Criegee intermediate inside fullerene cage: Evidence for size-dependent reactivity

In the theoretical calculations reported here, we show that the hydration of the Criegee intermediate within the sub-nanospace of fullerene cages occurs differently in different fullerenes, thereby providing evidence for the size-dependent reactivity inside these exotic carbon cages. Upon C₇₀ or C₈₄ encapsulation, the Criegee hydration occurs instantaneously without any activation barrier, whereas inside the C₁₂₀ cage, the hydration involves a small barrier of 4.4 kcal/mol. Our Born-Oppenheimer molecular dynamics simulations suggest that the Criegee intermediate and the product of its hydration, α-hydroxy methyl hydroperoxide, remain dynamically stable over 20 ps time scale at the 300 K, implying that fullerene cages provide a robust framework for reactivity.