Phototunable Chiral-Selective Nanoporous Material.

Herein, we present the development of tunable chiral nanoporous materials capable of enantioselectively adsorbing racemic mixtures. The materials are based on hydrogen-bonded supramolecular structures formed from a melamine derivative as the central core and three peripheral dendrons functionalized with coumarin and azobenzene moieties that are organized in hexagonal columnar phases. Upon irradiation with circularly polarized light (CPL), the azobenzene units induce controlled chirality in the material, which is stabilized by photodimerization of the coumarin moieties, obtaining mechanically stable films. The elimination of the melamine template results in nanoporous materials that retain their homeotropic hexagonal columnar alignment. These materials show selective adsorption of one particular enantiomer of racemic mixtures of (hexan-2-yl)-4-nitroaniline. Pore chirality can be reversed by changing the handedness of the CPL, allowing nanoporous materials to adsorb predominantly one or the other enantiomer. These findings offer a versatile strategy for enantioselective separation with potential applications in pharmaceuticals and materials science.