Publicaciones 2011-2020

@article{RN372,
title = {Experimental and Theoretical Reduction Potentials of Some Biologically Active Ortho-Carbonyl Para-Quinones},
author = { M. Martinez-Cifuentes and R. Salazar and O. Ramirez-Rodriguez and B. Weiss-Lopez and R. Araya-Maturana},
url = {/brokenurl#<Go to ISI>://WOS:000404517800075},
doi = {10.3390/molecules22040577},
issn = {1420-3049},
year = {2017},
date = {2017-01-01},
journal = {Molecules},
volume = {22},
number = {4},
abstract = {The rational design of quinones with specific redox properties is an issue of great interest because of their applications in pharmaceutical and material sciences. In this work, the electrochemical behavior of a series of four p-quinones was studied experimentally and theoretically. The first and second one-electron reduction potentials of the quinones were determined using cyclic voltammetry and correlated with those calculated by density functional theory (DFT) using three different functionals, BHandHLYP, M06-2x and PBE0. The differences among the experimental reduction potentials were explained in terms of structural effects on the stabilities of the formed species. DFT calculations accurately reproduced the first one-electron experimental reduction potentials with R-2 higher than 0.94. The BHandHLYP functional presented the best fit to the experimental values (R-2 = 0.957), followed by M06-2x (R-2 = 0.947) and PBE0 (R-2 = 0.942).},
keywords = {aprotic-solvents, aqueous-solution, batteries botrytis-cinerea, computational cyclic density density-functional electrochemistry, electron-transfer, functional ion models, p-benzoquinone, potential, properties, quinones, redox semiquinone, solvation theory, voltammetry},
pubstate = {published},
tppubtype = {article}
}

@article{RN213,
title = {Thermodynamics and (Hnmr)-H-2 Study on the Insertion of Small Quinones into a Discotic Nematic Lyotropic Liquid Crystal},
author = { V.E. Bahamonde-Padilla and J.J. Lopez-Cascales and R. Araya-Maturana and M. Martinez-Cifuentes and B. Weiss-Lopez},
url = {/brokenurl#<Go to ISI>://WOS:000335515900018},
doi = {10.1002/cphc.201301146},
issn = {1439-4235},
year = {2014},
date = {2014-01-01},
journal = {Chemphyschem},
volume = {15},
number = {7},
pages = {1422-1431},
abstract = {A detailed description of the distribution, interaction, and dynamics of molecules with biological activity dissolved in a hydrophobic bilayer, a simple model of a biological membrane, provides valuable information for a better understanding of drug functioning, which can be very useful in drug design. Here we present an H-2 NMR and molecular dynamics study on the insertion, distribution, interactions, and thermodynamics of two biologically active molecules, 9,10-dihydroxy-4,4-dimethyl-1,4,5,8-tetrahydroanthracen-1-one (HQ), with anticancer activity, and 4,4-dimethyl-1,4,5,8,9,10-hexahydroanthracen-1,9,10-trione (Q) a fungicide, dissolved in a nematic discotic lyotropic liquid crystal (ndllc) composed of sodium dodecylsulphate (SDS), decanol (DecOH) and Na2SO4 in water. H-2 NMR quadrupole splittings ((Q)) and longitudinal relaxation times (T-1) from HQ-d(6), Q-d(4), DecOH--d(2), partially deuterated water, and SDS-d(25) were measured and several molecular dynamics trajectories were also calculated. In particular, G, H, and S profiles for the process of both molecules crossing the bilayer were estimated. It was evidenced that the insertion of both molecules into the aggregate is a spontaneous process, and the molecules are mainly distributed in the internal side of the interface. Addition of HQ or Q decreased the mobility of all aggregate components, but this effect was more pronounced for HQ. The rotational correlation time of Q allowed an estimate of 5.3 cP for the microviscosity inside the ndllc aggregate, in the order of previously measured values in similar environments. Both guest molecules display similar free-energy profiles for the process of crossing the bilayer, with a calculated barrier height of 25 and 36 kJmol(-1) for HQ and Q, respectively.},
keywords = {aqueous-solution, crystals, derivatives, dynamics, ewald, force-field, free-energy, lipid-bilayer, liquid membrane, mesh micelle microviscosity, molecular molecular-dynamics nmr particle quinones, resonance, simulations, spectroscopy},
pubstate = {published},
tppubtype = {article}
}

@article{RN150,
title = {Cooperative Association of P-Alkylbenzene Sulfonates Sodium Salts to Poly-2-(Dimethylamino) Ethylmethacrylate-N-Alkyl Quaternized at the Water/Chloroform Interface},
author = { H. Rios and X. Briones and M. Urz\'{u}a and V. Vargas},
url = {/brokenurl#<Go to ISI>://WOS:000313621900008},
doi = {10.1080/00222348.2012.716334},
issn = {0022-2348},
year = {2013},
date = {2013-01-01},
journal = {Journal of Macromolecular Science Part B-Physics},
volume = {52},
number = {4},
pages = {614-622},
abstract = {The association of p-alkyl benzene sulfonate sodium salts with several poly-2-(dimethylamino) ethylmethacrylate-N-alkyl quaternized bromides at the water/chloroform interface was studied. High association percentages were found which increase with both the size of the sulfonate molecule and the length of the polyelectrolyte side chain: octyl, decyl, dodecyl and tetradecyl. The results fit well to the Hill's equation for the association of anionic surfactant to polyelectrolytes. Benzene sulfonate shows an anticooperative behavior for the association, whereas 4-methyl benzene sulfonate and 4-ethylbenzene sulfonate are increasingly cooperative for the association. From the association constants, the standard free energies of transfer from water to the interfacial polyelectrolytes were determined. Their values were a linear function of the number of carbon atoms of the aliphatic residue of the benzene sulfonate molecule ranging from -15.7 kJ/mol of CH2 groups for the octyl polyelectrolyte to -18.9 kJ/mol of CH2 groups for the tetradecyl derivative. These values are similar to those reported for the association of some of these sulfonates molecules with ammonium type cationic micelles. The results for the incremental free energy of transfer by mol of methylene group from water to micelles are in the same order of magnitude as those reported for p-alkyl phenoxides and p-alkylbenzoates to hexadecyltrimethyl ammonium bromide micelles. The results shows that amphipathic counterions as small as 4-ethylbenzenesulfonate are enough to induce a cooperative effect in their association to cationic polyelectrolytes.},
keywords = {aqueous-solution, association, binding, chloride chloroform-water cooperative counterions, dextran dodecyltrimethylammonium effects, hydrophobic interactions, interface, ions, micelles, polyelectrolyte polyelectrolytes, sulfate, sulfonate surfactant water},
pubstate = {published},
tppubtype = {article}
}