Tesseract meets aerogens: Dispersion-driven noble-gas binding in theoretical hypercubane complexes

Hypercubane, C₄₀H₂₄, is a theoretically designed hydrocarbon with a highly symmetric, tesseract-like architecture that provides an unusual framework for exploring weak host-guest interactions. Here, its association with one and six noble-gas atoms, Ng = He-Rn, was investigated using density functional theory, electron-density analyses, energy decomposition, and finite-temperature molecular dynamics. The dissociation energies of the mononuclear complexes increase systematically from He to Rn, consistent with the increasing polarizability of the noble-gas atoms. Although dissociation is thermodynamically favored at 298 K, particularly for the lighter guests, the Gibbs free energies approach the stability threshold for Xe and Rn and become progressively more positive upon cooling. QTAIM analysis reveals low electron densities, positive Laplacians and total energy densities at the respective bond critical points, while the nearly neutral NBO charges indicate negligible charge transfer. EDA identifies the dispersion term as the dominant attractive contribution, partially offset by increasing Pauli repulsion, and IGMH visualizes diffuse van der Waals regions between the noble-gas atoms and the hypercubane framework. GFN2-xTB molecular dynamics simulations of the six-guest assemblies reveal limited finite-temperature persistence, with guest retention increasing for the heavier noble gases and decreasing with temperature. Overall, hypercubane-Ng complexes represent weak, dispersion-driven host-guest assemblies whose stability is governed by noble-gas polarizability, confinement, and temperature.