Logomarca do periódico: Química Nova

Open-access Química Nova

Publicación de: Sociedade Brasileira de Química
Área: Ciências Exatas E Da Terra
Versión impresa ISSN: 0100-4042
Versión on-line ISSN: 1678-7064
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Química Nova, Volumen: 48, Numero: 1, Publicado: 2025

Química Nova, Volumen: 48, Numero: 1, Publicado: 2025

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Documents
Article
FACILE SYNTHESIS OF FUNCTIONALIZED UiO-66-TYPE MOFs FOR CO2 ADSORPTION Ge, Jinlong Jin, Xiaoqi Zhang, Liyuan Jiao, Yuhong Wang, Qiuqin Wang, Yongkui Gao, Yan Geng, Jiaojiao Wang, Tianqi

Resumen en Inglés:

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.
Artigo
EFEITO DAS DOSES DE DEJETO LÍQUIDO DE SUÍNOS NOS ATRIBUTOS FÍSICOS, QUÍMICOS E ELETROQUÍMICOS EM UM LATOSSOLO DO CERRADO Silva, Raysa Trindade da Jesus, Wagner Arruda de Soares, Mário Rodrigo dos Santos Barros, Ariane Isis Weber, Oscarlina Lúcia dos Santos

Resumen en Portugués:

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.
Article
REDOX POTENTIAL STUDIES BASED ON SCAN-RATE ANALYSIS OF THE DIFFUSIONAL CONTROL AND DFT CALCULATIONS OF THE SCHIFF BASE [(E)-4-AMINO-3-((3,5-DI-tert-BUTYL-2-HYDROXYBENZYLIDENE)AMINO) BENZOIC ACID] Morales-Guevara, Rosaly Páez-Hernández, Dayán Gacitúa, Manuel Fuentes, Juan A. Carreño, Alexander

Resumen en Inglés:

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.
Article
Chemical and dereplication studies of Palicourea tomentosa (Aubl.) Borhidi and their antimicrobial and anticholinesterase activities Cecatto, Ana J. Formagio, Anelise S. N. Buzanello-Martins, Cleide V. Fortuna, Caroline Cabral, Márcia R. P. Costa, Willian F. da Baldoqui, Débora C. Sarragiotto, Maria H.

Resumen en Inglés:

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.
Artigo
DESENVOLVIMENTO DE MATRIZ DE SÍLICA AMINOFUNCIONALIZADA COMO POTENCIAL ADSORVENTE DE ÍONS Pt4+ EM SISTEMAS DE PRÉ-CONCENTRAÇÃO PARA ANÁLISE POR FAAS Nascimento, Caio V. L. V. do Araújo, Arthur L. S. de Lima, Lidiane M. A. de Sousa, Filipe C. P. de Silva, Wagner E. Lavorante, André F. Belian, Mônica F.

Resumen en Inglés:

The use of materials such as organofunctionalized silica for application in solid phase extraction (SPE) allows the preconcentration of several ions, including Pt, and subsequent detection. This work aims to synthesize and characterize an organofunctionalized silica (Sil-TMSDT) with the silylant N’(trimethoxysilyl)propylethylenetriamine and its application as a solid phase in the preconcentration Pt4+ ions in aqueous media, using detection by flame atomization atomic absorption spectroscopy (FAAS). The Fourier-transform infrared spectroscopy (FTIR) spectra and scanning electron microscopy (SEM) coupled with energy-dispersive spectroscopy (EDS) confirmed the aminofunctionalization of the silica. For the adsorption process, a preconcentration mini-column with 200 mg of Sil-TMSDT, a solution of 0.485 mg L−1 of K2[PtCl6] at pH 10 and HNO3 0.5 mol L−1 as eluent were used, obtaining an enrichment factor of 15-fold with retention efficiency higher than 99%. The Pt4+ ion determined by FAAS showed a linear response between 0.02 and 0.40 mg L−1; a linear coefficient where R = 0.9981; a 16-fold preconcentration factor; a limit of quantification (LOQ) and limit of detection (LOD) of 0.045 and 0.014 mg L−1, respectively. The proposal system showed analytical applicability to determining Pt4+ ion in an aqueous medium and could be used to detect traces of this potentially toxic metal in biological fluids such as urine and blood.
Article
AMAZON ACAI AND PINEAPPLE RESIDUES INDUCE THE ENZYME LACCASE IN Pleurotus ostreatus: APPLICATION TO BISPHENOL A BIOREMEDIATION Golveia, Jhessica Cavalcante de Souza Nunes, Elaine Sousa Bulhões, Thiago Souza Oliveira Neto, Jerônimo Raimundo de Cunha, Luiz Carlos da Campos, Luiza Cintra Santiago, Mariângela Fontes Schimidt, Fernando

Resumen en Inglés:

Bisphenol A (BPA), an endocrine disruptor used in different commercial polymers, is a persistent pollutant commonly found in effluents. Conventional wastewater treatment processes have low chemical removal efficiency and are expensive. This work evaluated BPA removal using laccase enzyme produced from white rot fungus Pleurotus ostreatus. For the enzymatic production, residues of acai berry and pineapple were used as laccase inducers. The use of natural inducers led to a high enzyme production (1139 and 1031 U mL−1 to acai and pineapple, respectively). Bisphenol A was removed to a concentration lower than LOD (limit of detection) after 4 h. The degradation mechanism of BPA occurred by oxidation of methyl to hydroxymethyl group in a propane portion, with breakdown of the aromatic ring. The developed technology brought to the scene a new green, viable methodology, using vegetable waste, adding value to these residues and bringing an alternative to the BPA treatment.
Article
CHEMICAL CONSTITUENTS OF Amburana acreana Ducke A. C. Sm. LEAVES Ferreira, Adrianne B. Aguiar, Rosane M. Brandão, Hugo N. Santos, Rauldenis A. F. Freitas, Humberto F. de Teles, Catharine Reis, Joice N. Souza, Jessica L. de Alves, Clayton Q.

Resumen en Inglés:

This study aimed to isolate, purify and characterize secondary metabolites present in Amburana acreana leaves, native to the state of Rondônia, using classical chromatographic methods and 1D, 2D nuclear magnetic resonance spectroscopy. From the hydroethanolic leaves extract of A. acreana, p-hydroxybenzoic acid, vanillic acid, coumarin, campesterol 3-β-D-glucoside and amburoside B, all known compounds, were identified. To the best of our knowledge, this is the first report of isolation and chemical characterization of secondary metabolites in A. acreana. In addition, in vitro assays indicated that amburoside B does not have inhibitory potential on the growth of gram-negative bacteria. The presence of these compounds suggests that, thus far, amburosides (A and B) could be chemotaxonomic markers of the genus Amburana.
Article
Chemical constituents, antioxidant and antimicrobial activities of Pavonia glazioviana Gurke (Malvaceae) Oliveira, Micaelly S. Chaves, Otemberg S. Teles, Yanna C. F. Fernandes, Diégina A. Silva, Camila Macaúbas Queiroz, Wallace A. M. Lima, Jéssica B. Mazzotti, Maristela R. R. M. Lima, Edeltrudes O. Fernandes, Givanildo L. Conceição, Adilva S. Souza, Maria de Fátima Vanderlei de

Resumen en Inglés:

Species from Pavonia genus (Malvaceae) are traditionally used as antioxidant, n anti inflammatory and antimicrobial remedies. Previous studies have revealed their diversity of specialized metabolites widely used in the development of new medicines. This is the first study on Pavonia glazioviana Gurke, a Brazilian species known as “Malva da Chapada”. The research led to identify fifteen compounds: 132 (S) hydroxy pheophytin a; and 132(S) hydroxy 173 ethoxyphaeophorbide, n decanol, cycloart 23Z ene 3β,25 diol, cycloart 24S 25 ene 3β,24 diol, sitosterol 3 O β D glucopyranoside, stigmasterol 3 O β D glucopyranoside, quercetin, acacetin, kaempferol, tiliroside, 5 hydroxy 3,7,8,4’ tetramethoxyflavone, 5,7 dihydroxy 3,8,4’ trimethoxyflavone, 5,7 dihydroxy 4’ methoxyflavone, 5,7,4’ trihydroxy 3,8 dimethoxyflavone and 5,7,4’ trihydroxy 3 methoxyflavone. The major flavonoids were tested for their antimicrobial activity, and the compound 5,7 dihydroxy 3,8,4’ trimethoxyflavone showed strong activity against Escherichia coli (MIC = 512 μg mL1), Pseudomonas aeruginosa (MIC = 512 μg mL1), Candida albicans (MIC = 512 μg mL1), Candida tropicalis (MIC = 512 μg mL1), Candida parapsilosis (MIC = 512 μg mL1), Aspergillus flavus (MIC = 512 μg mL1) and A. fumigantus (MIC = 512 μg mL1). The total phenolic content, flavonoid content, and radical scavenging potential were determined showing its great production of phenolics and flavonoids, along with interesting radical scavenging potential (DPPH EC50 = 6.36 ± 0.029 mg mL 1). Our findings contributed to characterize P. glazioviana as a source of methoxylated flavonoids with antimicrobial potential.
Article
SOLID-STATE SPECTROSCOPIC, THERMOKINETICS AND THERMAL ANALYSIS OF ACECLOFENAC COORDINATION COMPLEXES WITH LANTHANUM AND GADOLINIUM Melo, Laís D. S. M. K. Carvalho, Cláudio T. Jiménez, Pedro Enrique Sánchez Sequinel, Thiago Perejón, Antonio Maqueda, Luis Allan Pérez Colman, Tiago A. D.

Resumen en Inglés:

In recent years, the field of coordination chemistry has experienced a surge in interest regarding the synthesis and characterization of coordination complexes for diverse applications. This study is dedicated to investigating coordination compounds resulting from the interaction of nonsteroidal anti-inflammatory drugs (NSAIDs) with metal ions. The study research places significant emphasis on understanding the stability and thermal behavior of these coordination compounds. The utilization of thermoanalytical techniques is crucial in achieving this goal. Thermal analysis and thermokinetics provide valuable insights into the underlying mechanisms, kinetics, and energetics of these reactions, thereby facilitating the optimization of synthesis procedures. The research employs concurrent techniques, namely thermogravimetric analysis (TG) and differential scanning calorimetry (DSC), to explore the thermal stability and decomposition pathways of these coordination compounds. Thermokinetic models and optimization methodologies are subsequently applied to identify key reaction parameters. The primary aim of this research is to unveil the thermal behavior, stability, and reaction kinetics of aceclofenac coordination compounds, thus contributing significantly to the understanding of thermokinetics and thermal analysis in the domain of coordination chemistry. Specifically, this study is focused on aceclofenac coordination complexes involving lanthanum and gadolinium, with the ultimate goal of advancing the field of coordination chemistry.
Article
FACILE HYDROTHERMAL SYNTHESIS OF NIOBIUM PENTOXIDE SEMICONDUCTOR AND THEIR APPLICATION IN THE PHOTODEGRADATION OF DYES AND REDUCTION OF FREE FAT ACIDS IN WASTE OIL Crisóstomo, Camilo Aurélio Brandão Damacenoa, Fernanda Barbos Barbosa, Luele Ribeiro de Sousa Almeida, Jânio Santos Batista, Walker Vinicius Ferreira do Carmo Malagutti, Andréa Renata Mesquita, João Paulo de Torres, Juliana Arriel Iga, Gustavo Duran Oliveira, Caue Ribeiro de Ribeiro, Roberto Ananias Mourão, Henrique A. J. L.

Resumen en Inglés:

We report a facile hydrothermal method for the synthesis of niobium pentoxide (Nb2O5) under two different temperatures, 120 °C (Nb2O5-120) and 150 °C (Nb2O5-150). The obtained materials were characterized by structural, optical and morphological techniques. Also, the photocatalytic properties of the Nb2O5 samples were evaluated in two reactions under ultraviolet (UVC) irradiation: degradation of methylene blue (MB) and indigo carmine (IC) dyes; and esterification of free fatty acids (FFA) present in waste cooking oil (WCO). The Nb2O5 was formed at different temperatures of synthesis, and the increase in temperature did not cause significant changes in the structural and optical characteristics, but resulted in an increased surface area of the synthesized materials. Both synthesized materials showed excellent efficiency for dye photodegradation. The sample Nb2O5-150 presented the best performance for the MB photodegradation, with almost 85% of the removal efficiency. In this case, the adsorption of MB molecules on the surface of the material was high due to the favorable electrostatic interaction and also because of its high surface area. For the IC photodegradation, the adsorption was insignificant, and both samples presented approximately 100% of the removal efficiency. These materials were also promising for the reduction of free fat acids in waste oil by photoesterification.
Article
TRANSACETALIZATION OF GLYCEROL WITH 2,2-DIMETHOXYPROPANE USING ZEOLITES UNDER MILD CONDITIONS Veiga, Paula M. Dias, Ayres G. Veloso, Cláudia de O. Henriques, Cristiane A.

Resumen en Inglés:

The acetalization or transacetalization reactions produce acetals or ketals used in cosmetics, food, pharmaceuticals, and fuel additives. Besides synthesizing several products, the acetalization or transacetalization reactions can protect carbonyl groups, 1,2 and 1,3-diols in multi-step synthesis. This work studies the transacetalization of glycerol with 2,2-dimethoxypropane (2,2-DMP) to yield 2,2-dimethyl-4-hydroxymethyl-1,3-dioxolane (solketal) by catalyzing with USY, HBeta, and HZSM-5 zeolites under cleaner and mild reaction conditions (reaction temperature: 25 °C; 2,2-DMP/glycerol molar ratio: 1; reaction time: 1 h; and catalyst concentration: 0.05-5 wt.%). For catalyst concentration equal to or greater than 2,5 wt.%, glycerol conversion stabilized near 96-97% for the three zeolites tested. The product selectivities also assume a constant value, close to 97% for solketal. For the lowest concentration of catalyst, the influence of the zeolite properties on the glycerol conversion, such as acidity and the strong/weak acid site ratio, was observed. Concerning the selectivity of the products, the results suggested that it can be based on zeolite topology, active sites at the particle surface, and the relative amount of micro and mesoporous HBeta, the most selective catalyst for acetals production, was reused at least once without loss of activity and selectivity.
Artigo
MODELAGEM DE MISTURAS BINÁRIAS PELA APLICAÇÃO DA EQUAÇÃO DE SCHRÖEDER-van LAAR A UM CONJUNTO DE SUBSTÂNCIAS COM DIVERSIDADE ESTRUTURAL Matos, Ursula Paôla Rudolph de Lopes, Luana Dezingrini Scheeren, Ana Paula Schneider, Juliana Maria Forain Miolo Bortoluzzi, Adailton João Bonacorso, Helio Gauze Gonçalves, Itamar Luís Merlo, Aloir Antonio

Resumen en Portugués:

The Schröeder-van Laar equation to predict the theoretical eutectic melting temperature values was applied to a set of fourteen binary mixtures (UR1 to UR14). The fourteen binary mixtures belong to a structurally diverse group of organic molecules. They are represented by the 5-membered heterocycles containing N-S and N-O rings, flexible methylene chains (RH), semi-rigid semi-fluorinated chains (RF), and hydrogen bonds (HB). A virtual screening totalizing ninety-one possible theoretical combinations was planned. The UR1 to UR14 were prepared by mixing individual components using the calculated mole fractions. The experimental (Te) and theoretical (Tt) temperatures for the eutectic melting points were determined using polarized optical microscopy (POM) and differential scanning calorimetry (DSC) techniques. Heterogeneous mixtures were formed for components with large structural diversity as seen by POM. During the melting of the mixtures, irregular behavior through the segregation of the components was recorded. The study showed that the similarities in structural diversities favor the formation of homogeneous mixtures, with Te values approaching Tt, as predicted by the Schröeder-van Laar equation and by the theory of eutectic mixtures. Liquid crystal properties were affected in homogeneous binary mixtures containing one of the individual liquid crystal components.
Artigo
APLICAÇÃO DA ESPECTROMETRIA DE MASSAS COM IONIZAÇÃO POR PAPER SPRAY E MÉTODO QUIMIOMÉTRICO OPLS-DA PARA O DIAGNÓSTICO DO CÂNCER DE PRÓSTATA PELA ANÁLISE DE AMOSTRAS DE URINA Silva, Thifanny T. P. da Máquina, Ademar D. V. Durans, Anízia F. F. Costa, Lucas G. da Pinto, Frederico G. Garrett, Timothy J. Borges Neto, Waldomiro

Resumen en Portugués:

APPLICATION OF MASS SPECTROMETRY WITH PAPER SPRAY IONIZATION AND THE OPLS-DA CHEMOMETRIC METHOD FOR THE DIAGNOSIS OF PROSTATE CANCER BY ANALYSIS OF URINE SAMPLES. In this study, paper spray ionization mass spectrometry (PSI-MS) allied to orthogonal projections on the latent structure-discrimination analysis (OPLS-DA) was employed to differentiate urine samples from patients with prostate cancer and control individuals (without prostate cancer). The parameters of sensitivity, specificity, efficiency and Matthew’s correlation coefficient determined to analyze the efficiency and quality of the OPLS-DA model obtained a value equal to 1, which means, respectively, that the model has a good performance to correctly classify true positive samples and true negatives. These results showed 100% correct classification of the samples from the training and test set, demonstrating a high efficiency of the OPLS-DA model when classifying all samples considered as belonging to the class of interest (urine from control patient) into class 1 and all samples considered as belonging to the non-interest class (urine from patients with prostate cancer) in class 0. This efficiency resulting from the application of this model suggests that the PSI-MS combined to OPLS-DA is a promisor approach for a rapid diagnosis of prostate cancer, via chemical fingerprints of urine samples.
Article
RAPID QUANTITATIVE ANALYSIS OF METHAMPHETAMINE BY PORTABLE NEAR-INFRARED SPECTROSCOPY AND PLS MODELING Liu, Shan Chen, Yuemeng Wang, Fang Wu, Jingjie Tang, Guo Bai, Song

Resumen en Inglés:

To rapidly detect different types of methamphetamine in the field, a portable near infrared spectroscopy (NIR) method was used to model and analyze the collected samples. Transmission spectra of 359 methamphetamine crystal samples (content range of 7.5-99.4%) and 187 methamphetamine tablet samples (content range of 2.43-23.91%) were collected, first-order derivatives and the Savitaki-Golay smoothing method were applied for spectral preprocessing. The drug concentrations in the calibration and validation sample sets were analyzed using high-performance liquid chromatography. The partial least squares quantitative analysis models were built, and the quantitative models for methamphetamine crystals were 2.10, 2.12 and 2.19% for root mean square error of cross-validation (RMSECV), root mean square error of validation (RMSEV) and root mean square error of prediction (RMSEP), respectively; in contrast, RMSECV, RMSEV, and RMSEP of methamphetamine tablets were 0.78, 0.80, and 0.82%, respectively. The results of the internal cross-validation and the methodology review show that the measurements of the modeled results are consistent with the true values, and that the model has good stability and can be used for accurate field measurements. Therefore, real time sample analysis can be performed using NIR technology combined with chemometric models, which helps the police to determine the quality of drugs in a timely manner for case analysis.
Artigo
CORROSÃO LOCALIZADA DO ALUMÍNIO EM MEIOS AERADOS E EM MEIOS COM BAIXO TEOR OXIGÊNIO: ESTUDO E COMPARAÇÃO POR MEIO DE CURVAS DE POLARIZAÇÃO Araujo, João Victor de S. Gabbardo, Aline D. Fernandes, Stela M. Costa, Isolda

Resumen en Portugués:

In this study, the influence of deaeration on the electrochemical behavior of aluminum was studied by polarization techniques. The advantages of deaeration for the evaluation of localized corrosion on aluminum are discussed. The influence of the corrosive environment with low oxygen contents on the electrochemical response of aluminum was evaluated by anodic and cathodic potentiodynamic polarization curves. The polarization tests were carried out in chloride solutions followed by optical and scanning electron microscopy characterization. It was observed that deaeration of the solution significantly influences the electrochemical behavior of aluminum, as predicted by corrosion kinetics theories. For the cathodic curves, a decrease in the limiting current density for the oxygen reduction reaction (ORR) was observed for low oxygen solutions, while the “apparent” initiation of the hydrogen evolution reaction (HER) was shifted to higher potentials. In the anodic curves, a common passive behavior was not observed in aerated conditions, however, at the corrosion potential, localized pitting was observed indicating that the material was already above the breakdown potential (Ebr). In the low oxygen content solution, however, a passive region with a breakdown potential, was observed on the anodic curves.
Article
SYNTHESIS OF Zn-Fe BIMETALLIC ZIFs AND STUDY OF THE PHOTOCATALYTIC NITROGEN FIXATION PERFORMANCE Cao, Fuchen Li, Feilong He, Tianping

Resumen en Inglés:

In recent years, in-depth studies of zeolitic imidazolate framework-8 (ZIF-8) materials have revealed that they have many unique properties and uses. Zn-Fe bimetallic ZIFs with bimetallic active centers can be designed and fabricated based on ZIF-8 with good water resistance. The structure, composition, and photoelectrochemical properties of the Zn-Fe bimetallic ZIFs were systematically analyzed by field emission scanning electron microscopy (FESEM), mapping, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT IR), X-ray photoelectron spectroscopy (XPS), ultraviolet-visible diffuse reflectance spectroscopy (UV-Vis DRS), and photoluminescence (PL). The bimetallic Zn-Fe ZIFs exhibited strong light absorption properties in the visible region at 390 nm, and the forbidden bandwidths were greatly reduced compared to those of ZIF-8. The photoelectrochemical properties of bimetallic Zn-Fe ZIFs and the separation and migration efficiency of photogenerated charge carriers can be optimized by adjusting the amount of metal introduced. The highest average photocatalytic rate of 1363.53 μmol L-1 g-1 h-1 was observed for bimetallic Zn-Fe ZIFs when Zn:Fe = 1:0.3. Finally, the photocatalytic nitrogen fixation performance of Zn-Fe bimetallic ZIFs is discussed.
Artigo
ANÁLISE DOS EFEITOS DE CORROSÃO SOB CHAPAS DE AÇO-CARBONO 1020 CAUSADAS POR AEROSSOL MARINHO E POLUIÇÃO: UM ESTUDO COMPARATIVO EM CHAPAS EXPOSTAS AO AMBIENTE E EM SIMULAÇÃO DE DUTOS SUBTERRÂNEOS Nocera, Arthur K. Souza, Guilherme S. Almeida, Mateus B. de Santos, Matheus S. e Gil, Noemi L. Corrêa, Thaís

Resumen en Portugués:

This work aims to analyze the effects of corrosion in different municipalities through the exposure of 1020 carbon-steel plates to the atmosphere and buried in soil. Sea air and pollution were treated as major corrosion agents and zinc has been tested to prove its effectiveness as a sacrificial anode. For this analysis, weighing and spectrophotometric methods were used to determine the iron mass loss after five months of exposure. From the data obtained, corrosion rates were calculated and compared based on different regional conditions. The results showed that the coastal region of the state of São Paulo presented higher corrosion rates compared to places of higher altitudes and further away from the sea, indicating that sea air and pollution are important agents in catalyzing the deterioration processes. In addition, zinc was efficient as a sacrificial anode, demonstrating its potential application as corrosion protection in 1020 carbon-steel plates.
Review
EMERGING TRENDS OF ORGANIC ELECTROSYNTHESIS IN BRAZIL Martins, Guilherme M. Oliveira, Kleber T. de

Resumen en Portugués:

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.
Revisão
TRANSPORTE MEDIADO POR COLOIDES E O SEU EFEITO NA DINÂMICA DOS POLUENTES NO SOLO Cicilinski, Alana Deduck Melo, Vander de Freitas Peralta-Zamora, Patricio

Resumen en Inglés:

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.
Revisão
HIDRÓXIDOS DUPLOS LAMELARES EM PROCESSOS CATALÍTICOS PARA A QUÍMICA FINA, DEGRADAÇÃO DE POLUENTES E GERAÇÃO DE ENERGIA LIMPA: UMA BREVE REVISÃO Tomaso, Luiz Phelipe de Souza Bomfim, Joice Florenço Carvalho, Nakédia M. F. Senra, Jaqueline Dias Malta, Luiz Fernando Brum

Resumen en Portugués:

Layered double hydroxides (LDHs) and related materials have been studied for a long time and their application in catalytic processes remain attractive due to the tuned properties, morphologies and metal-support interactions obtained from a variety of composition and synthesis route. In this mini-review, some important reactions, such as photocatalysis, electrocatalysis, reduction, carbon-carbon cross-couplings and water-gas shift will be emphasized along with the role of LDHs as catalysts, co-catalysts or catalytic precursors when it was clearly indicated.
Education
The role of jj coupling on the energy levels of heavy atoms Dias, Lucas A. L. Cardozo, Thiago M. Faria, Roberto B.

Resumen en Inglés:

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.
Educação
CONCEITOS EM CRISTALOGRAFIA ESTRUTUAL: UMA ABORDAGEM COMPREENSIVA DA LEI DE BRAGG E DO FATOR DE ESTRUTURA Machado, Rafael P. Doriguetto, Antônio C.

Resumen en Portugués:

It is not uncommon that as a chemistry course progresses, along with the deepening of the content studied, the tendency of not carefully revisiting the foundations of the concepts covered and deepened also increases. The understanding of the structure of matter that develops throughout the course, starting from the first concepts of atomic theory, going through chemical bonds, molecules, intermolecular interactions to the study of how matter is aggregated in the solid state, is an example of knowledge that grows in depth and complexity. In this context, crystallography presents itself as a vast interdisciplinary area that contributes to understanding the matter. This article explores fundamental mathematical, historical, chemical, and physical concepts, connecting them to offer a more comprehensive and logically coherent understanding of key crystallography principles.
Assuntos Gerais
ALFRED SCHAEFFER E SUAS CONTRIBUIÇÕES PARA A QUÍMICA Silva, Rodrigo Régis C. Marques, Rita de Cássia Filgueiras, Carlos A. L.

Resumen en Portugués:

Alfred Schaeffer (1879-1957) was a German chemist who arrived in Minas Gerais in 1911 hired by the state government to organize the state health service in its newly established capital. He directed the Laboratory of Chemical Analysis of the State, and his analytical methods in dairy and mineral waters became a reference in Brazil. He also became professor of Chemistry at the new Faculty of Medicine of Belo Horizonte and founded the Chemistry Institute of the Engineering School in that city, influencing several students who became important names in Brazilian science. In addition, he was responsible for the assembly and technical coordination of pioneering industries in the dairy and wood distillation sector in the city of Santos Dumont. Later he assumed the post of technical director of Merck, also in Minas Gerais. Moving to Rio de Janeiro, he assumed a chair at the Technical School, working in teaching and research, and remained active even after retiring, publishing in important scientific journals.
General Subjects
BRIEF REFLECTIONS ON THE 4th INDUSTRIAL REVOLUTION AND ITS IMPACT IN CHEMICAL SCIENCES Souza, Ana Paula N. de Silva, Gabriel Francisco S. da Darzé, Bernardo Cardeal Senra, André Vinícius D. Senra, Jaqueline D.

Resumen en Inglés:

The 4th Industrial Revolution is well described as a digital revolution in which the integration between the physical, biological and digital fields can prompt unprecedented results in terms of research, innovation and products. Our brief discussion is built upon chemistry as a fundamental science in this context: it emerges with contributions for advanced digital technologies along with clean energy, sustainable processes and circular economy for the industry 4.0. Since the previous industrial revolutions brought uncertainty in the environment-chemistry binomial it is urgent achieving a systemic industrial innovation in order to promote a technological, energetic and social transition toward a sustainable future, especially in the alarming context of climate change. Despite the Brazilian chemical industry represents the largest in the Southern hemisphere it has few integrated chemical supply chains which represents a bottleneck toward advances in the manufacturing base. Within both academy and industry, the groundbreaking shift in the chemical sector can enable opportunities to chemists build a better future. At the same time, a paradigm shift is leading us to new methods, models and, consequently, disruption in the way of producing and sharing knowledge. Finally, some skills were proposed for chemists within the framework of the 4.0 era.
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Sociedade Brasileira de Química Instituto de Química, Universidade Estadual de Campinas (Unicamp), CP6154, 13083-0970 - Campinas - SP - Brazil
E-mail: quimicanova@sbq.org.br
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