Publicaciones 2011-2020

@article{orellana2017palmitic,
title = {Palmitic Acid and Hexadecylamine Molecules Assdsorbed on Titania Surface in Hybrid Composites. Effect of Surfactants Using Density Functional Theory},
author = { C. Orellana and F. Mendizabal and G. Gonz\'{a}lez and S. Miranda-Rojas and L. Barrientos-Poblete},
url = {/brokenurl#<Go to ISI>://WOS:000401679900007},
doi = {10.1016/j.comptc.2017.04.006},
issn = {2210-271x},
year = {2017},
date = {2017-01-01},
journal = {Computational and Theoretical Chemistry},
volume = {1110},
pages = {50-59},
publisher = {2017 Elsevier B.V.},
abstract = {A complete theoretical characterization of the factors involved in the stabilization of hybrid laminar composites is reported, with the purpose of understanding the main interactions involved in the formation of these types of systems. The models were built using two different surfactants: hexadecylamine (HDA) and palmitic acid (PAc), on a cluster of titania (TiO2) which represents its anatase crystalline phase. We explored the relevance of the titania-surfactant and surfactant-surfactant interactions, and of the protonation state of the palmitic acid in the stabilization of the hybrid laminar composites. The results were rationalized using energy decomposition analysis (EDA) and the non-covalent interaction index (NIC). The interaction energies between HDA and the TiO2 surface without the contribution of the dispersion forces were -25 kcal/mol and -29 kcal/mol for the (1 0 0) and (1 01) surfaces, respectively. These results suggest the formation of a donor-acceptor bond between HDA-TiO2 allowing its stabilization. On the other hand, the interaction energy between PAc and the TiO2 (1 0 1) surface was about -45 kcal/mol without the dispersion term. Thus, the PAc-TiO2 model has a higher covalent character than the HDA-TiO2 interaction, as confirmed by the energy decomposition analyses. The results suggest new hybrid laminar composites which are better when carboxylic acid was used instead of amines. Therefore, the use of surfactants with the carboxyl functional group yielded more stable TiO2 hybrid composites. The interaction energy between surfactant chains was about -13 kcal/mol, confirming the importance of dispersion forces in the stabilization of these types of systems. The study of systems with palmitic acid was complemented by building some anionic models to show the importance of acid protons in those systems. However, when the acidic hydrogens were removed, the interaction energy between the PAc molecules considering the dispersion correction increased to 45 kcal/mol, with a highly repulsive character. These results suggest that the acid hydrogens of the PAc surfactants play a fundamental role in terms of correctly representing the carboxylic acid-TiO2 interface and the stabilization of the laminar hybrid composites.},
keywords = {basis-sets, bsse, calculations, catalysis, clusters, compounds, dft dft, dioxide dispersion enzymatic hexadecylamine, hydrogen-bonds, interactions, laminar n-body noncovalent palmitic photocatalysis properties, sensitized solar-cells, spectroscopic strong term, tio2, titanium},
pubstate = {published},
tppubtype = {article}
}

@article{RN306,
title = {Theoretical Exploration of Seleno and Tellurophenols as Promising Alternatives to Sulfur Ligands for Anchoring to Gold (111) Materials},
author = { S. Miranda-Rojas and R. Salazar-Molina and J. Kastner and R. Arratia-Perez and F. Mendizabal},
url = {/brokenurl#<Go to ISI>://WOS:000369510500023},
doi = {10.1039/c5ra21964g},
issn = {2046-2069},
year = {2016},
date = {2016-01-01},
journal = {Rsc Advances},
volume = {6},
number = {6},
pages = {4458-4468},
abstract = {It is widely known that sulfur ligands, such as alkanethiols or phenothiols and their derivatives, are useful anchor systems for gold materials due to the high affinity of sulfur to gold surfaces. In this study we use DFT calculations and a 42-atom gold cluster model to study the interaction between selenophenol and tellurophenol-derivatives with the Au(111) surface to gain information towards potential new gold-based materials. We modulated the interaction strength by controlling the charge transfer process of a particular interaction by chemically modifying the ligands. To obtain a complete analysis, we studied the ligands in their protonated, anionic and radical states aiming to cover the three possibilities in which these may interact with the gold cluster. In order to get a deeper insight into the nature of the interaction we used several analysis techniques such as energy decomposition analysis (EDA), non-covalent interactions (NCI) and natural population analysis (NPA). Our results reveal that tellurium in the anionic state provides complexes of better thermodynamic stability by similar to 12.0 kcal mol, when compared with the strongest sulfur-gold complex, also in the anionic state. Furthermore, this indicates that the anionic ligand is probably the dominant state for both selenium and tellurium as observed previously for sulfur. The extent to which the interaction strength could be controlled directly depends on the state of the anchor atom. In our case the anionic state is the most suitable for tuning the interaction. Finally, our main findings suggest that exchanging sulfur with selenium or tellurium involves an important increase of the interaction strength, thus, making these selenophenol and tellurophenol derivatives attractive for the development of new functional materials.},
keywords = {basis-sets, chain-length, charge-transfer, chemistry, complexes, interface, monolayers, nanoparticles, pseudopotentials, self-assembled tellurium titanium},
pubstate = {published},
tppubtype = {article}
}

@article{RN305,
title = {Calculations of the Light Absorption Spectra of Porphyrinoid Chromophores for Dye-Sensitized Solar Cells},
author = { R. Mera-Adasme and W.H. Xu and D. Sundholm and F. Mendizabal},
url = {/brokenurl#<Go to ISI>://WOS:000385180600020},
doi = {10.1039/c6cp04627d},
issn = {1463-9076},
year = {2016},
date = {2016-01-01},
journal = {Physical Chemistry Chemical Physics},
volume = {18},
number = {40},
pages = {27877-27884},
abstract = {Solar power is a strong alternative to the currently used fossil fuels in order to satisfy the world's energy needs. Among them, dye-sensitized solar cells (DSSC) represent a low-cost option. Efficient and cheap dyes are currently needed to make DSSCs competitive. Computational chemistry can be used to guide the design of new light-absorbing chromophores. Here, we have computationally studied the lowest excited states of ZnPBAT, which is a recently synthesized porphyrinoid chromophore with high light-absorption efficiency. The calculations have been performed at ab initio correlated levels of theory employing second-order coupled clusters (CC2) and algebraic diagrammatic construction using second order (ADC(2)) methods and by performing density functional theory (DFT) calculations using the time-dependent DFT (TDDFT) approach for excitation energies. The ultraviolet-visible (UV-vis) spectrum calculated at the ADC(2) and CC2 levels agrees well with the experimental one. The calculations show that ZnPBAT has six electronic transitions in the visible range of the absorption spectrum. The ab initio correlated calculations and previously reported experimental data have been used to assess the performance of several well-known density functionals that have been employed in the present TDDFT study. Solvent effects have been estimated by using the conductor-like screening model (COSMO). The influence of the addition of a TiO2 cluster to the chromophore systems has also been investigated. The results indicate that both CAM-B3LYP and Becke's "half-and-half'' (BHLYP) density functionals are appropriate for the studies of excitation energies in the blue range of the visible spectrum for these kinds of porphyrinoid chromophores, whereas the excitation energies of the Q band calculated at the ab initio correlated level are more accurate than those obtained in the present TDDFT calculations. The inclusion of solvent effects has a modest influence on the spectrum of the protonated form of the studied chromophores, whereas solvent models are crucial when studying the absorption spectrum of the anionic chromophore. The calculated UV-vis spectrum for the chromophore anion is not significantly affected by attaching a TiO2 cluster to it.},
keywords = {adsorption, approximation, basis-sets, correlation-energy, dft, efficiency hartree-fock, model, organic-dyes, performance, screening},
pubstate = {published},
tppubtype = {article}
}

@article{RN141,
title = {Theoretical Insights into the Adsorption of Neutral, Radical and Anionic Thiophenols on Gold(111)},
author = { S. Miranda-Rojas and A. Munoz-Castro and R. Arratia-Perez and F. Mendizabal},
url = {/brokenurl#<Go to ISI>://WOS:000326747200048},
doi = {10.1039/c3cp53591f},
issn = {1463-9076},
year = {2013},
date = {2013-01-01},
journal = {Physical Chemistry Chemical Physics},
volume = {15},
number = {46},
pages = {20363-20370},
abstract = {The interaction of thiol and thiolate containing molecules with gold (S-Au) has gained increasing interest because of its applications in molecular electronic devices and catalysis. In this context, the enhanced conductivity of thiophenol compared to alkanethiol represents an opportunity to develop more sensitive and selective gold-based devices by incorporating molecules with the aryl-thiol moiety into their structures. As has been proposed earlier, the thiol moiety is deprotonated after binding to gold, hence, we present here a comparative study of the S-Au bond strength between several neutral and deprotonated aromatic-sulfur systems in their anionic and radical forms with a detailed description of the nature of this interaction. The study was performed by means of computational chemistry methods, using a cluster of 42 Au atoms as a model of the Au(111) surface that allowed us to provide new chemical insights to control the S-Au interface interaction strength. Our results revealed that the thiophenols-gold interaction is mainly dispersive where the interaction energies range between 31 and 43 kcal mol(-1). The radical and anionic thiophenolates-gold interaction increases due to a strong charge transfer character, depicting interaction energies in the range of 50 to 55 kcal mol(-1) and 62 to 92 kcal mol(-1), respectively. These results suggest that for the anionic thiophenolate the binding strength can be tailored according to the electron-donor capabilities of the ligand which in turn can be finely tuned by several substituents. Our results are of possible impact for the design of new devices.},
keywords = {basis-sets, chemisorption, complexes dft, electronic-structure, gold interface, metallic monolayers, nanoparticles, self-assembled surfaces},
pubstate = {published},
tppubtype = {article}
}

@article{RN34e,
title = {Nmr Assignment in Regioisomeric Hydroquinones},
author = { J.A. Dobado and J.C. Gomez-Tamayo and F.G. Calvo-Flores and H. Martinez-Garcia and W. Cardona and B. Weiss-Lopez and O. Ramirez-Rodriguez and H. Pessoa-Mahana and R. Araya-Maturana},
url = {/brokenurl#<Go to ISI>://WOS:000291114500009},
doi = {10.1002/mrc.2745},
issn = {0749-1581},
year = {2011},
date = {2011-01-01},
journal = {Magnetic Resonance in Chemistry},
volume = {49},
number = {6},
pages = {358-365},
publisher = {2011 John Wiley & Sons, Ltd.},
abstract = {A set of regioisomeric pairs of tricyclic hydroquinones, analogues of antitumor 9,10-dihydroxy-4,4-dimethyl-5,8dihydroanthracen- 1(4H)-one (1) and other derivatives, were synthesized and their regiochemistry and NMR spectra assigned by using 1H-detected one-bond(C-H) HMQC and long-range C-HHMBC, in good agreement with theoretical O3LYP/Alhrichs-pVTZ calculations. The 5-hydroxymethyl derivatives (11, 15, 19) showed a 3 integral H,H coupling constant of methylene protons evidencing the presence of a seven-membered intramolecular hydrogen bonded ring, not observed for the 8-hydroxymethyl isomers.},
keywords = {basis-sets, c-13 calculations, chemical-shifts, coupling-constants, derivatives, dft, diels-alder giao, h, h-1 hmbc, hmqc, hydroquinone, nmr, o3lyp, organic-molecules, reaction, respiration, sensitivity, spin theoretical tumor-cell},
pubstate = {published},
tppubtype = {article}
}