Theoretical prediction of maximum capacity of C80 and Si80 fullerenes for noble gas storage

Ngn (Ng= Ne, Ar, Kr, Xe, and Rn; n=1, 2) encapsulated porphyrin-like porous C24N24 fullerene: A quantum chemical study

This study focused on the theoretical viability of Ng_n@C₂₄N₂₄ (Ng = Ne, Ar, Kr, Xe, and Rn; n = 1, 2) complexes using density functional theory at the computational level of ωB97X-D/def2-TZVP. Thermodynamic and kinetic stabilities of these complexes have been evaluated by calculating the interaction energy of Ng atoms encapsulated C₂₄N₂₄ cage (ΔE_int), and the corresponding dissociation energy barrier (ΔG^‡), respectively. The obtained results predict that although these complexes are thermodynamically unstable compared to their dissociation into free Ng atoms and the bare C₂₄N₂₄ cage, but once formed, they are protected by the activation energy barrier of the corresponding dissociation process. Furthermore, natural population analysis (NPA) and topological analysis of the electron density have been employed to investigate the nature of Ng-Ng and Ng-cage interactions. The results demonstrate that these interactions are highly significant compared to similar cases in the free state; and the amounts of energy of the interaction gradually increases as the Ng atom becomes heavier. Surprisingly in the Kr₂@C₂₄N₂₄ complex the Kr-Kr bond is somewhat covalent in nature relative to non-bonded interaction in Kr₂ free dimer.

Unprecedented saturation limit achieved by inorganic polycationic cluster (Sb7Te8)5+ for light noble gases (He & Ne)

Among noble gases, Helium and Neon have smaller size, high ionization potential and low polarizability due to which these two gases exhibit weak binding affinities toward any surface. Bartlet's discovery and subsequent similar successful discoveries of stable complexes of noble gases opened new avenues for the storage of noble gases particularly on the new surfaces and their interactions for the storage of these gases. Here, we report the adsorption of light noble gases on polycationic clusters. Our current work not only investigates the interaction behavior of He and Ne with (Sb7Te8)⁵⁺ cluster but also explores the saturation limit of the cluster for He and Ne. Stability of various complexes of He and Ne with cationic surfaces is determined by the calculation of their interaction energies which reveal that the adsorption of single and multiple atoms of noble gases at faces of double cubic cluster is comparatively more favorable than at the bond lengths. Electronic properties such as HOMO-LUMO gaps show that complexes of He and Ne are more stable electronically than that of pure cluster, because HOMO-LUMO gap of complexes are higher than the bare polycationic cluster. NCI analysis of iso-surfaces and RDG maps confirms the presence of van der Waals forces between light noble gases and polycationic clusters. Saturation studies reveal that cluster can adsorb eleven He and/or ten Ne atoms with no or minimum distortion in the geometry of cluster. The results showed that Ne has greater tendency to interact with polycationic clusters due to the large electronic cloud and polarizability value than He.

Noble gas endohedral fullerenes

This review focuses on the available experimental and theoretical investigations on noble gas (Ng) endohedral fullerenes, addressing essential questions related to the mutual effects that confinement of one or more Ng atoms induces on the electronic structure, bonding, and different properties of fullerenes. It also summarizes the different contributions to the mechanisms of formation and decomplexation, the reactivity towards Diels-Alder cycloaddition reactions, the chemical bonding situation of Ng endohedral fullerenes, and the interactions that dominate within these systems.

Carbon and boron nanotubes as a template material for adsorption of 6-Thioguanine chemotherapeutic: a molecular dynamics and density functional approach

The interaction of 6-Thioguanine molecule, an antitumor drug with carbon nanotube and boron nitride nanotube (BNNT) is investigated using molecular dynamics simulations. Based on the obtained results, the strongest negative van der Waals interaction is found between 6-TG and BNNT among the studied nanotubes, which indicated BNNT is a better nanocarrier of the 6-TG drug than CNT within biological systems. Moreover, the adsorption and electronic properties of the 6-Thioguanine interacted with boron-nitride nanotube has been studied within the framework of density functional theory calculations. The negative binding energy values denote that there is the favorable interaction between 6-TG drug and BNNT at the studied 6-TG/BNNT complexes. Also, the amounts of the binding energies indicated that the 6-Thioguanine molecule physically interacts with the surface of BNNT. The values of electron densities and their Laplacian have been analyzed using the Bader's theory of atoms in molecules to characterize the nature of the intermolecular interactions through the topological parameters. We hope that the results of this work may provide useful information about the nature of the nanotube-drug molecule interactions and highlight the ability of these materials to be used as an adsorbent enhancing delivery of drug to cancer cells. Communicated by Ramaswamy H. Sarma.

Theoretical investigation of the use of nanocages with an adsorbed halogen atom as anode materials in metal-ion batteries

The applicability of C₄₄, B₂₂N₂₂, Ge₄₄, and Al₂₂P₂₂ nanocages, as well as variants of those nanocages with an adsorbed halogen atom, as high-performance anode materials in Li-ion, Na-ion, and K-ion batteries was investigated theoretically via density functional theory. The results obtained indicate that, among the nanocages with no adsorbed halogen atom, Al₂₂P₂₂ would be the best candidate for a novel anode material for use in metal-ion batteries. Calculations also suggest that K-ion batteries which utilize these nanocages as anode materials would give better performance and would yield higher cell voltages than the corresponding Li-ion and Na-ion batteries with nanocage-based anodes. Also, the results for the nanocages with an adsorbed halogen atom imply that employing them as anode materials would lead to higher cell voltages and better metal-ion battery performance than if the nanocages with no adsorbed halogen atom were to be used as anode materials instead. Results further implied that nanocages with an adsorbed F atom would give higher cell voltages and better battery performance than nanocages with an adsorbed Cl or Br atom. We were ultimately able to conclude that a K-ion battery that utilized Al₂₁P₂₂ with an adsorbed F atom as its anode material would afford the best metal-ion battery performance; we therefore propose this as a novel highly efficient metal-ion battery. Graphical abstract The results of a theoretical investigation indicated that Al₂₂P₂₂ is a better candidate for a high-performance anode material in metal-ion batteries than Ge₄₄ is. Calculations also showed that K-ion batteries with nanocage-based anodes would produce higher cell voltages and perform better than the equivalent Li-ion and Na-ion batteries with nanocage-based anodes, and that anodes based on nanocages with an adsorbed F atom would perform better than anodes based on nanocages with an adsorbed Cl or Br atom.

Na-ion batteries based on the inorganic BN nanocluster anodes: DFT studies

It has been recently indicated that the Li-ion batteries may be replaced by Na-ion batteries because of their low safety, high cost, and low-temperature performance, and lack of the Li mineral reserves. Here, using density functional theory calculations, we studied the potential application of B₁₂N₁₂ nanoclusters as anode in Na-ion batteries. Our calculations indicate that the adsorption energy of Na⁺ and Na are about -23.4 and -1.4kcal/mol, respectively, and the pristine BN cage to improve suffers from a low cell voltage (∼0.92V) as an anode in Na-ion batteries. We presented a strategy to increase the cell voltage and performance of Na-ion batteries. We showed that encapsulation of different halides (X=F^-, Cl^-, or Br^-) into BN cage significantly increases the cell voltage. By increasing the atomic number of X, the Gibbs free energy change of cell becomes more negative and the cell voltage is increased up to 3.93V. The results are discussed based on the structural, energetic, frontier molecular orbital, charge transfer and electronic properties and compared with the performance of other nanostructured anodes.