The growing concern about the emergence of increasingly antibiotic-r4esistant bacteria imposes the need to search and develop drugs to combat these microorganisms. This, combined with the search for low-cost synthesis methods, was the motivation for the elaboration of this work. Abietic acid present in the resin of Pinus elliotti var. elliotti was used to generate a sodium salt by salification. The synthesis route was low-cost, consisting of only two reaction steps at mild temperatures without toxic organic solvents, and eco-friendly and easy to conduct on an industrial scale. Sodium abietate (Na-C20H29O2) was characterized by mass spectrometry, infrared spectroscopy, elemental analysis, X-ray diffraction, scanning electron microscopy, and energy-dispersive spectroscopy. To perform the antimicrobial tests, the determination of minimum inhibitory concentration and the disk diffusion assay was performed. The results obtained showed that the salt Na abietate performed an antimicrobial action against the bacterial strains S. aureus, E. coli, L.monocytogenes, and S. enterica Typhimurium and the yeast C. albicans. The disk diffusion test showed a high inhibition potential against S. enterica compared to the standard antimicrobial tetracycline, as an inhibition index of 1.17 was found. For the other bacterial strains, the inhibition values were above 40%. The MIC test showed promising results in the inhibition of E. coli, L. monocytogenes, and C. albicans, indicating bacteriostatic activity against the first microorganism and bactericidal and fungicidal activities against the others. Therefore, the results showed the action of Na abietate as a possible effective antimicrobial drug, highlighting its sustainability within a circular economy.

Bentonite clay sourced from the Guarapuava region, Brazil, was modified with niobium oxide (BEOx) and niobium phosphate (BEPh) to act as an adsorbent and photocatalyst in the remediation of wastewater containing methylene blue (MB) dye. Additionally, colored materials were evaluated for their potential as antibacterial hybrid pigments. The bentonite clay modified with niobium was prepared by a solution containing swelling clay mixed with niobium oxide (NbOx) and niobium phosphate (NbPh) in a water solution; after that, the suspension was calcinated. X-ray diffractometry, X-ray photoelectron spectroscopy, and laser-induced breakdown spectroscopy assessed the modifications induced by the incorporation of niobium compounds into the clay, confirming the presence of niobium in the bentonite clay. Following characterization, the BEOx and BEPh samples were used as adsorbents or photocatalysts for treating solutions containing the MB dye (400 mg·L⁻¹) at 25 °C. The results showed adsorption and photocatalysis efficiency above 94% for both samples. The blue-colored BEOx and BEPh samples were then applied as a hybrid pigment. The power pigment and its dispersion in colorless paint were evaluated by the CIEL*a*b* color space, and the ΔE parameters show values above 12, indicating a very strong color parameter difference. Subsequently, the efficacy of BEOx and BEPh as a hybrid pigment was assessed using the minimum inhibitory concentration (MIC) assay against two bacteria strains: Bacillus cereus (ATCC 10876) and Proteus mirabilis (ATCC 35649). The analysis revealed remarkable antibacterial activity against Proteus mirabilis, suggesting a preferential selectivity for Gram-negative bacteria.

In this study, raw smectite (Sm), from the Guarapuava–Parana–Brasil region, was saturated with copper ions (Cu-Sm) by ion exchange and the samples Sm and Cu-Sm were used in crystal violet (CV) adsorption and applied as an antimicrobial and antifungal hybrid pigment. Samples (Sm and Cu-Sm) were used to remove crystal violet (CV) dye from aqueous media, simulating wastewater. Samples after use as adsorbents were characterized and named smectite/adsorbed dye (Sm/Dye) and copper smectite/adsorbed dye (Cu-Sm/Dye); and they were applied as hybrid pigments with antimicrobial action. The Sm and Cu-Sm were characterized by X-ray diffractometry (XRD), energy dispersive X-ray fluorescence (EDXRF), vibrational spectroscopy (FTIR), Zeta potential (ζ), scanning electron microscopy (SEM), and colorimetry (CIE L*a*b*), enabling the identification of the presence of intercalated copper ions and on the smectite surface. The adsorption assays were carried out to evaluate the effects of initial dye concentration and contact time. Tests for application as a hybrid pigment showed good compatibility with commercial white paint being applied on plaster blocks and later photoaging and chemical stability tests were performed in acid and basic environments, both were discussed by colorimetry (CIE L*a*b*), thus being able to relate it to the color variation (∆E). The samples (Sm, Cu-Sm, Sm/Dye, and Cu-Sm/Dye) were dispersed in white paint at 10% and 20% (% w/w) to evaluate the ability to inhibit different microorganisms. The modification with copper ions promoted an increase in the adsorptive capacity relative to the raw smectite and provided antibacterial and antifungal action to the hybrid pigment against Escherichia coli, Staphylococcus aureus, Listeria monocytogenes, and Candida albicans. The Cu-Sm and Cu-Sm/Dye samples showed excellent results against all studied microorganisms and reveal successful materials that can be used in environments that require microbiological protection.

The search for less expensive and viable products is always one of the challenges for research development. Commonly, the synthesis of coordination compounds involves expensive ligands, through expensive and low-yield routes, in addition to generating toxic and unusable residues. In this work, the organic ligand used is derived from the resin of a reforestation tree, Pinus elliottii var. elliottii. The synthesis method used Pinus resin and an aqueous solution of vanadium(III) chloride at a temperature of 80 °C. The procedure does not involve organic solvents and does not generate toxic residues, thus imparting the complex formation reaction a green chemistry character. The synthesis resulted in an unprecedented oxovanadium(IV)-bis(abietate) complex, which was characterized by mass spectrometry (MS), chemical analysis (CHN), vibrational (FTIR) and electronic spectra (VISIBLE), X-ray diffraction (XRD), and thermal analysis (TG/DTA). Colorimetric studies were performed according to the CIELAB color space. The structural formula found, consisted of a complex containing two abietate ligands, [VO(C₂₀H₂₉O₂)₂]. The VO(IV)-bis(abietate) complex was applied against microorganisms and showed promising results in antibacterial and antifungal activity. The best result of inhibitory action was against the strains of Gram-positive bacteria S. aureus and L. monocytogenes, with minimum inhibitory concentration (MIC) values of 62.5 and 125 μmol L⁻¹, respectively. For Gram-negative strains the results were 500 μmol L⁻¹ for E. coli; and 1000 μmol L⁻¹ for Salmonella enterica Typhimurium. Antifungal activity was performed against Candida albicans, where the MIC was 15.62 μmol L⁻¹, and for C. tropicalis it was 62.5 μmol L⁻¹. According to the MFC analysis, the complex presented, in addition to the fungistatic action, a fungicidal action, as there was no growth of fungi on the plates tested. The results found for the tests demonstrate that the VO(IV)-bis(abietate) complex has great potential as an antimicrobial and mainly antifungal agent. In this way, the pigmented ink with antimicrobial activity could be used in environments with a potential risk of contamination, preventing the spread of microorganisms harmful to health.

O trabalho apresenta os resultados de ação extensionista que procurou elaborar, adaptar e aplicar jogos didáticos para o Ensino de Química em diferentes ambientes escolares, bem como verificar os resultados dessa ação na melhoria da aprendizagem e da instigação. Foram desenvolvidos e aplicados onze jogos didáticos. O objetivo foi o de testar as possibilidades de ressignificação das estratégias de ensino-aprendizagem da Química a partir da ludicidade dos processos e fenômenos científicos. Essa atividade foi aplicada em três Escolas diferentes pertencentes a região de Guarapuava-PR e avaliada pelos estudantes participantes por meio do preenchimento de formulário com perguntas sobre suas experiências a respeito dos jogos. Através dos dados coletados, observou-se que os alunos apresentaram maior interesse com as atividades desenvolvidas, relatando que os jogos contribuíram para o aprendizado de conteúdos da referida disciplina. Também, considera-se que o uso dessa ferramenta auxilia no desenvolvimento dos alunos, estimula o raciocínio, melhora as relações interpessoais e o estudante aprende de forma autônoma, sendo o protagonista do seu conhecimento.

Magnesium oxide is typically white and can be colorized with transition metal insertion by doping. We present the preparation of a green-colored hydroxide by the exchange of Mg²⁺ on the crystalline lattice with Ni²⁺ in MgO, using three nickel salts. MgO_st was prepared by the colloidal starch suspension method, using cassava starch. The oxides and hydroxides, before and after, were characterized by X-ray diffraction (XRD), and show that a phase change occurs: a transition from periclase (MgO) to brucite (Mg(OH)₂) due to the incorporation of nickel ions from different salts (acetate, chloride, and nitrate), resulting in the solid solution [Ni_xMg_1−x(OH)₂]. The FTIR spectrum corroborates the crystallographic structure identified through XRD patterns, confirming the formation of a crystal structure resembling brucite. The new samples present a green color, indicative of the incorporation of the Ni²⁺ ions. The antimicrobial activity of products resulting from the doping of magnesium oxide with nickel and the precursor MgO_st was assessed through the minimum inhibitory concentration (MIC) test. The evaluation included three bacterial strains: Staphylococcus aureus (ATCC 25923), Escherichia coli (ATCC 25922), Salmonella gallinarum (ATCC 9184), and a yeast strain, Candida albicans (ATCC 10231). The obtained results were promising; the tested samples exhibited antimicrobial activity, with a MIC ranging from 0.312 to 0.625 μg.μL⁻¹. The nickel compound, derived from the precursor chloride salt, demonstrated superior MIC activity. Notably, all tested samples displayed bactericidal activity against the S. aureus strain and exhibited a broad spectrum of inhibition, encompassing both Gram-positive and Gram-negative strains. Only the nickel compounds derived from precursors with acetate and nitrate anions demonstrated antimicrobial activity against C. albicans, exhibiting a fungistatic behavior. Based on the conducted studies, [Ni_xMg_1−x(OH)₂] has emerged as a promising antimicrobial agent, suitable for applications requiring the delay or inhibition of bacterial growth.