Binding affinity and permeation of X12Y12 nanoclusters for helium and neon

Abstract

Helium and neon are two most inert noble gases, and they resist to binding with any surface. Continuous strides are being made to explore materials capable of binding with helium and neon. In this report, inorganic fullerenes are studied for their ability to adsorb and encapsulate helium and neon atoms. Both endohedral and exohedral complexes of X12Y12 with helium and neon are considered. Moreover, interconversion of exohedral and endohedral complexes is explored through an unprecedented approach where noble gases translate into the nano-cage through boundary crossing. The translation of He and Ne through the surface of X12Y12 (X=B, Al and Y=N, P) nano-cages (permeability of the nano-cage) is studied theoretically at B971 method of density functional theory. The kinetic barrier for encapsulation of helium and neon is obtained through scanning potential energy surface for motion of He/Ne through hexagons of the nano-cage. The translation of He and Ne is not feasible process at room temperature however, permeation selectivity can be achieved with controlled temperature. The effect of temperature n the boundary crossing barrier is also explored. The estimate of stabilities of exohedral and endohedral complexes of He and Ne with X12Y12 nano-cages is obtained through binding energy analysis. The exohedral binding of He/Ne with X12Y12 nano-cages is a favorable process whereas the encapsulation is thermodynamically unfavorable except for Ne in AlP nano-cage. The highest interaction energy is observed for exohedral doping of Ne with AlN nano-cage (−4.86kcalmol−1) which is comparable to Ne binding with highly electrophilic Be(CN)2. Adsorption/encapsulation energies of noble gases on/in nano-cages show strong correlation with the size of the nano-cage. The interaction energies at B97-1 method are also compared with those from M05-2X, B3LYP-D2 and PBE-D2 methods. SAPT analysis is also performed for evaluating the components of interaction energies. Electronic structures of nano-cages including energies of HOMO, LUMO, HOMO-LUMO gap, and excitation energies are analyzed. Electronic properties of endohedral X12Y12 complexes are remarkably different than those of exohedral complexes. The H-L gaps for exohedral complexes are almost comparable to bare X12Y12 nano-cages; however, the endohedral complexation causes significant increase in the H-L gap.