Formation of a Large Confined Spherical Space with a Small Aperture Using Flexible Hexasubstituted Sumanene

Two sumanene-based porous coordination networks were successfully prepared by the complexation of hexapyridylsumanene with Zn(NO3)(2)center dot 6H(2)O or Cd(NO3)(2)center dot 4H(2)O. X-ray single crystal analysis unambiguously revealed that the curved structure of the central sumanene skeleton of the ligand resulted in the formation of a large confined space with a small aperture size. In the Zn2+ network, the beltlike trimer units were connected to each other to form a 1D channel separated by the counteranion to afford isolated spaces. The Cd2+ network formed spherical tetramer units, which also eventually afforded a 1D channel with open windows smaller than the kinetic diameter of helium. The investigation of the structural parameters of the ligand in both networks revealed the unique feature of hexapyridylsumanene, which flexibly changed its bond length and angles depending on the structural requirements for the network formations.