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An azobenzene‐functionalized bis‐bis(urea) ligand (Lazo) and phosphate anion assemble to give the first photoactive "aniono" constructs, tetrahedron (A4L6) and helicate (A2L3), which readily undergo interconversion through cis‐trans isomerization of the azo group under irradiation/heating. Most strikingly, the tetrahedral cage can accommodate an [18]crown‐6 molecule, which can capture two tetramethylammonium (TMA+) ions with an unusually high affinity, even capable of replacing K+ in [K([18]crown‐6)]+ to form a {(TMA)2⊂ ([18]crown‐6)}⊂ cage "Russian doll" structure. Thus, the current work may provide a model for the light‐driven binding and exchange of the biologically important K+ and TMA+ ions. [ABSTRACT FROM AUTHOR]