Permeable, Microporous Polymeric Membrane Materials Constructed from Discrete Molecular Squares

Microporous polyester membranes (see Figure) have been formed via interfacial polymerization. The reactants were porphyrin‐based square assemblies functionalized with phenol groups and bis(acid chloride) linkers. The membranes are free‐standing and display size‐selective porosity, allowing transport of molecules smaller than the intra‐square cavity and displaying blocking behavior with respect to larger molecules.