We hypothesized that such sensitized disequilibration might be achieved using a PS that acts on the E isomer of azobenzene with high selectivity. Although the triplet excited state of azobenzene relaxes to the Z isomer only occasionally , a hypothetical E-selective PS would not excite Z once it is generated; therefore, we expect the repeated action of such a PS on E-azobenzene to eventually accumulate a substantial amount of the metastable Z state (Fig. ). Here, we build on our previous work, where we showed that i) the water-soluble coordination cage C (Fig. ) binds two molecules of various E-azoarenes (which are planar and readily stack on top of each other to form noncovalent homodimers), but only one molecule in the Z configuration (because of their non-planar geometry), ii) cage C can also encapsulate-and thus induce dimerization of-molecules structurally similar to Eazobenzene (i.e., planar aromatic molecules), including various dyes , and iii) mixing two different inclusion complexes (each binding two molecules of a given guest), induces a rapid guest exchange between the cages, affording heterodimeric complexes, whereby each cage encapsulates two different guest molecules . Taken together, these observations make us pose the following question: can cage C co-encapsulate E-azobenzene with a PS while preventing close encounters of the same PS with Z-azobenzene? The concept of DESC is illustrated in Fig. . The addition of an encapsulated PS (as PS2⊂C) to E-azobenzene induces the formation of a ternary complex (E⋅PS)⊂C (step i). Upon exposure to visible light, PS is promoted to a singlet excited state, which converts into a triplet state via intersystem crossing (ISC) (step ii). In step iii, PS transfers its triplet energy to the nearby E-azobenzene. The resulting triplet azobenzene can either decay to the initial E isomer (step iv') or transform into the Z state (step iv). The former case regenerates (E⋅PS)⊂C, which can be re-excited. In contrast, the latter case results in (Z⋅PS)⊂C, which is an unstable species since Z-azobenzene is too bulky to coexist inside the cage with the PS. Hence, it is expelled from the cage and effectively removed from the equilibrium. Thus, the azobenzene-free inclusion complex of the PS is regenerated (step v) and available for transforming additional molecules of E-into Z-azobenzene.