Doubly and triply deprotonated 2-bromo-C-alkylresorcinarene anions form host−guest complexes with both tetramethylammonium cations and bis-protonated dimethyl piperazine cations. The trianion forms a fully closed dimeric capsule with one endo-and two exo-cavity bis-protonated dimethyl piperazine cations. Interestingly, the dianion crystallized from a mixture of the 2-bromo-C-methylresorcinarene, dimethylethylenediamine, and tetramethylammonium chloride forms a nanotube consisting of only the 2-bromo-C-methylresorcinarene anion and the tetramethylammonioum cation. The nanotube has an exofunctionalized anionic hydrophilic outer surface that interacts with cationic guests and a hydrophobic interior channel. Solution studies support the deprotonation and the formation of these host−guest complexes. Quantification of binding in chloroform shows a very strong binding constant between the 2-bromo-Cpentylresorcinarene and tetramethylammonium chloride (K 1 = 3.63 × 10 5 M −1 , K 2 = 2.32 × 10 4 M −1 ), far higher than that observed for the unfunctionalized C-pentylresorcinarene (K 1 = 5.10 × 10 4 M −1 , K 2 = 1.30 × 10 3 M −1 ). We attribute this to the stronger ionpair in the former as the halogen increases the acidity of the phenolic hydroxyl groups.

Weak intermolecular forces are typically very difficult to observe in highly competitive polar protic solvents as they are overwhelmed by the quantity of competing solvent. This is even more challenging for three‐component ternary assemblies of pure organic compounds. In this work, we overcome these complications by leveraging the binding of fused aromatic N‐heterocycles in an open resorcinarene cavity to template the formation of a three‐component halogen‐bonded ternary assembly in a protic polar solvent system.