Anion Binding Induces Helicity in a Hydrogen-Bonding Receptor: Crystal Structure of a 2,6-Bis(anilinoethynyl)pyridinium Chloride

The synthesis and solid-state of 2,6-bis(anilinoethynyl)pyridine amide 1 is presented. Neutral receptor 1 forms a polymeric chain through hydrogen bonds and π stacking in the solid state. Upon protonation, receptor 1 undergoes significant conformational rearrangement to hydrogen bond to Cl−, forming a helix (H1+Cl−). This rare example of anion-induced helicity is detailed in the solid state and initial solution studies are presented.