A cocrystallisation-based strategy to construct isostructural solids

Cocrystallisation provides a means for dissimilar functional groups to become structurally equivalent, i.e. adopt similar structural roles in the solid. We describe a strategy to systematically construct sets of isostructural solids by using this cocrystallisation-induced structural equivalence. The strategy utilises cocrystallisation to combine different types of structurally equivalent functionalities in the solid state and enlarge an already existing set of isostructural cocrystals from two to four members. Halogen-bonded cocrystals of acridine (acr) and phenazine (phen) with iodopentafluorobenzene (ipb) form a pair of isostructural solids related by cocrystallisation-induced structural equivalence of aromatic CH and N groups. Structural equivalence of halogen-bonded Br and I groups allowed the replacement of ipb in these cocrystals with its bromo analogue, bromopentafluorobenzene (bpb), without disturbing the cocrystal architecture. Consequently, combining structurally equivalent groups allowed the construction of a set of four solids based on the same supramolecular blueprint.