Resumo em Inglês:

The metal-organic frameworks (MOFs) UiO-66-NH2, UiO-66-2,5-(OH)2, UiO-66-NO2, UiO-66-NDC, and UiO-66-BPDC were synthesized under solvothermal conditions using different functionalized organic linkers. The structures and properties of the samples were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, thermogravimetric analysis, scanning electron microscopy, and nitrogen adsorption-desorption isotherms. The crystal structures of these functionalized UiO-66(Zr) forms were similar. A series of functionalized UiO-66(Zr) samples were used in the adsorption of carbon dioxide (CO2). UiO-66-NH2 had the highest CO2 adsorption capacity (about 3.35 mmol g-1) due to its small polar -NH2 group. The performance of UiO-66-NH2 in CO2 adsorption at different temperatures was also determined. The amino-functionalized material possessed better adsorption properties at 273 K than at 303 K, while the CO2 working capacity of UiO-66-NH2 was fully recovered after cyclic regeneration.

Resumo em Português:

EFFECT OF LIQUID SWINE WASTEWATER DOSES ON PHYSICAL, CHEMICAL AND ELECTROCHEMICAL ATTRIBUTES IN A CERRADO OXISOL. The addition of organic residues enhances soil and plant organic matter and nutrient content. To gauge the impact of varying liquid swine waste (LSW) levels on soil, we studied changes in a clayey Oxisol’s physical, chemical, and electrochemical traits from the Cerrado. LSW doses (0, 50, 150, 450, 600 m3 ha−1) were applied to the 0-0.20 m layer in a randomized design with three replicates. Post a 30-day incubation at 60% field capacity, the soil underwent mineralogical, physical (clay dispersed in water - CDW), chemical (sodium adsorption ratio - SAR, cation exchange capacity - CEC, base saturation - V%), and electrochemical (pH in H2O and KCl, ApH, point of zero charge - PZC, point of zero salt effect - PZSE, surface electric potential - iµo, and electrical conductivity - EC) analyses. The levels of exchangeable Ca, K, Mg, Na, and available P increased with increasing LSW doses. Increasing LSW doses in the soil led to an increase in EC, but soil salinization was not observed at the highest dose. With the application of LSW doses, there was a decrease in pH, ApH, PZSE, and an increase in CEC, PZC and ψo. Despite the increase in ψo, low clay dispersibility was observed.

Resumo em Inglês:

Schiff bases are diverse organic compounds with an azomethine structure (–C=N–), holding potential in both chemistry and biology. They serve as catalysts, stabilizers, and exhibit various biological activities. The molecular structure of Schiff bases influences their biological properties, including antimicrobial effects. Redox-active compounds with more negative potentials tend to be more effective against microbes. In one of our recent studies, we explored the antimicrobial properties of two Schiff bases derivatives, SB-1 ((E)-4-amino-3-((3,5-di-tert-butyl-2-hydroxybenzylidene)amino) and SB-2 ((E)-2-((4-nitrobenzilidene)amino)aniline). SB-1 showed antibacterial activity against certain Gram-positive bacteria, while SB-2 did not. The difference in their cyclic voltametric profiles, especially SB-1’s more negative reduction potential, prompted us to carry out further characterizations, including scan-rate studies, solvent analysis, and computational calculations. We found that SB-1, which presents a stable intramolecular hydrogen bond, undergoes irreversible oxidation, likely at the –NH2 group, and a quasi-reversible reduction via an intramolecular reductive coupling of the (–C=N–) azomethine group, supported by orbital theoretical calculations. This research sheds light on the potential applications of Schiff bases in antimicrobial contexts, guided by their redox properties and structure.

Resumo em Inglês:

Palicourea tomentosa (Aubl.) Borhidi (Rubiaceae, Palicoureeae), earlier classified as Psychotria poeppigiana Müll. Arg., is used in folk medicine for a variety of diseases. Biological studies on the plant describes their vasorelaxant, antiplasmodial, antitumoural and anticholinesterase activities. To expand the knowledge on the chemical and biological potential of this species, in this work, phytochemical and dereplication studies, as well as antimicrobial and anticholinesterase evaluation of Palicourea tomentosa were carried out. Phytochemical investigation deals with the isolation of lutein (1), a mixture of dehydrovomifoliol (2) and megastigma-4,7-dien-3-one (3), loliolide (4), 5,13-epoxy-9-hydroxy-megastigma-7-en,3-one (5), vomifoliol (6), asperuloside (7), 3-O-p-coumaroylquinic acid (8), and a mixture of the pyrrolizidinoindoline alkaloids hodgkinsine (9), chimonanthine (10) and psychotriasine (11). The ultra-high performance liquid chromatography coupled to high-resolution mass spectrometry (UHPLC HRMS/MS) based on molecular networking dereplication of dichloromethane fraction led to putative identification of other two megastigmanes, one terpene lactone and three carotenoids, besides seven triterpenes and four indole alkaloids. The dichloromethane, ethyl acetate and hydromethanol fractions of P. tomentosa were able to inhibit Candida albicans with minimum inhibitory concentrations (MICs) of 125, 250 and 125 µg mL-1, respectively. The methanol crude extract, dichloromethane and alkaloid fractions inhibited selectively the butyrilcholinesterase (BuChE) at percentages of 63.09, 60.39 and 56.22%, respectively.

Resumo em Português:

This review provides an overview of the recent progress in organic electrosynthesis in Brazil, ranging from 2013 to 2023. By highlighting the principles, applications, and limitations of various electrosynthetic methodologies, this article aims to contribute to the understanding of basic principles and stimulate research in this field in Brazil. Moreover, the limitations and challenges associated with organic electrosynthesis are covered. Factors such as electrode material selection, solvent effects, and reaction optimization are discussed, highlighting the need for further research and development to overcome these obstacles. Finally, future prospects are outlined.

Resumo em Inglês:

Assessing the dynamics of pollutants in the environment is a very complex challenge, primarily because of the large number of variables involved. Thus, in addition to processes that depend on the physicochemical properties of the pollutant and the main characteristics of the contaminated environment, there are less obvious phenomena that also influence the dynamics of pollutants, such as colloid-mediated transport. The objective of this work is to elucidate the main characteristics of this process and its influence on the transport of pollutants through the soil, taking glyphosate as an example. Although this pollutant is strongly retained by soil components, its presence in groundwater is quite frequent, often due to this facilitated transport by colloids.

Resumo em Inglês:

The study of atomic spectroscopy has a profound relationship with quantum mechanics and its comprehension. Since Bohr’s success with a theory for the atom, it has been established that spectrum lines originate from transitions between different states. Moreover, the analysis of complex spectra reveals that there are groups of spectral lines that compose what is called a multiplet. To rationalize the multiplet structure, we need models to characterize and label the quantum states. The characterization of the atomic states is a common subject in classes of physical chemistry and inorganic chemistry, and there are basically two approaches to infer and label the energy states: (i) the LS coupling scheme and (ii) the jj coupling scheme. Usually, only the LS coupling is presented, and this ends up omitting its underlying assumptions. Here, we present a survey of both approaches, highlighting their premises and their adequacy towards different groups of the periodic table, ions, and excited states configurations. We show that by using benchmark data together with the Landé interval rule, the appropriate use of the jj coupling to understand the atomic spectra of heavier atoms is easily conveyed.