Formation of a strandlike polycatenane of icosahedral cages for reversible one-dimensional encapsulation of guests.

Self-assembly of ZnCl(2) and the ligand 2,4,6-tris(4-pyridyl)pyridine (pytpy) in solution yields [(ZnCl(2))(12)(pytpy)(8)](n)·xCHCl(3), a polycatenane consisting of a strand of mechanically interlocking icosahedral cages with an inner volume of more than 2700 Å(3). 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.