Crystal and modelled structures of five N 1 ,N 3-di(5-X-pyridin-2-yl)isophthalamides (X = H, F to I) as (X-DIP) are reported. The roles that their molecular conformations and interactions play in solid-state aggregation are assessed. Cl-DIP (Z' = 3) exhibits both syn/anti and anti/anti molecular conformations in 2:1 ratio. The hydrogen bonding hierarchy and sheet formation in Br-DIP induces the formation of a bromine-rich environment manifesting as a 'wall of bromine atoms' at the sheet interfaces. The hydrate in I-DIP• 1 /2(H 2 O) forms a rare synthon.