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Pingitore V.,University of Calabria | Gugliuzza A.,CNR Institute on Membrane Technology
Journal of Physical Chemistry C | Year: 2013

Semiconductor hybrid structures are achieved by interfacing single-walled carbon nanotubes (CNTs) with microstructured porous membranes. Interconnectivity and interplay of nanotubes are achieved by the assistance of adaptive polymers on 3D ordered honeycomb membranes. The buildup of semiconductor interfaces is based on the nanoassembly concept, which includes (a) self-assembly of sacrificial water droplets for tailoring 3D ordered polymeric platforms; (b) directed assembly of carbon nanotubes by sequential layer-by-layer (LBL) deposition; and (c) improvement of the electrical contact between nanotubes and stabilization of the organic-inorganic interface by pH-directed forces. Unprecedented better-quality charge-transfer pathways are achieved by making a large number of connections between nanotubes rather than increasing the adsorption of conductive inorganic materials onto the membrane platforms. Electrical current transfer is generated in hybrid interfaces, wherein fine conductivity function (σ 102 S/m) is associated with high-defined porous structure, through a rationalization of the role of intermolecular forces in the assembly process. © 2013 American Chemical Society.

Saielli G.,CNR Institute on Membrane Technology
Journal of Physical Chemistry A | Year: 2010

We have employed computational protocols to determine the differential solvation free energy in water of oxonium and ammonium ions. We have focused our analysis on pairs of onium ions having the same hydrocarbon content and substitutional pattern (HCSP pairs). In agreement with previous suggestions (Taft, R. W.; Wolf. J. F.; Beauchamp, J. L.; Scorrano, G.; Arnett, E. M. J. Am. Chem. Soc. 1978, 100, 1240), we found that cavitation and van der Waals terms do not contribute to the differential solvation free energy. Moreover, we observe that oxonium ions are more strongly solvated than the analogous ammonium ions even though the former ones have fewer H-bond donor sites. The performance of two different continuum solvation models, PCM and SMD, is discussed. © 2010 American Chemical Society.

Saielli G.,CNR Institute on Membrane Technology
Journal of Physical Chemistry B | Year: 2016

We present a fully atomistic molecular dynamics simulation of the smectic phase of the ionic liquid crystal (ILC) 1-hexadecyl-3-methylimidazolium nitrate, [C16MIm][NO3]. We have characterized the structure of the phase by means of a set of radial distribution functions resolved along the director and in the plane of the smectic layers. The results obtained allow us to discuss the similarities in the microscopic structure of ionic liquids (ILs) and ILCs. In addition to this, we have calculated the orientational order parameters, S, of the methylene groups of the alkyl chain and compared them with the results obtained for phospholipidic membranes from 2H NMR experiments. We also discuss the orientational order parameters of the imidazolium ring. Finally, we analyze the distribution of voids in the ILC phase. We have found that voids of considerable volume to host a nonpolar gas, e.g. xenon, are localized in the hydrophobic layers and almost absent in the ionic layers. © 2016 American Chemical Society.

We report on the thermal behaviour of a model system based on a coarse-grained force field (CG-FF) developed for ionic liquids here extended to the description of the ionic liquid crystal 1-hexadecyl-3-methylimidazolium nitrate. The phase diagram has been investigated as a function of the temperature in the NPT ensemble. We have identified three distinct phases, a crystal phase, the smectic A phase and the isotropic liquid phase. The various phases have been characterized by several pair distribution functions, density profiles and order parameters. A comparison is made with the experimental data available and suggestions on how to re-parameterise the CG-FF in order to achieve a better accuracy for the description of ionic mesophases are presented. On the other hand the results reported in this work demonstrate that the model potential is sufficiently accurate, at a qualitative level, to obtain useful insights into the relation between structural parameters, such as anion and cation core size, chain lengths and others, and the thermal range of stability of the ionic mesophases. © The Royal Society of Chemistry 2012.

Bagno A.,University of Padua | Saielli G.,CNR Institute on Membrane Technology
Chemistry - A European Journal | Year: 2012

Shift change: Relativistic ZORA DFT calculations highlight the various factors (solvent effect, spin-orbit coupling, number and type of metal centres) responsible of the extraordinarily large deshielding of xenon encapsulated in a metallated cryptophane (see figure). Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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