Self-assembly of a tetradentate ligand, N,N'-bi(salicylidene)-2,6-pyridinediamine (H2L), with Cu(II) or Co(II), affords a dinuclear [Cu2L2] complex (1) or a trinuclear [Co3L3] complex (2), which were characterized by the single crystal X-ray diffraction study. The coordination geometry of the Cu-II centers in 1 is between square planar and tetrahedral, with the ligand adopting a cis-cis conformation to give a centrally symmetric structure, which can be regarded as a mesocate. However, the coordination geometry of Co-II centers in 2 is distortedly tetrahedral, and the ligand adopts a cis-trans conformation. The whole complex of 2 is of a pseudo-C-3 symmatrical, torus-like structure, which can be regarded as a circular helicate. Both the mesocate and the helicate exhibit expanded supramolecular structures due to elaborate intercomplex pi-stacking interactions. These two complexes were also characterized by element analysis, IR spectra, and TGA. To verify the stability of 2, ESI-MS was carried out on both the crystal and the powdered samples. Variable temperature magnetic susceptibility measurements reveal that both 1 and 2 display antiferromagnetic properties. DFT calculations were carried out on I to verify the antiferromagnetic coupling between intracluster metal centers.