The synthesis and characterization of hexametallic host molecules is described. The new molecules utilize 2,2'-bipyrimidine to bridge rhenium(I) tricarbonyls at three points along the short edge of the cavity, and triply functional pyridine-based ligands (2,4,6-tripyridyl-1,3,5-triazine or 1,3,5-tris (4-ethynylpyridyl) benzene) as a top and bottom. Modeling has been done to determine the volumes of the cavities and the sizes of the entry ports for the host molecules.