Publications

Abstract The study of sensing materials to the detection of carbon dioxide (CO2) was achieved using p-nitrophenol (pNPh) as a colorimetric indicator. The sensing material was polymerized (NPLn), functionalized with 3-triethoxysilyl propyl isocyanate (IPTES) which sensitivity was tested in the form of a membrane as is and encapsulated in hollow silica nanoparticles. The sensing membranes were tested in a closed gas system comprising very precise flow controllers to deliver different concentrations of CO2 (vs. N2). The combination of the sensing membranes with multimode optical fibers and a dual-wavelength diode (LED) allows the measurement of the CO2 through the analysis of the induced absorbance changes with a self-referenced ratiometric scheme. The analysis of the sensing materials have shown significant changes in their chemical and physical properties and the results attest these materials with a strong potential for assessing CO2 dynamics in environmental, medical, and industrial applications.

Abstract Adenosine receptors participate in many physiological functions. Molecules that may selectively interact with one of the receptors are favorable multifunctional chemical entities to treat or decelerate the evolution of different diseases. 3-Arylcoumarins have already been studied as neuroprotective agents by our group. Here, differently 8-substituted 3-arylcoumarins are complementarily studied as ligands of adenosine receptors, performing radioligand binding assays. Among the synthesized compounds, selective A(3) receptor antagonists were found. 3-(4-Bromophenyl)-8-hydroxycoumarin (compound 4) displayed the highest potency and selectivity as A(3) receptor antagonist (K-i = 258 nM). An analysis of its X-ray diffraction provided detailed information on its structure. Further evaluation of a selected series of compounds indicated that it is the nature and position of the substituents that determine their activity and selectivity. Theoretical modeling calculations corroborate and explain the experimental data, suggesting this novel scaffold can be involved in the generation of candidates as multitarget drugs.

Abstract The impact of fullerene side chain functionalization with thiophene and carbazole groups on the device properties of bulk-heterojunction polymer:fullerene solar cells is discussed through a systematic investigation of material blends consisting of the conjugated polymer poly[(5,6-difluoro-2,1,3-benzothiadiazol-4,7-diyl)-alt-(3,3'"-di(2-octyldodecyl)-2,2 ' ;5 ' ,2 '' ;5 '' ,2'"-quaterthiophen-5,5'"-diyl)] (PffBT4T-2OD) as donor and C-60 or C-70 fulleropyrrolidines as acceptors. The photovoltaic performance clearly depended on the molecular structure of the fulleropyrrolidine substituents although no direct correlation with the surface morphology of the photoactive layer, as determined by atomic force microscopy, could be established. Although some fulleropyrrolidines possess favorable lowest unoccupied molecular orbital levels, when compared to the standard PC71BM, they originated OPV cells with inferior efficiencies than PC71BM-based reference cells. Fulleropyrrolidines based on C-60 produced, in general, better devices than those based on C-70, and we attribute this observation to the detrimental effect of the structural and energetic disorder that is present in the regioisomer mixtures of C-70-based fullerenes, but absent in the C-60-based fullerenes. These results provide new additional knowledge on the effect of the fullerene functionalization on the efficiency of organic solar cells.

Abstract The synthesis of noble metal nanoparticles (i.e., silver and gold) for electrochemical applications has been widely studied using mainly wet synthesis chemical methods or electrochemical deposition methods. In this work, we propose a single-step flash photochemical method for synthesizing noble metal nanoparticles (i.e., silver, gold, and Au:Ag) in solution for electrochemical applications. The method is based on the intense pulsed radiation emitted from a xenon flashlamp, which induce the reduction of metal cations in solution to form metallic nanoparticles. The present method is based on the selective light absorption of the metal precursor salts combined with the decomposition of polyvinylpyrrolidone added to the solution. This approach can be termed as flash light synthesis.

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.