abstract
The motion of molecular fragments in close contact with atomically flat surfaces is still not fully understood. Does a more favorable interaction imply a larger barrier toward motion even if there are no obvious minima? Here, we use mechanically interlocked rotaxane-type derivatives (MINTs) of single-walled carbon nanotubes (SWNTs) 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 that for the rotation around the C-C bond in ethane.
keywords
MOLECULAR MOTORS; AMONTONS LAW; FRICTION; TRANSLOCATION; DYNAMICS; GRAPHENE; RELEASE; DFTB3
subject category
Chemistry; Science & Technology - Other Topics; Materials Science
authors
Villalva, J; Nieto-Ortega, B; Melle-Franco, M; Perez, EM
our authors
Manuel Melle-Franco
Principal Researcheracknowledgements
We acknowledge funding from the European Union (ERC-StG-307609 and ERC PoC 842606), MINECO (CTQ2014-60541P and CTQ2017-86060-P), the Comunidad de Madrid, and the European Structural Funds for their financial support through the FotoArt-CM project (S2018/NMT-4367) and MAD2DCM S2013/MIT-3007. IMDEA Nanociencia acknowledges support from the Severo Ochoa Programme for Centres of Excellence in R&D (MINECO, grant SEV-2016-0686). The computational work was supported by the Campus de Excelencia Internacional UAM + CSIC. MMF would like to acknowledge support from the Portuguese Foundation for Science and Technology (FCT), under the projects IF/00894/2015, and CICECO-Aveiro Institute of Materials, FCT Ref. UID/CTM/50011/2019, UIDB/50011/2020, and UIDP/50011/2020, financed by national funds through the FCT/MEC and when appropriate cofinanced by FEDER under the PT2020 Partnership Agreement. Additionally, we express our gratitude to the Supercomputing and Bioinnovation Center (SCBI) of the University of Malaga (Spain) for their support and resources.