Open Frameworks Formed from Iodoalkyne∙∙∙Halide Halogen Bonds

Despite the apparently attractive characteristics of halogen bonds for preparing open/porous framework structures, very few such materials containing substantial void space have been reported. Iodoalkynes are readily prepared halogen bond donors with rigid rod-like structures and form halogen bonded assemblies with halide anions, although these typically have densely-packed structures. Here we show that rigid tetratopic and hexatopic halogen bond donor molecules containing unactivated iodoalkyne groups give a family of highly open 2D and 3D structures, where up to 47% of the unit cell volume is made up of solvent-filled voids. Interestingly, several different framework topologies are observed, all with high void volumes, even when very similar starting materials are used. While in the current work, the frameworks lose crystallinity upon removal from solvent, we believe this is an important step towards highly porous halogen bonded materials.