Gating of a Water nanochannel Driven by dipolar molecules

X.W.Meng1, Y. Wang1, Y. J. Zhao2 and J. P. Huang1

1Department of Physics and State Key Laboratory of Surface Physics, Fudan University, Shanghai 200433, China;

2 Advanced Materials Laboratory, Fudan University, Shanghai 20038,China

It is known that the transportation of water molecules across water nanochannels in membranes plays an important role in biological activities . Water permeation through membranes can be regulated by pH, solute concentration and temperature.To realize water channel gating , we choose LiF dipolar molecules , we find that the electrostatic generated by LiF molecules play an critical role in realizing water nanochannel gating

Introduction

Conclusions

•The designed system shows an excelle- nt on-off gating behavior; it is in the on /off state when the distance between Li- F and the SWCNT is larger/smaller than a critical distance 0.944nm.

•The finite element method helps us re- veal that the electrostatic field generate- d by LiF dipolar molecules play an im- portan role in achieving the gating of the WCNT water channel.

Water numbers in the SWCNT Simulation Result

Molecular dynamics simulation

Our Simulation System

Figure 3. Average orientations (angle 1-5) of water molecules inside the SWCNT as a function of time for two positions of R : (a) R=0.533nm (b) R=1.856nm

Water orientation transitions

Figure 6. Schematic graphs showing four 2D virtual planes in the simulation system: (a) plane 1 and plane 2 (b) plane 3 and plane 4 . The finite element method is performed to show 2D electrostatic field strengthen distributionin (c,g) plane1,(d,h)plane2,( e,i)plane3 ,(f,j) plane 4 ,for (c-f) R =0.533nm,for (g-j) R=1.856nm

Reference

X.W.Meng, Y. Wang, Y. J. Zhao and J.P. Huang. J. Phys. Chem. B 2011,115,4768