As the third-generation rigid macrocycles evolved from progenitor >1, cyclic aromatic oligoamides >3, with a backbone of reduced constraint, exhibit extremely strong stacking with an astoundingly high affinity (estimated lower limit of K dimer > 1013 M–1 in CHCl3), which leads to dispersed tubular stacks that undergo further assembly in solution. Computational study reveals a very large binding energy (–49.77 kcal mol–1) and indicates highly cooperative local dipole interactions that account for the observed strength and directionality for the stacking of >3. In the solid-state, X-ray diffraction (XRD) confirms that the aggregation of >3 results in well-aligned tubular stacks. The persistent tubular assemblies of >3, with their non-deformable sub-nm pore, are expected to possess many interesting functions. One such function, transmembrane ion transport, is observed for >3.
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