Halogen-bonded supramolecular assemblies based on phenylethynyl pyridine derivatives: driving crystal packing through systematic chemical modifications

Abstract

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 (ID) 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. © 2008 American Chemical Society.