Straightening out halogen bonds

The fine control of molecular arrangements using intermolecular interactions is essential for the reliable formation of complex materials. The predictable directionality of supramolecular forces is a key aspect that allows bottom-up design of such architectures. Here we describe a way to quantify the linearity of intermolecular halogen bonds and show that pyridyl halogen bond acceptors are more reliable than equivalent nitrile systems in forming predictable assemblies. A new parameter is presented to more accurately describe the linearity of halogen bonds.