On the chemical behavior of C60 hosting H2O and other isoelectronic neutral molecules

Abstract

The density functional theory (DFT) was used to investigate the chemical behavior of C60 hosting neutral guest molecules (NGM). The deformed atoms in molecules (DAM) allowed identifying the regions of electron density depletion and accumulation. The studied NGM are CH4, NH3, H2O, and HF. Based on dipole moment and polarizabilities analyses it is predicted that the NGM@C60 should be more soluble in polar solvents than C60. The deformations on the surface electron density of the fullerenes explain this finding, which might be relevant for further applications of these systems. It was found that the intrinsic reactivity of studied NGM@C60 is only moderately higher than that of C60. This trend is supported by the global reactivity indexes and the frontier orbitals analyses. The free radical scavenging activity of the studied systems, via single electron transfer, was found to be strongly dependent on the chemical nature of the reacting free radical. The presence of the studied NGM inside the C60 influences only to some extent the reactivity of C60 toward free radicals. The distortion of the electron density on the C60 cage, caused by the NGM, is directly related to the electron withdrawing capacity of the later.

The dipolar endofullerene HF@C60

“…The obtained dipole moment is in good agreement with some theoretical estimates 17,18,20 and indicates that shielding by the fullerene cage reduces the dipole moment of HF@C 60 to about 25% of that for isolated HF. 42 …”

“…Predictions of the properties of HF@C 60 have been made using classical, 14 semiempirical 15,16 and quantum chemistry techniques. [17][18][19][20] Furthermore it has been postulated that endofullerenes containing freely rotating electric dipoles could exhibit ferroelectricity, due to cooperative alignment of the interacting electric dipole moments. 21…”

Fully Coupled Quantum Treatment of Nanoconfined Systems: A Water Molecule inside a Fullerene C60

“…Although, such finding may indicate some sensitivity to the external to the fullerene molecular environment, the authors have concluded, 25 on the basis of NMR, FIR and UV/Vis spectroscopic analysis, that the H 2 O molecule is electrochemically stable under the hydrophophic environment inside C 60 . On the other hand, earlier and current electronic structure studies [33][34][35][36][37][38] indicate that the encaged H 2 O molecule is not chemically isolated, and there are significant noncovalent interactions within the cage, causing the elongation of the OH bonds, decrease in the HOH angle, offcenter location of the trapped water molecule, and a notable reduction of the dipole moment of the H 2 O molecule upon confinement in the C 60 cage.…”

DAMQT 2.0: A new version of the DAMQT package for the analysis of electron density in molecules

“…As starting point, we have carried out a DFT calculation with the PW81 functional and the 6 −311+G(d) basis set (1107 contractions), using the geometry reported in Ref. [23]. The corresponding files with geometry and basis set, c60-nh3.ggbs, and with density matrix, c60-nh3.den.gz, are included in the $DAMQT/samples/ Molpro/C60-NH3/ directory to facilitate replication.…”

“…To mention some recent applications, it has been used in the analysis of electron delocalization and reactivity [17], the rapid topography mapping of density and electrostatic potential [18,19], the investigation of molecular diseases [20], the interpretation of conformers properties in ionic liquids [21,22], and the study of electron distribution in C-60 hosting small molecules [23].…”