Publications

Abstract Ion transfer electrochemistry is a powerful tool for the study of ionic species in solution. In this paper, square wave voltammetry and chronoamperometry are applied for the quantification and characterization of denatonium ion (N-benzyl-2-(2,6-dimethylphenylamino)-N,N-diethyl-2-oxoethanarninium) in water, an important additive present in commercial products. The method presented is based on the monitoring of the transfer of the cation across a microporous membrane separating an aqueous solution and an organic solution of 1,2-dichloroethane. Calibration curves are built with both techniques and the resulting detection limits and linear ranges of response are discussed. Furthermore, the different performance characteristics of the two techniques are exploited to extract the values of the aqueous diffusion coefficient of the ion denatonium and its standard transfer potential from water to 1,2-dichloroethane. The last parameter is of great importance for the evaluation of the ion lipophilicity, that plays a role in its distribution in living organisms and its impact on biological media. (C) 2020 Elsevier B.V. All sights reserved.

Abstract New molecular dynamics (MD) simulations and experimental data on a deep eutectic solvent, propeline, composed by choline chloride, ChCl, and propylene glycol, PG, in a molar ratio of 1:2 are reported in this work. The experimental physicochemical properties (density, viscosity and self-diffusion coefficients) were used as support in the development of a new OPLS based force field model (FFM) for propeline. Validation of the new force field was established both through measuring physicochemical properties over a range of temperatures (298.15-373.15 K) and by comparison with experimental and simulated data of ethaline (ChCl:ethylene glycol, at a molar ration of 1:2). Classical MD simulations using the new FFM led to good agreement between experimental and simulated data. Structural properties, namely radial and spatial distribution functions, coordination numbers, and hydrogen bonding were analyzed. Moreover, it was found that the interactions between the anion, Cl-, and the hydrogen bond donor (HBD) form a network that is immutable with increasing temperature. The higher prevalence of anion-HBD hydrogen bonds is likely the major reason for the relatively high viscosity of propeline.

Abstract Relevant thermochemical data of gamma-butyrolactone (GBL), a compound of considerable industrial and environmental significance, obtained from experimental and computational studies are reported in this work. The standard (p degrees = 0.1 MPa) molar enthalpy of formation, at T = 298.15 K, in the gaseous phase, was determined from the enthalpy of combustion and vaporization, obtained by static bomb calorimetry in oxygen and by Calvet microcalorimetry, respectively. The enthalpy of formation in the gaseous phase was also determined from G3 calculations. The excellent agreement between the experimental and computational thermochemical data provided a critical literature review of GBL and the proposal of new reference values for this lactone.

Abstract Cancer is a major cause of death worldwide and novel anticancer agents for its better management are much needed. Benzopyrone-based compounds, such as chromones, possess several distinctive chemical and biological properties, of which the cytotoxicity against cancer cells seems to be prominent. In this study, two series of compounds based on chromen-4-one (3-10) and chromane-2,4-dione (11-18) scaffolds were synthesized in moderate/high yields and evaluated for cytotoxicity against HL-60, MOLT-4, and MCF-7 cancer cells using MTT assay. In general, the compounds exhibited moderate cytotoxic effects against the cancer cell lines, among which, a superior potency could be observed against MOLT-4 cells. Chroman-2,4dione (11-18) derivatives had overall higher potencies compared to their chromen-4-one (3-10) counterparts. Compound 13 displayed the lowest IC50 values against HL-60 (IC50, 42.0 +/- 2.7 mu M) and MOLT-4 cell lines (IC50, 24.4 +/- 2.6 mu M), while derivative 11 showed the highest activity against MCF-7 cells (IC50, 68.4 +/- 3.9 04). In conclusion, this study provides important information on the cytotoxic effects of chromone derivatives. Benzochroman-2,4-dione has been identified as a promising scaffold, which its potency can be modulated by tailored synthesis with the aim of finding novel and dissimilar anticancer compounds.

Abstract The discovery and development of multitarget-directed ligands (MTDLs) is a promising strategy to find new therapeutic solutions for neurodegenerative diseases (NDs), in particular for Alzheimer's disease (AD). Currently approved drugs for the clinical management of AD are based on a single-target strategy and focus on restoring neurotransmitter homeostasis. Finding disease-modifying therapies AD and other NDs remains an urgent unmet clinical need. The growing consensus that AD is a multifactorial disease, with several interconnected and deregulated pathological pathways, boosted an intensive research in the design of MTDLs. Due to this scientific boom, the knowledge behind the development of MTDLs remains diffuse and lacks balanced guidelines. To rationalize the large amount of data obtained in this field, we herein revise the progress made over the last 5 years on the development of MTDLs inspired by drugs approved for AD. Due to their putative therapeutic benefit in AD, MTDLs based on MAO-B inhibitors will also be discussed in this review.

Abstract The polycondensation of silicic acid, methylsilicic acid, or their mixture was studied by reactive force field simulation. These were found to be feasible systems for the simulation of two-step acid hydrolysis-alkaline condensation of their alkoxysilane counterparts, usually taken experimentally as sol-gel precursors. The approach avoided the alkoxysilane hydrolysis step and allowed high degrees of polycondensation at relatively low temperature (700-1000 K), from the computational efficiency perspective. Being the ultimate interest of the present study the sol-gel polycondensation of templated gels whose microstructural pattern is affected by the presence of a template, the role of the intermolecular forces was decisive, and promoted high polycondensation at the lowest possible temperature. Polycondensation with added damascenone did not result in any perceived templating effect, i.e., damascenone was not able to interact significantly with the growing clusters, in a way that would allow its occlusion or a surface molding effect on the clusters. A possible reason for this is the intermolecular interaction strength being too weak at the temperatures set for the simulations. However, when using luteolin as the template, a molecule with several hydrogen bond interaction points, it was possible to observe different microscopic events involving the template molecules, some of them corresponding to actual templating effects, such as partial enveloping by the network around the template. These restricted events did not allow the inference of any macroscopic property of the final gel. However, it was shown that polycondensates shaped by the template or a template dimer may be obtained. The sites thus obtained will be essential for future in silico studies of the selectivity of such sites.

Abstract In this work we report a new potential model for classical molecular dynamics (MD) simulation of two dipolar aprotic solvents - propylene carbonate (PC) and gamma-butyrolactone (GBL). Parameters for intramolecular interactions as well as the partial atomic charges were derived from quantum chemical calculations, while the OPLS/AA force field Lennard-jones intermolecular parameters were adjusted to reproduce the experimental thermodynamic and the transport properties of these solvents in the wide temperature range. The comparison of new potential models with existing models for PC and GBL is given. Using the proposed models, the local structure of these solvents was studied in detail, paying special attention to packing ability, dipole-dipole orientation and hydrogen-bonding (H-bonding) interactions. Based on the results of MD simulations and QTAIM analysis, it was shown that H-bonds involving carbonyl oxygen atoms in PC and GBL are rather weak, while no H-bonds are formed with ester oxygen atoms. According to the present results, the mutual molecular orientation in PC and GBL varies with the distance, being above/below plane-parallel configuration for closest neighbors, and in-plane T-shaped configurations for farther neighbors. The nearest neighbors approach coupled with angular distribution functions was applied for the estimation of the Kirkwood factor in the framework of the OnsagerKirkwood-Frohlich theory. Our results shows that in order to reproduce the corresponding experimental values the Kirkwood factor it is necessary to take in account the mutual orientation of similar to 8-9 neighboring molecules for GBL and similar to 5-6 molecules for PC. (C) 2019 Published by Elsevier B.V.

Abstract Concerns for the environment and sustainability are a priority to modern societies and one of the reasons for the emergence of movements against mining exploration. To avoid the opposition of local populations to mining activity, especially open-pit mining, there is a need to proceed with both best practices and technical knowledge that involve the local population and also carry out systematic environmental monitoring. The aim of this study is to evaluate the potential environmental impacts of C57 lithium mine exploration in the village of Goncalo, district of Guarda, Portugal, on water, soil and atmospheric air quality. Determining the concentration of cations, anions, pH and conductivity for water and soil quality evaluation was performed by atomic absorption spectroscopy, ion chromatography and potentiometric methods. For the evaluation of atmospheric air quality, beta radiation absorption, chemiluminescence, UV absorption photometric and infrared radiation methods were used. The results lead to the conclusion that there is no evidence of soil and water quality degradation due to mine exploration. However, there is a perception of the existence of environmental impact on air quality, especially on nitrogen dioxide and particulate matter (PM1, PM2.5 and PM10), although the emissions of air pollutants are below the limits established by Portuguese legislation.

Abstract Modern societies are great producers of waste because of their energy and natural resource needs. Many of these wastes are disposed of in landfills, which require a significantly sized area of soil and special geotechnical conditions. The reaction between alumina-silicate and an aqueous alkali hydroxide and silicate solution produces an alkali-activated cement (AAC). The use of AAC, an inorganic material with a chemical structure of polymeric Si-O-Al bonds, can promote the stabilisation and immobilisation of a wide variety of waste sources containing hazardous materials. The purpose of this study is to evaluate the effect of curing conditions on the resistance and permeability and in the quality of the seepage water generated over time in transport infrastructure platforms built with soil stabilised with AAC. The strength results show that the material meets the requirements for use in building low-cost roads. Permeability tests of AAC samples show a relatively low permeability (between 10(-8) and 10(-7) m/s), a positive factor for environmental and geotechnical considerations. However, this permeability still results in significant leachate water with quality and contaminant issues, particularly in chromium (Cr), cadmium (Cd), aluminium (Al), sodium and silicon (Si), and high pH.