| Popis: |
The dynamic adaptability of tetragonal prismatic nanocapsule18+in the selective separation of fullerenes and endohedral metallofullerenes (EMFs) remains unexplored. Therefore, the essential molecular details of the fullerene recognition and binding process into the coordination capsule and the origins of fullerene selectivity remain elusive. In this work, the key steps of fullerene recognition and binding processes have been deciphered by designing a protocol which combines1H-1H exchange spectroscopy (2D-EXSY) NMR experiments, long time-scale Molecular Dynamics (MD) and accelerated Molecular Dynamics (aMD) simulations, which are combined to completely reconstruct the spontaneous binding and unbinding pathways from nanosecond to second time-range. On one hand, binding (k’on) and unbinding (koff) rate constants were extracted from1H-1H exchange spectroscopy (EXSY) NMR experiments for both C60and C70. On the other hand, MD and aMD allowed monitoring the molecular basis of the encapsulation and guest competition processes at a very early stage under non-equilibrium conditions, displaying dynamical adaptability features similar to those observed in the process of biomolecular recognition in proteins. In addition, the encapsulation of azafullerene (C59N)2within a supramolecular coordination capsule has been studied for the first time, showcasing the pros and cons of the dumbbell-shaped in the dynamics of the encapsulation process and in the stability of the final bound adduct. The powerful combination of NMR, MD, and aMD methodologies allows to obtain a precise picture of the subtle events directing the encapsulation, and is thus a predictive tool for understanding host-guest encapsulation and interactions in numerous supramolecular systems. |
