Cu n Clusters (n = 13, 43, and 55) as Possible Degradant Agents of mSF6 Molecules (m = 1, 2): A DFT Study.

In order to obtain the structural and electronic properties of pristine copper clusters and Cu13-SF6, Cu43-SF6, Cu55-SF6, Cu13-2SF6, Cu43-2SF6, and Cu55-2SF6 systems, DFT calculations were carried out. For Cu13-mSF6, its surface suffers a drastic deformation, and Cu43-mSF6 at its outer surface reveals strong interaction for the first chemical molecule; when the second molecule is interacting, these outer surfaces are not severely affected. These two cases degraded fully the first SF6 molecule; however the second molecule is bonded to the latter systems and for Cu55-mSF6 (m = 1 and 2) a structural transformation from SF6 →SF4 appears as well as inner and outer shells that display slight deformations. The electronic gaps do not exhibit drastic changes after adsorption of mSF6 molecules, and the magnetic moment remains without alterations. The whole system shows thermal and vibrational stability. In addition, for Cu13-mSF6 the values of the optical gap and intensity of the optical exhibit changes with respect to the pristine case (Cu13), and the rest of the systems do not exhibit major oscillations. These icosahedral copper clusters emerge as a good option to degrade mSF6 molecules.

In-silico study of the adsorption of H2, CO and CO2 chemical species on (TiO2)n n=15-20 clusters: The (TiO2)19 case as candidate promising.

In order to obtain an adsorption tendency of H2, CO and CO2 molecules on (TiO2)n n = 15-20 clusters, DFT calculations were carried out to evaluate the interaction among these systems. The (TiO2)19 cluster emerges as the best candidate to storage these chemical species. Then, two adsorption sites were considered to attach these molecules onto (TiO2)19 cluster: through of surface formed by i) titanium and ii) oxygen atoms, respectively. The adsorption energy values are more favored for case 1 than the case 2, due to short distances between titanium atom and these chemical species. In this sense, the larger values of chemisorption are related to great decreasing of values of vibrational modes for gases isolated respect to those bonded to bare cluster. In general, the values of electronic gap do not suffer drastic changes, however the HOMO iso-surfaces are displayed in different way for both cases, and LUMO is located at center of cluster for the whole set of systems analyzed in this study. The electronic transference occurs from chemical species toward atoms at adsorption site, in all systems. These results reveal that this (TiO2)19 cluster is good candidate to storage or sense different kind of gases; thereby, this system can be used as a hydrogen storage device for energy green applications.

Interactions of B12N12 fullerenes on graphene and boron nitride nanosheets: A DFT study.

In the search of nanomaterials to be used in drug delivery applications, Density Functional Theory calculations were implemented to study the interaction between graphene (G) and hexagonal boron nitride nanosheet (hBNN) with octahedral B12N12 fullerenes. These B12N12 fullerenes were considered in two cases: pristine and the modified one with boron-boron, nitrogen-nitrogen (tetragon) and boron-boron-boron (hexagon) homo-nuclear bonds. The whole systems were analyzed in the gas and aqueous phases. The results reveal for all these systems that the interaction is in the range of physisorption (Eads = from -0.03 to -0.37 eV) for both phases, limiting its functions as a vehicle. However, for the nano-composite: B12N12 fullerene modified and hBNNs, the values of average chemical reactivity and HOMO-LUMO gap decreased whereas the polarity was improved, thereby this combination of quantum descriptors lead them to be considered as potential vehicle for drug delivery.

Non-covalent functionalization of hexagonal boron nitride nanosheets with guanine.

Density functional theory (DFT) calculations were performed to analyze changes in the structural and electronic properties generated by the interaction of a single nucleobase group (guanine) with the surface of boron nitride nanosheets with hexagonal symmetry (hBNNs). Nanosheets in two contexts were tested: pristine sheets and with point defects (doped with carbon atoms). The criterion of energy minimum was used to find the ground state of the nine possible isomers generated by the hBNNs-guanine interaction. The phenomenon of physisorption is known to occur at values less than 1.0 eV; the adsorption energy results revealed that the preferential geometry was a parallel arrangement between the two partners, with van der Waals-type bonds generated for the hBNNs doped with two carbon atoms. This was the only energetically stable configuration, thus revealing a vibrational mode rather than imaginaries. Furthermore, the hBNNs/C-guanine system has a low value for work function, and therefore could be used in health applications such drug transport and delivery. The increased polarity values suggest that these nanosheets could be solubilized in common solvents used in experimental processes.