Publications

Abstract Herein, the synthesis and crystal structure of 7-hydroxy-3-(2-methoxyphenyl)-2trifluoromethyl-4H-chromen-4-one, C17H11F3O4, are reported. This isoflavone is used as a starting material in the preparation an array of potent and competitive FPR antagonists. The pyran ring significantly deviates from planarity and the dihedral angle between the benzopyran mean plane and that of the exocyclic benzene ring is 88.18 (4)degrees.In the crystal, O-H center dot center dot center dot O hydrogen bonds connect the molecules into C(8) chains propagating in the [010] direction.

Abstract The strategy of combining electroactive polymers and inorganic nanomaterials has been widely explored in recent years in order to improve some of their properties, namely electrocatalysis and electrochromism. This report focuses on a new composite prepared through the electropolymerization of the transition metal complex [Ni(3-Mesalen)], designated as [1] in the presence of WO3 nanoparticles (NPs) and its electrochromic (EC) performance. The WO3 NPs were prepared using tungsten metal powder; their characterization indicated quasi-spherical morphology, high crystallinity and particle sizes in the range 30-40 nm. The nanocomposite WO3@poly[1] films displayed similar electrochemical responses to those of pristine poly[1] films in LiClO4/CH3CN, but higher electroactive surface coverages, an advantage of NPs incorporation in the nanocomposite. The presence of the WO3 NPs in the poly[1] matrix was assessed by X-ray photoelectron spectroscopy and scanning electronic microscopy. The nanocomposite presented similar electronic spectra to those of poly[1], indicating that the electronic structure of the pristine film is maintained in the nanocomposite, but exhibited lower e-values for bands associated with charge transfer transitions for high oxidised states, revealing an enhanced stability towards ligand over-oxidation. The WO3@ poly[1] nanocomposite showed more favourable EC properties in LiClO4/CH3CN than the pristine film. For typical coverages ( Gamma = 0.06-0.10 mu mol cm (2)) the composite showed lower switching times (tau = 1.3 - 3.6 s), higher optical contrast (Delta T approximate to 31%, an improvement of ca. 40%) and better colouration efficiencies (in the range eta = 104 - 115 cm(2)C (1), improvement of ca. 13 - 22%).

Abstract The use of privileged structures in drug discovery has proven to be an effective strategy, allowing the generation of innovative hits/leads and successful optimization processes. Chromone is recognized as a privileged structure and a useful template for the design of novel compounds with potential pharmacological interest, particularly in the field of neurodegenerative, inflammatory, and infectious diseases as well as diabetes and cancer. This perspective provides the reader with an update of an earlier article entitled "Chromone: A Valid Scaffold in Medicinal Chemistry" (Chem. Rev. 2014, 114, 4960-4992) and is mainly focused on chromones of biological interest, including those isolated from natural sources. Moreover, as drug repurposing is becoming an attractive drug discovery approach, recent repurposing studies of chromone-based drugs are also reported.

Abstract We report the electrochromic properties of a polymeric nanocomposite prepared by potentiodynamic deposition of transition-metal complex [Ni(3-Mesalen)], designated as [1], in the presence of TiO2 nanoparticles (NPs) with an average size of 9.7 +/- 1.1 nm. Entrapment of TiO2 NPs in the poly[1] matrix was confirmed by several techniques. The nanocomposite TiO2@poly[1] films showed similar electrochemical responses to the original (nanoparticle-free) poly[1] films, but with higher electroactive surface coverages (G), showing the advantage of the nanocomposite preparation. The results indicated that the electronic structure of poly[1] was retained in the nanocomposite; nonetheless, a lower e value was obtained for the charge-transfer band of the former, revealing superior stability of the nanocomposite for ligand high oxidation states. The TiO2@poly[1] nanocomposite showed interesting color changes, from yellow (reduced state) to green and russet (oxidized states), with enhanced electrochemical stability, demonstrated by a charge loss of only 7.3% over ca. 10?000 redox cycles surpassing the original polymer film stability: the loss of electroactivity is a factor of ca. 2 less than for pristine poly[1]. Furthermore, an enhancement of 16.7% in the optical modulation (Delta OD = 0.48) was also observed for the nanocomposite, confirming the benefit of TiO2 incorporation into the EC properties of the original polymer film.

Abstract An electrochromic nanocomposite based on a nickel-salen polymeric film - poly[Ni(3-Mesalen)], Mesalen = N,N'-bis(3-methylsalicylideneiminate) - and graphene nanoplatelets (GFNPs) with enhanced electrochromic stability was successfully prepared by anodic electropolymerization. Although the electrochemical processes typical of the polymer film were not changed by the presence of graphene, higher electroactive surface coverages could be obtained for nanocomposite films, which suggest the incorporation of GFNPs into the polymeric network. The nanocomposite showed multi-electrochromic behavior, with color changes between yellow (reduced state) and green (oxidized state). The inclusion of GFNPs into the poly[Ni(3-Mesalen)] structure accelerates the switching process, with the response time for green coloration decreasing by 50.7% and for yellow coloration by 60.0%, for films prepared with 30 electropolymerization cycles. In terms of electrochemical stability, after 10,000 electrochemical cycles the loss of charge was 7% for the graphene nanocomposite. The nanocomposite film was used as electrochromic material to assemble a flexible solid-state electrochromic device (ECD), which exhibited an outstanding electrochemical stability - only 3% of charge loss after 15 days of continuous activity.

Abstract Molecular modeling indicates the general process of describing complex chemical systems in terms of a realistic atomic model, with the goal being to understand and predict macroscopic properties based on detailed knowledge on an atomic scale. Often, molecular modeling is used to design new materials, for which the accurate prediction of physical properties of realistic systems is required. These properties could be divided in two main groups: static equilibrium properties, like the binding constant of a drug to a receptor, and dynamic or non-equilibrium properties, like the diffusion of molecules through two phases or reaction kinetics and so on. Due to the great variety of techniques we will carefully choose the most appropriate to our problem. In any case, the most accurate is the so called ab initio which uses. © 2017 by Taylor & Francis Group, LLC.

Abstract The standard molar enthalpies of formation of maleic anhydride and vinylene carbonate in gaseous phase, at T = 298.15 K, were derived from the standard molar enthalpies of formation of the compounds in condensed phase combined with the phase transition enthalpies. The standard molar enthalpies of formation in condensed phase were obtained from the enthalpies of combustion measured using static bomb combustion calorimetry and mini-bomb combustion calorimetry for vinylene carbonate and maleic anhydride, respectively. Phase transition enthalpies were obtained by Calvet micro-calorimetry. High level quantum calculations were performed at the composite G3 level of theory in order to estimate the standard molar enthalpies of formation of both compounds in gaseous phase. Good agreement was obtained between experimental and computational results. In addition, analysis of the factors affecting the relative stability of both systems has been carried out in the framework of the ab initio valence bond (VB) theory in order to clarify the aromaticity/antiaromaticity issues involving these molecular systems.

Abstract Fucoidan, a sulfated polysaccharide extracted from brown seaweed, was, in the form of a silica composite, studied as a prospective cation imprinting matrix. The preparation of such composites in the presence of cations with a strong interaction with the biopolymer chains was expected to direct them towards arrangements, optimized for the sorption of those cations. As expected, the presence of Cu(II), a weakly fucoidan-binding cation, in the synthesis of the composites did not result in the production of significantly stronger Cu(II)-oriented binding arrangements, and therefore the imprinting was not successful. However, with Pb(II), with much stronger affinity for fucoidan, the materials obtained exhibited stronger (22%) binding as compared to the non-imprinted counterparts, and increased selectivity (1.4-1.6 fold) against Cd(II). Although these imprinting features were close to those observed previously with other sulfated polysaccharides, the fucoidan-based Pb(II) imprints developed here presented superior sorption properties, namely a higher capacity and higher binding strength for Pb(II). These features, demonstrated by the material developed here, may easily be put to work in different areas where Pb(II) sensing, determination, separation or remediation is of the utmost importance.

Abstract An electrochemical biosensor was developed by merging the features of Molecular Imprinting technique and Screen-Printed Electrode (SPE) for the simple and fast screening of cardiac biomarker myoglobin (Myo) in point-of-care (POC). The MIP artificial receptor for Myo was prepared by electrooxidative polymerization of phenol (Ph) on a AuSPE in the presence of Myo as template molecule. The choice of the most effective protein extraction procedure from the various extraction methods tested (mildly acidic/basic solutions, pure/mixed organic solvents, solutions containing surfactants and enzymatic digestion methods), and the optimization of the thickness of the polymer film was carefully undertaken in order to improve binding characteristics of Myo to the imprinted polymer receptor and increase the sensitivity of the MIP biosensor. The film thickness was optimized by adjusting scan rate and the number of cycles during cyclic voltammetric electropolymerization of Ph. The thickness of the polyphenol nanocoating of only few nanometres (similar to 4.4 nm), and similar to the protein diameter, brought in significant improvements in terms of sensor sensitivity. The binding affinity of MIP receptor film was estimated by fitting the experimental data to Freundlich isotherm and a similar to 8 fold increase in the binding affinity of Myo to the imprinted polymer (K-F = 0.119 +/- 0.002 ng(-1) mL) when compared to the non- imprinted polymer (K-F = 0.015 +/- 0.002 ng(-1) mL) which demonstrated excellent (re) binding affinity for the imprinted protein. The incubation of the Myo MIP receptor modified electrode with increasing concentration of protein (from 0.001 ng mL(-1) to 100 mu g mL(-1)) resulted in a decrease of the ferro/ferricyanide redox current. LODs of 2.1 and 14 pg mL(-1) were obtained from calibration curves built in neutral buffer and diluted artificial serum, respectively, using SWV technique, enabling the detection of the protein biomarker at clinically relevant levels. The prepared MIP biosensor was applied to the determination of Myo spiked serum samples with satisfactory results.

Abstract The effect of the addition of a group of organic additives on the electrodeposition behavior of zinc was investigated in choline chloride:ethylene glycol (ChC1:EG) eutectic mixture in the molar ratio of 1:2. Cyclic voltammograms recorded on steel electrode showed a cathodic peak is only observed after reversing of the scan. Chronoamperometric measurements indicated that the deposition of zinc occurs through 3D progressive nucleation mechanism. The morphology of the zinc deposits and was evident that additives influence the deposits morphologies. X-ray diffraction confirmed the presence of crystalline zinc and reveal the grain refinement effect obtained by using the additives selected where the smallest grain size of 31.7 nm was obtained in the presence of Dimethyl sulfoxide (DMSO). Moreover the XRD data showed that the addition of additives modified the preferential growth plane. The corrosion resistance properties of the electrodeposited Zn coatings were evaluated in 3% NaCI aqueous solution using potentiodynamic polarization. The results showed that the zinc film deposited with DMSO was the best corrosion resistant coating.