Cobalt(II), zinc(II) and cadmium(II) salts react with the new spacer ligand 2,2′-bi-1,6-naphthyridine 1 to give 2D-planar (4,4) frameworks which interpenetrate such that each grid window of each sheet has two other sheets passing through it with all sheets being equivalent whereas copper(I) tetrafluoroborate and 1 form a 21-helicoidal chain with neigboring chains interlocking through an aromatic π–π interaction.
