Caroline Raquel Bender

The investigation of crystalline structures using the supramolecular cluster approach, which has been successfully applied to charged and uncharged compounds, is extended here to the analysis of zwitterionic systems.

Ionic liquids are highly versatile in supramolecular chemistry, where adjustable physicochemical properties enable the development of functional materials.

In this study, we report the design, synthesis, structural characterization (1H- and 13C-NMR, HRMS, and single-crystal X-ray diffraction analysis), and biological evaluation of two novel series of N-(4,6-dialkyl(aryl)-pyrimidinyl)-1H-(benzo[d]thiazolyl)-2-amines (4a-e) and their N-methylated derivatives (5a-e) as dual antibacterial and antifungal agents.Comprehensive structure-activity relationship (SAR) analysis revealed that N-methylation at the exocyclic amine acts as a molecular switch, drastically enhancing anti-staphylococcal activity. In silico ADME profiling and molecular docking simulations were performed to establish correlations between structural features and biological performance. To rationalize the experimental antimicrobial activity, molecular docking simulations were performed against Staphylococcus aureus peptide deformylase (PDB: 3U7K) and Candida albicans sterol-14α-demethylase (PDB: 5TZ1). The calculations revealed favorable binding energies and additional hydrophobic and π-interactions for the N-methylated derivative 5d, establishing a clear correlation between structural modification, target interaction, and the enhanced antimicrobial activity observed experimentally. Among the series, compound 5d exhibited exceptional inhibitory potency against S. aureus (MIC = 0.25 µg/mL) and potent fungistatic activity against Candida spp. (MIC = 4 µg/mL), while maintaining acceptable drug-likeness parameters according to ADME predictions. These combined structural and computational analyses provide mechanistic insight into the observed bioactivity and establish N-methyl-N-(pyrimidin-2-yl)-1H-benzo[d]thiazol-2-amine scaffolds as promising candidates for further antimicrobial optimization.

This work presents the synthesis of mono- and dicationic ionic liquids (ILs) that combine the cations 1-butyl-3-methylimidazolium ([C₄MIM]⁺), 1-decyl-3-methylimidazolium ([C₁₀MIM]⁺), 1,4-bis(3-methylimidazolium-1-yl)butane ([C₄(MIM)₂]²⁺), and 1,10-bis(3-methylimidazolium-1-yl)decane ([C₁₀(MIM)₂]²⁺) with the anion dodecanoate ([C₁₁COO]^-), along with a study into their thermal stability and mechanism for thermal decomposition. Thermal stability was investigated using the Kissinger-Akahira-Sunose (KAS) isoconversional method to determine the isoconversional activation energies (E _α ) and compensation effect to calculate the pre-exponential factor (ln A _α ). The results showed that there was no significant difference in the thermal stabilities between the ILs, with all compounds being thermally stable up to 450 K. The thermal decomposition mechanism was analyzed using nuclear magnetic resonance (NMR), electrospray ionization mass spectrometry (ESI-MS), and thermogravimetric analysis coupled with Fourier-transform infrared spectroscopy (TGA-FTIR). The main decomposition pathways were nucleophilic substitution at the lateral or spacer chain and the methyl group.

Powder metallurgy is an attractive method for cost effective production of near net shape Ti-Nb alloys, and, when elemental powders and coarse HDH powders are used, a higher flexibility in alloy composition and low processing costs can be achieved. In this study, manufacturing of (α+β) Ti-Nb alloys by powder metallurgical techniques using coarse HDH Nb (D₅₀= 110 μm and D₅₀= 255 μm) and HDH Ti (D₅₀= 22.6 μm) powders as starting materials was described. Tape casting was applied for the production of porous sheets while warm compaction of Metal Injection Molding (MIM) feedstock was applied for the production of dense parts. Microstructural and mechanical tests were employed to investigated the effect of coarse Nb powders on the sintering behavior and mechanical properties. Tape casting enabled to produce porous sheets of Ti16Nb alloy with an interconnected porosity varying from 14 - 31 vol.%. Warm compaction enabled to produce Ti-Nb parts with less than 2% porosity and Yield strength in compression of 975-1100 MPa, which is similar to the values reported for Ti-Nb based alloys produced by powder metallurgy of finer powders. A dynamic Young’s Modulus of 37-52 GPa, significantly lower than that of cp-Ti was achieved. These results might provide guidelines for the use of coarse Nb powders as starting materials for the powder metallurgical development of low-cost Ti-Nb based alloys.

This research reports accelerated stability experiments, the evaluation of intermolecular interactions, and antifungal assays for fluconazole emulsions prepared using ultrasound (US) and magnetic stirring (MS) in the presence of ionic liquids derived from 1,n-(3-methylimidazolium-1-yl)alkane bromide ([C_nMIM]Br; n = 12 or 16). The goals of the investigation are to quantify the stability, identify the forces that drive the formation and stability, and determine the antifungal activity of fluconazole-containing emulsions, and corroborate the data from our previous results that indicated that the emulsion based on [C₁₆MIM]Br seemed to be more stable. In this study, accelerated stability experiments evidenced a considerable stability for the [C₁₆MIM]Br emulsions at two temperatures (25 and 37 °C)—the instability index increased in the following order: US40% < US20% < MS. The ¹H NMR data showed that the ILs interacts differently with medium-chain triglycerides (MCT). Two distinct interaction mechanisms were also observed for [C₁₂MIM]Br and [C₁₆MIM]Br with fluconazole, in which the latter formed more compact mixed aggregates than the former. The result was corroborated by diffusion data, which showed that ILs suffered a decrease in diffusion in the presence of fluconazole. The antifungal assay showed that emulsions containing ILs displayed superior activity compared with fluconazole alone. The emulsions also showed potent activity in inhibiting a resistant species (C. glabrata—CG34) to FLZ. All emulsions showed weak irritant potential in HET-CAM assay.

O uso de metodologias ativas tem sido amplamente discutido em todos os níveis de ensino como uma tendência para a superação das aulas em um formato exclusivamente transmissivo e focado no professor, para dar protagonismo aos discentes durante o desenvolvimento didático. A crítica aos modelos tradicionais de ensino não é recente e tem sido amplamente discutida pela comunidade acadêmica; entretanto, para além do aparato teórico mobilizado quando um docente se dispõe a adotar uma metodologia ativa, seja ela qual for, torna-se necessário contrapor os pressupostos do modelo adotado ao que, de fato, é possível operacionalizar em cada contexto específico, com suas próprias características, expectativas e dificuldades, para, a cada nova experiência docente com o uso da metodologia adotada, outros aspectos não previstos pelo aparato teórico serem (re)dimensionados à luz da prática docente. Nesse sentido, este trabalho se configura como um relato de experiência a respeito do uso da metodologia da Sala de Aula Invertida (SAI), na disciplina de Tópicos em Química, em um curso de Especialização em Ciências Exatas e Tecnologia, ofertado em uma universidade pública no interior do Rio Grande do Sul. O texto do relato apresenta dois focos: no primeiro, o enquadramento docente sobre a experiência e, no segundo, a percepção dos alunos a respeito do modelo SAI, a partir de um questionário com perguntas abertas, respondido ao término da disciplina. Os resultados apontam que, no contexto em questão, ou seja, um curso de especialização lato sensu, foram evidenciados ganhos na aprendizagem dos discentes e as dificuldades pontuais na compreensão dos conteúdos previstos pela disciplina foram equalizadas durante as aulas presenciais. Por sua vez, alguns discentes, ao avaliarem a transposição da SAI, especialmente para o contexto da Educação Básica, embora evidenciem as vantagens do modelo, também apontam alguns desafios, os quais precisam ser equacionados ou minimamente previstos durante cada experiência de ensino, de forma a compreendê-la sempre de maneira situada.