Highly Selective Construction of Unique Cyclic [4]Catenanes Induced by Multiple Noncovalent Interactions

Abstract The synthesis of high‐ordered mechanically interlocked supramolecular structures is an extremely challenging topic. Only two linear [4]catenanes have been reported so far and there is no defined strategy to obtain cyclic [4]catenane. Herein, two unprecedented cyclic [4]catenanes, 1 and 2 , were prepared in high yields. The syntheses rely on the strategic selection of naphthalenediimide (NDI) based Cp*Rh/Ir building blocks E1 / E2 ( Cp*=pentamethyl‐cyclopentadienyl ) and nonlinear diimidazole ligand precursor L1 , exhibiting large conjugate plane, appropriate coordination angles, and freely rotating imidazole units, thereby enabling multiple π⋅⋅⋅π stacking interactions to maintain the supramolecular structures. The use of other Cp*Rh building blocks E3 , E4 or E5 featuring slightly shorter metal‐to‐metal distances than E1/E2 and different chemical properties led to the formation of a complex 3 and two metallamacrocycles 4 or 5 , respectively. The structures of these assemblies were confirmed by X‐ray crystallographic analysis, ESI‐TOF‐MS and NMR spectroscopy. Complex 1 , exhibiting a broad‐band absorption in the UV/Vis to NIR regions and a remarkable photothermal conversion was thereafter used to build the new 1 membrane. The solar power‐induced water steam generation performance of 1 membrane was investigated, reaching a value of 2.37 kg ⋅ m −2 ⋅ h −1 , making it suitable for collection of fresh water via desalination and wastewater.