Selective filling of n-hexane in a tight nanopore

Journal Article · 12 January 2021 · Nature Communications

DOI: https://doi.org/10.1038/s41467-020-20587-1 · OSTI ID:1756902

Qu, Haoran ; Rayabharam, Archith ; Wu, Xiaojian ; Wang, Peng ; Li, Yunfeng; Fagan, Jeffrey ; Aluru, Narayana R. ; Wang, YuHuang

Abstract Molecular sieving may occur when two molecules compete for a nanopore. In nearly all known examples, the nanopore is larger than the molecule that selectively enters the pore. Here, we experimentally demonstrate the ability of single-wall carbon nanotubes with a van der Waals pore size of 0.42 nm to separate n-hexane from cyclohexane—despite the fact that both molecules have kinetic diameters larger than the rigid nanopore. This unexpected finding challenges our current understanding of nanopore selectivity and how molecules may enter a tight channel. Ab initio molecular dynamics simulations reveal that n-hexane molecules stretch by nearly 11.2% inside the nanotube pore. Although at a relatively low probability (28.5% overall), the stretched state of n-hexane does exist in the bulk solution, allowing the molecule to enter the tight pore even at room temperature. These insights open up opportunities to engineer nanopore selectivity based on the molecular degrees of freedom.

• Sponsoring Organization: National Institutes of Standards and Technology (NIST); National Science Foundation (NSF); USDOE; USDOE Office of Science (SC), Basic Energy Sciences (BES)
• Grant/Contract Number: SC0019112
• OSTI ID: 1756902
• Journal Information: Nature Communications, Journal Name: Nature Communications Journal Issue: 1 Vol. 12; ISSN 2041-1723
• Publisher: Nature Publishing GroupCopyright Statement
• Country of Publication: United Kingdom
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
42 ENGINEERING
chemical physics
energy
imaging techniques