  We combine quantum-chemical calculations and molecular dynamics simulations
to consider aqueous ion flow across non-axisymmetric nanopores in monolayer
graphene and MoS$_2$. When the pore-containing membrane is subject to uniaxial
tensile strains applied in various directions, the corresponding permeability
exhibits considerable directional dependence. This anisotropy is shown to arise
from directed perturbations of the local electrostatics by the corresponding
pore deformation, as enabled by the pore edge geometries and atomic
compositions. By considering nanopores with ionic permeability that depends on
the strain direction, we present model systems that may yield a detailed
understanding of the structure-function relationship in solid-state and
biological ion channels. Specifically, the observed anisotropic effects
potentially enable the use of permeation measurements across strained membranes
to obtain directional profiles of ion-pore energetics as contributed by groups
of atoms or even individual atoms at the pore edge. The resulting insight may
facilitate the development of subnanoscale pores with novel functionalities
arising from locally asymmetric pore edge features.
