An unusual 3D pillared-layer cobalt(II) coordination polymer containing helical motifs and novel topology constructed from mixed ligands

An unusual 3D pillared-layer CoII coordination polymer, namely [Co(pda)(bpe)]n (1) [H2pda = 1,3-phenylenediacetic acid, bpe = 1,2-bi(4-pyridyl)ethylene], has been successfully prepared under hydrothermal condition. X-ray crystal analysis indicates that the structure of 1 is constructed from 2D undulated [Co(pda)]n layers, which consists of alternating left- and right-handed helical motifs, and then further pillared by bpe ligands into a 3D structural framework. Topologically, complex 1 shows an intriguing binodal (3,5)-connected fsc network with the Schläfli symbol of (4.62)(4.66.83) which is completely different from the reported (4,6)-connected fsc nets; and if the dimeric [Co2] units (SBUs) are considered as the single 6-connected nodes, 1 displays a familiar uninodal pcu net with the Schläfli symbol of (412.63). In addition, magnetic measurement revealed that 1 shows the antiferromagnetic coupling between CoII ions.