The Mesoproterozoic Conselheiro Mata Group is the uppermost sequence of the Proterozoic intracontinental Espinhaço basin that developed on the Congo-São Francisco Paleoplate. This sequence is represented by a marine shallow-water platform that experienced a sag phase followed by a rift phase in the Upper Espinhaço. We used combined sedimentological-stratigraphic descriptions of sections, whole-rock (WR) geochemistry and U-Pb detrital zircon dating to develop a regional paleogeographic evolution model of the sag phase. The succession corresponds to transgressive-regressive cycles in the following ascending order: 1) offshore to lower shoreface facies represented by quiescent periods and episodic sediment supply (Santa Rita Formation); 2) upper shoreface to foreshore and coastal desert facies with a reworking of the underlying units (Córrego dos Borges Formation); 3) lower shoreface with fallout of suspended fine sediments and a combination of unidirectional and oscillatory flows generated by storm waves (Córrego da Bandeira Formation); 4) tidal-influenced upper shoreface to foreshore facies with the migration of subaqueous dunes, wave swash in a beach environment and cycles of neap-spring tides (Córrego Pereira Formation); and 5) the resumption of lower-shoreface sedimentation and the subsequent development of a stromatolitic carbonate-siliciclastic platform (Rio Pardo Grande Formation). The geochemical data indicate that the studied units contain input from felsic rocks and sedimentary rocks. The basal marine to eolian sediments of the Galho do Miguel Formation are dominated by Rhyacian sources (2.1 Ga). The basal and intermediate units of the Conselheiro Group contain Archean, Rhyacian, Statherian and Calymmian-Ectasian (1.6-1.33 Ga) zircon grains, whereas Orosirian (1.9-2.0 Ga) sources dominate in the upper strata of the group. The study of this Stenian (Mesoproterozoic) intracratonic sequence provides clues to understanding the history of sedimentation and the potential source areas on the São Francisco Craton and adjacent areas, which are very useful for comparison to Phanerozoic intracratonic basins and the reconstruction of Paleoproterozoic and Mesoproterozoic supercontinents.
The synthesis of a series of 1,2,3-triazoles using glycerol as starting material is described. The key step in the preparation of these triazolic derivatives is the copper(I)-catalyzed azide-alkyne cycloaddition (CuAAC), also known as click reaction, between 4-(azidomethyl)-2,2-dimethyl-1,3-dioxolane (3) and different terminal alkynes. The eight prepared derivatives were evaluated with regard to their fungicide, phytotoxic and cytotoxic activities. The fungicidal activity was assessed in vitro against Colletotrichum gloeosporioides, the causative agent of papaya anthracnose. It was found that the compounds 1-(1-((2,2-dimethyl-1,3-dioxolan-4-yl)methyl)-1H-1,2,3-triazol-4-yl)-cyclo-hexanol (4g) and 2-(1-((2,2-dimethyl-1,3-dioxolan-4-yl)methyl)-1H-1,2,3-triazol-4-yl)propan-2-ol (4h) demonstrated high efficiency in controlling C. gloeosporioides when compared to the commercial fungicide tebuconazole. The triazoles did not present any phytotoxic effect when evaluated against Lactuca sativa. However, five derivatives were mitodepressive, inducing cell death detected by the presence of condensed nuclei and acted as aneugenic agents in the cell cycle of L. sativa. It is believed that glycerol derivatives bearing 1,2,3-triazole functionalities may represent a promising scaffold to be explored for the development of new agents to control C. gloeosporioides.
Herein, the synthesis of nine novel glycerol-derived 4-alkyl-substituted 1,2,3-triazoles, using the Cu I-catalyzed alkyne-azide cycloaddition reaction as the key step, is reported. The triazoles were characterized by infrared and nuclear magnetic resonance (NMR 1 H and 13 C) spectroscopy and mass spectrometry. The nine prepared compounds were evaluated with regard to their phytotoxic, antiproliferative, and fungicidal activities. The fungicidal activity was assessed on Colletotrichum gloeosporioides, the causative agent of papaya anthracnose. All compounds presented high efficiency (comparable to the commercial fungicide tebuconazole) in inhibiting C. gloeosporioides sporulation. The phytotoxicity of the triazoles was assessed against Lactuca sativa. Germination was the less-affected parameter, whereas the most pronounced effects of the triazoles were on the germination speed index and root growth of the L. sativa seedlings. As indicators of antiproliferative activity, the mitotic index was evaluated along with chromosomal and nuclear alterations, all of which were influenced to different degrees by the triazoles. In addition, all derivatives demonstrated aneugenic and clastogenic actions in meristematic cells of L. sativa roots. Therefore, these 4-alkyl-substituted triazoles may represent a scaffold to be explored for the development of new fungicidal agents.
Abstract:Glycerol is a subproduct of biodiesel production and represents an important problem 26 when generated in large scale. Alternatives that can utilize this unrefined byproduct is of potential 27 interest. It is herein described the synthesis of a series of 1,2,3-triazoles using glycerol as starting
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