Mechanochemical synthesis of mechanical bonds in M12L8 poly-[n]-catenanes

Using mechanochemistry by grinding TPB and ZnBr₂, an amorphous poly-[n]-catenane of interlocked M12L8 nanocages is obtained in good yields (∼80%) and within 15 minutes. The mechanical bond among the icosahedral M12L8 cages in the amorphous phase has been demonstrated by single crystal XRD, powder XRD and FT-IR spectroscopy following an amorphous-to-crystalline transformation by guest uptake of the amorphous phase. High-resolution solid-state ¹³C NMR spectroscopy gives insights into the local structure of the amorphous catenane focusing on TPB aromatic-aromatic interactions.