Design of a hydroxy channel based on the selectivity of water permeation via ions exclusion

Abstract

The Artificial water channels (AWCs) encapsulate water wires or clusters, analogous to natural porins, and offer iterative and continuous hydrogen bonding that plays an essential role in their stabilization. During the last few years, significant progress has been made in AWCs characterization and synthesis, and bridging these advancements to practical development remains a unique challenge. In this study, the possibility of high water selectivity and permeability, as well as the stability of the AWCs channel, is examined via classical molecular dynamic (MD) simulations and well-tempered metadynamics (Wt-metaD) simulations. The results of MD simulations demonstrated that AWCs could provide paths for rapid and selective water permeation via the formation of water-wire networks. Moreover, our findings revealed that the AWC is stable during the simulation time and non-bonded interactions, especially hydrogen bonding, have an essential role in forming a stable OH channel for transporting water molecules. However, the obtained water fluxes (L m−2 h−1) using nanofiltration AWC give us a high flux value, 19.08 (L m−2 h−1), 17.96, and 20.2 (L m−2 h−1), for AWC/ NO3−, AWC/Mg2+, and AWC/Ca2+, respectively. Well-tempered metadynamics simulations of water transport in the OH channel also report similar activation energy values and provide molecular-scale details of the mechanism for water entry into these channels. The free energy values for the AWC/water complexes at their global minima are about ~−241.912, ~−223.479, and ~−255.98 kJ mol−1 in systems AWC/NO3−, AWC/Mg2+, and AWC/Ca2+, respectively.