The Dancer in the Dark: Dynamical Motion of Zirconium Carbide Clusters inside Fullerenes

This study investigates the dynamic behavior and molecular machinery of zirconium carbide endohedral metallofullerenes (EMFs), given by Zr 2 C 2 @ D 3h -C 78, Zr 2 C 2 @ I h -C 80, and Zr 3 C 2 @ I h -C 80 . Molecular dynamics (MD) simulations demonstrate a progression from one-dimensional pirouette-like motion to two-dimensional rotation to a complex three-dimensional gyroscopic-like motion, governed by cavity size and cluster coordination. Energy decomposition analysis (EDA) coupled to molecular dynamics (MD + EDA) confirms stable interaction energies supporting tunable molecular motions within confined nanospaces. Magnetic response analyses indicate spherical aromaticity, supporting the stability of the overall complex with intermediate Hirsch electron counts. These findings elucidate how endohedral Zr fullerenes enable MD, offering insights for designing artificial molecular machines with controllable motions.