Synergistic regulation of metal-organic cage architectures via temperature- and solvent-driven atropisomerism.

Regulating multistimulus responses in artificial systems remains a challenge in smart material development. We present a versatile chemical switching system that precisely controls the self-assembly of metal-organic cages via temperature and solvent changes. The key component, cyclo2 (4-pyridine)6 (), was generated as three atropisomers (, , and ) with , , and symmetries. Thermally, metastable isomers ( and ) convert into the stable isomer (), which reacts with Pd to form specific molecular cages. Depending on the solvent, either rectangular ML cages ( and ) form in 1,4-dioxane or hexagonal ML cages () in 1,1',2,2'-tetrachloroethane. The solvent dictates the cage type and enables reversible transformation between cages and . Additionally, cage ', formed from metastable isomer , can switch to other cage types (i.e., or ) depending on temperature and solvent conditions. This multipathway system offers a precise strategy for controlling self-assembly in smart materials.