluentes do Solo , Suínos , Animais , Solo/química , Chumbo , Metais Pesados/química , Substâncias Húmicas/análise , Poluentes do Solo/análise , Carbono/química , PlantasRESUMO
A four-stage reaction sequence has been designed and developed for the synthesis of highly functionalized enolate esters as key building blocks for the synthesis of novel heteropolycyclic compounds of potential pharmaceutical value. The sequence starts with simple commercially available indoles and proceeds via 3-(indol-3-yl)-3-oxopropanenitriles, which react with 2-bromobenzaldehyde to form the corresponding chalcones; these are readily reduced to dihydrochalcones, which are in turn acylated to form the enolate esters. The compounds in this sequence have been characterized by IR and 1H and 13C NMR spectroscopy, by mass spectrometry and by elemental analysis. The molecular and supramolecular structures are reported for representative examples, namely (E)-3-(2-bromophenyl)-2-(1-methyl-1H-indole-3-carbonyl)acrylonitrile, C19H13BrN2O, (Ib), (2RS)-2-(2-bromobenzyl)-3-(1-methyl-1H-indol-3-yl)-3-oxopropanenitrile, C19H15BrN2O, (IIb), and (2RS)-3-(1-benzyl-1H-indol-3-yl)-2-(2-bromobenzyl)-3-oxopropanenitrile, C25H19BrN2O, (IIc), the latter two of which crystallize with Z' = 2, and (E)-1-(1-acetyl-1H-indol-3-yl)-3-(2-bromophenyl)-2-cyanoprop-1-en-1-yl acetate, C22H17BrN2O, (III), and (E)-1-(1-benzyl-1H-indol-3-yl)-3-(2-bromophenyl)-2-cyanoprop-1-en-1-yl benzoate, C32H23BrN2O, (IV). The structure of the related chalcone (E)-2-benzoyl-3-(2-bromophenyl)prop-2-enenitrile, (V), has been redetermined at 100â K, where it is monoclinic, as opposed to the triclinic form reported at ambient temperature.
RESUMO
Rice plants accumulate cadmium (Cd2+) within the grain, increasing the danger of human exposure. Natural materials have been used in soil remediation, but few studies have examined the risks (based on the bioavailability of these metals to plants) of using these materials, so the practice remains controversial. In the present study, we evaluated the effectiveness of biochar produced from sugarcane bagasse, vermicompost (VC), vermicompost solid residue (VCR) and humin for remediation of Cd2+-contaminated soils. We characterized the interactions between these materials and Cd2+ and evaluated their capacity to alter Cd2+ availability to rice plants. Our results show that under the conditions in this study, biochar and humin were not effective for soil remediation. Although biochar had high Cd2+ retention, it was associated with high Cd2+ bioavailability and increased Cd2+ accumulation in rice plants. VC and VCR had high Cd2+ retention capacity as well as low Cd2+ availability to plants. These characteristics were especially notable for VCR, which was most effective for soil remediation. The results of our study demonstrate that in the tested materials, the bioavailability of Cd2+ to plants is related to their structural characteristics, which in turn determine their retention of Cd2+.