A layered grid divalent cobalt coordination polymer constructed from ferromagnetically coupled linear trimeric units

► Cobalt 5-tert-butylisophthalate coordination polymer has embedded linear trinuclear units. ► Metal carboxylate ribbons link into layers through bis(4-pyridylmethyl) piperazine ligands. ► Three-fold interpenetrated 6-connected supramolecular network. ► Ferromagnetic coupling within {Co3(m-O)4(m-OCO)2} trimeric units.