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The effect of SnO2 surface properties on CO2 photoreduction to higher hydrocarbons.
(2023) Torres, Juliana Arriel; Nogueira, André Esteves; Silva, Gelson Tiago dos Santos Tavares da; Oliveira, Cauê Ribeiro de
Several photocatalysts have been developed for applications in reduction reactions, including tin oxide-based semiconductors. Although its band structure is unfavorable for CO2 reduction reactions, strategies to modify its surface properties directly impacted its activity and selectivity during these reactions. Here, we analyze the influence of heat treatment and decoration of SnO2 with gold nanoparticles on the gas phase CO2 photoreduction process. In both cases, a deleterious effect was observed during reactions under UV radiation (with a drop of 59.81% and 51.45% in CH4 production for SnO2_150°C and SnO2/Au_cop, respectively, compared to SnO2_cop), which is directly related to the availability of surface hydroxyl groups that play a crucial role in CO2 adsorption. Under visible radiation, the gold plasmonic resonance took place in the production of methane (0.33 μmolg 1 for SnO2/Au_cop and 0.29 μmolg 1 for SnO2/Au_150°C), with small amounts of carbon monoxide (0.06 μmolg 1 for SnO2/Au_cop and 0.03 μmolg 1 for SnO2/Au_150°C). These results demonstrate that, though the SnO2 band structure does not indicate a good semiconductor for CO2 reduction, its surface characteristics are responsible for its catalytic activity.
Transição progressiva dos modelos explicativos de estudantes do nível médio sobre a natureza das forças intermoleculares.
(2022) Miranda, Ana Carolina Gomes; Pazinato, Maurícius Selvero; Braibante, Mara Elisa Fortes
O foco de investigação desta pesquisa foi o processo de ensino e aprendizagem de forças intermoleculares no nível médio. O principal objetivo foi investigar a evolução conceitual, por meio de modelos explicativos de estudantes da 1ª série do ensino médio, sobre a natureza das forças intermoleculares. Para isso o conteúdo foi desenvolvido por intermédio de uma sequência didática (SD). Baseando-se na perspectiva de Lakatos, procurou-se verificar se os modelos explicativos dos sujeitos formam sequências de transição progressiva, similares ao que Lakatos, na História da Ciência, se refere a "problemática" que aumenta o poder explanatório/heurístico do modelo. A evolução dos modelos, que geralmente consiste em transições progressivas, está relacionada ao entendimento sobre o conteúdo de forças intermoleculares e a capacidade de transitar entre os níveis de representação da matéria em relação ao entendimento sobre a natureza das forças intermoleculares. O acompanhamento das ideias dos estudantes ao longo do estudo do conteúdo revelou que houve um número significativo deles que conseguiu progredir conceitualmente. De forma geral, é possível afirmar que as atividades desenvolvidas na SD contribuíram significativamente para a transição progressiva dos modelos explicativas da maioria dos participantes. Além disso, a abordagem do conteúdo de forças intermoleculares na SD desenvolvida capacitou os estudantes a interpretarem os fenômenos em estudo, por meio dos níveis de representação da matéria.
Batch and continuous adsorption of Cd(II) and Pb(II) on polycarboxylated sugarcane bagasse.
(2023) Carvalho, Megg Madonyk Cota Elias; Soares, Liliane Catone; Maia, Luisa Cardoso; Taylor, Jason Guy; Herrera Adarme, Oscar Fernando; Ferreira, Gabriel Max Dias; Azevedo, Eduardo Ribeiro de; Siervo, Abner de; Silva, Luis Henrique Mendes da; Gurgel, Leandro Vinícius Alves
A bioadsorbent composed of polycarboxylated sugarcane bagasse (PSB) was prepared in a one-step reaction by the esterification of sugarcane bagasse hydroxyl groups with butane-1,2,3,4-tetracarboxylic dianhydride. 13C SS NMR measurements showed that 0.3 butane-1,2,3,4-tetracarboxylic acid units were grafted per cellobiose unit. PSB was used in the batch adsorption of Cd(II) and Pb(II) from mono-, bi-, and multicomponent aqueous solutions. For upscaling of the technology aiming at practical applications, evaluation was made of 4 cycles of continuous adsorption of Cd(II) and Pb(II) on PSB in a fixed-bed column. The maximum adsorption capacities for Cd(II) and Pb(II) on PSB in batch and continuous modes were 0.55 and 1.164 mmol g− 1 (62 and 241.2 mg g− 1 ), and 0.58 and 0.71 mmol g− 1 (65 and 153 mg g− 1 ), respectively. The standard adsorption enthalpy change (ΔadsH◦) values for Cd(II) and Pb(II) were 8.6 ± 0.5 and − 0.28 ± 0.03 kJ mol− 1 , respectively. The interactions involved in the adsorption of Cd(II) and Pb(II) on PSB were investigated. Multicomponent studies showed that Pb (II) and Cd(II) acted to suppress the adsorption of each other. In the presence of Cu(II) and Zn(II), the adsorption capacity followed the order: Pb(II) > Cu(II) > Cd(II) > Zn(II). Batch and continuous adsorption-desorption studies showed that PSB could be reused in at least 4 successive cycles, with desorption efficiencies of 88–100 %, which is essential for minimizing waste generation and reducing process costs.
Memórias e saberes : a adoção de plantas alimentícias não convencionais (PANC) na cozinha tradicional mineira.
(2022) Andreoli, Cristiana Santos; Melo, Tânia Márcia Sacramento; Nogueira, Stephânia da Consolação Silva
Este artigo faz a interface entre a Gastronomia e a Memória Afetiva das autoras, enfatizando o emprego de Plantas Alimentícias não Convencionais (PANC) nas tradições culinárias das famílias dessas pessoas. O objetivo deste estudo foi mostrar como essas tradições estão conectadas à alimentação passada de geração em geração, na qual há a valorização dos produtos cultivados e colhidos nos quintais e hortas. Trata-se de uma pesquisa exploratória de caráter qualitativo, cuja coleta de dados foi feita por meio de pesquisa de campo através de arquivos fotográficos e entrevista semiestruturada na qual mostrou que os entrevistados atuam como guardiões do saber-fazer dessa prática. Além disso, foi um momento de acolhida aos entrevistados devido ao isolamento social provocado pela SARS-Cov-2.
Use of hollow fibre membrane contactors to remove dissolved gases from effluents of UASB reactors treating sewage after its conditioning with dynamic membrane filtration.
(2023) Mora, Erick Centeno; Paranhos, Aline Gomes de Oliveira; Aquino, Sergio Francisco de; Chernicharo, Carlos Augusto de Lemos
Dissolved gases in the effluent of anaerobic reactors, such as dissolved methane (D-CH4) and sulphide (S2− ), are a drawback for anaerobic-based sewage treatment plants. Hollow fibre membrane contactors (HFMCs) have been tested for the removal of these compounds, and this paper evaluated a novel configuration with pressurised dynamic membrane modules (PDMMs) for conditioning an anaerobic effluent (from UASB reactor fed with sewage) as a means to reduce HFMCs clogging and fouling. Three PDMMs were used for the anaerobic effluent conditioning before two types of HFMCs (dense and microporous membranes). An automated backwash with a tap water cleaning protocol complemented with a chemical cleaning protocol (NaOH and citric acid) was applied for fouling control. The microporous HFMC could not maintain a stable performance (D-CH4 and S2− removal drop of 30 % and 40 %, respectively, in 10 days of operation), arguably due to membrane wetting, meanwhile the dense HFMC showed a more stable behaviour (removal efficiencies close to 100 % and 90 % for S2− and D-CH4, respectively in >30 days). The water backwash removed an important fraction of the entrapped organic solids. Meanwhile, the NaOH cleaning was efficient in removing inorganic compounds. Citric acid contributed to the removal of calcium and phosphate.
Occurrence and environmental risk assessment of 22 pesticides in Brazilian freshwaters.
(2023) Brovini, Emília Marques; Quadra, Gabrielle Rabelo; Teixeira, José Reinaldo Paranaíba Vilela Alves; Carvalho, Luana; Pereira, Renata de Oliveira; Aquino, Sergio Francisco de
Pesticide contamination in water resources is a global threat. Although usually found at low concentrations, pesticides raise considerable toxicological concerns, mainly when mixtures are considered. The occurrence of 22 pesticides (2,4 D, alachlor, aldicarb, aldrin, atrazine, carbendazim, carbofuran, chlordane, chlorpyrifos, DDT, diuron, glyphosate, lindane, mancozeb, methamidophos, metolachlor, molinate, profenofos, simazine, tebuconazole, terbufos, and trifluralin) was investigated, through consolidated database information, in surface freshwaters of Brazil. Moreover, scenarios of environmental risk assessment considering isolated compounds and mixtures were performed, as well as a meta-analytic approach for toxicity purposes. Pesticides in freshwater have been reported from 719 cities (12.9% of Brazilian cities), where 179 (3.2%) showed pesticide occurrence above the limit of detection or quantification. Considering cities with more than five quantified, 16 cities were prone to environmental risks considering individual risks. However, the number increased to 117 cities when the pesticide mixture was considered. The mixture risk was driven by atrazine, chlorpyrifos, and DDT. The national maximum acceptable concentrations (MAC) for nearly all pesticides are higher than the predicted no-effect concentration (PNEC) for the species evaluated, except aldrin. Our results show the need to consider mixtures in the environmental risk assessment to avoid underestimation and review MAC to protect aquatic ecosystems. The results presented here may guide the revision of the national environmental legislation to ensure the protection of Brazilian aquatic ecosystems.
Water treatment technologies for removing priority pesticides.
(2023) Brovini, Emília Marques; Moreira, Fernanda Deister; Martucci, Maria Elvira Poleti; Aquino, Sergio Francisco de
The development of technologies to remove pesticides from environmental matrices is an important issue as they may be toxic to the environment and human health. The objective of this review is to understand the treatability of five selected pesticides including the main treatment processes and conditions employed worldwide to remove them. Despite its widespread use in water treatment plants (WTP), conventional technologies alone were only tested for atrazine and resulted in low average removal (up to 50 %). Several studies using advanced oxidation processes have been successful for atrazine, but few experiments have been performed under practical conditions. Regarding reported efficiencies, 80 % of atrazine was degraded when conventional treatment was followed by ozonation using aluminum sulfate and magnafloc LT 22 as coagulants and ozone as disinfectant. For acephate and methamidophos, the use of titanium dioxide was the best treatment, leading to 87.7 % to 100 % removal in laboratory-scale experiments. Anodic Fenton treatment and a combination of Fenton and ultrasound exhibited high (99 and 100 %, respectively) carbofuran removal efficiencies. In terms of time and conditions tested, the membrane anodic Fenton treatment was the best one, but large-scale application needs to be further evaluated. In general, advanced oxidation processes are good complementary technologies. However, understanding the fate and toxicity of the transformation by-products is crucial, as well as its applicability (economic and environmental sustainability) on a large scale.
Avaliação de risco ambiental de fármacos e desreguladores endócrinos presentes no esgoto sanitário brasileiro.
(2023) Barán, Tatiana Wieczorko; Aquino, Sergio Francisco de; Sanson, Ananda Lima
Este estudo investigou a ocorrência, remoção e impacto na biota aquática de 19 contaminantes de preocupação emergente (CEC) comumente reportados no esgoto brasileiro bruto e/ou tratado. Para 14 CEC (E1, E2, EE2, GEN, DCF, PCT, BPA, IBU, NPX, CAF, TMP, SMX, CIP, LEV), sua presença em esgoto tratado apresentou um alto risco ambiental em pelo menos 2 dos 6 cenários de diluição considerados. Os quocientes de risco (RQ) para o cenário com capacidade de diluição ótima foram estimados em 13584 para EE2; 2604 para E2; 1068 para E1; 193 para TMP; 160 para SMX; 12 para NPX; 7 para DCF; 4 para CAF e 3 para BPA. Os CEC mais preocupantes do ponto de vista ecotoxicológico (EE2, E2, E1 com RQ>1000) foram detectados em efluentes de estações de tratamento de esgoto (ETE) brasileiras em concentrações que variaram de 122 a 288 μg L-1. Constatou-se também que para 15 dos 19 CEC, o valor limite para proteção ambiental também protegeria a saúde humana se tais compostos não forem removidos durante o tratamento de água.
Aerobic post-treatment of effluent from anaerobic reactors fed with residues from 1G and 2G sugarcane biorefineries.
(2022) Procópio, Paula Fontoura; Aquino, Sergio Francisco de; Herrera Adarme, Oscar Fernando
This study aimed to evaluate an activated sludge system as a post-treatment step of anaerobic effluents from the co-digestion of sugarcane vinasse and hemicelluloses hydrolysate. The system consisted, initially, of a two-stage anaerobic system followed by a continuously fed activated sludge, all in bench scale. After adaptation of aerobic microorganisms to effluent conditions, the anaerobic digestion was conducted in a single-stage anaerobic reactor, increasing the influent organic loading rate (OLR) of activated sludge from 0.73 to an average of 2.36 gCOD/L day. Under optimal conditions (12-h hydraulic retention time [HRT]), a 62 ± 9% efficiency was observed on the aerobic post-treatment, resulting in effluent chemical oxygen demand (COD) of 414.3 ± 95 mg/ L. Overall efficiency of the combined system (anaerobic + aerobic) averaged 88 ± 3%. Influent and effluent characteristics were then analyzed by Folin-Ciocalteau method, UV–Vis spectrophotometry, and gas chromatography–mass spectrometry (GC–MS) for identification of potentially toxic and recalcitrant compounds. Compounds that absorb light within the visible spectra were well removed by the combined treatment system. Most compounds identified by GC–MS in the influent were completely removed by aerobic microorganisms. Saturated fatty acids such as adipic acid, hexadecanoic acid, and octadecanoic acid were observed in the final effluent, as well as other potentially toxic compounds such as stigmasterol, di-isobutyl phthalate, and benzene. Activated sludge proved to be an efficient post-treatment for anaerobic co-digestion, able to cope with changes of anaerobic effluent quality and providing a final effluent of stable organic load. However, phenol removal was not efficient and further studies could be performed to optimize its degradation.
Hydrothermal pretreatment of poultry litter for biogas production.
(2023) Oliveira, Mayara Pires de; Paranhos, Aline Gomes de Oliveira; Herrera Adarme, Oscar Fernando; Aquino, Sergio Francisco de
Hydrothermal pretreatment (HPT) allows the solubilization of the hemicellulose, leading to increased biodegradability for microorganisms. This paper presents a study based on the evaluation of the variables time (12 to 60 min), temperature (80 to 200°C), and solid/liquid ratio (4 to 8 g mL-1) for the HPT (autohydrolysis) of synthetic poultry litter (rice straw: poultry manure 1:5) using the Doehlert matrix. Twelve HPT conditions followed by anaerobic digestion were evaluated with a focus on methane production. Firstly, tests were conducted to evaluate biogas production in a single stage in a single reactor, where both the acidogenic and methanogenic phases occur. Subsequently, tests were conducted to evaluate biogas production in a two-stage, consisting of separating hydrogen and methane production phases. The best performance of the biochemical potential of methane was the conditions 6 (24 min, 120 °C, and solid-liquid ratio = 4) in a single stage and 3 (48 min, 160 °C, and SLR = 8) in a two-stage, producing 255.6 and 277.6 NmL CH4 gVS-1, respectively. Using the desirability criteria, two hydrothermal pretreatment (HPT) conditions were evidenced/ condition 1 in two stages (12 min, 80 °C, and SLR = 4)- (D1-2S) and condition two in two stages (12 min, 98 °C, and SLR = 4) - (D2-2S) showed high methane production, 248.9 and 249.3NmL CH4 ∙gVS-1, respectively.
O uso de materiais dinâmico - táteis na elaboração conceitual por um estudante cego : trabalhando o efeito de forças e a estabilidade energética de sistemas intramoleculares.
(2023) Silva, Marcos Antonio Pereira da; Patrocínio, Sandra de Oliveira Franco; Fernandes, Jomara Mendes
Essa pesquisa tem por objetivo compartilhar a experienciação do uso de dois objetos dinâmico-táteis (ODTs) como mediadores na construção de modelos mentais de conceitos químicos abstratos por um estudante com deficiência visual (ECDV). Os ODTs são ferramentas que, por aplicação de forças (mecânica ou magnética, obtidas, por exemplo, pela tensão de elásticos ou de borrachas e de ímãs, respectivamente), geram movimentos e alterações da configuração inicial do sistema. A presente investigação se trata de um estudo de caso único, de natureza qualitativa. Os resultados revelaram que o ECDV, a partir da experienciação tátil em nível sensorial muscular possibilitada pelos ODTs, desenvolveu uma integração dinâmica e simultânea de informações permitindo a construção de modelos mentais dos conceitos e dos fenômenos estudados. Portanto, a utilização de ODTs pode contribuir de forma significativa como mediador para a construção de modelos mentais de conceitos químicos abstratos por estudantes cegos.
A história da ciência na temática "leis de Newton" em livros didáticos de ciências da natureza e suas tecnologias indicados pelo PNLD 2021.
(2023) Paula, Joyce Cristina Mendes de; Patrocínio, Sandra de Oliveira Franco
Diante do importante papel do livro didático nos processos de ensino e aprendizagem, tanto para estudantes quanto para professores, buscamos, neste trabalho, analisar como a história da ciência está sendo empregada nos livros didáticos de Ciências da Natureza e suas Tecnologias voltados para o Ensino Médio indicados pelo Programa Nacional do Livro e do Material Didático em 2021 dentro da temática “Leis de Newton”. Colocando luz sobre o potencial que a história da ciência carrega de formar concepções dos estudantes sobre o caráter do conhecimento científico, utilizamos a metodologia criada por Laurinda Leite (2002), adotando uma abordagem qualitativa, para compreender quais são as perspectivas que as obras estão trazendo para seus leitores. Embora haja a presença de elementos da história da ciência e uma tentativa discreta, em alguns livros, de introduzila de uma forma um pouco mais explanativa, de modo geral, apresenta-se uma história da ciência linear, alheia a fatores humanos e sociais que permeiam a construção histórica do conhecimento, inculcando uma imagem de neutralidade da ciência e inexorabilidade do método científico.
Equilíbrio químico : tendências do ensino e aprendizagem em publicações científicas a partir da análise de periódicos nacionais e internacionais.
(2022) Silva, Daniel de Lima; Miranda, Ana Carolina Gomes; Patrocínio, Sandra de Oliveira Franco
O processo de ensinar e aprender conceitos relacionados ao Equilíbrio Químico (EQ) vem se mostrando desafiador em todos os níveis da educação. A presente investigação tem como objetivo identificar as tendências de ensino e aprendizagem relacionadas ao tema. Para isso, foi realizada uma pesquisa de caráter bibliográfico, empregando da análise de artigos publicados em periódicos nacionais e internacionais da área do ensino de Química e Ciências durante o período compreendido entre 2001- 2021. Os resultados revelaram as principais concepções alternativas dos estudantes e algumas das tendências que marcaram os estudos nessa área, tais como predominância da abordagem cinética do EQ; emprego da base teórica construtivista nas abordagens; utilização estratégias didáticas do tipo analogias, resolução de problemas, estudo de caso, atividades experimentais e utilização das Tecnologias da Informação e Comunicação (TIC).
Molecular structure of Ru(II)/diphosphine/4,6-dimethyl-2-pyrimidinethiol complexes : a combined experimental and density functional theory study.
(2023) Lima, Benedicto Augusto Vieira; Varela Júnior, Jaldyr de Jesus Gomes; Ellena, Javier Alcides; Batista, Alzir Azevedo; Silva, Albérico Borges Ferreira da; Correa, Rodrigo de Souza
Reactions of cis-[RuCl2(P-P)(bipy)] precursors with the SpymMe2 ligand (4,6-dimethyl-2- pyrimidinethiol) yielded complexes of the [Ru(SpymMe2)(P-P)(bipy)]PF6 type, where P-P = 1,2- bis(diphenylphosphino)ethane (dppe - for complex 1), 1,3-bis(diphenylphosphino)propane (dppp - for complex 2) and 1,1’-bis(diphenylphosphino)ferrocene (dppf - for complex 3) and bipy = 2,2’-bipyridine. The new compounds were obtained by displacing the chlorido ligands from the precursors and coordination of one monoanionic 4,6-dimethyl-2-pyrimidinethiol ligand. All complexes were characterized by spectroscopic, electrochemical and elemental analysis techniques, as well as single-crystal X-ray diffraction, where the structures of complexes 1, 2 and 3 showed that the SpymMe2 ligand coordinates to the ruthenium(II) center as bidentated, yielding complexes with the sulfur atom trans positioned to the nitrogen atom from the bipy ligand. A theoretical study of the structures of the complexes was performed using the DFT/B3LYP method. Distances and angles of optimized structures agree with X-ray experimental data. Furthermore, the calculated IR and UV-Vis spectra are compatible with experimental data. Charge decomposition analysis (CDA) and NBO (natural bond orbitals) charges showed that there was an overall charge transfer from bipy and P-P ligands to the ruthenium centers. Higher electrochemical stability and 1H and 31P{1H} NMR shifts of 1, 2 and 3 compared with precursors could be explained by the lower values of calculated molecular orbital energies, NBO charge on atoms and CDA data. Finally, the structure of the isomers of complexes 1, 2 and 3, considering the sulfur atom trans positioned to the phosphorus atom, were optimized, showing that they are slightly less stable, presenting total energy higher, 10.4, 31.5 and 60.5 kJ/mol than 1, 2 and 3, where nitrogen is trans to the phosphorus atom.
Cytotoxic activity of Ru(II)/DPEPhos/N,S-mercapto complexes (DPEPhos = bis-[(2-diphenylphosphino)phenyl]ether).
(2023) Grawe, Gregory Ferreira; Oliveira, Katia Mara de; Leite, Celisnolia Morais; Oliveira, Tamires Donizeth de; Costa, Analu Rocha; Moraes, Carlos André Ferreira; Araujo Neto, João Honorato de; Cominetti, Márcia Regina; Castellano, Eduardo Ernesto; Correa, Rodrigo de Souza; Machado, Sérgio de Paula; Batista, Alzir Azevedo
We report here on three new ruthenium(II) complexes, [Ru(DPEPhos)(mtz)(bipy)]PF6 (Ru1), [Ru(DPEPhos) (mmi)(bipy)]PF6 (Ru2) and [Ru(DPEPhos)(dmp)(bipy)]PF6 (Ru3). DPEPhos = bis-[(2-diphenylphosphino) phenyl]ether, mtz = 2-mercapto-2-thiazoline, mmi = 2-mercapto-1-methylimidazole, dmp = 4,6-diamino-2- mercaptopyrimidine and bipy = 2,2′ -bipyridine. The compounds were characterized by several spectroscopic techniques, and the molecular structure of Ru1 complex was determined by single-crystal X-ray diffraction. The cytotoxicity of Ru1 – Ru3 complexes were tested against the A549 (human lung) and the MDA-MB-231 (human breast) cancer cell lines and against MRC-5 (non-tumor lung) and MCF-10A (non-tumor breast) cell lines through the MTT assay. All three complexes are cytotoxic against the cell lines studied, with IC50 values lower than those found for the cisplatin. Among them, the Ru2 complex has shown the best selectivity against MDA-MB-231 cancer cell lines, with an IC50 value 12 times lower than that on MCF-10A. The complex Ru2 was capable to induce changes in MDA-MB-231 cells morphology, with loss of cellular adhesion, inhibited colony formation and induce an accumulation of cells at the sub-G1 phase, with an increase in S-phase and decrease of cells at G2 phase. Viscosity, electrochemical and Hoechst 33258 displacement experiments for Ru1 – Ru3 complexes with calf thymus DNA (CT-DNA) showed an electrostatic and groove binding mode of interaction. Additionally, the complexes interact with the protein Human Serum Albumin (HSA) by static mechanism. The negative values for ΔH and ΔS indicate that van der Waals forces and hydrogen bonding may occurs between the complexes and HSA. Therefore, this class of complexes are promising anticancer candidates and may be selected to further detailed studies.
Copper(II)/diiminic complexes based on 2-hydroxybenzophenones : DNA-and BSA-binding studies and antitumor activity against HCT116 and HepG2 tumor cells.
(2023) Rodrigues, Júlia Helena Valadares; Carvalho, Alexandre Bizzotto de; Silva, Valdenizia Rodrigues; Santos, Luciano de Souza; Soares, Milena Botelho Pereira; Bezerra, Daniel Pereira; Oliveira, Katia Mara de; Correa, Rodrigo de Souza
Here, we report four new heteroleptic Cu(II) complexes with the formula [Cu(bipy)(2H4MeBz)]NO3 (1), [Cu (phen)(2H4MeBz)]NO3 (2), [Cu(bipy)(2H4OcBz)]NO3 (3) and [Cu(phen)(2H4OcBz)]NO3 (4), where the ligands are 2-hydroxy-4-methoxybenzophenone (2H4MeBz), 2-hydroxy-4-(octyloxy)benzophenone (2H4OcBz), 2,2′ - bipiridine (bipy) and 1,10-phenantroline (phen). All compounds present two bidentate ligands, a monoanionic 2- hydroxybenzophenone, forming a six-membered chelate ring and the diiminic ring forming a five-membered chelate ring, as well as one nitrate as counterion located at the axial position, as suggested by the crystal structure of complex 2. Complex/DNA interaction studies were also performed using spectroscopic titration (Kb close to 104 M− 1 ), viscosity, Hoechst 33258 competition, and circular dichroism, revealing a moderate interaction between them. Additionally, complexes 1–4 moderately interact with BSA (Bovine Serum Albumin). The compounds were evaluated against HCT116 (human colon carcinoma) and HepG2 (human hepatocellular carcinoma) cancer cells and against MRC-5 (human lung fibroblast), a noncancer cells. The cytotoxic results suggest that complexes 2 and 4 are more cytotoxic than 1 and 3, showing that the presence of phen ligand may play an important role in increasing the biological effect of the compounds.
N–H–O and weak interactions stabilizing the schiff base/picrate multicomponent salt.
(2023) Niquini Junior, Fabiano Maﬁa; Machado, Pedro Henrique; Montilla Suárez, Jerica Margely; Moura, Ana Luiza S.; Correa, Rodrigo de Souza
Here, a new picrate salt containing a protonated Schiff base (SB) is presented. The new compound presents a high melting point (246-250 °C), compared to base free (99-101 °C), such as expected for a salt. Also, UV-Vis and infrared experiments were carried out to in order to confirm the presence of both components, a protonated SB and the picrate anion. The single-crystal X-ray diffraction reveals the formation of the new compound, containing an ion pair in the asymmetric unit. The intramolecular interactions and, mainly, the intermolecular interactions were explored in detail. The salt presents strong N–H…O hydrogen bonds and π–π stacking interactions stabilize the crystal self-assembly, differing from neutral SB which presents only weak interactions. Finally, we investigate the fluorescence properties and capability coordination with metals by Jobs method of the SB, however, no significant results were observed.
Nitrosyl/Diphenylphosphine/Amino Acid–Ruthenium complexes as inhibitors of MDA-MB-231 breast cancer cells.
(2023) Barbosa, Marília Imaculada Frazão; Correa, Rodrigo de Souza; Macedo, Adriana Pereira Mundim Guedes; Graça, Alex Marchezini; Andrade, Francyelli Mello; Leite, Celisnolia Morais; Lacerda, Elisângela de Paula Silveira; Ellena, Javier Alcides; Silva, Henrique Vieira Reis; Doriguetto, Antônio Carlos; Batista, Alzir Azevedo
Herein, we report on the synthesis and characterization of ruthenium compounds with the general formula [RuCl(AA-H)(NO)(dppb]PF6 , where AA = glycine (1), L-alanine (2), L-phenylalanine (3) and L-valine (4), and dppb = 1,4-bis(diphenylphosphine)butane. The complexes were characterized using elemental analysis, UV/Vis and infrared spectroscopies, 1H, 13C, 31P NMR techniques, and cyclic voltammetry. Furthermore, the structures of the compounds (1) and (3) were determined using single-crystal X-ray diffraction. In vitro evaluation of the Ru(II)/nitrosyl/amino acid complexes revealed their cytotoxic activities against triple-negative MDA-MB-231 breast cancer cells, and against the non-tumor murine fibroblast cells. All the compounds decreased the percentage of viable cells, inducing cell death by apoptosis. Additionally, the Ru(II) complexes inhibited the migration of MDA-MB-231 cells at concentrations lower than 35 µM, after 48 h of exposure. Thus, these complexes may be promising agents for the treatment of triple-negative MDA-MB-231 breast cancer.
New ruthenium complexes containing salicylic acid and derivatives induce triple-negative tumor cell death via the intrinsic apoptotic pathway.
(2022) Graminha, Angelica Ellen; Popolin, Cecília; Araujo Neto, João Honorato de; Correa, Rodrigo de Souza; Oliveira, Katia Mara de; Godoy, Luani Rezende; Colina Vegas, Legna Andreina; Ellena, Javier Alcides; Batista, Alzir Azevedo; Cominetti, Márcia Regina
In this work we present the synthesis and characterization of six new ruthenium compounds with general formulae [Ru(L)(dppb)(bipy)]PF6 and [Ru(L)(dppe)2]PF6 where L = salicylic acid (Sal), 4-aminosalicylic acid (AmSal) or 2,4-dihydroxybenzoic acid (DiSal), dppb = 1,4-bis(diphenylphosphino)butane, dppe = 1,2-bis (diphenylphosphino)ethane and bipy = 2,2′ -bipyridine. The complexes were characterized by elemental analysis, molar conductivity, cyclic voltammetry, NMR, UV–vis and IR spectroscopies, and two by X-ray crystallography. The 31P{1 H} NMR spectra of the complexes with the general formula [Ru(L)(dppe)2]PF6 showed that the phosphorus signals are solvent-dependent. Aprotic solvents, which form strong hydrogen bonds with the complexes, inhibit the free rotation of the salicylic acid-based, modifying the diphosphine cone angles, leading to distortion of the phosphorus signals in the NMR spectra. The cytotoxicity of the complexes was evaluated in MCF7, MDA-MB-231, SKBR3 human breast tumor cells, and MCF-10 non-tumor cell lines. The complexes with the structural formula [Ru(L)(dppe)2]PF6 were the most cytotoxic, and the complex [Ru(AmSal)(dppe)2]PF6 with L = 4-aminosalicylic acid ligand was the most selective for the MDA-MB-231 cell line. This complex interacts with the transferrin and induces apoptosis through the intrinsic pathway, as demonstrated by increased levels of proteins involved in apoptotic cell death.
Dynamics of formation of binuclear metal complexes : a new Cu(I) compound with N-(2-thiophenecarbonyl)-N’-(3- Cl, 4-F-phenyl) thiourea as ligand.
(2022) Ramos Cairo, Raúl; Plutín Stevens, Ana María; Mocelo Castell, Raúl Oscar; Castellano, Eduardo Ernesto; Correa, Rodrigo de Souza; Nossa González, Diana Lisseth; Erben, Mauricio Federico; Cominetti, Márcia Regina; Leite, Celisnolia Morais; Oliveira, Tamires Donizeth de; Batista, Alzir Azevedo
Herein we report the synthesis and characterization of a new copper(I) complex with triphenylphosphine (PPh3) and N-(2- thiophenecarbonyl)-N’-(3-Cl, 4-F-phenyl)thiourea (HL), as ligands. The complex was characterized by vibrational (FTIR and FT-Raman) and multinuclear ( 1 H, 13C { 1 H}, 31P{1 H}) NMR spectroscopies. The crystalline structure of the complex was determined by single-crystal X-ray diffraction, confirming that a neutral binuclear compound, identified as [Cu(PPh3)(L-k2 -N,μ-S)]2, was obtained. The anionic thiourea ligand coordinates to the metal through the sulfur and nitrogen atoms in an unusual bidentate k2 -N,μ-S coordination mode. The complex is a dimer sited on a crystallographic center of symmetry. Each Cu2(μ-S)2 cation bridges trough the sulfur atoms of two symmetry related thiourea moieties and is also coordinated to the nitrogen atom of the thiourea ligand and the phosphorus atom from PPh3 coligand, forming a slightly distorted tetrahedral geometry. An intramolecular N H⋅⋅⋅O=C hydrogen bond is observed in the anionic ligand, forming a six-membered ring that stabilizes the N H thioamide group. Hirshfeld surface analysis shows that the molecules are connected by weak intermolecular contacts C⋅⋅⋅C, H⋅⋅⋅C and H⋅⋅⋅H which add to the stability of the crystalline packing. The in vitro cytotoxicity study of the complex indicates that it is more active against human lung carcinoma cells (A549), when compared to the free ligand.

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