Directing the Mobility of Guest Molecules in Nanoporous Materials by Linearly Polarized Light.

For the advancements of photoresponsive materials with tunable properties, the usage of multidimensional signals is desired. Using the polarization of the light in addition to the wavelength represents a further parameter to control the materials properties. Here, the first-time dynamic and reversible manipulation of the guest-host properties of a nanoporous material by linearly polarized light (LPL) is reported. The material is based on a metal-organic framework (MOF) with photoresponsive azobenzene side groups covalently connected to the MOF structure. The azobenzene moieties are reversibly reoriented by LPL, making the MOF structure and, thus, the pores anisotropic. As a result, the mobility of the guest molecules in the pores of the initially isotropic material becomes anisotropic, which can be dynamically controlled by the light polarization. The experiments by impedance spectroscopy are supported by molecular dynamics (MD) simulations. The study shows that the light polarization can be a further parameter to modify the material properties, allowing a more complex and more refined level of control for smart materials.