Synthesis of i-Corona[6]arenes for Selective Anion Binding: Interdependent and Synergistic Anion-π and Hydrogen-Bond Interactions

i-Corona[3]arene[3]tetrazines were synthesized from the nucleophilic aromatic substitution reaction of resorcinol and its derivatives with 3,6-dichlorotetrazine in a one-pot fashion under mild conditions. All of the resulting macrocycles adopted 1,3,5-alternate conformation irrespective of the nature of the substituents on both upper- and lower-rims. i-Corona[3]arene[3]tetrazine was found to self-regulate its macrocyclic conformation and cavity to recognize anions with binding constants spanning from 26 M(-1)to 2.2x10(3) M(-1)depending on the structure of the anions. The selective binding resulted from a significant interdependent and synergistic effect between multiple tetrazine pi/anion and C-aryl-H/anion hydrogen bond interactions. Taking advantage of synergistic effect revealed, a cyanobenzene-embedded i-corona[3]arene[3]tetrazine was designedly synthesized and highly selective and very strong affinity toward nitrate with a binding constant of 2.2x10(5) M(-1)was achieved.