http://hdl.handle.net/10174/29584 Fri, 03 Apr 2026 20:20:22 GMT 2026-04-03T20:20:22Z http://hdl.handle.net/10174/41398 Title: Exploring cation size effects in eutectic solventes: an experimental and molecular Dynamics approach Authors: Moreira, Mariana H.; Duarte, Aimone J. C.; Branco, Luís C.; Marrucho, Isabel M. Abstract: Eutectic solvents (ES) represent a promising class of environmentally friendly solvents, yet many aspects of their structural characteristics remain poorly understood. In this study, we have used molecular dynamics (MD) simulations in combination with experimental data to investigate the molecular structure and physicochemical properties of eutectic systems formed by combining carboxylic salts of sodium, potassium, and lithium with fatty acids. Our results highlight the key role of the cation in molecular arrangement, with the analysis revealing that metal cations promote interactions between salt and acid molecules. In addition, we observed that the size of the ionic radius significantly influences the eutectic point, to the extent that the eutectic may not be detected depending on the metal selected. Wed, 01 Jan 2025 00:00:00 GMT http://hdl.handle.net/10174/41398 2025-01-01T00:00:00Z http://hdl.handle.net/10174/41363 Title: Preaggregation of Asphaltenes in the Presence of Natural Polymers by Molecular Dynamics Simulation Authors: Celia-Silva, Lucas G.; Vilela, Patrícia B.; Morgado, Pedro; Lucas, Elizaabete F.; Martins, Luís F. G.; Filipe, Eduardo J. M. Abstract: Cashew nut shell liquid (CNSL), its extract, cardanol, and polycardanol, are known to influence the dispersion behavior of asphaltenes in model solvent mixtures. CNSL and cardanol act as dispersants, while polycardanol can act as both dispersant or flocculant depending on its molecular architecture, concentration, and asphaltene source. In this work, the preaggregation of asphaltenes in model solvents (toluene, n-heptane, and their mixtures) has been studied by atomistic molecular dynamics simulation. The influence of cardanol, addition polycardanol, and condensation polycardanol as additives has been addressed. The simulation results remarkably reproduce the experimental trends, thus contributing to a better understanding of the molecular processes underlying the stabilization or precipitation of asphaltenes by cardanols and their polymers. Thu, 09 Jan 2020 00:00:00 GMT http://hdl.handle.net/10174/41363 2020-01-09T00:00:00Z http://hdl.handle.net/10174/41302 Title: Probing the organization of liquids using 129Xe NMR spectroscopy III: Linear hydrogenated and fluorinated alcohols Authors: Eusébio, Tiago M.; Morgado, Pedro; Martins, Luís F. G.; Filipe, Eduardo J. M. Abstract: The liquid organization of six alcohols (CH3(CH2)nOH, n = 1, 2, 3, 5, 7, 9) and five fluorinated alcohols (CF3(CF2)nCH2OH, n = 1, 2, 3, 4, 5) was studied using 129Xe as an NMR probe. For the first time, spectra were obtained as a function of temperature to allow the comparison of the different solvents at similar thermodynamic conditions. Correlations of the xenon medium shifts as a function of group density were obtained, assessing the relative interactivity of the different groups forming the solvent molecules. Molecular dynamics simulations confirm and complement the molecular interpretations obtained from the NMR results. It is shown that xenon is not randomly distributed throughout the liquid, but preferentially located near the aliphatic end of the solvent molecules, resulting in an enrichment of CH3 and CF3 groups around xenon. Conversely, xenon’s coordination sphere is depleted in CH2OH groups relatively to the stoichiometric proportion. This work extends to n-alkanols and 1H,1H-perfluoroalkanols the methodology previously applied to n-alkanes, perfluoroalkanes and perfluoroalkylalkanes, allowing the prediction of the 129Xe medium shift in all these solvents, at any temperature, providing the density is known. The advantages of using xenon as an NMR probe are clearly demonstrated. The high sensitivity of the xenon atom provides detailed information on the nature, density and organization of the solvent’s chemical groups within its coordination sphere. Wed, 01 Jan 2025 00:00:00 GMT http://hdl.handle.net/10174/41302 2025-01-01T00:00:00Z http://hdl.handle.net/10174/41298 Title: Proposing a new anti-Covid-19 agent by using molecular docking and dynamics simulation Authors: Silva, Izabella R. F.; Martins, Luís F. G.; Yoneda, Julliane Abstract: The Covid-19 pandemic, caused by SARS-CoV-2, was responsible for millions of deaths worldwide. The main protease (Mpro) of SARS-CoV-2 is considered one of the important drug targets for the treatment of Covid-19. Recent studies have shown that anisotine should be a potent Mpro inhibitor. In the present work, four oxoquinoline derivatives are proposed as candidates for Mpro inhibitors. The main functional group of these derivatives shows similarity to anisotine, and they are active against the HSV-1, as well as the latter. Molecular docking studies evaluated whether these compounds could be active against Mpro of SARS-CoV-2. Structural modifications were proposed on the oxoquinoline derivative which formed a more stable complex with Mpro and this proposal formed an even more stable complex besides exhibiting improvements in the toxicological profile. Molecular dynamics simulations indicated that derivatives proposed promote greater stabilization by complexing with Mpro than anisotine. Wed, 01 Jan 2025 00:00:00 GMT http://hdl.handle.net/10174/41298 2025-01-01T00:00:00Z