Side-Chain and Ring-Size Effects on Permeability in Artificial Water Channels

Journal Article · 01 January 2025 · Journal of Physical Chemistry. B

DOI: https://doi.org/10.1021/acs.jpcb.4c05244 · OSTI ID:2506755

Duncan, Tyler J. ^[1]; Behera, Harekrushna  ^[2]; Meng, Michael F. ^[2]; Zhang, Zidan  ^[2]; Marioni, Nico  ^[2]; Tadesse, Meron ^[2]; Kumar, Manish  ^[2]; Ganesan, Venkat  ^[2]

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1. University of Texas at Austin, TX (United States); University of Texas at Austin
2. University of Texas at Austin, TX (United States)

Artificial water channels (AWCs) have emerged as a promising framework for stable water permeation, with water transport rates comparable to aquaporins (3.4–40.3 × 10⁸ H₂O/channel/s). In this study, we probe the influence of ring-size and side-chain length on the water permeability observed within a class of AWCs termed ligand-appended pillar[n]arenes (LAPs) that have an adjustable ring-size (m) and side-chain length (n). Through all-atom molecular dynamics simulations, we calculate the permeability of these channels using the collective diffusion model and find their permeabilities. We characterize the mechanistic influence of pillar[n]arene ring-size and side-chain length on the channel water permeability by analyzing the characteristics of the internal permeating water-wire and the surrounding channel structure. We observe that water permeability decreases as a function of increasing ring-size due to increases in hydrophilic contacts between the permeating water-wire and the oxygen groups on the channel wall. Further, we observe an increase in water permeability as a function of side-chain length due to increased partitioning of the channel terminal groups into the hydrophilic blocks of the surrounding bilayer. For the LAP6 channel, with increase in side-chain length, the distance between terminal groups increases and leads to an increase in pore size, thereby enhancing water permeability. In the case of LAP5, as side-chain length increases, the channel displays a compensatory effect between tilt and bend angle due to the flexible side-chains. Such flexibility leads to higher terminal group partitioning in the hydrophilic blocks of the bilayer and extends the permeating water-wire. Furthermore, this increase in water-wire length and hydrophilic block access overcomes the nonmonotonic pore size trend in pillar[5]arene channels.

• Research Organization: University of Texas at Austin, TX (United States)
• Sponsoring Organization: National Science Foundation (NSF); USDOE Office of Science (SC), Basic Energy Sciences (BES)
• Grant/Contract Number: SC0019272; SC0023265
• OSTI ID: 2506755
• Journal Information: Journal of Physical Chemistry. B, Journal Name: Journal of Physical Chemistry. B Journal Issue: 2 Vol. 129; ISSN 1520-6106
• Publisher: American Chemical SocietyCopyright Statement
• Country of Publication: United States
• Language: English