Fig. 1. (a) Schematic representation of the ability of AzaEx²Cage⁶⁺ to recognize a variety of guests, including pyrene, PCA, and BH4EN. In the cases of pyrene and PCA, 2 : 1 complexes are formed, even though the ability of the cage to host the former guest is much weaker. In the case of BH4EN, the complex BH4EN·AzaEx²Cage⁶⁺ forms in a peripheral and inclusion manner in CD₃CN and D₂O, respectively. ¹H NMR spectra of AzaEx²Cage·6PF₆ (500 MHz, 1.0 mM in CD₃CN, 298 K) (b) before and after adding (c) pyrene (8.4 equiv.), (d) PCA (10.8 equiv.), and (e) BH4EN (11.4 equiv.). The resonances of the protons in AzaEx²Cage⁶⁺ are labeled in the corresponding spectra. Addition of pyrene and PCA results in upfield shifts of the resonances of the phenylene residues (H_c and H_d) in AzaEx²Cage⁶⁺, while the presence of BH4EN leads to upfield shifting of the resonances for the protons on BIPY²⁺ (H_a and H_b).