Fig. 2. ¹H NMR spectra of the cage and some host–guest complexes. (a) Ligand L², (b) cage [Pd₂L²₄], (c) [G¹@Pd₂L²₄], and (d) [G²@Pd₂L²₄] (400 MHz, 298 K, CD₃CN). The signals of the encapsulated guest molecules are highlighted in red. H_i, H_j and H_k represent outside (exo) and H_i′, H_j′ and H_k′ inside (endo) pointing hydrogen atoms of the adamantyl substituent with respect to the acridone backbone (compare Fig. 4a). Empty circle: [K(18-crown-6)]⁺.