Construction of methylene-bridged electron-deficient corona[n]arenes and selective fluoride recognition through anion-pi interactions

Despite significant development of the nascent anion-pi interactions in recent years, the noncovalent interactions between fluoride ion, a unique species that plays important roles in chemistry, biological and environmental sciences, and electron-neutral aromatic rings remain rare and even controversial. We disclose herein the construction of highly electron-deficient corona[n]arenes from the reaction of p-phenylenediacetonitrile and hydrazine, and show an unprecedented example of very selective fluoride recognition by a box-like corona[2]arene[2]tetrazine. We also report the formation of tetrazine radical anion from the interaction of tetrazine with hydroxide, with a warning on the influence of deprotonation of water by fluoride in the study of fluoride recognition by tetrazine-containing hosts.