Publicaciones 2011-2020

@article{RN402,
title = {Influence of the Anion Nature and Alkyl Substituents in the Behavior of Ionic Liquids Derived from Phenylpyridines},
author = { P. Dreyse and D.A. Alarcon and A. Gald\'{a}mez and I. Gonz\'{a}lez and D. Cortes-Arriagada and F. Castillo and A. Mella},
url = {/brokenurl#<Go to ISI>://WOS:000418212000043},
doi = {10.1016/j.molstruc.2017.10.062},
issn = {0022-2860},
year = {2018},
date = {2018-01-01},
journal = {Journal of Molecular Structure},
volume = {1154},
pages = {382-391},
publisher = {2017 Elsevier B.V.},
abstract = {Quaternary alkyl 2-phenylpyridinium and 2-(2,4-difluorophenyl)pyridinium amines with iodide, hexafluorophosphate and bis(trifluoromethylsulfonyl)imide anions have been fully characterized by H-1 NMR, FT-IR and MALDI mass spectroscopic methods and studied by quantum chemistry calculations. The compounds with bis(trifluoromethylsulfonyl)imide anion can be classified as ionic liquids, because they melt at room temperature. The quaternary amines with iodide and hexafluorophosphate anions are solid at 25 degrees C. The X-ray diffraction characterization of the 2-(2,4-difiuorophenyl)-1-methylphenylpyridinium hexafluorophosphate and 1-ethyl-2-(2,4-difluorophenyl)phenylpyridinium hexafluorophosphate show an extensive series of C-H center dot center dot center dot F, C-F center dot center dot center dot pi and P-F center dot center dot center dot pi it intermolecular interactions, which give rise to a supramolecular network. The relationship between the solid-state structures and the melting points is discussed by the evaluation of the thermal behavior based on experimental data from Differential Scanning Calorimetry (DSC) studies, and also using the analysis of the ion pairs binding energies. These new compounds based on phenylpyridine allow us to grow the diversity of ionic liquids and their crystalline salts, increasing the knowledge about the chemical and physical properties of these ionic species.},
keywords = {binding compounds, crystal design electrochemical-cells, emitting energies, gold ion ionic liquids, nanoparticles, pairs phenylpyridiniums, salts, solvents, structure, temperature, transition, transport, water},
pubstate = {published},
tppubtype = {article}
}

@article{RN421,
title = {Solvent Effect on a Model Snar Reaction in Ionic Liquid/Water Mixtures at Different Compositions},
author = { B. Sanchez and C. Calderon and C. Garrido and R. Contreras and P.R. Campodonico},
url = {/brokenurl#<Go to ISI>://WOS:000435298100034},
doi = {10.1039/c7nj04820c},
issn = {1144-0546},
year = {2018},
date = {2018-01-01},
journal = {New Journal of Chemistry},
volume = {42},
number = {12},
pages = {9645-9650},
abstract = {The reaction of phenyl 2,4,6-trinitrophenyl ether and piperidine was kinetically evaluated in BMIMBF4/water mixtures as the reaction media. This study shows the dramatic effect of the mixture composition on the reacting pair and its reaction rate, highlighting two strongly demarcated zones. The first one, rich in water, is characterized by strong variations in the rate coefficient values, suggesting the presence of preferential solvent effects in the aqueous phase. The second zone shows high rate coefficient values independent of the composition of the solvent mixture, suggesting predominant anion solvent effects. These results were validated using fluorescence spectroscopy and the Kamlet-Taft parameter.},
keywords = {aromatic binary-mixtures, catalysis, kinetics liquids, mixed-solvents, molecules, nitro-group, nucleophilic-substitution, preferential solvation, water},
pubstate = {published},
tppubtype = {article}
}

@article{RN406,
title = {Synthesis and Characterization of Poly (Ionic Liquid) Derivatives of N -Alkyl Quaternized Poly(4-Vinylpyridine)},
author = { X. Briones and R.A. Tapia and P.R. Campodonico and M. Urz\'{u}a and A. Leiva and R. Contreras and J. Gonz\'{a}lez-Navarrete},
url = {/brokenurl#<Go to ISI>://WOS:000429499900008},
doi = {10.1016/j.reactfunctpolym.2018.01.003},
issn = {1381-5148},
year = {2018},
date = {2018-01-01},
journal = {Reactive & Functional Polymers},
volume = {124},
pages = {64-71},
abstract = {The main motivation of this work is to obtain poly (ionic liquids) (PILs) derived from poly (4-vinyl pyridine) of different hydrophobic character containing BF4-, PF6-, (CF3SO2)(2) N- and CF3SO3- as counterions. PILs were synthesized from N -alkyl quaternized poly(4-vinylpyridine) P-4VP(+) -CnBr- with different alkyl chain length},
keywords = {bromide, carbon, chromium chromium, composite, liquid), liquid)s, removal, retention, salts, separation, water},
pubstate = {published},
tppubtype = {article}
}

@article{RN325,
title = {Composition Effect on the Aggregate/Solution Interface of a Nematic Lyotropic Liquid Crystal},
author = { A. Ruiz-Fernandez and J.J. Lopez-Cascales and J.J. Giner-Casares and R. Araya-Maturana and F.G. Diaz-Banose and B. Weiss-Lopez},
url = {/brokenurl#<Go to ISI>://WOS:000384139000097},
doi = {10.1039/c6ra13597h},
issn = {2046-2069},
year = {2016},
date = {2016-01-01},
journal = {Rsc Advances},
volume = {6},
number = {88},
pages = {85411-85419},
abstract = {Lyotropic nematic liquid crystals (lnlc) have attracted attention due to their resemblance to natural membranes and several technological applications. The effect of tetradecyltrimethyl ammonium chloride (TTAC) in the viscosity of a new lnlc containing also decanol, NaCl and natural lipids, was studied. In this article we study how the concentration of phospholipids, decanol and NaCl affects the bilayer and the liquid crystal/solution interface structures. H-2-NMR quadrupole splittings and longitudinal relaxation times of several deuterated species were measured. Polarized light microscopy, transmission electron microscopy and kinematic viscosity measurements were also obtained. The structure of the bilayer is dominated by the surface charge density of TTAC. Water rotation, translation and ion solvation depend on the charge and distance from the interface. With increasing TTAC, MD predicts hydrocarbon chain inter-digitation and lipid rafts formation. This was rationalized using energy arguments.},
keywords = {aqueous-solutions, chloride-ions, coefficients, diffraction ewald, free-energy, lipid-bilayers, mesh molecular-dynamics, particle self-diffusion simulation, water},
pubstate = {published},
tppubtype = {article}
}

@article{RN175,
title = {Rotating Disk Sorptive Extraction of Cu-Bisdiethyldithiocarbamate Complex from Water and Its Application to Solid Phase Spectrophotometric Quantification},
author = { C. Munoz and M.I. Toral and I. Ahumada and P. Richter},
url = {/brokenurl#<Go to ISI>://WOS:000336512600013},
issn = {0910-6340},
year = {2014},
date = {2014-01-01},
journal = {Analytical Sciences},
volume = {30},
number = {5},
pages = {613-617},
abstract = {This study demonstrates the first use of polydimethylsiloxane (PDMS) immobilized on a rotating disk for the extraction of copper from aqueous matrices and its subsequent direct determination by solid phase UV-Visible spectrophotometry. To accomplish the solid-phase extraction and the direct solvent-free spectrophotometric measurement, sodium diethyldithiocarbamate (NaDDTC) was used as an analytical reagent to form the uncharged chromophore complex Cu(DDTC)(2), which absorbs at 432 nm. Different physicochemical conditions (pH, temperature, reagent concentration, chemical modifiers) and hydrodynamic factors (rotation velocity, extraction time, sample volume) were optimized. Under the optimized conditions, extraction equilibrium times of 30, 53 and 90 min were obtained for 100, 500 and 1000 mL of sample, respectively, with preconcentration factors of 286, 712 and 1284, respectively. The methodology was precise (repeatability and reproducibility of 7.2 and 8.4%, respectively, as relative standard deviation) and accurate (recovery of 96.7%) when analyzing a multielement certified reference standard. The latter study also confirmed the high selectivity of the extraction and determination of the copper chromophore over other metal ions. The obtained limits of detection and quantification reached values lower than 12 mu g L-1, which can be reduced further by increasing the sample volume. Accuracy was also assessed using both recovery tests on drinking water matrices (95.5% recovery) and comparison with results obtained by an independent method using inductively coupled plasma-optical emission spectroscopy (ICP-OES); no significant differences were observed.},
keywords = {copper copper, disk extraction, methodology, optimization, phase rotating samples, solid solvent solvent-free sorptive spectrophotometry, water},
pubstate = {published},
tppubtype = {article}
}

@article{RN117,
title = {Lichens: Might Be Considered as a Source of Gastroprotective Molecules?},
author = { B. Sepulveda and M.C. Chamy and M. Piovano and C. Areche},
url = {/brokenurl#<Go to ISI>://WOS:000331237700024},
issn = {0717-9707},
year = {2013},
date = {2013-01-01},
journal = {Journal of the Chilean Chemical Society},
volume = {58},
number = {2},
pages = {1750-1752},
abstract = {Lichens are symbiotic relationship between fungi and algae or cyanobacteria. Secondary metabolites from lichens are known as lichen substances. We investigated depsidone and depside from lichens 1-6 in the context of their action to prevent gastric ulcer on the model of HCl/ethanol in mice for the first time. Doses of 30 mg/kg of lichen substances 1-6 and positive control (lansoprazole) significantly diminished the lesion index compared with negative control (treated only with HCl/EtOH). Lobaric acid 1, atranorin 2 and psoromic acid 5 reduced the gastric lesions by 76%, 63% and 65%, while for variolaric acid 3, diffractaic acid 4 and perlatolic acid 6 their values were 32%, 14% and 45%, respectively. Our results suggest that lichens have potential as a suite of gastroprotective molecules.},
keywords = {chilean damage, depside, depsidone, extract, gastric indomethacin, lichens, mucosal neutrophil-infiltration, oxidative rats stress, ulcer, water},
pubstate = {published},
tppubtype = {article}
}

@article{RN110,
title = {Determination of Crystal Violet in Water by Direct Solid Phase Spectrophotometry after Rotating Disk Sorptive Extraction},
author = { V. Manzo and O. Navarro and L. Honda and K. Sanchez and M.I. Toral and P. Richter},
url = {/brokenurl#<Go to ISI>://WOS:000319088600045},
doi = {10.1016/j.talanta.2012.11.004},
issn = {0039-9140},
year = {2013},
date = {2013-01-01},
journal = {Talanta},
volume = {106},
pages = {305-308},
publisher = {2012 Elsevier B.V.},
abstract = {The microextraction of crystal violet (CV) from water samples into polydimethylsiloxane (PDMS) using the rotating disk sorptive extraction (RDSE) technique was performed. The extracting device was a small Teflon disk that had an embedded miniature magnetic stirring bar and a PDMS (560 mu L) film attached to one side of the disk using double-sided tape. The extraction involves a preconcentration of CV into the PDMS, where the analyte is then directly quantified using solid phase spectrophotometry at 600 nm. Different chemical and extraction device-related variables were studied to achieve the best sensitivity for the determination. The optimum extraction was performed at pH 14 because under this condition, CV is transformed to the neutral and colorless species carbinol, which can be quantitatively transferred to the PDMS phase. Although the colorless species is the chemical form extracted in the PDMS, an intense violet coloration appeared in the phase because the -OH bond in the carbinol molecule is weakened through the formation of hydrogen bonds with the oxygen atoms of the PDMS, allowing the resonance between the three benzene rings to compensate for the charge deficit on the central carbon atom of the molecule., The accuracy and precision of the method were evaluated in river water samples spiked with 10 and 30 mu gL(-1) of CV, yielding a relative standard deviation of 6.2% and 8.4% and a recovery of 98.4% and 99.4%, respectively. The method detection limit was 1.8 mu gL(-1) and the limit of quantification was 5.4 mu gL(-1), which can be decreased if the sample volume is increased.},
keywords = {aqueous chromatography-mass-spectrometry, crystal disk extraction, green, malachite microextraction, polydimethylsiloxane, rotating samples samples, sorptive thin-film violet, water},
pubstate = {published},
tppubtype = {article}
}

@article{RN155,
title = {Effect of Lithium on the Properties of a Liquid Crystal Formed by Sodium Dodecylsulphate and Decanol in Aqueous Solution},
author = { V.E. Bahamonde-Padilla and J. Espinoza and B. Weiss-Lopez and J.J.L. Cascales and R. Montecinos and R. Araya-Maturana},
url = {/brokenurl#<Go to ISI>://WOS:000321716400032},
doi = {10.1063/1.4811678},
issn = {0021-9606},
year = {2013},
date = {2013-01-01},
journal = {Journal of Chemical Physics},
volume = {139},
number = {1},
publisher = {2013 AIP Publishing LLC.},
abstract = {Understanding the molecular interactions that rule the physicochemical properties of molecular assemblies is of particular interest when trying to explain the behavior of much more complicated systems, such as the cell membranes. This work was devoted to study a discotic nematic lyotropic liquid crystal, formed by sodium dodecylsulphate (3% SDS-d(25)) and decanol (20% DeOH-alpha-d(2)), dissolved in aqueous solutions (0.1% D2O) of Na2SO4 or Li2SO4. The average size of the aggregates was estimated using fluorescence quenching experiments, and their dynamics were studied by measuring the H-2-NMR quadrupole splitting (Delta nu(Q)) and the longitudinal relaxation times (T-1) of the deuterated species. To provide an atomic insight into these assemblies, molecular dynamics simulations of the systems were carried out with atomic detail. As a previous step in this study, a reparameterization of the standard GROMOS 87 force field was required to perform the equilibrated simulations and to prevent instabilities emerging during the simulations. Finally, an excellent agreement between simulation and experimental data was obtained. In addition, variations in the long range electrostatic interactions at the aggregate/solution interface, the orientation and the re-orientational relaxation time of the water dipole, the translational diffusion coefficient of sodium ions, and the amphiphile-counterion coordination associated with the presence of Li+ in the solution were other keywords aspects investigated to explain the variation in the quadrupole splittings (Delta nu(Q)) in the presence of lithium in solution.},
keywords = {ewald, membrane, mesh micelle, molecular-dynamics number, particle phase, simulation, state systems, water},
pubstate = {published},
tppubtype = {article}
}

@article{sotodelgado2012catalytic,
title = {On the Catalytic Effect of Water in the Intramolecular Diels-Alder Reaction of Quinone Systems: A Theoretical Study},
author = { J. Soto-Delgado and A. Aizman and R. Contreras and L.R. Domingo},
url = {/brokenurl#<Go to ISI>://WOS:000311428400087},
doi = {10.3390/molecules171113687},
issn = {1420-3049},
year = {2012},
date = {2012-01-01},
journal = {Molecules},
volume = {17},
number = {11},
pages = {13687-13703},
abstract = {The mechanism of the intramolecular Diels-Alder (IMDA) reaction of benzoquinone 1, in the absence and in the presence of three water molecules, 1w, has been studied by means of density functional theory (DFT) methods, using the M05-2X and B3LYP functionals for exploration of the potential energy surface (PES). The energy and geometrical results obtained are complemented with a population analysis using the NBO method, and an analysis based on the global, local and group electrophilicity and nucleophilicity indices. Both implicit and explicit solvation emphasize the increase of the polarity of the reaction and the reduction of activation free energies associated with the transition states (TSs) of this IMDA process. These results are reinforced by the analysis of the reactivity indices derived from the conceptual DFT, which show that the increase of the electrophilicity of the quinone framework by the hydrogen-bond formation correctly explains the high polar character of this intramolecular process. Large polarization at the TSs promoted by hydrogen-bonds and implicit solvation by water together with a high electrophilicity-nucleophilicity difference consistently explains the catalytic effects of water molecules.},
keywords = {catalysis, characterization, chemistry density dft dft, diels-alder difference electrophilicity, functionals, index, indices, intramolecular local molecules, polar quantitative reactions, reactivity regioselectivity, solvent, thermochemistry, water},
pubstate = {published},
tppubtype = {article}
}

@article{RN21,
title = {Ferrospectral Sorbed on Deae Sephadex a-25 for the Solid Phase Spectrophotometric Determination of Iron and Cobalt by Batch and Continuous Flow Modes},
author = { M.I. Toral and G. Sanchez and P. Fernandez and P. Pizarro and V. Moncada and J. Rivas and P. Richter},
url = {/brokenurl#<Go to ISI>://WOS:000293676300013},
doi = {10.4067/S0717-97072011000200013},
issn = {0717-9324},
year = {2011},
date = {2011-01-01},
journal = {Journal of the Chilean Chemical Society},
volume = {56},
number = {2},
pages = {682-687},
abstract = {In this work, Ferrospectral;3-(2-pyridyl)-5,6-bis(4-phenylsulfonic acid)-1,2,4-triazine (FST) sorbed on DEAE Sephadex A-25 is used as solid phase for spectrophotometric determination of iron and cobalt by batch and continuos flow modes. In batch simultaneous determination, the second derivative at 536.0 and 601.4 nm were used for iron and cobalt determination, respectively. In this modality, the detection limits (3 sigma criterion), for iron and cobalt were 1.3, 9.1, mu g L(-1) and the determination ranges were: 4.3 to 220 and 30.3 to 800 mu g L(-1). The method by FIA mode was carried out by stopped flow and then the analytical signal was evaluated by second derivative at 560.9 and 482.3 nm for iron and cobalt determination; respectively. In FIA modality, the detection limits for iron and cobalt were 6.4, 31 mu g L(-1), and the determination ranges 21 to 200 and 106 to 1000 mu g L(-1) iron and cobalt, respectively. In both modalities the repeatability for iron and cobalt were <4% and the recovery was near to 100%. These methods were applied successfully in drinking water and soil samples.},
keywords = {continuous determination, determinations, electrode, elements extraction, fe food heavy-metal ions, mixtures, phase samples, sephadex solid spectrometric spectrometry, stripping voltammetry, water},
pubstate = {published},
tppubtype = {article}
}

@article{RN17e,
title = {The Development of a Fluorescence Turn-on Sensor for Cysteine, Glutathione and Other Biothiols. A Kinetic Study},
author = { O. Garcia-Beltran and N. Mena and E.G. Perez and B.K. Cassels and M. Nunez and F. Werlinger and D. Zavala and M.E. Aliaga and P. Pavez},
url = {/brokenurl#<Go to ISI>://WOS:000297442400022},
doi = {10.1016/j.tetlet.2011.09.137},
issn = {0040-4039},
year = {2011},
date = {2011-01-01},
journal = {Tetrahedron Letters},
volume = {52},
number = {49},
pages = {6606-6609},
publisher = {2011 Elsevier Ltd.},
abstract = {Two fluorescence probes for the detection of cysteine (Cys), glutathione (GSH) and other biothiols, such as homocysteine (Hcy) and cysteinyl-glycine (Cys-Gly), were developed. These molecular probes are coumarin-based derivatives containing a chalcone-like moiety that reacts with biothiols through a Michael addition reaction, leading to strong fluorescence enhancements. The reactivity of the tested biothiols toward both probes (ChC1 and ChC2) follows the order Cys > GSH > Hcy > Cys-Gly, ChC1 being less reactive than ChC2. Possible interference with other amino acids was assessed. ChC1 and ChC2 display a highly selective fluorescence enhancement with thiols, allowing these probes to be used for fluorimetric thiol determination in SH-SY5Y cells.},
keywords = {addition, biothiols, coumarin-based derivatives, disease, fluorescence homocysteine, michael probe, probes, thiols, water},
pubstate = {published},
tppubtype = {article}
}