Three-dimensional van der Waals open frameworks.

Open-framework materials are constructed by connecting molecular components via strong bonds. It is generally believed that non-covalent interactions are too weak to hold the building blocks and generate stable open voids. Here we show that van der Waals interactions enable the construction of robust three-dimensional frameworks, referred to as van der Waals open frameworks (WaaFs). The key to successful synthesis of WaaFs is the use of octahedral metal-organic polyhedra with size larger than 2 nm as building blocks and their packing into a sparse diamond network with large extrinsic porosity. The well-defined faces composed of multiple planar moieties increase the intermolecular contact area to achieve an interaction energy above 400 kJ mol. We show that the WaaFs exhibit high thermal stability and high specific surface area as well as framework assembly with a reversible nature.