Cavities are a ubiquitous feature of chemical structures encountered in various fields ranging from supramolecular chemistry to molecular biology. They are involved in the encapsulation, transport and transformation of guest molecules, thus necessitating a precise and accessible tool for estimating and visualizing their size and shape. MoloVol, a free user-parametrizable open-source software, developed for calculating a range of geometric features for both unit-cell and isolated structures, is presented here. MoloVol utilizes up to two spherical probes to define cavities, surfaces and volumes. The program was optimized by combining an octree data structure with voxel-partitioned space, allowing for even high-resolution protein structure calculations on reasonable timescales. MoloVol comes with a user-friendly graphic interface along with a command-line interface for high-throughput calculations. It was written in C++ and is available on Windows, macOS and Linux distributions.

Here we report a new supramolecular strategy for the selective separation of specific polycyclic aromatic hydrocarbons (PAHs) from mixtures. The use of a triethyleneglycol-functionalized formylpyridine subcomponent allowed the construction of a FeII4L4 tetrahedron 1, which was capable of transferring between water and nitromethane layers, driven by anion metathesis. Cage 1 selectively encapsulated coronene from among a mixture of eight different types of PAHs in nitromethane, bringing it into a new nitromethane phase by transiting through an intermediate water phase. The bound coronene was released from 1 upon addition of benzene, and both the cage and the purified coronene could be separated via further phase separation.

Covalent macrocycles and three-dimensional cages were prepared by the self-assembly of di- or tri-topic anilines and 2,6-diformylpyridine subcomponents around palladium(II) templates. The resulting 2,6-bis(imino)pyridyl-Pd^II motif contains a tridentate ligand leaving a free coordination site on the Pd^II centers, which points inward. The binding of ligands to the free coordination sites in these assemblies was found to alter the product stability, and multi-topic ligands could be used to control product size. Multi-topic ligands also bridged metallomacrocycles to form higher-order supramolecular assemblies, which were characterized via NMR spectroscopy, mass spectrometry and X-ray crystallography. An efficient method was developed to reduce the imine bonds to secondary amines, leading to fully organic covalent macrocycles and cages, which were inaccessible through other means.