Synthesis ofi‐Corona[6]arenes for Selective Anion Binding: Interdependent and Synergistic Anion–π and Hydrogen‐Bond Interactions

Abstract

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 2.2×103 M−1 depending on the structure of the anions. The selective binding resulted from a significant interdependent and synergistic effect between multiple tetrazine π/anion and Caryl–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 2.2×105 M−1 was achieved.

Dynamic Nucleophilic Aromatic Substitution of Tetrazines

“…[ 27 , 101 , 102 , 103 , 104 , 105 , 106 , 107 , 108 , 109 , 110 ] We reasoned that phloroglucinol and Cl‐Tz‐Cl should lead to a truncated [4+6] tetrahedral cage, where each of the four faces is actually an i‐corona[6]arene (Figure 7 a ). [111] As expected, cage 17 was successfully synthesized in one step in 43 % yield.…”

“…In spite of the reported good anion binding abilities of i‐corona[6]arenes, [111] cage 17 shows no remarkable association constant with any anion tested. This fact is probably due to rigidity of the cage compared with i‐corona[6]arenes: In the macrocycle the aromatic proton can be accommodated towards the cavity and plays a key role on the binding event, which is obviously not possible with the cage.…”

Design and property investigation on a five-interaction-based fluorescent anion receptor clip

“…Up to date, anion receptors combining on a tetrazine core and a hydrogen bond donor are scarcely described. 35,36 Only one aliphatic mono-substituted tetrazine receptor has been recently reported by us. 27 The impact of a double substitution on receptor properties was therefore evaluated based on descriptors such as (a) geometrical parameters (b) NMR shis (c) photophysical properties and (d) association constants determined by NMR experiments.…”

Synthesis ofi‐Corona[6]arenes for Selective Anion Binding: Interdependent and Synergistic Anion–π and Hydrogen‐Bond Interactions

“…Benzyl groups of 3fand all solvent moleculesa re hidden for clarity. [46] Angewandte Chemie Forschungsartikel constructed by six aromatic rings.T he centroids of tetrazine rings in 3 and of pyridazines in 9 formed roughly equilateral triangles with the average edge length in an arrow range of 7.05 to 7.43 .Furthermore,judging from the bond lengths (Supporting Information, Figures S1-S5 and S9), all bridging oxygen atoms tend to form stronger conjugation with their adjacent heterocyclic rings rather than benzene ring.…”

“…Tetrabutylammonium cation and solvent molecules are hidden for clarity.D istances are given in angstroms. [46]…”