Fig. 4: MD simulation of ion transport across MLM-EDTA.

a Snapshots of MD simulation for K⁺ and Mg²⁺ passing the MLM and MLM-EDTA systems at 20 ns. K⁺, Mg²⁺, and Cl^– ions are in green, purple and silver, respectively. b Average entry time and passing time of K⁺ and Mg²⁺ passing the MLM and MLM-EDTA systems. c Radial distribution function (RDF) of oxygen in water molecules around K⁺ and Mg²⁺ locating at the solution and MLM-EDTA channel entrance. The valid range of the data was taken from 0 to the hydration radius of the ions, K⁺ and Mg²⁺ are 3.31 Å and 4.28 Å (Supplementary Table 1), respectively. d Average entry time and passing time of K⁺ and Mg²⁺ passing MLM-EDTA systems with different number of negatively charged oxygen atoms. e RDF of oxygen in water molecules around K⁺ and Mg²⁺ locating at the solution and inside of MLM-EDTA channel, the channel with different charge densities. f Schematic illustration of the possible mechanism for the role of charge density on cations transport and separation in sub-nanochannels.