Mukherjee and co-workers reported that a structurally similar ligand, in which the central benzene core is decorated with three imidazolyl groups (TImB in Figure ) co-assembles with cis-blocked Pd 2+ into a D2hsymmetric cage with a tube-like shape (T in Figure and Figure ). Owing to its cavity shape and high flexibility, T was reported to encapsulate a wide range of elongated guest molecules, including polycyclic aromatic hydrocarbons, azobenzenes, BODIPYs, and other dye molecules. In TImB, θ = 144ºsignificantly closer to θ3-TPyT than θ4-TPyT, which explains the formation of T. At the same time, we note that θTImB is smaller than θ4-TPyT, but larger than θ3-TPyT, which suggests that the putative Td-symmetric Pd6(TImB)4 cage (C in Figure ) might be energetically accessible. Here, we identify minor contamination notoriously accompanying cage T as its isomeric form C. A series of experimental observations led to a rational design of guests stabilizing increasingly higher fractions of C, all the way to 100%. Furthermore, we demonstrate reversible cycling between the two isomeric states of the cage.