Halogen-Bonded Supramolecular Assemblies Based on Phenylethynyl Pyridine Derivatives: Driving Crystal Packing through Systematic Chemical Modifications

A series of phenylethynyl pyridine derivatives 1 − 4 possessing both perfluorocarbon (PFC) and hydrocarbon (HC) moieties have been synthesized and used for the formation of halogen bonding (XB)-based networks. X-ray crystal structure analyses indicate the dominance of XB synthons, which represent the one-dimensional (1D) structure directing interaction, leading to the formation of supramolecular chains. The influence of structural/electronic factors (e.g., electron donor/acceptor strength, sterically demanding substituents) on XB formation of compounds 1 − 4 have been compared with structurally related stilbazole systems ( I, II ). The XB-bonded networks are formed in collaboration with other noncovalent interactions such as π−π stacking, hydrogen bonding, C−H···F and F···F. Molecular electrostatic potentials and atomic polar tensor (APT) charges of the donor and acceptor sites have been determined by density functional theory (DFT) calculations.