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.

Given the nondestructive nature and high spatiotemporal resolution of the light source, studies of photoresponsive systems have gained great attention and made considerable progresses in the past decades. By incoporationg photoswitch molecules with noncovalent interaction, photoresoive, supramolecular systems can be designed for tailored properties, e.g., guest delivery, catalysis, sensing, and information processing. Here, we introduced a new photoresponsive ligand (L) comprised of azobenzene spacer and two tris(urea) binding moiety. The latter component displayed characteristic coordination property with anions. Upon light irradiation, we observed reversible photoswitching of free ligand. The Z/E thermal relaxation half-life of free ligand L was determined to be 3.4 h at room temperature. By coordinating to phosphate anion, double helicate structure was believed to form and can be subsequently regulated by light and heat.

An azobenzene-functionalized bis-bis(urea) ligand (L azo ) and phosphate anion assemble to give the first photoactive "aniono" constructs, tetrahedron (A 4 L 6 ) and helicate (A 2 L 3 ), 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.