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)2·6H2O or Cd­(NO3)2·4H2O. 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.