Quasi-Barrierless Submolecular Motion in Mechanically Interlocked Carbon Nanotubes

24 April 2020, Version 2
This content is a preprint and has not undergone peer review at the time of posting.


The motion of molecular fragments in close contact with atomically flat surfaces is still not fully understood. Does a more favourable interaction imply a larger barrier towards motion even if there are no obvious minima? Here, we use mechanically interlocked rotaxane-type derivatives of SWNTs (MINTs) featuring four different types of macrocycles with significantly different affinities for the SWNT thread as models to study this problem. Using molecular dynamics, we find that there is no direct correlation between the interaction energy of the macrocycle with the SWNT and its ability to move along or around it. Density functional tight-binding calculations reveal small (<2.5 Kcal·mol-1) activation barriers, the height of which correlates with the commensurability of the aromatic moieties in the macrocycle with the SWNT. Our results show that macrocycles in MINTs rotate and translate freely around and along SWNTs at room temperature, with an energetic cost lower than the rotation around the C−C bond in ethane.


Carbon Nanotubes
submolecular motion
Shuttling Motion
pirouetting motion
atomic-scale friction

Supplementary materials

JV Barrierless motion in MINTs ChemRxiv SI


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