The role of shape and interaction directionality in the crystalline phase behaviour of octahedral metal-organic cages.

Despite advances in crystal engineering, predicting the packing of metal-containing molecules remains a significant challenge due to their increased structural complexity and computational cost relative to purely organic compounds. Yet, predicting solid-state structures is critical for understanding structureproperty relationships, particularly in modular porous systems such as metal-organic cages (MOCs), where packing governs access to the internal pores and thereby impacts functionality. Here, we present a computationally inexpensive methodology that combines semi-empirical dimer calculations with coarse-grained modelling to predict the packing behaviour of MOCs. This approach enables a priori prediction of the solid state and allows insight into how molecular shape and intermolecular interactions influence the crystalline phase behaviour of MOCs. Our findings provide a foundation for the rational design of MOCs with tailored solid-state structures and properties.