A packing model for interpenetrated diamondoid structures - An interpretation based on the constructive interference of supramolecular networks

The ability to predict and subsequently control solid-state structure has been identified as a major challenge in the field of crystal engineering. Here we suggest the concept of constitutive models as a tool for understanding crystal packings and for designing new solid-state structures. Such models are intended to relate molecular interactions and their geometrical constraints with solid-state organization. These models will most likely be of greatest use for crystals consisting of supramolecular networks, that is, infinite assemblies of small molecules associating through strong, directional, and selective noncovalent interactions. The concept of the constitutive packing model is illustrated for interpenetrated diamondoid coordination networks based on crystalline adducts of 4,4'-biphenyldicarbonitrile with silver(I) salts. Observed structural deformations induced by counterions of varying size may be understood in terms of the interference of two supramolecular networks within this system: the diamondoid metal-ligand coordination network and face-to-face aromatic stacks of the organic ligand. The constitutive model developed here has been applied to other diamondoid coordination networks in the literature and is found to be general.