Host-guest dynamics in porous trimesic acid supramolecular network on graphene. Outstanding stability of the coronene guest

Abstract

We performed reactive molecular dynamics (ReaxFF-MD) simulations to investigate host-guest interactions between the porous honeycomb supramolecular network formed by trimesic acid (TMA) and the following guests: coronene (COR), C60, C84, and C98 fullerenes, a 5-membered cyclodextrin macrocycle (CD5) and pentanoic acid (PA) molecules. Coronene imparts outstanding stability to the TMA network as compared to the other guests. Whereas the fullerenes destabilize the TMA network, CD5 and PA molecules induce a small stabilization. The mechanism of COR-enhanced stability involves synergistic effects between the COR-graphene and COR-TMA interactions. Strongly bound coronene molecules impose steric restraints on the twisting dynamics of carboxylic groups of TMA molecules. This impedes the breakage of hydrogen bonds between the cyclic dimers formed by opposing COOH groups of TMA molecules, which has a stabilizing effect on the network structure up to high temperatures. CD5 molecules have higher host-guest interactions than coronene, however, the TMA/CD5 network has lower thermal stability because CD5 molecules desorb from the pore due to its lower binding energy to graphene. Therefore, an adequate balance between host-guest and guest-surface interactions is required to increase the thermal stability of the host-guest superstructure.