While the C 18 -1 entered the loop to form the complex C 18 @OPP and remained stable there, the C 18 -2 still wanders freely. C 18 -2 did not collide with the empty loop of C 18 @OPP and was bound to it until the simulation time reached about 870 fs. After entering the empty cavity of C 18 @OPP, C 18 -2 leaned on the inner edge of the loop for a long while and then suddenly tilted at about 1448 fs to form a stable in-plane binding configuration. From the snapshots of some featured processes of the selfassembly of C 18 -2 into C 18 @OPP (Figure ), readers can clearly recognize all details. The above observations fully demonstrate that C 18 can enter OPP spontaneously and remain stable at ambient temperature. This also reminds us that OPP can be used as a functional material for enriching C 18 molecules. As can be seen from the interaction energy between two C 18 and OPP during the MD simulation of 2000 fs (Figure ), the intermolecular interaction increases sharply twice when the first C 18 enters one loop of the OPP and the second C 18 enters another one, respectively. Careful inspection shows that the overall interaction energy increases slightly as the C 18 -2 tilts and eventually forms a stable in-plane configuration. The changes in the interaction energy clearly show how the selfassembly process of 2C 18 @OPP is spontaneously driven by intermolecular interactions.