Roles of Hydrogen, Halogen Bonding and Aromatic Stacking in a Series of Isophthalamides

The synthesis and spectroscopic characterisation of six bis(5-X-pyridine-2-yl)isophthalamides (X = H, F, Br, Cl, I, NO2) are reported, together with five crystal structure analyses (for X F to I). isophthalamides span a range conformations as syn/anti (H-DIP; I-DIP), anti/anti- (F-DIP; Br-DIP) both present in ratio 2:1 Cl-DIP. essentially isostructural F-DIP Br-DIP molecules (using strong amide…amide interactions) aggregate into 2D molecular sheets that align either F/H or Br atoms at the sheet surfaces (interfaces), respectively. Sheets linked by weak C-H⋯F contacts Br⋯Br halogen bonding interactions ‘wall bromines’ atom rich interfaces Br-DIP. Cl-DIP is an unusual incorporating anti/anti asymmetric unit (Z’ 3). I-DIP•½(H2O) hemihydrate has water molecule residing on twofold axis between two I-DIPs hydrogen N⋯I (Nc 0.88) bonding. hydrate central synthon involved interactions/contacts. Contact enrichment analysis Hirshfeld surface demonstrates F-DIP, have especially over-represented halogen···halogen interactions. With having elongated skeleton, formation layers planes perpendicular long cell occurs packings. All DIPs were analysed ab initio calculations conformational analysis; comparisons made their minimized structures structures. In addition, physicochemical properties compared assessed.