Publications

Abstract Ohmic heating offers a very efficient way to perform organic reactions in aqueous media. Potentially bioactive (E)-3-styrylquinolin-4(1H)-ones were synthesized by the Heck reaction of 3-iodo-1-methylquinolin-4(1H)-one with styrenes in water and with ohmic heating. Pd(OAc)(2) was used as catalyst, and tetrabutylammonium bromide was used as phase-transfer catalyst in the presence of an inorganic base. Comparison with other established procedures highlight the benefits of this new methodology.

Abstract In this work, the effect of the alkyl chain size in 1-ethylpyridinium cation-based ionic liquids are used to explore the nanostructuration effect. Densities and viscosities and their dependence on temperature were measured for the 2-alkyl-l-ethylpyridinium bis(trifluoromethanesulfonyl)imide, [(CN-2C2Py)-C-2-C-1] [NTf2] (N = 4,5, 6, 7, 8, 9, 10, 11,12) ionic liquid series. Molar volume, thermal expansion coefficients, VET parameters, as well as, the energy barrier related to the fluid shear at T= 298.15 K, were derived. Highly precise measurements of the heat capacities, at T = 298.15 K, were performed using a drop calorimeter. In agreement with the previously studies based on the alkylimidazolium ionic liquids series, the studied thermophysical and transport properties of the series presents an indication that in the pyridinium based ionic liquids the nanostructuration is intensified after a critical alkyl length, [(C5C2Py)-C-2-C-1][NTf2]. The observed trend shift in the viscosity and heat capacities of the pyridinium ionic liquids is more pronounced in the pyridinium than in the imidazolium ionic liquids series.

Abstract Photodynamic therapy (PDT) of cancer is known for its limited number of side effects, and requires light, oxygen and photosensitizer. However, PDT is limited by poor penetration of light into deeply localized tissues, and the use of external light sources is required. Thus, researchers have been studying ways to improve the effectiveness of this phototherapy and expand it for the treatment of the deepest cancers, by using chemiluminescent or bioluminescent formulations to excite the photosensitizer by intracellular generation of light. The aim of this Minireview is to give a precis of the most important general chemi-/bioluminescence mechanisms and to analyze several studies that apply them for PDT. These studies have demonstrated the potential of utilizing chemi-/bioluminescence as excitation source in the PDT of cancer, besides combining new approaches to overcome the limitations of this mode of treatment.

Abstract In the original article[1] there is an error in the structure of compound 3j (the methyl group should be attached to the β-position and not to the α-position) and in some NMR resonances; also the name of compound 3g and two of its NMR assignments are erroneous. Correct versions are given below in Scheme 1, Figure 2, and the two related paragraphs of the Exp. Sect. An amended file of the Supporting Information is also available. (Figure presented.) © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Abstract Gas-phase electronic and structural properties of the room temperature ionic liquid 1-ethyl-3-methylimidazolium tris(perfluoroethyl) trifluorophosphate ([EMIM][FAP]) were studied using density functional theory, and confirmed with results from infrared spectroscopy. A conformational analysis allowed the identification of several plausible conformers of the ion pairs. For the detected conformers, the infrared spectra were predicted and their thermodynamic properties were evaluated. The topology of the electronic density of the most stable conformers of [EMIM][FAP] ion pairs were characterised using the quantum theory of atoms in molecules. A number of possible hydrogen bonds between the cations and anions of the ionic liquid were identified. Excellent correspondence was found between the predicted spectra of gas-phase [EMIM][FAP] conformers and the experimental infrared spectrum, which in turn allowed a clear attribution of the vibration modes of [EMIM][FAP]. Finally, the contribution of the various conformers of both isomers of the [FAP](-) anion to the ionic liquid macro-properties is shown.

Abstract Highly and stable fluorescent carbon dots (CQDs), with lambda(ex)/lambda(em) = 350/465 nm were obtained using a strong acid oxidation of activated carbon in aqueous suspension. The nanoparticles had a mean size of 12 nm and quantum yield of 3.94%. After functionalization with amine groups by PAMAM-NH2 dendrimer (CQDs@PAMAM-NH2), the size of particles increased and aggregates of 65 nm were formed. Quantum yield also increased to 6.33%. CQDs were characterized by various analytical techniques including ATR-FTIR, Raman, XPS and fluorescence spectroscopies. The prepared CQDs@PAMAM-NH2 were used as fluorescent ratiometric nanosensor of 4-chloro-2,6-dinitroaniline, which is a constituent of explosives. As a result of interactions, the fluorescence at 465 nm was quenched. Moreover, a new band at 507 nm emerged and it is linked to a charge transfer and the formation of a Meisenheimer complex. A ratio of fluorescence intensities at 465 and 507 nm (I-465/I-507) is used for a ratiometric fluorescence sensing. A linear detection ranges from 1.0 x 10(-5) to 6.0 x 10(-4) M with a detection limit of 2 mu M and accuracy of 0.85% as standard relative deviation (RSD, n = 10). The detection accuracy in the presence of other nitrocompounds was 2.80% as RSD.

Abstract In this work, we combined various parameters found in the literature for the choline cation, chloride anion, and ethylene glycol to set up force field models (FFMs) for a eutectic mixture, namely, ethaline (1:2 choline chloride/ethylene glycol (ChCl:2EG)). The validation of these models was carried out on the basis of physical and chemical properties, such as the density, expansion coefficient, enthalpy of vaporization, self-diffusion coefficients, isothermal compressibility, surface tension, and shear viscosity. After the initial evaluation of the FFMs, a refinement was found necessary and accomplished by taking into account polarization effects in a mean-field manner. This was achieved by rescaling the electrostatic charges of the ions based on partial charges derived from ab initio molecular dynamics (MD) simulations of the bulk system. Classical all-atom MD simulations performed over a large range of temperatures (298.15-373.15 K) using the refined FFMs clearly showed improved results, allowing a better prediction of experimental properties. Specific structural properties (radial distribution functions and hydrogen bonding) were then analyzed in order to support the adequacy of the proposed refinement. The final selected FFM leads to excellent agreement between simulated and experimental data on dynamic and structural properties. Moreover, compared to the previously reported force field model (Perkins, S. L.; Painter, P.; Colina, C. M. Experimental and Computational Studies of Choline Chloride-Based Deep Eutectic Solvents. J. Chem. Eng. Data 2014, 59, 3652-3662), a 10% improvement in simulated transport properties, i.e., self-diffusion coefficients, was achieved. The isothermal compressibility, surface tension, and shear viscosity for ethaline are accessed in MD simulations for the first time.

Abstract Cadmium-based quantum dots (QDs) are increasingly applied in existent and emerging technologies, especially in biological applications due to their exceptional photophysical and functionalization properties. However, they are very toxic compounds due to the high reactive and toxic cadmium core. The present study aimed to determine the toxicity of three different QDs (CdS 380, CdS 480 and CdSeS/ZnS) before and after the exposure of suspensions to sunlight, in order to assess the effect of environmentally relevant irradiation levels in their toxicity, which will act after their release to the environment. Therefore, a battery of ecotoxicological tests was performed with organisms that cover different functional and trophic levels, such as Vibrio fischeri, Raphidocelis subcapitata, Chlorella vulgaris and Daphnia magna. The results showed that core-shell type QDs showed lower toxic effects to V. fischeri in comparison to core type QDs before sunlight exposure. However, after sunlight exposure, there was a decrease of CdS 380 and CdS 480 QD toxicity to bacterium. Also, after sunlight exposure, an effective decrease of CdSeS/ZnS and CdS 480 toxicity for D. magna and R. subcapitata, and an evident increase in CdS 380 QD toxicity, at least for D. magna, were observed. The results of this study suggest that sunlight exposure has an effect in the aggregation and precipitation reactions of larger QDs, causing the degradation of functional groups and formation of larger bulks which may be less prone to photo-oxidation due to their diminished surface area. The same aggregation behaviour after sunlight exposure was observed for bare QDs. These results further emphasize that the shell of QDs seems to make them less harmful to aquatic biota, both under standard environmental conditions and after the exposure to a relevant abiotic factor like sunlight.

Abstract In the past few years a large effort is being made aiming at the development of fast and reliable tests for cancer biomarkers. Protein imprinted sensors can be a fast and reliable strategy to develop tailor made sensors for a large number of relevant molecules. This work aims to produce, optimize and use in biological samples a biosensor for microseminoproteinbeta (MSMB). Caffeic acid (CAF) electropolimerization was performed in the presence of microseminoprotein-beta (MSMB) creating target protein specific cavities on the surface of a screen-printed carbon. Dopamine was introduced as charged monomer labelling the binding site and was allowed to self-organize around the protein. The subsequent electropolimerization was made by applying a constant potential of +2.0 V, for 30s, on a carbon screen-printed electrode, immersed in a solution of protein and CAF prepared in phosphate buffer. The sensor with charged monomers showed a more sensitive response, with an average slope of -7.59 mu A/decade, linear concentration range of 0.5-100 ng/mL and a detection limit of 0.12 ng/mL. The corresponding non-imprinted sensor displayed an inconsistent response over the range of the calibration curve. The biosensor was successfully applied to the analysis of MSMB in serum and urine samples.