Formation of a Strandlike Polycatenane of Icosahedral Cages for Reversible One-Dimensional Encapsulation of Guests

Self-assembly of ZnCl2 and the ligand 2,4,6-tris(4-pyridyl)pyridine (pytpy) in solution yields [(ZnCl2)12(pytpy)8]n·xCHCl3, a polycatenane consisting of a strand of mechanically interlocking icosahedral cages with an inner volume of more than 2700 Å3. This can be used to encapsulate guest molecules of appropriate size and polarity, forming a precisely defined three-dimensional array of solvent nanodroplets within the crystalline framework. The dynamic composition of these droplets was studied using quantitative solid-state NMR spectroscopy.